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Suh E, Stopard IJ, Lambert B, Waite JL, Dennington NL, Churcher TS, Thomas MB. Estimating the effects of temperature on transmission of the human malaria parasite, Plasmodium falciparum. Nat Commun 2024; 15:3230. [PMID: 38649361 PMCID: PMC11035611 DOI: 10.1038/s41467-024-47265-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024] Open
Abstract
Despite concern that climate change could increase the human risk to malaria in certain areas, the temperature dependency of malaria transmission is poorly characterized. Here, we use a mechanistic model fitted to experimental data to describe how Plasmodium falciparum infection of the African malaria vector, Anopheles gambiae, is modulated by temperature, including its influences on parasite establishment, conversion efficiency through parasite developmental stages, parasite development rate, and overall vector competence. We use these data, together with estimates of the survival of infected blood-fed mosquitoes, to explore the theoretical influence of temperature on transmission in four locations in Kenya, considering recent conditions and future climate change. Results provide insights into factors limiting transmission in cooler environments and indicate that increases in malaria transmission due to climate warming in areas like the Kenyan Highlands, might be less than previously predicted.
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Affiliation(s)
- Eunho Suh
- Center for Infectious Disease Dynamics, Department of Entomology, The Pennsylvania State University, University Park, PA, USA.
| | - Isaac J Stopard
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Ben Lambert
- Department of Statistics, University of Oxford, Oxford, UK
| | - Jessica L Waite
- Center for Infectious Disease Dynamics, Department of Entomology, The Pennsylvania State University, University Park, PA, USA
- Research Development, University of Vermont, Burlington, VT, USA
| | - Nina L Dennington
- Center for Infectious Disease Dynamics, Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, The Pennsylvania State University, University Park, PA, USA
- Department of Biology, University of York, York, UK
- Invasion Science Research Institute and Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
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Andolina C, Graumans W, Guelbeogo M, van Gemert GJ, Ramijth J, Harouna S, Soumanaba Z, Stoter R, Vegte-Bolmer M, Pangos M, Sinnis P, Collins K, Staedke SG, Tiono AB, Drakeley C, Lanke K, Bousema T. Quantification of sporozoite expelling by Anopheles mosquitoes infected with laboratory and naturally circulating P. falciparum gametocytes. eLife 2024; 12:RP90989. [PMID: 38517746 PMCID: PMC10959522 DOI: 10.7554/elife.90989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2024] Open
Abstract
It is currently unknown whether all Plasmodium falciparum-infected mosquitoes are equally infectious. We assessed sporogonic development using cultured gametocytes in the Netherlands and naturally circulating strains in Burkina Faso. We quantified the number of sporozoites expelled into artificial skin in relation to intact oocysts, ruptured oocysts, and residual salivary gland sporozoites. In laboratory conditions, higher total sporozoite burden was associated with shorter duration of sporogony (p<0.001). Overall, 53% (116/216) of infected Anopheles stephensi mosquitoes expelled sporozoites into artificial skin with a median of 136 expelled sporozoites (interquartile range [IQR], 34-501). There was a strong positive correlation between ruptured oocyst number and salivary gland sporozoite load (ρ = 0.8; p<0.0001) and a weaker positive correlation between salivary gland sporozoite load and number of sporozoites expelled (ρ = 0.35; p=0.0002). In Burkina Faso, Anopheles coluzzii mosquitoes were infected by natural gametocyte carriers. Among salivary gland sporozoite positive mosquitoes, 89% (33/37) expelled sporozoites with a median of 1035 expelled sporozoites (IQR, 171-2969). Again, we observed a strong correlation between ruptured oocyst number and salivary gland sporozoite load (ρ = 0.9; p<0.0001) and a positive correlation between salivary gland sporozoite load and the number of sporozoites expelled (ρ = 0.7; p<0.0001). Several mosquitoes expelled multiple parasite clones during probing. Whilst sporozoite expelling was regularly observed from mosquitoes with low infection burdens, our findings indicate that mosquito infection burden is positively associated with the number of expelled sporozoites. Future work is required to determine the direct implications of these findings for transmission potential.
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Affiliation(s)
- Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Wouter Graumans
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Moussa Guelbeogo
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Jordache Ramijth
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Soré Harouna
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Zongo Soumanaba
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Rianne Stoter
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Marga Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Martina Pangos
- Department of Plastic and Reconstructive Surgery, Azienda Ospedaliero Universitaria GiulianoIsontina TriesteTriesteItaly
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, Johns HopkinsBloomberg School of Public HealthBaltimoreUnited States
| | - Katharine Collins
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Sarah G Staedke
- Liverpool School of Tropical MedicineLiverpoolUnited Kingdom
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
- Department of Immunology and Infection, London School of Hygiene and Tropical MedicineLondonUnited Kingdom
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Kanatani S, Stiffler D, Bousema T, Yenokyan G, Sinnis P. Revisiting the Plasmodium sporozoite inoculum and elucidating the efficiency with which malaria parasites progress through the mosquito. Nat Commun 2024; 15:748. [PMID: 38272943 PMCID: PMC10811227 DOI: 10.1038/s41467-024-44962-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/05/2024] [Indexed: 01/27/2024] Open
Abstract
Malaria is initiated when infected anopheline mosquitoes inoculate sporozoites as they probe for blood. It is thought that all infected mosquitoes are equivalent in terms of their infectious potential, with parasite burden having no role in transmission success. In this study, using mosquitoes harboring the entire range of salivary gland sporozoite loads observed in the field, we demonstrate a strong and highly significant correlation between mosquito parasite burden and inoculum size. We then link the inoculum data to oocyst counts, the most commonly-used metric to assess mosquito infection in the field, and determine the efficiency with which oocyst sporozoites enter mosquito salivary glands. Taken together our data support the conclusion that mosquitoes with higher parasite burdens are more likely to initiate infection and contribute to onward transmission. Overall these data may account for some of the unexplained heterogeneity in transmission and enable more precise benchmarks for transmission-blocking interventions.
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Affiliation(s)
- Sachie Kanatani
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
- Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
| | - Deborah Stiffler
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Teun Bousema
- Department of Medical Microbiology & Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Gayane Yenokyan
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Photini Sinnis
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
- Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
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4
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Hofer LM, Kweyamba PA, Sayi RM, Chabo MS, Maitra SL, Moore SJ, Tambwe MM. Malaria rapid diagnostic tests reliably detect asymptomatic Plasmodium falciparum infections in school-aged children that are infectious to mosquitoes. Parasit Vectors 2023; 16:217. [PMID: 37391770 DOI: 10.1186/s13071-023-05761-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 03/29/2023] [Indexed: 07/02/2023] Open
Abstract
BACKGROUND Asymptomatic malaria infections (Plasmodium falciparum) are common in school-aged children and represent a disease transmission reservoir as they are potentially infectious to mosquitoes. To detect and treat such infections, convenient, rapid and reliable diagnostic tools are needed. In this study, malaria rapid diagnostic tests (mRDT), light microscopy (LM) and quantitative polymerase chain reaction (qPCR) were used to evaluate their performance detecting asymptomatic malaria infections that are infectious to mosquitoes. METHODS One hundred seventy asymptomatic school-aged children (6-14 years old) from the Bagamoyo district in Tanzania were screened for Plasmodium spp. infections using mRDT (SD BIOLINE), LM and qPCR. In addition, gametocytes were detected using reverse transcription quantitative polymerase chain reaction (RT-qPCR) for all qPCR-positive children. Venous blood from all P. falciparum positive children was fed to female Anopheles gambiae sensu stricto mosquitoes via direct membrane feeding assays (DMFAs) after serum replacement. Mosquitoes were dissected for oocyst infections on day 8 post-infection. RESULTS The P. falciparum prevalence in study participants was 31.7% by qPCR, 18.2% by mRDT and 9.4% by LM. Approximately one-third (31.2%) of asymptomatic malaria infections were infectious to mosquitoes in DMFAs. In total, 297 infected mosquitoes were recorded after dissections, from which 94.9% (282/297) were derived from infections detected by mRDT and 5.1% (15/297) from subpatent mRDT infections. CONCLUSION The mRDT can be used reliably to detect children carrying gametocyte densities sufficient to infect high numbers of mosquitoes. Subpatent mRDT infections contributed marginally to the pool of oocyts-infected mosquitoes.
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Affiliation(s)
- Lorenz M Hofer
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health, Institute, Kreuzstrasse 2, 4123, Allschwil, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
| | - Prisca A Kweyamba
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
| | - Rajabu M Sayi
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
| | - Mohamed S Chabo
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
| | - Sonali L Maitra
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health, Institute, Kreuzstrasse 2, 4123, Allschwil, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
| | - Sarah J Moore
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health, Institute, Kreuzstrasse 2, 4123, Allschwil, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), 447, Tengeru, Arusha, Tanzania
| | - Mgeni M Tambwe
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, 74, Bagamoyo, Tanzania.
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Miglianico M, Bolscher JM, Vos MW, Koolen KJM, de Bruijni M, Rajagopal DS, Chen E, Kiczun M, Gray D, Campo B, Sauerwein RW, Dechering KJ. Assessment of the drugability of initial malaria infection through miniaturized sporozoite assays and high-throughput screening. Commun Biol 2023; 6:216. [PMID: 36823266 PMCID: PMC9950425 DOI: 10.1038/s42003-023-04599-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
The sporozoite stages of malaria parasites are the primary cause of infection of the vertebrate host and are targeted by (experimental) vaccines. Yet, little is known about their susceptibility to chemical intervention. Phenotypic high-throughput screens have not been feasible due to a lack of in vitro systems. Here we tested 78 marketed and experimental antimalarial compounds in miniaturized assays addressing sporozoite viability, gliding motility, hepatocyte traversal, and intrahepatocytic schizogony. None potently interfered with sporozoite viability or motility but ten compounds acted at the level of schizogony with IC50s < 100 nM. To identify compounds directly targeting sporozoites, we screened 81,000 compounds from the Global Health Diversity and reFRAME libraries in a sporozoite viability assay using a parasite expressing a luciferase reporter driven by the circumsporozoite promoter. The ionophore gramicidin emerged as the single hit from this screening campaign. Its effect on sporozoite viability translated into reduced gliding motility and an inability of sporozoites to invade human primary hepatocytes and develop into hepatic schizonts. While providing proof of concept for a small molecule sporontocidal mode of action, our combined data indicate that liver schizogony is more accessible to chemical intervention by (candidate) antimalarials.
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Affiliation(s)
| | | | | | | | | | | | - Emily Chen
- Calibr, a division of The Scripps Research Institute, La Jolla, California, United States of America
| | - Michael Kiczun
- Drug Discovery Unit, University of Dundee, Dundee, United Kingdom
| | - David Gray
- Drug Discovery Unit, University of Dundee, Dundee, United Kingdom
| | - Brice Campo
- Medicines for Malaria Venture, Geneva, Switzerland
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6
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Kamiya T, Paton DG, Catteruccia F, Reece SE. Targeting malaria parasites inside mosquitoes: ecoevolutionary consequences. Trends Parasitol 2022; 38:1031-1040. [PMID: 36209032 PMCID: PMC9815470 DOI: 10.1016/j.pt.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/13/2022] [Accepted: 09/13/2022] [Indexed: 11/05/2022]
Abstract
Proof-of-concept studies demonstrate that antimalarial drugs designed for human treatment can also be applied to mosquitoes to interrupt malaria transmission. Deploying a new control tool is ideally undertaken within a stewardship programme that maximises a drug's lifespan by minimising the risk of resistance evolution and slowing its spread once emerged. We ask: what are the epidemiological and evolutionary consequences of targeting parasites within mosquitoes? Our synthesis argues that targeting parasites inside mosquitoes (i) can be modelled by readily expanding existing epidemiological frameworks; (ii) provides a functionally novel control method that has potential to be more robust to resistance evolution than targeting parasites in humans; and (iii) could extend the lifespan and clinical benefit of antimalarials used exclusively to treat humans.
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Affiliation(s)
- Tsukushi Kamiya
- Centre for Interdisciplinary Research in Biology, Collège de France, Paris, France; HRB Clinical Research Facility, National University of Ireland, Galway, Ireland; Institute of Ecology and Evolution, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
| | - Douglas G Paton
- Department of Immunology and Infectious Disease, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Flaminia Catteruccia
- Department of Immunology and Infectious Disease, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA
| | - Sarah E Reece
- Institute of Ecology and Evolution, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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Abate A, Kedir S, Bose M, Hassen J, Dembele L, Golassa L. Infectivity of Symptomatic Patients and Their Contribution for Infectiousness of Mosquitoes following a Membrane Feeding Assay in Ethiopia. Microbiol Spectr 2022; 10:e0062822. [PMID: 36066239 PMCID: PMC9602676 DOI: 10.1128/spectrum.00628-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 08/05/2022] [Indexed: 12/30/2022] Open
Abstract
The membrane feeding assay is widely used to evaluate the efficacy of transmission-blocking interventions (TBIs) and identify the reservoir of malaria. This study aimed to determine the infectivity of blood meals from symptomatic Plasmodium-infected patients to an Anopheles arabiensis colony in Ethiopia. A membrane feeding assay was conducted on a total of 63 Plasmodium falciparum- and/or Plasmodium vivax-infected clinical patients in East Shoa Zone, Ethiopia. Detection of P. falciparum and P. vivax in blood samples was done using microscopy. Mosquito infection rates were determined by dissection of mosquitoes' midguts, while mosquito infectiousness was observed by dissection of their salivary glands. The proportion of infectious symptomatic patients was 68.3% (43/63). Using the chi-square or Fisher's exact test, the oocyst infection levels were higher among patients infected with P. vivax, females, and rural residents. Nearly 57% (56.7%, 17/30) of assays produced sporozoites in the salivary glands of mosquitoes. Both oocyst and sporozoite infection rates had positive correlations with parasitemia and gametocytemia. High infectiousness of symptomatic patients was observed, with a greater proportion of infectious mosquitoes per assay. Demonstrating oocyst infection in the mosquitoes might confirm estimates of the infectiousness of mosquitoes, although some of the oocyst-infected mosquitoes failed to produce sporozoites. IMPORTANCE Malaria remains one of the most devastating infectious diseases globally, and transmission-blocking activities are needed. Plasmodium transmission from human to mosquitoes is poorly studied, particularly in endemic countries, and the membrane feeding assay allows it to be determined. In this study, we demonstrated human infectious reservoirs of malaria. Moreover, the effect of Plasmodium-infected patients on the infectiousness of mosquitoes was also observed. These findings are therefore important for designing future evaluation of transmission-blocking interventions that will support the malaria elimination program.
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Affiliation(s)
- Andargie Abate
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| | - Soriya Kedir
- Adama Regional Laboratory, Oromia Region Health Bureau, Adama, Ethiopia
| | - Mitiku Bose
- Adama Regional Laboratory, Oromia Region Health Bureau, Adama, Ethiopia
| | - Jifar Hassen
- Adama Science and Technology University, Adama, Ethiopia
| | - Laurent Dembele
- Université des Sciences, des Techniques et des Technologies de Bamako (USTTB), Malaria Research and Training Center (MRTC), Bamako, Mali
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
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Roberds A, Kifude C, Oyieko J, Ocholla S, Mutunga J, Oullo D, Waga C, Li Z, Luckhart S, Stewart VA. Longitudinal impact of asymptomatic malaria/HIV-1 co-infection on Plasmodium falciparum gametocyte transcript expression and transmission to Anopheles mosquitoes. Front Cell Infect Microbiol 2022; 12:934641. [PMID: 36189366 PMCID: PMC9523792 DOI: 10.3389/fcimb.2022.934641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/25/2022] [Indexed: 11/28/2022] Open
Abstract
Despite significant developments towards malaria reduction, parasite transmission in the common context of HIV-1 co-infection and treatment for one or both infections has not been fully characterized. This is particularly important given that HIV-1 and malaria chemotherapies have the potential to alter gametocyte burden and mosquito infectivity. In this study, we examined 782 blood samples collected from a longitudinal cohort of 300 volunteers with asymptomatic parasitemia seeking HIV testing or treatment in the endemic region of Kisumu, Kenya, to define the impacts of HIV-1-malaria co-infection, antiretroviral therapy (ART) plus trimethoprim-sulfamethoxazole (TS) and the antimalarials artemether/lumefantrine (AL) on Plasmodium falciparum gametocyte transcript prevalence and parasite transmission to the African malaria mosquito Anopheles gambiae. Volunteers were assigned to three distinct HIV-1 groups: HIV-1 positive on treatment, HIV-1 positive newly diagnosed, and HIV-1 negative. Volunteers were monitored monthly over the course of six months. Using our highly sensitive digital droplet PCR (ddPCR) assay of three gametocyte specific transcript markers, we detected gametocyte transcripts in 51.1% of 18S positive volunteers across all study groups and time points. After correcting for multiple comparisons, the factors of HIV-1 status, time, CD4+ T-cell levels and hematocrit were not predictive of gametocyte prevalence or transmission. However, among those volunteers who were newly diagnosed with HIV-1 and malaria positive by rapid diagnostic test (RDT) at enrollment, the initiation of ART/TS and AL treatment was associated with a significant reduction in gametocyte transcript prevalence in the subsequent month when compared to HIV-1 negative volunteers treated with AL. To assess gametocyte transmissibility, volunteer blood samples were used in standard membrane feeding assays (SFMA) with laboratory-reared A. gambiae, with evidence of transmission confirmed by at least one of 25 dissected mosquitoes per sample positive for at least one midgut oocyst. HIV-1 status, CD4+ T-cell levels and hematocrit were not significantly associated with successful transmission to A. gambiae. Analysis of SMFA blood samples revealed that 50% of transmission-positive blood samples failed to test positive by Plasmodium-specific 18S ribosomal RNA quantitative PCR (qPCR) and 35% failed to test positive for any gametocyte specific transcript marker by droplet digital (ddPCR), documenting that transmission occurred in the absence of molecular parasite/gametocyte detection. Overall, these findings highlight the complexity of HIV-1 malaria co-infection and the need to further define the unpredictable role of asymptomatic parasitemia in transmission to mosquitoes.
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Affiliation(s)
- Ashleigh Roberds
- Department of Preventive Medicine and Biostatistics, Division of Global Public Health, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- *Correspondence: Ashleigh Roberds,
| | - Carolyne Kifude
- Kombewa Clinical Research Center, Kenya Medical Research Institute - United States Army Medical Research Directorate - Africa, Kisumu, Kenya
| | - Janet Oyieko
- Kombewa Clinical Research Center, Kenya Medical Research Institute - United States Army Medical Research Directorate - Africa, Kisumu, Kenya
| | - Stephen Ocholla
- Kombewa Clinical Research Center, Kenya Medical Research Institute - United States Army Medical Research Directorate - Africa, Kisumu, Kenya
| | - James Mutunga
- Department of Entomology and Vector Biology, United States Army Medical Research Directorate - Africa/Kenya Medical Research Institute, Kisumu, Kenya
- Department of Biological Sciences, Mount Kenya University, Thika, Kenya
| | - David Oullo
- Department of Entomology and Vector Biology, United States Army Medical Research Directorate - Africa/Kenya Medical Research Institute, Kisumu, Kenya
| | - Charles Waga
- Department of Entomology and Vector Biology, United States Army Medical Research Directorate - Africa/Kenya Medical Research Institute, Kisumu, Kenya
| | - Zhaozhang Li
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Shirley Luckhart
- Department of Entomology, Plant Pathology and Nematology and Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - V. Ann Stewart
- Department of Preventive Medicine and Biostatistics, Division of Global Public Health, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Pathak AK, Shiau JC, Franke-Fayard B, Shollenberger LM, Harn DA, Kyle DE, Murdock CC. Streamlining sporozoite isolation from mosquitoes by leveraging the dynamics of migration to the salivary glands. Malar J 2022; 21:264. [PMID: 36100902 PMCID: PMC9472382 DOI: 10.1186/s12936-022-04270-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 08/12/2022] [Indexed: 12/05/2022] Open
Abstract
Background Sporozoites isolated from the salivary glands of Plasmodium-infected mosquitoes are a prerequisite for several basic and pre-clinical applications. Although salivary glands are pooled to maximize sporozoite recovery, insufficient yields pose logistical and analytical hurdles; thus, predicting yields prior to isolation would be valuable. Preceding oocyst densities in the midgut is an obvious candidate. However, it is unclear whether current understanding of its relationship with sporozoite densities can be used to maximize yields, or whether it can capture the potential density-dependence in rates of sporozoite invasion of the salivary glands. Methods This study presents a retrospective analysis of Anopheles stephensi mosquitoes infected with two strains of the rodent-specific Plasmodium berghei. Mean oocyst densities were estimated in the midguts earlier in the infection (11–15 days post-blood meal), with sporozoites pooled from the salivary glands later in the infection (17–29 days). Generalized linear mixed effects models were used to determine if (1) mean oocyst densities can predict sporozoite yields from pooled salivary glands, (2) whether these densities can capture differences in rates of sporozoite invasion of salivary glands, and (3), if the interaction between oocyst densities and time could be leveraged to boost overall yields. Results The non-linear effect of mean oocyst densities confirmed the role of density-dependent constraints in limiting yields beyond certain oocyst densities. Irrespective of oocyst densities however, the continued invasion of salivary glands by the sporozoites boosted recoveries over time (17–29 days post-blood meal) for either parasite strain. Conclusions Sporozoite invasion of the salivary glands over time can be leveraged to maximize yields for P. berghei. In general, however, invasion of the salivary glands over time is a critical fitness determinant for all Plasmodium species (extrinsic incubation period, EIP). Thus, delaying sporozoite collection could, in principle, substantially reduce dissection effort for any parasite within the genus, with the results also alluding to the potential for changes in sporozoites densities over time to modify infectivity for the next host. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04270-y.
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Wong W, Volkman S, Daniels R, Schaffner S, Sy M, Ndiaye YD, Badiane AS, Deme AB, Diallo MA, Gomis J, Sy N, Ndiaye D, Wirth DF, Hartl DL. R H: a genetic metric for measuring intrahost Plasmodium falciparum relatedness and distinguishing cotransmission from superinfection. PNAS NEXUS 2022; 1:pgac187. [PMID: 36246152 PMCID: PMC9552330 DOI: 10.1093/pnasnexus/pgac187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 09/08/2022] [Indexed: 01/29/2023]
Abstract
Multiple-strain (polygenomic) infections are a ubiquitous feature of Plasmodium falciparum parasite population genetics. Under simple assumptions of superinfection, polygenomic infections are hypothesized to be the result of multiple infectious bites. As a result, polygenomic infections have been used as evidence of repeat exposure and used to derive genetic metrics associated with high transmission intensity. However, not all polygenomic infections are the result of multiple infectious bites. Some result from the transmission of multiple, genetically related strains during a single infectious bite (cotransmission). Superinfection and cotransmission represent two distinct transmission processes, and distinguishing between the two could improve inferences regarding parasite transmission intensity. Here, we describe a new metric, R H, that utilizes the correlation in allelic state (heterozygosity) within polygenomic infections to estimate the likelihood that the observed complexity resulted from either superinfection or cotransmission. R H is flexible and can be applied to any type of genetic data. As a proof of concept, we used R H to quantify polygenomic relatedness and estimate cotransmission and superinfection rates from a set of 1,758 malaria infections genotyped with a 24 single nucleotide polymorphism (SNP) molecular barcode. Contrary to expectation, we found that cotransmission was responsible for a significant fraction of 43% to 53% of the polygenomic infections collected in three distinct epidemiological regions in Senegal. The prediction that polygenomic infections frequently result from cotransmission stresses the need to incorporate estimates of relatedness within polygenomic infections to ensure the accuracy of genomic epidemiology surveillance data for informing public health activities.
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Affiliation(s)
- Wesley Wong
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Sarah Volkman
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
- College of Natural, Behavioral, and Health Sciences, Simmons University, Boston, MA 02115, USA
| | - Rachel Daniels
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Stephen Schaffner
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Mouhamad Sy
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Yaye Die Ndiaye
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Aida S Badiane
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Awa B Deme
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Mamadou Alpha Diallo
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Jules Gomis
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Ngayo Sy
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Daouda Ndiaye
- Laboratory of Parasitology and Mycology, Aristide le Dantec Hospital, Cheikh Anta Diop University, Dakar 10200, Senegal
| | - Dyann F Wirth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Daniel L Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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11
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Sukkanon C, Masangkay FR, Mala W, Kotepui KU, Wilairatana P, Chareonviriyaphap T, Kotepui M. Prevalence of Plasmodium spp. in Anopheles mosquitoes in Thailand: a systematic review and meta-analysis. Parasit Vectors 2022; 15:285. [PMID: 35933389 PMCID: PMC9357324 DOI: 10.1186/s13071-022-05397-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/14/2022] [Indexed: 11/12/2022] Open
Abstract
Background The entomological inoculation rate (EIR) is one of the key indices used to evaluate malaria transmission and vector control interventions. One of the components of the EIR is the sporozoite rate in Anopheles vectors. A systematic review and meta-analysis was performed to identify the prevalence of Plasmodium spp. in field-collected Anopheles species across Thailand. Methods This systematic review was registered under the PROSPERO number CRD42021297255. Studies that focused on the identification of Plasmodium spp. in Anopheles mosquitoes were identified from the electronic databases PubMed, Web of Science, and Scopus. The quality of the identified studies was determined using the Strengthening the Reporting of Observational Studies in Epidemiology approach. The proportion of Anopheles mosquitoes collected, Anopheles vectors for Plasmodium species, and specificity of Anopheles vectors for Plasmodium species were analyzed. The pooled prevalence of Plasmodium species among the primary vectors (Anopheles dirus, Anopheles minimus, and Anopheles maculatus) was estimated using the random-effects model. Results Of the 1113 studies identified, 31 were included in the syntheses. Of the 100,910 Anopheles mosquitoes identified for species and sibling species, An. minimus (40.16%), An. maculatus (16.59%), and Anopheles epiroticus (9.18%) were the most prevalent Anopheles species. Of the 123,286 Anopheles mosquitoes identified, 566 (0.46%) were positive for Plasmodium species. The highest proportions of Plasmodium species were identified in Anopheles hodgkini (2/6, 33.3%), Anopheles nigerrimus (2/24, 8.33%), Anopheles balabacensis (4/84, 4.76%), An. dirus (114/4956, 2.3%), Anopheles annularis (16/852, 1.88%), Anopheles kochi (8/519, 1.54%), Anopheles vagus (3/215, 1.4%), and Anopheles baimaii (1/86, 1.16%). The pooled prevalence of Plasmodium species identified in the main Anopheles vectors was 0.4% of that of Plasmodium species identified in An. dirus was 2.1%, that of Plasmodium species identified in An. minimus was 0.4%, and that of Plasmodium species identified in An. maculatus was 0.4%. Conclusions We found a low prevalence of Plasmodium infection in Anopheles mosquitoes across Thailand. Therefore, the use of EIR to determine the impact of vector control intervention on malaria parasite transmission and elimination in Thailand must be undertaken with caution, as a large number of Anopheles specimens may be required. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05397-2.
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Affiliation(s)
- Chutipong Sukkanon
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand
| | | | - Wanida Mala
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand
| | - Kwuntida Uthaisar Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand
| | - Polrat Wilairatana
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Theeraphap Chareonviriyaphap
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.,Royal Society of Thailand, Sanam Suea Pa, Dusit, Bangkok, Thailand
| | - Manas Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand.
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12
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de Jong RM, Singh SK, Teelen K, van de Vegte-Bolmer M, van Gemert GJ, Stone WJR, Locke E, Plieskatt J, Theisen M, Bousema T, Jore MM. Heterologous Expression and Evaluation of Novel Plasmodium falciparum Transmission Blocking Vaccine Candidates. Front Immunol 2022; 13:909060. [PMID: 35812379 PMCID: PMC9259988 DOI: 10.3389/fimmu.2022.909060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/17/2022] [Indexed: 11/27/2022] Open
Abstract
Malaria transmission blocking vaccines (TBV) aim to induce antibodies that can interrupt Plasmodium falciparum development in the mosquito midgut and thereby prevent onward malaria transmission. A limited number of TBV candidates have been identified and only three (Pfs25, Pfs230 and Pfs48/45) have entered clinical testing. While one of these candidates may emerge as a highly potent TBV candidate, it is premature to determine if they will generate sufficiently potent and sustained responses. It is therefore important to explore novel candidate antigens. We recently analyzed sera from naturally exposed individuals and found that the presence and/or intensity of antibodies against 12 novel putative surface expressed gametocyte antigens was associated with transmission reducing activity. In this study, protein fragments of these novel TBV candidates were designed and heterologously expressed in Drosophila melanogaster S2 cells and Lactococcus lactis. Eleven protein fragments, covering seven TBV candidates, were successfully produced. All tested antigens were recognized by antibodies from individuals living in malaria-endemic areas, indicating that native epitopes are present. All antigens induced antigen-specific antibody responses in mice. Two antigens induced antibodies that recognized a native protein in gametocyte extract, and antibodies elicited by four antigens recognized whole gametocytes. In particular, we found that antigen Pf3D7_0305300, a putative transporter, is abundantly expressed on the surface of gametocytes. However, none of the seven novel TBV candidates expressed here induced an antibody response that reduced parasite development in the mosquito midgut as assessed in the standard membrane feeding assay. Altogether, the antigen fragments used in this study did not prove to be promising transmission blocking vaccine constructs, but led to the identification of two gametocyte surface proteins that may provide new leads for studying gametocyte biology.
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Affiliation(s)
- Roos M. de Jong
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Susheel K. Singh
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - Karina Teelen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Will J. R. Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Emily Locke
- PATH‘s Malaria Vaccine Initiative, Washington, DC, United States
| | - Jordan Plieskatt
- PATH‘s Malaria Vaccine Initiative, Washington, DC, United States
| | - Michael Theisen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Matthijs M. Jore
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
- *Correspondence: Matthijs M. Jore,
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13
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Ramjith J, Alkema M, Bradley J, Dicko A, Drakeley C, Stone W, Bousema T. Quantifying Reductions in Plasmodium falciparum Infectivity to Mosquitos: A Sample Size Calculator to Inform Clinical Trials on Transmission-Reducing Interventions. Front Immunol 2022; 13:899615. [PMID: 35720362 PMCID: PMC9205189 DOI: 10.3389/fimmu.2022.899615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Malaria transmission depends on the presence of mature Plasmodium transmission stages (gametocytes) that may render blood-feeding Anopheles mosquitos infectious. Transmission-blocking antimalarial drugs and vaccines can prevent transmission by reducing gametocyte densities or infectivity to mosquitos. Mosquito infection outcomes are thereby informative biological endpoints of clinical trials with transmission blocking interventions. Nevertheless, trials are often primarily designed to determine intervention safety; transmission blocking efficacy is difficult to incorporate in sample size considerations due to variation in infection outcomes and considerable inter-study variation. Here, we use clinical trial data from studies in malaria naive and naturally exposed study participants to present an online sample size calculator tool. This sample size calculator allows studies to be powered to detect reductions in the proportion of infected mosquitos or infection burden (oocyst density) in mosquitos. The utility of this online tool is illustrated using trial data with transmission blocking malaria drugs.
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Affiliation(s)
- Jordache Ramjith
- Radboud Institute for Molecular Life Sciences, Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands.,Department for Health Evidence, Biostatistics Research Group, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Manon Alkema
- Radboud Institute for Molecular Life Sciences, Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | - John Bradley
- Medical Research Council (MRC) International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Chris Drakeley
- Medical Research Council (MRC) International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Will Stone
- Medical Research Council (MRC) International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Radboud Institute for Molecular Life Sciences, Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
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14
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Hendershot AL, Esayas E, Sutcliffe AC, Irish SR, Gadisa E, Tadesse FG, Lobo NF. A comparison of PCR and ELISA methods to detect different stages of Plasmodium vivax in Anopheles arabiensis. Parasit Vectors 2021; 14:473. [PMID: 34526109 PMCID: PMC8442364 DOI: 10.1186/s13071-021-04976-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/23/2021] [Indexed: 11/10/2022] Open
Abstract
Background In characterizing malaria epidemiology, measuring mosquito infectiousness informs the entomological inoculation rate, an important metric of malaria transmission. PCR-based methods have been touted as more sensitive than the current “gold-standard” circumsporozoite (CSP) ELISA. Wider application of PCR-based methods has been limited by lack of specificity for the infectious sporozoite stage. We compared a PCR method for detecting the parasite’s mitochondrial (mt) cytochrome oxidase I (COX-I) gene with ELISA for detecting circumsporozoite protein for identification of different life stages of the parasite during development within a mosquito. Methods A PCR-based method targeting the Plasmodium mt COX-I gene was compared with the CSP ELISA method to assess infectivity in Anopheles arabiensis colony mosquitoes fed on blood from patients infected with Plasmodium vivax. Mosquitoes were tested at six post-infection time points (days 0.5, 1, 6, 9, 12, 15). The head and thorax and the abdomen for each specimen were tested separately with each method. Agreement between methods at each infection stage was measured using Cohen’s kappa measure of test association. Results Infection status of mosquitoes was assessed in approximately 90 head/thorax and 90 abdomen segments at each time point; in total, 538 head/thorax and 534 abdomen segments were tested. In mosquitoes bisected after 0.5, 1, and 6 days post-infection (dpi), the mt COX-I PCR detected Plasmodium DNA in both the abdomen (88, 78, and 67%, respectively) and head/thorax segments (69, 60, and 44%, respectively), whilst CSP ELISA detected sporozoites in only one abdomen on day 6 post-infection. PCR was also more sensitive than ELISA for detection of Plasmodium in mosquitoes bisected after 9, 12, and 15 dpi in both the head and thorax and abdomen. There was fair agreement between methods for time points 9–15 dpi (κ = 0.312, 95% CI: 0.230–0.394). Conclusions The mt COX-I PCR is a highly sensitive, robust method for detecting Plasmodium DNA in mosquitoes, but its limited Plasmodium life-stage specificity cannot be overcome by bisection of the head and thorax from the abdomen prior to PCR. Thus, the mt COX-I PCR is a poor candidate for identifying infectious mosquitoes. Graphical Abstract ![]()
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Affiliation(s)
| | - Endashaw Esayas
- Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Alice C Sutcliffe
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Seth R Irish
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA.,President's Malaria Initiative, Bureau for Global Health, Office of Infectious Disease, United States Agency for International Development, Washington DC, USA
| | - Endalamaw Gadisa
- Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Fitsum G Tadesse
- Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia.,Radboud University Medical Center, Nijmegen, The Netherlands
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
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15
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de Jong RM, Meerstein-Kessel L, Da DF, Nsango S, Challenger JD, van de Vegte-Bolmer M, van Gemert GJ, Duarte E, Teyssier N, Sauerwein RW, Churcher TS, Dabire RK, Morlais I, Locke E, Huynen MA, Bousema T, Jore MM. Monoclonal antibodies block transmission of genetically diverse Plasmodium falciparum strains to mosquitoes. NPJ Vaccines 2021; 6:101. [PMID: 34385463 PMCID: PMC8361195 DOI: 10.1038/s41541-021-00366-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 07/29/2021] [Indexed: 11/09/2022] Open
Abstract
Malaria parasite transmission to mosquitoes relies on the uptake of sexual stage parasites during a blood meal and subsequent formation of oocysts on the mosquito midgut wall. Transmission-blocking vaccines (TBVs) and monoclonal antibodies (mAbs) target sexual stage antigens to interrupt human-to-mosquito transmission and may form important tools for malaria elimination. Although most epitopes of these antigens are considered highly conserved, little is known about the impact of natural genetic diversity on the functional activity of transmission-blocking antibodies. Here we measured the efficacy of three mAbs against leading TBV candidates (Pfs48/45, Pfs25 and Pfs230) in transmission assays with parasites from naturally infected donors compared to their efficacy against the strain they were raised against (NF54). Transmission-reducing activity (TRA) was measured as reduction in mean oocyst intensity. mAb 45.1 (α-Pfs48/45) and mAb 4B7 (α-Pfs25) reduced transmission of field parasites from almost all donors with IC80 values similar to NF54. Sequencing of oocysts that survived high mAb concentrations did not suggest enrichment of escape genotypes. mAb 2A2 (α-Pfs230) only reduced transmission of parasites from a minority of the donors, suggesting that it targets a non-conserved epitope. Using six laboratory-adapted strains, we revealed that mutations in one Pfs230 domain correlate with mAb gamete surface binding and functional TRA. Our findings demonstrate that, despite the conserved nature of sexual stage antigens, minor sequence variation can significantly impact the efficacy of transmission-blocking mAbs. Since mAb 45.1 shows high potency against genetically diverse strains, our findings support its further clinical development and may inform Pfs48/45 vaccine design.
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Affiliation(s)
- Roos M de Jong
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lisette Meerstein-Kessel
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
- Center for Molecular and Biomolecular Informatics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dari F Da
- Institut de Recherche en Sciences de la Santé, Direction Régionale, Bobo Dioulasso, Burkina Faso
| | - Sandrine Nsango
- Malaria Research Laboratory, OCEAC, Yaoundé, Cameroon
- Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
| | - Joseph D Challenger
- Medical Research Council Centre for Global Infections Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elias Duarte
- EPPIcenter Research Program, Division of HIV, ID, and Global Medicine, Department of Medicine, University of California, San Francisco, CA, USA
| | - Noam Teyssier
- EPPIcenter Research Program, Division of HIV, ID, and Global Medicine, Department of Medicine, University of California, San Francisco, CA, USA
| | - Robert W Sauerwein
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
- TropIQ Health Sciences, Nijmegen, Netherlands
| | - Thomas S Churcher
- Medical Research Council Centre for Global Infections Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Roch K Dabire
- Institut de Recherche en Sciences de la Santé, Direction Régionale, Bobo Dioulasso, Burkina Faso
| | - Isabelle Morlais
- Malaria Research Laboratory, OCEAC, Yaoundé, Cameroon
- MIVEGEC, Université Montpellier, IRD, CNRS, Montpellier, France
| | - Emily Locke
- PATH's Malaria Vaccine Initiative, Washington, DC, USA
| | - Martijn A Huynen
- Center for Molecular and Biomolecular Informatics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Matthijs M Jore
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands.
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16
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CRISPR/Cas9-engineered inducible gametocyte producer lines as a valuable tool for Plasmodium falciparum malaria transmission research. Nat Commun 2021; 12:4806. [PMID: 34376675 PMCID: PMC8355313 DOI: 10.1038/s41467-021-24954-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/08/2021] [Indexed: 12/18/2022] Open
Abstract
The malaria parasite Plasmodium falciparum replicates inside erythrocytes in the blood of infected humans. During each replication cycle, a small proportion of parasites commits to sexual development and differentiates into gametocytes, which are essential for parasite transmission via the mosquito vector. Detailed molecular investigation of gametocyte biology and transmission has been hampered by difficulties in generating large numbers of these highly specialised cells. Here, we engineer P. falciparum NF54 inducible gametocyte producer (iGP) lines for the routine mass production of synchronous gametocytes via conditional overexpression of the sexual commitment factor GDV1. NF54/iGP lines consistently achieve sexual commitment rates of 75% and produce viable gametocytes that are transmissible by mosquitoes. We also demonstrate that further genetic engineering of NF54/iGP parasites is a valuable tool for the targeted exploration of gametocyte biology. In summary, we believe the iGP approach developed here will greatly expedite basic and applied malaria transmission stage research.
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17
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Rashidzadeh H, Tabatabaei Rezaei SJ, Adyani SM, Abazari M, Rahamooz Haghighi S, Abdollahi H, Ramazani A. Recent advances in targeting malaria with nanotechnology-based drug carriers. Pharm Dev Technol 2021; 26:807-823. [PMID: 34190000 DOI: 10.1080/10837450.2021.1948568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Malaria, as one of the most common human infectious diseases, remains the greatest global health concern, since approximately 3.5 billion people around the world, especially those in subtropical areas, are at the risk of being infected by malaria. Due to the emergence and spread of drug resistance to the current antimalarials, malaria-related mortality and incidence rates have recently increased. To overcome the aforementioned obstacles, nano-vehicles based on biodegradable, natural, and non-toxic polymers have been developed. Accordingly, these systems are considered as a potential drug vehicle, which due to their unique properties such as the excellent safety profile, good biocompatibility, tunable structure, diversity, and the presence of functional groups within the polymer structure, could facilitate covalent attachment of targeting moieties and antimalarials to the polymeric nano-vehicles. In this review, we highlighted some recent developments of liposomes as unique nanoscale drug delivery vehicles and several polymeric nanovehicles, including hydrogels, dendrimers, self-assembled micelles, and polymer-drug conjugates for the effective delivery of antimalarials.
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Affiliation(s)
- Hamid Rashidzadeh
- Department of Pharmaceutical Biomaterials, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran.,Laboratory of Novel Drug Delivery Systems, Department of Chemistry, Faculty of Science, University of Zanjan, Zanjan, Iran.,Cancer Gene Therapy Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Seyed Jamal Tabatabaei Rezaei
- Laboratory of Novel Drug Delivery Systems, Department of Chemistry, Faculty of Science, University of Zanjan, Zanjan, Iran
| | - Seyed Masih Adyani
- Department of Pharmaceutical Biomaterials, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Morteza Abazari
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Samaneh Rahamooz Haghighi
- Department of Plant Production and Genetics, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
| | - Hossien Abdollahi
- Department of Polymer Engineering, Faculty of Engineering, Urmia University, Urmia, Iran
| | - Ali Ramazani
- Cancer Gene Therapy Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
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18
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Optimization of the feeding rate of Anopheles farauti s.s. colony mosquitoes in direct membrane feeding assays. Parasit Vectors 2021; 14:356. [PMID: 34233734 PMCID: PMC8261992 DOI: 10.1186/s13071-021-04842-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/11/2021] [Indexed: 12/28/2022] Open
Abstract
Background Direct membrane feeding assays (DMFA) are an important tool to study parasite transmission to mosquitoes. Mosquito feeding rates in these artificial systems require optimization, as there are a number of factors that potentially influence the feeding rates and there are no standardized methods that apply to all anopheline species. Methods A range of parameters prior to and during direct membrane feeding (DMF) were evaluated for their impact on Anopheles farauti sensu stricto feeding rates, including the starving conditions and duration of starving prior to feeding, membrane type, DMF exposure time, mosquito age, feeding in the light versus the dark, blood volume, mosquito density and temperature of water bath. Results The average successful DMFA feeding rate for An. farauti s.s. colony mosquitoes increased from 50 to 85% when assay parameters were varied. Overnight starvation and Baudruche membrane yielded the highest feeding rates but rates were also affected by blood volume in the feeder and the mosquito density in the feeding cups. Availability of water during the pre-feed starvation period did not significantly impact feeding rates, nor did the exposure duration to blood in membrane feeders, the age of mosquitoes (3, 5 and 7 days post-emergence), feeding in the light versus the dark, or the temperature (34 °C, 38 °C, 42 °C and 46 °C) of the water bath. Conclusion Optimal feeding conditions in An. farauti s.s. DMFA were to offer 50 female mosquitoes in a cup (with a total surface area of ~ 340 cm2 with 1 mosquito/6.8 cm2) that were starved overnight 350–500 µL of blood (collected in heparin-coated Vacutainer tubes) per feeder in feeders with a surface area ~ 5 cm2 (with a maximum capacity of 1.5 mL of blood) via a Baudruche membrane, for at least 10–20 min. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04842-y.
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19
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Thai E, Costa G, Weyrich A, Murugan R, Oyen D, Flores-Garcia Y, Prieto K, Bosch A, Valleriani A, Wu NC, Pholcharee T, Scally SW, Wilson IA, Wardemann H, Julien JP, Levashina EA. A high-affinity antibody against the CSP N-terminal domain lacks Plasmodium falciparum inhibitory activity. J Exp Med 2021; 217:152019. [PMID: 32790871 PMCID: PMC7596816 DOI: 10.1084/jem.20200061] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/21/2020] [Accepted: 07/01/2020] [Indexed: 11/04/2022] Open
Abstract
Malaria is a global health concern, and research efforts are ongoing to develop a superior vaccine to RTS,S/AS01. To guide immunogen design, we seek a comprehensive understanding of the protective humoral response against Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP). In contrast to the well-studied responses to the repeat region and the C-terminus, the antibody response against the N-terminal domain of PfCSP (N-CSP) remains obscure. Here, we characterized the molecular recognition and functional efficacy of the N-CSP-specific monoclonal antibody 5D5. The crystal structure at 1.85-Å resolution revealed that 5D5 binds an α-helical epitope in N-CSP with high affinity through extensive shape and charge complementarity and the unusual utilization of an antibody N-linked glycan. Nevertheless, functional studies indicated low 5D5 binding to live Pf sporozoites and lack of sporozoite inhibition in vitro and in vivo. Overall, our data do not support the inclusion of the 5D5 N-CSP epitope into the next generation of CSP-based vaccines.
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Affiliation(s)
- Elaine Thai
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Giulia Costa
- Vector Biology Unit, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Anna Weyrich
- Vector Biology Unit, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Rajagopal Murugan
- B Cell Immunology, German Cancer Research Institute, Heidelberg, Germany
| | - David Oyen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA
| | - Yevel Flores-Garcia
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Katherine Prieto
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Alexandre Bosch
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Angelo Valleriani
- Vector Biology Unit, Max Planck Institute for Infection Biology, Berlin, Germany.,Department of Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Nicholas C Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA
| | - Tossapol Pholcharee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA
| | - Stephen W Scally
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA.,The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA
| | - Hedda Wardemann
- B Cell Immunology, German Cancer Research Institute, Heidelberg, Germany
| | - Jean-Philippe Julien
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Elena A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology, Berlin, Germany
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20
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Abstract
Introduction: An effective vaccine against malaria forms a global health priority. Both naturally acquired immunity and sterile protection induced by irradiated sporozoite immunization were described decades ago. Still no vaccine exists that sufficiently protects children in endemic areas. Identifying immunological correlates of vaccine efficacy can inform rational vaccine design and potentially accelerate clinical development.Areas covered: We discuss recent research on immunological correlates of malaria vaccine efficacy, including: insights from state-of-the-art omics platforms and systems vaccinology analyses; functional anti-parasitic assays; pre-immunization predictors of vaccine efficacy; and comparison of correlates of vaccine efficacy against controlled human malaria infections (CHMI) and against naturally acquired infections.Expert Opinion: Effective vaccination may be achievable without necessarily understanding immunological correlates, but the relatively disappointing efficacy of malaria vaccine candidates in target populations is concerning. Hypothesis-generating omics and systems vaccinology analyses, alongside assessment of pre-immunization correlates, have the potential to bring about paradigm-shifts in malaria vaccinology. Functional assays may represent in vivo effector mechanisms, but have scarcely been formally assessed as correlates. Crucially, evidence is still meager that correlates of vaccine efficacy against CHMI correspond with those against naturally acquired infections in target populations. Finally, the diversity of immunological assays and efficacy endpoints across malaria vaccine trials remains a major confounder.
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Affiliation(s)
| | - Matthew B B McCall
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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21
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Plasmodium oocysts respond with dormancy to crowding and nutritional stress. Sci Rep 2021; 11:3090. [PMID: 33542254 PMCID: PMC7862253 DOI: 10.1038/s41598-021-81574-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/08/2021] [Indexed: 12/13/2022] Open
Abstract
Malaria parasites develop as oocysts in the mosquito for several days before they are able to infect a human host. During this time, mosquitoes take bloodmeals to replenish their nutrient and energy reserves needed for flight and reproduction. We hypothesized that these bloodmeals are critical for oocyst growth and that experimental infection protocols, typically involving a single bloodmeal at the time of infection, cause nutritional stress to the developing oocysts. Therefore, enumerating oocysts disregarding their growth and differentiation state may lead to erroneous conclusions about the efficacy of transmission blocking interventions. Here, we examine this hypothesis in Anopheles coluzzii mosquitoes infected with the human and rodent parasites Plasmodium falciparum and Plasmodium berghei, respectively. We show that oocyst growth and maturation rates decrease at late developmental stages as infection intensities increase; an effect exacerbated at very high infection intensities but fully restored with post infection bloodmeals. High infection intensities and starvation conditions reduce RNA Polymerase III activity in oocysts unless supplemental bloodmeals are provided. Our results suggest that oocysts respond to crowding and nutritional stress with a dormancy-like strategy, which urges the development of alternative methods to assess the efficacy of transmission blocking interventions.
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22
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Stopard IJ, Churcher TS, Lambert B. Estimating the extrinsic incubation period of malaria using a mechanistic model of sporogony. PLoS Comput Biol 2021; 17:e1008658. [PMID: 33591963 PMCID: PMC7909686 DOI: 10.1371/journal.pcbi.1008658] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 02/26/2021] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
During sporogony, malaria-causing parasites infect a mosquito, reproduce and migrate to the mosquito salivary glands where they can be transmitted the next time blood feeding occurs. The time required for sporogony, known as the extrinsic incubation period (EIP), is an important determinant of malaria transmission intensity. The EIP is typically estimated as the time for a given percentile, x, of infected mosquitoes to develop salivary gland sporozoites (the infectious parasite life stage), which is denoted by EIPx. Many mechanisms, however, affect the observed sporozoite prevalence including the human-to-mosquito transmission probability and possibly differences in mosquito mortality according to infection status. To account for these various mechanisms, we present a mechanistic mathematical model, which explicitly models key processes at the parasite, mosquito and observational scales. Fitting this model to experimental data, we find greater variation in the EIP than previously thought: we estimated the range between EIP10 and EIP90 (at 27°C) as 4.5 days compared to 0.9 days using existing statistical methods. This pattern holds over the range of study temperatures included in the dataset. Increasing temperature from 21°C to 34°C decreased the EIP50 from 16.1 to 8.8 days. Our work highlights the importance of mechanistic modelling of sporogony to (1) improve estimates of malaria transmission under different environmental conditions or disease control programs and (2) evaluate novel interventions that target the mosquito life stages of the parasite.
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Affiliation(s)
- Isaac J. Stopard
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom
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23
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Ekoka E, Maharaj S, Nardini L, Dahan-Moss Y, Koekemoer LL. 20-Hydroxyecdysone (20E) signaling as a promising target for the chemical control of malaria vectors. Parasit Vectors 2021; 14:86. [PMID: 33514413 PMCID: PMC7844807 DOI: 10.1186/s13071-020-04558-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/19/2020] [Indexed: 01/07/2023] Open
Abstract
With the rapid development and spread of resistance to insecticides among anopheline malaria vectors, the efficacy of current World Health Organization (WHO)-approved insecticides targeting these vectors is under threat. This has led to the development of novel interventions, including improved and enhanced insecticide formulations with new targets or synergists or with added sterilants and/or antimalarials, among others. To date, several studies in mosquitoes have revealed that the 20-hydroxyecdysone (20E) signaling pathway regulates both vector abundance and competence, two parameters that influence malaria transmission. Therefore, insecticides which target 20E signaling (e.g. methoxyfenozide and halofenozide) may be an asset for malaria vector control. While such insecticides are already commercially available for lepidopteran and coleopteran pests, they still need to be approved by the WHO for malaria vector control programs. Until recently, chemicals targeting 20E signaling were considered to be insect growth regulators, and their effect was mostly studied against immature mosquito stages. However, in the last few years, promising results have been obtained by applying methoxyfenozide or halofenozide (two compounds that boost 20E signaling) to Anopheles populations at different phases of their life-cycle. In addition, preliminary studies suggest that methoxyfenozide resistance is unstable, causing the insects substantial fitness costs, thereby potentially circumventing one of the biggest challenges faced by current vector control efforts. In this review, we first describe the 20E signaling pathway in mosquitoes and then summarize the mechanisms whereby 20E signaling regulates the physiological processes associated with vector competence and vector abundance. Finally, we discuss the potential of using chemicals targeting 20E signaling to control malaria vectors.![]()
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Affiliation(s)
- Elodie Ekoka
- WITS Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. .,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa.
| | - Surina Maharaj
- WITS Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Luisa Nardini
- WITS Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Yael Dahan-Moss
- WITS Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Lizette L Koekemoer
- WITS Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
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24
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Ferreira JL, Heincke D, Wichers JS, Liffner B, Wilson DW, Gilberger TW. The Dynamic Roles of the Inner Membrane Complex in the Multiple Stages of the Malaria Parasite. Front Cell Infect Microbiol 2021; 10:611801. [PMID: 33489940 PMCID: PMC7820811 DOI: 10.3389/fcimb.2020.611801] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/30/2020] [Indexed: 01/31/2023] Open
Abstract
Apicomplexan parasites, such as human malaria parasites, have complex lifecycles encompassing multiple and diverse environmental niches. Invading, replicating, and escaping from different cell types, along with exploiting each intracellular niche, necessitate large and dynamic changes in parasite morphology and cellular architecture. The inner membrane complex (IMC) is a unique structural element that is intricately involved with these distinct morphological changes. The IMC is a double membrane organelle that forms de novo and is located beneath the plasma membrane of these single-celled organisms. In Plasmodium spp. parasites it has three major purposes: it confers stability and shape to the cell, functions as an important scaffolding compartment during the formation of daughter cells, and plays a major role in motility and invasion. Recent years have revealed greater insights into the architecture, protein composition and function of the IMC. Here, we discuss the multiple roles of the IMC in each parasite lifecycle stage as well as insights into its sub-compartmentalization, biogenesis, disassembly and regulation during stage conversion of P. falciparum.
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Affiliation(s)
- Josie Liane Ferreira
- Centre for Structural Systems Biology, Hamburg, Germany
- Heinrich Pette Institut, Leibniz-Institut für Experimentelle Virologie, Hamburg, Germany
| | - Dorothee Heincke
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- University of Hamburg, Hamburg, Germany
| | - Jan Stephan Wichers
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- University of Hamburg, Hamburg, Germany
| | - Benjamin Liffner
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Danny W. Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
- Burnet Institute, Melbourne, VIC, Australia
| | - Tim-Wolf Gilberger
- Centre for Structural Systems Biology, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- University of Hamburg, Hamburg, Germany
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25
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Watson OJ, Okell LC, Hellewell J, Slater HC, Unwin HJT, Omedo I, Bejon P, Snow RW, Noor AM, Rockett K, Hubbart C, Nankabirwa JI, Greenhouse B, Chang HH, Ghani AC, Verity R. Evaluating the Performance of Malaria Genetics for Inferring Changes in Transmission Intensity Using Transmission Modeling. Mol Biol Evol 2021; 38:274-289. [PMID: 32898225 PMCID: PMC7783189 DOI: 10.1093/molbev/msaa225] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Substantial progress has been made globally to control malaria, however there is a growing need for innovative new tools to ensure continued progress. One approach is to harness genetic sequencing and accompanying methodological approaches as have been used in the control of other infectious diseases. However, to utilize these methodologies for malaria, we first need to extend the methods to capture the complex interactions between parasites, human and vector hosts, and environment, which all impact the level of genetic diversity and relatedness of malaria parasites. We develop an individual-based transmission model to simulate malaria parasite genetics parameterized using estimated relationships between complexity of infection and age from five regions in Uganda and Kenya. We predict that cotransmission and superinfection contribute equally to within-host parasite genetic diversity at 11.5% PCR prevalence, above which superinfections dominate. Finally, we characterize the predictive power of six metrics of parasite genetics for detecting changes in transmission intensity, before grouping them in an ensemble statistical model. The model predicted malaria prevalence with a mean absolute error of 0.055. Different assumptions about the availability of sample metadata were considered, with the most accurate predictions of malaria prevalence made when the clinical status and age of sampled individuals is known. Parasite genetics may provide a novel surveillance tool for estimating the prevalence of malaria in areas in which prevalence surveys are not feasible. However, the findings presented here reinforce the need for patient metadata to be recorded and made available within all future attempts to use parasite genetics for surveillance.
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Affiliation(s)
- Oliver J Watson
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Joel Hellewell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - H Juliette T Unwin
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute—Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Kirk Rockett
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Christina Hubbart
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Hsiao-Han Chang
- Center for Communicable Disease Dynamics, Harvard TH Chan School of Public Health, Boston, MA
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Robert Verity
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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26
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Shaw WR, Holmdahl IE, Itoe MA, Werling K, Marquette M, Paton DG, Singh N, Buckee CO, Childs LM, Catteruccia F. Multiple blood feeding in mosquitoes shortens the Plasmodium falciparum incubation period and increases malaria transmission potential. PLoS Pathog 2020; 16:e1009131. [PMID: 33382824 PMCID: PMC7774842 DOI: 10.1371/journal.ppat.1009131] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/08/2020] [Indexed: 12/15/2022] Open
Abstract
Many mosquito species, including the major malaria vector Anopheles gambiae, naturally undergo multiple reproductive cycles of blood feeding, egg development and egg laying in their lifespan. Such complex mosquito behavior is regularly overlooked when mosquitoes are experimentally infected with malaria parasites, limiting our ability to accurately describe potential effects on transmission. Here, we examine how Plasmodium falciparum development and transmission potential is impacted when infected mosquitoes feed an additional time. We measured P. falciparum oocyst size and performed sporozoite time course analyses to determine the parasite's extrinsic incubation period (EIP), i.e. the time required by parasites to reach infectious sporozoite stages, in An. gambiae females blood fed either once or twice. An additional blood feed at 3 days post infection drastically accelerates oocyst growth rates, causing earlier sporozoite accumulation in the salivary glands, thereby shortening the EIP (reduction of 2.3 ± 0.4 days). Moreover, parasite growth is further accelerated in transgenic mosquitoes with reduced reproductive capacity, which mimic genetic modifications currently proposed in population suppression gene drives. We incorporate our shortened EIP values into a measure of transmission potential, the basic reproduction number R0, and find the average R0 is higher (range: 10.1%-12.1% increase) across sub-Saharan Africa than when using traditional EIP measurements. These data suggest that malaria elimination may be substantially more challenging and that younger mosquitoes or those with reduced reproductive ability may provide a larger contribution to infection than currently believed. Our findings have profound implications for current and future mosquito control interventions.
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Affiliation(s)
- W. Robert Shaw
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Inga E. Holmdahl
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
- Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Maurice A. Itoe
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Kristine Werling
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Meghan Marquette
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Douglas G. Paton
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Naresh Singh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Caroline O. Buckee
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
- Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Lauren M. Childs
- Department of Mathematics, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Flaminia Catteruccia
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
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27
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Loonen JACM, Dery DB, Musaka BZ, Bandibabone JB, Bousema T, van Lenthe M, Pop-Stefanija B, Fesselet JF, Koenraadt CJM. Identification of main malaria vectors and their insecticide resistance profile in internally displaced and indigenous communities in Eastern Democratic Republic of the Congo (DRC). Malar J 2020; 19:425. [PMID: 33228693 PMCID: PMC7684733 DOI: 10.1186/s12936-020-03497-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 11/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria remains a major public health concern in the Democratic Republic of the Congo (DRC) and its control is affected by recurrent conflicts. Médecins Sans Frontières (MSF) initiated several studies to better understand the unprecedented incidence of malaria to effectively target and implement interventions in emergency settings. The current study evaluated the main vector species involved in malaria transmission and their resistance to insecticides, with the aim to propose the most effective tools and strategies for control of local malaria vectors. METHODS This study was performed in 52 households in Shamwana (Katanga, 2014), 168 households in Baraka (South Kivu, 2015) and 269 households in Kashuga (North Kivu, 2017). Anopheles vectors were collected and subjected to standardized Word Health Organization (WHO) and Center for Disease Control (CDC) insecticide susceptibility bioassays. Mosquito species determination was done using PCR and Plasmodium falciparum infection in mosquitoes was assessed by ELISA targeting circumsporozoite protein. RESULTS Of 3517 Anopheles spp. mosquitoes collected, Anopheles gambiae sensu lato (s.l.) (29.6%) and Anopheles funestus (69.1%) were the main malaria vectors. Plasmodium falciparum infection rates for An. gambiae s.l. were 1.0, 2.1 and 13.9% for Shamwana, Baraka and Kashuga, respectively. Anopheles funestus showed positivity rates of 1.6% in Shamwana and 4.4% in Baraka. No An. funestus were collected in Kashuga. Insecticide susceptibility tests showed resistance development towards pyrethroids in all locations. Exposure to bendiocarb, malathion and pirimiphos-methyl still resulted in high mosquito mortality. CONCLUSIONS This is one of only few studies from these conflict areas in DRC to report insecticide resistance in local malaria vectors. The data suggest that current malaria prevention methods in these populations are only partially effective, and require additional tools and strategies. Importantly, the results triggered MSF to consider the selection of a new insecticide for indoor residual spraying (IRS) and a new long-lasting insecticide-treated net (LLIN). The reinforcement of correct usage of LLINs and the introduction of targeted larviciding were also included as additional vector control tools as a result of the studies.
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Affiliation(s)
| | - Dominic B Dery
- Médecins Sans Frontières (MSF), Amsterdam, The Netherlands
| | - Bertin Z Musaka
- Département de Biologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Bukavu, South Kivu, Democratic Republic of the Congo
| | - Janvier B Bandibabone
- Département de Biologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Bukavu, South Kivu, Democratic Republic of the Congo
| | - Teun Bousema
- Department of Medical Microbiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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28
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Graumans W, Jacobs E, Bousema T, Sinnis P. When Is a Plasmodium-Infected Mosquito an Infectious Mosquito? Trends Parasitol 2020; 36:705-716. [PMID: 32620501 DOI: 10.1016/j.pt.2020.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/19/2022]
Abstract
Plasmodium parasites experience significant bottlenecks as they transit through the mosquito and are transmitted to their mammalian host. Oocyst prevalence on mosquito midguts and sporozoite prevalence in salivary glands are nevertheless commonly used to confirm successful malaria transmission, assuming that these are reliable indicators of the mosquito's capacity to give rise to secondary infections. Here we discuss recent insights in sporogonic development and transmission bottlenecks for Plasmodium. We highlight critical gaps in our knowledge and frame their importance in understanding the human and mosquito reservoirs of infection. A better understanding of the events that lead to successful inoculation of infectious sporozoites by mosquitoes is critical to designing effective interventions to shrink the malaria map.
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Affiliation(s)
- Wouter Graumans
- Radboud University Medical Center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Ella Jacobs
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Teun Bousema
- Radboud University Medical Center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands; Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
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Choi R, Michaels SA, Onu EC, Hulverson MA, Saha A, Coker ME, Weeks JC, Van Voorhis WC, Ojo KK. Taming the Boys for Global Good: Contraceptive Strategy to Stop Malaria Transmission. Molecules 2020; 25:molecules25122773. [PMID: 32560085 PMCID: PMC7356879 DOI: 10.3390/molecules25122773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/10/2020] [Accepted: 06/14/2020] [Indexed: 12/21/2022] Open
Abstract
Transmission of human malaria parasites (Plasmodium spp.) by Anopheles mosquitoes is a continuous process that presents a formidable challenge for effective control of the disease. Infectious gametocytes continue to circulate in humans for up to four weeks after antimalarial drug treatment, permitting prolonged transmission to mosquitoes even after clinical cure. Almost all reported malaria cases are transmitted to humans by mosquitoes, and therefore decreasing the rate of Plasmodium transmission from humans to mosquitoes with novel transmission-blocking remedies would be an important complement to other interventions in reducing malaria incidence.
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Affiliation(s)
- Ryan Choi
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Samantha A. Michaels
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Emmanuel C. Onu
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria; (E.C.O.); (M.E.C.)
| | - Matthew A. Hulverson
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Aparajita Saha
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Morenike E. Coker
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria; (E.C.O.); (M.E.C.)
| | - Janis C. Weeks
- Department of Biology, University of Oregon, Eugene, OR 97403, USA;
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Kayode K. Ojo
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
- Correspondence: ; Tel.: +1-206-543-0821
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Chali W, Ashine T, Hailemeskel E, Gashaw A, Tafesse T, Lanke K, Esayas E, Kedir S, Shumie G, Behaksra SW, Bradley J, Yewhalaw D, Mamo H, Petros B, Drakeley C, Gadisa E, Bousema T, Tadesse FG. Comparison of infectivity of Plasmodium vivax to wild-caught and laboratory-adapted (colonized) Anopheles arabiensis mosquitoes in Ethiopia. Parasit Vectors 2020; 13:120. [PMID: 32143713 PMCID: PMC7059271 DOI: 10.1186/s13071-020-3998-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/26/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mosquito-feeding assays that assess transmission of Plasmodium from man-to-mosquito typically use laboratory mosquito colonies. The microbiome and genetic background of local mosquitoes may be different and influence Plasmodium transmission efficiency. In order to interpret transmission studies to the local epidemiology, it is therefore crucial to understand the relationship between infectivity in laboratory-adapted and local mosquitoes. METHODS We assessed infectivity of Plasmodium vivax-infected patients from Adama, Ethiopia, using laboratory-adapted (colony) and wild-caught (wild) mosquitoes raised from larval collections in paired feeding experiments. Feeding assays used 4-6 day-old female Anopheles arabiensis mosquitoes after starvation for 12 h (colony) and 18 h (wild). Oocyst development was assessed microscopically 7 days post-feeding. Wild mosquitoes were identified morphologically and confirmed by genotyping. Asexual parasites and gametocytes were quantified in donor blood by microscopy. RESULTS In 36 paired experiments (25 P. vivax infections and 11 co-infections with P. falciparum), feeding efficiency was higher in colony (median: 62.5%; interquartile range, IQR: 47.0-79.0%) compared to wild mosquitoes (median: 27.8%; IQR: 17.0-38.0%; Z = 5.02; P < 0.001). Plasmodium vivax from infectious individuals (51.6%, 16/31) infected a median of 55.0% (IQR: 6.7-85.7%; range: 5.5-96.7%; n = 14) of the colony and 52.7% (IQR: 20.0-80.0%; range: 3.2-95.0%; n = 14) of the wild mosquitoes. A strong association (ρ(16) = 0.819; P < 0.001) was observed between the proportion of infected wild and colony mosquitoes. A positive association was detected between microscopically detected gametocytes and the proportion of infected colony (ρ(31) = 0.452; P = 0.011) and wild (ρ(31) = 0.386; P = 0.032) mosquitoes. CONCLUSIONS Infectivity assessments with colony and wild mosquitoes yielded similar infection results. This finding supports the use of colony mosquitoes for assessments of the infectious reservoir for malaria in this setting whilst acknowledging the importance of mosquito factors influencing sporogonic development of Plasmodium parasites.
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Affiliation(s)
- Wakweya Chali
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Temesgen Ashine
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Elifaged Hailemeskel
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia.,Department of Microbial, Cellular and Molecular Biology, College of Natural and Computational Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia.,Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Abrham Gashaw
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Temesgen Tafesse
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Endashaw Esayas
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Soriya Kedir
- Oromia Regional Laboratory, Oromia Regional Health Bureau, Adama, Ethiopia
| | - Girma Shumie
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Sinknesh Wolde Behaksra
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - John Bradley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Delenasaw Yewhalaw
- Tropical and Infectious Diseases Research Center, Jimma University, P.O.Box 5195, Jimma, Ethiopia
| | - Hassen Mamo
- Department of Microbial, Cellular and Molecular Biology, College of Natural and Computational Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular and Molecular Biology, College of Natural and Computational Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Endalamaw Gadisa
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Fitsum G Tadesse
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia. .,Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands. .,Institute of Biotechnology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia.
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31
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Lampe L, Jentzsch M, Kierszniowska S, Levashina EA. Metabolic balancing by miR-276 shapes the mosquito reproductive cycle and Plasmodium falciparum development. Nat Commun 2019; 10:5634. [PMID: 31822677 PMCID: PMC6904670 DOI: 10.1038/s41467-019-13627-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 11/14/2019] [Indexed: 12/21/2022] Open
Abstract
The blood-feeding behavior of Anopheles females delivers essential nutrients for egg development and drives parasite transmission between humans. Plasmodium growth is adapted to the vector reproductive cycle, but how changes in the reproductive cycle impact parasite development remains unclear. Here, we show that the bloodmeal-induced miR-276-5p fine-tunes the expression of branched-chain amino acid transferase to terminate the reproductive cycle. Silencing of miR-276 prolongs high rates of amino acid (AA) catabolism and increases female fertility, suggesting that timely termination of AA catabolism restricts mosquito investment into reproduction. Prolongation of AA catabolism in P. falciparum-infected females also compromises the development of the transmissible sporozoite forms. Our results suggest that Plasmodium sporogony exploits the surplus mosquito resources available after reproductive investment and demonstrate the crucial role of the mosquito AA metabolism in within-vector parasite proliferation and malaria transmission. Plasmodium growth is adapted to the reproductive cycle of mosquitoes, but underlying mechanisms are unclear. Here, Lampe et al. show that the blood-meal induced miR-276 balances the termination of the mosquito amino acid catabolism and egg development, providing nutrients for Plasmodium sporozoite development.
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Affiliation(s)
- Lena Lampe
- Vector Biology Unit, Max Planck Institute for Infection Biology, Charitéplatz 1, 10117, Berlin, Germany.,Physiology and Metabolism Laboratory, Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Marius Jentzsch
- Vector Biology Unit, Max Planck Institute for Infection Biology, Charitéplatz 1, 10117, Berlin, Germany
| | | | - Elena A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology, Charitéplatz 1, 10117, Berlin, Germany.
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32
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Pathak AK, Shiau JC, Thomas MB, Murdock CC. Field Relevant Variation in Ambient Temperature Modifies Density-Dependent Establishment of Plasmodium falciparum Gametocytes in Mosquitoes. Front Microbiol 2019; 10:2651. [PMID: 31803169 PMCID: PMC6873802 DOI: 10.3389/fmicb.2019.02651] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/30/2019] [Indexed: 12/29/2022] Open
Abstract
The relationship between Plasmodium falciparum gametocyte density and infections in mosquitoes is central to understanding the rates of transmission with important implications for control. Here, we determined whether field relevant variation in environmental temperature could also modulate this relationship. Anopheles stephensi were challenged with three densities of P. falciparum gametocytes spanning a ~10-fold gradient, and housed under diurnal/daily temperature range ("DTR") of 9°C (+5°C and -4°C) around means of 20, 24, and 28°C. Vector competence was quantified as the proportion of mosquitoes infected with oocysts in the midguts (oocyst rates) or infectious with sporozoites in the salivary glands (sporozoite rates) at peak periods of infection for each temperature to account for the differences in development rates. In addition, oocyst intensities were also recorded from infected midguts and the overall study replicated across three separate parasite cultures and mosquito cohorts. While vector competence was similar at 20 DTR 9°C and 24 DTR 9°C, oocyst and sporozoite rates were also comparable, with evidence, surprisingly, for higher vector competence in mosquitoes challenged with intermediate gametocyte densities. For the same gametocyte densities however, severe reductions in the sporozoite rates was accompanied by a significant decline in overall vector competence at 28 DTR 9°C, with gametocyte density per se showing a positive and linear effect at this temperature. Unlike vector competence, oocyst intensities decreased with increasing temperatures with a predominantly positive and linear association with gametocyte density, especially at 28 DTR 9°C. Oocyst intensities across individual infected midguts suggested temperature-specific differences in mosquito susceptibility/resistance: at 20 DTR 9°C and 24 DTR 9°C, dispersion (aggregation) increased in a density-dependent manner but not at 28 DTR 9°C where the distributions were consistently random. Limitations notwithstanding, our results suggest that variation in temperature could modify seasonal dynamics of infectious reservoirs with implications for the design and deployment of transmission-blocking vaccines/drugs.
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Affiliation(s)
- Ashutosh K. Pathak
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
- Center for Ecology of Infectious Diseases, University of Georgia, Athens, GA, United States
- Center for Tropical Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Justine C. Shiau
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Matthew B. Thomas
- The Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, United States
| | - Courtney C. Murdock
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
- Center for Ecology of Infectious Diseases, University of Georgia, Athens, GA, United States
- Center for Tropical Emerging Global Diseases, University of Georgia, Athens, GA, United States
- Odum School of Ecology, University of Georgia, Athens, GA, United States
- Center for Vaccines and Immunology, University of Georgia, Athens, GA, United States
- Riverbasin Center, University of Georgia, Athens, GA, United States
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33
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Is that a real oocyst? Insectary establishment and identification of Plasmodium falciparum oocysts in midguts of Anopheles mosquitoes fed on infected human blood in Tororo, Uganda. Malar J 2019; 18:287. [PMID: 31455343 PMCID: PMC6712792 DOI: 10.1186/s12936-019-2922-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 08/17/2019] [Indexed: 11/23/2022] Open
Abstract
Background The human infectious reservoir for malaria consists of individuals capable of infecting mosquitoes. Oocyst prevalence and density are typical indicators of human infectivity to mosquitoes. However, identification of oocysts is challenging, particularly in areas of low malaria transmission intensity where few individuals may infect mosquitoes, and infected mosquitoes tend to have few oocysts. Here, features that differentiate oocysts from other oocyst-like in mosquito midguts are explained and illustrated. In addition, the establishment and maintenance of infrastructure to perform malaria transmission experiments is described. This work may support other initiatives to set up membrane feeding infrastructure and guide oocyst detection in low transmission settings. Methods In 2014, an insectary was developed and equipped in Tororo district, Uganda. A colony of Anopheles gambiae s.s. mosquitoes (Kisumu strain) was initiated to support infectivity experiments from participants enrolled in a large cohort study. Venous blood drawn from participants who were naturally infected with malaria parasites was used for membrane feeding assays, using 60–80 mosquitoes per experiment. Approximately 9–10 days after feeding, mosquitoes were dissected, and midguts were stained in mercurochrome and examined by light microscopy for Plasmodium falciparum oocysts and similar structures. In supportive experiments, different staining procedures were compared using in vitro cultured parasites. Results A stable colony of the Kisumu strain of An. gambiae s.s. was achieved, producing 5000–10,000 adult mosquitoes on a weekly basis. Challenges due to temperature fluctuations, mosquito pathogens and pests were successfully overcome. Oocysts were characterized by: presence of malaria pigment, clearly defined edge, round shape within the mosquito midgut or on the peripheral tissue and always attached to the epithelium. The main distinguishing feature between artifacts and mature oocysts was the presence of defined pigment within the oocysts. Conclusions Oocysts may be mistaken for other structures in mosquito midguts. Distinguishing real oocysts from oocyst-like structures may be challenging for inexperienced microscopists due to overlapping features. The characteristics and guidelines outlined here support identification of oocysts and reliable detection at low oocyst densities. Practical advice on sustaining a healthy mosquito colony for feeding experiments is provided. Following the reported optimization, the established infrastructure in Tororo allows assessments of infectivity of naturally infected parasite carriers.
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34
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Ramírez AL, van den Hurk AF, Mackay IM, Yang ASP, Hewitson GR, McMahon JL, Boddey JA, Ritchie SA, Erickson SM. Malaria surveillance from both ends: concurrent detection of Plasmodium falciparum in saliva and excreta harvested from Anopheles mosquitoes. Parasit Vectors 2019; 12:355. [PMID: 31319880 PMCID: PMC6639908 DOI: 10.1186/s13071-019-3610-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 07/08/2019] [Indexed: 12/03/2022] Open
Abstract
Background Malaria is the most important vector-borne disease in the world. Epidemiological and ecological studies of malaria traditionally utilize detection of Plasmodium sporozoites in whole mosquitoes or salivary glands by microscopy or serological or molecular assays. However, these methods are labor-intensive, and can over- or underestimate mosquito transmission potential. To overcome these limitations, alternative sample types have been evaluated for the study of malaria. It was recently shown that Plasmodium could be detected in saliva expectorated on honey-soaked cards by Anopheles stephensi, providing a better estimate of transmission risk. We evaluated whether excretion of Plasmodium falciparum nucleic acid by An. stephensi correlates with expectoration of parasites in saliva, thus providing an additional sample type for estimating transmission potential. Mosquitoes were exposed to infectious blood meals containing cultured gametocytes, and excreta collected at different time points post-exposure. Saliva was collected on honey-soaked filter paper cards, and salivary glands were dissected and examined microscopically for sporozoites. Excreta and saliva samples were tested by real time polymerase chain reaction (RT-rtPCR). Results Plasmodium falciparum RNA was detected in mosquito excreta as early as four days after ingesting a bloodmeal containing gametocytes. Once sporogony (the development of sporozoites) occurred, P. falciparum RNA was detected concurrently in both excreta and saliva samples. In the majority of cases, no difference was observed between the Ct values obtained from matched excreta and saliva samples, suggesting that both samples provide equally sensitive results. A positive association was observed between the molecular detection of the parasites in both samples and the proportion of mosquitoes with sporozoites in their salivary glands from each container. No distinguishable parasites were observed when excreta samples were stained and microscopically analyzed. Conclusions Mosquito saliva and excreta are easily collected and are promising for surveillance of malaria-causing parasites, especially in low transmission settings or in places where arboviruses co-circulate. Electronic supplementary material The online version of this article (10.1186/s13071-019-3610-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ana L Ramírez
- College of Public Health, Medical and Veterinary Sciences, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia. .,Australian Institute of Tropical Health and Medicine, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia.
| | - Andrew F van den Hurk
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, QLD, 4108, Australia
| | - Ian M Mackay
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, QLD, 4108, Australia
| | - Annie S P Yang
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3052, Australia.,Department of Medical Microbiology Parasitology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB, Nijmegen, The Netherlands
| | - Glen R Hewitson
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, QLD, 4108, Australia
| | - Jamie L McMahon
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, QLD, 4108, Australia
| | - Justin A Boddey
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3052, Australia
| | - Scott A Ritchie
- College of Public Health, Medical and Veterinary Sciences, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia.,Australian Institute of Tropical Health and Medicine, James Cook University, PO Box 6811, Cairns, QLD, 4870, Australia
| | - Sara M Erickson
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3052, Australia
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35
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Miura K, Swihart BJ, Deng B, Zhou L, Pham TP, Diouf A, Fay MP, Long CA. Strong concordance between percent inhibition in oocyst and sporozoite intensities in a Plasmodium falciparum standard membrane-feeding assay. Parasit Vectors 2019; 12:206. [PMID: 31060594 PMCID: PMC6501457 DOI: 10.1186/s13071-019-3470-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/29/2019] [Indexed: 11/22/2022] Open
Abstract
Background Effective malaria transmission-blocking vaccines (TBVs) can support malaria eradication programmes, and the standard membrane-feeding assay (SMFA) has been used as a “gold standard” assay for TBV development. However, in SMFA, the inhibitory activity is commonly measured at oocyst stage of parasites, while it is the sporozoites which transmit malaria from a mosquito to a human. A handful of studies have shown that there is a positive correlation between oocyst and sporozoite intensities. However, no study has been completed to compare inhibition levels in oocyst and sporozoite intensities in the presence of transmission-blocking (TB) antibodies. Results Plasmodium falciparum NF54 gametocytes were fed to Anopheles stephensi mosquitoes with or without anti-Pfs25 or anti-Pfs48/45 TB antibodies in 15 independent assays. For each group, a portion of the mosquitoes was dissected for oocyst counts (day 8 after feed), and a portion of the remaining mosquitoes was dissected for sporozoite counts (day 16). This study covered a large range of oocyst and sporozoite intensities: 0.2 to 80.5 on average for oocysts, and 141 to 77,417 for sporozoites. The sporozoite data were well explained by a zero-inflated negative binomial model, regardless of the presence or absence of TB antibodies. Inhibition levels in both oocyst and sporozoite intensities were determined within the same groups in 9 independent assays. When the level of inhibition in sporozoite number (expressed as Log Mean Ratio, LMR; average number in a control group was divided by the one in a test group, then took a log of the ratio) was plotted against LMR in oocyst number, the best-fit slope of a linear regression was not different from 1 (the best estimate, 1.08; 95% confidence interval, 0.87 to 1.29). Furthermore, a Bland–Altman analysis showed a strong agreement between inhibitions in oocysts and in sporozoites. Conclusions The results indicate that percent inhibition in oocyst intensity of a test sample can be directly converted to % inhibition in sporozoite intensity in P. falciparum SMFA. Therefore, if sporozoite intensity determines transmission rate from mosquitoes to humans, the percent inhibition in oocyst intensity measured by SMFA can be used to estimate the TBV efficacy. Electronic supplementary material The online version of this article (10.1186/s13071-019-3470-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA.
| | - Bruce J Swihart
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 5601 Fishers Lane, Rockville, MD, 20852, USA
| | - Bingbing Deng
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Luwen Zhou
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Thao P Pham
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Michael P Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 5601 Fishers Lane, Rockville, MD, 20852, USA
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
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Slater HC, Ross A, Felger I, Hofmann NE, Robinson L, Cook J, Gonçalves BP, Björkman A, Ouedraogo AL, Morris U, Msellem M, Koepfli C, Mueller I, Tadesse F, Gadisa E, Das S, Domingo G, Kapulu M, Midega J, Owusu-Agyei S, Nabet C, Piarroux R, Doumbo O, Doumbo SN, Koram K, Lucchi N, Udhayakumar V, Mosha J, Tiono A, Chandramohan D, Gosling R, Mwingira F, Sauerwein R, Paul R, Riley EM, White NJ, Nosten F, Imwong M, Bousema T, Drakeley C, Okell LC. The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density. Nat Commun 2019; 10:1433. [PMID: 30926893 PMCID: PMC6440965 DOI: 10.1038/s41467-019-09441-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 03/07/2019] [Indexed: 02/08/2023] Open
Abstract
Malaria infections occurring below the limit of detection of standard diagnostics are common in all endemic settings. However, key questions remain surrounding their contribution to sustaining transmission and whether they need to be detected and targeted to achieve malaria elimination. In this study we analyse a range of malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections. Asymptomatically infected individuals have lower parasite densities on average in low transmission settings compared to individuals in higher transmission settings. In cohort studies, subpatent infections are found to be predictive of future periods of patent infection and in membrane feeding studies, individuals infected with subpatent asexual parasite densities are found to be approximately a third as infectious to mosquitoes as individuals with patent (asexual parasite) infection. These results indicate that subpatent infections contribute to the infectious reservoir, may be long lasting, and require more sensitive diagnostics to detect them in lower transmission settings. The role of subpatent infections for malaria transmission and elimination is unclear. Here, Slater et al. analyse several malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections.
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Affiliation(s)
- Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK.
| | - Amanda Ross
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland.,University of Basel, Basel, 4001, Switzerland
| | - Ingrid Felger
- University of Basel, Basel, 4001, Switzerland.,Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland
| | - Natalie E Hofmann
- University of Basel, Basel, 4001, Switzerland.,Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland
| | - Leanne Robinson
- Vector-borne Diseases Unit, Papua New Guinea Institute for Medical Research, Madang, Papua New Guinea.,Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia.,Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia.,Disease Elimination, Burnet Institute, Melbourne, 3004, VIC, Australia
| | - Jackie Cook
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Anders Björkman
- Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Andre Lin Ouedraogo
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso.,Institute for Disease Modeling, Intellectual Ventures, Bellevue, 98005, Washington, USA
| | - Ulrika Morris
- Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Mwinyi Msellem
- Department of Training and Research, Mnazi Mmoja Hospital, Zanzibar, Tanzania
| | - Cristian Koepfli
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, 3052, Victoria, Australia.,Department of Biological Sciences, University of Notre Dame, Indiana, 46556, USA
| | - Ivo Mueller
- Division of Population Health and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, VIC, Australia.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, 75015, France.,Medical Biology, University of Melbourne, Melbourne, 3010, VIC, Australia
| | - Fitsum Tadesse
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands.,Armauer Hansen Research Institute, Addis Ababa, Ethiopia.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | - Smita Das
- Diagnostics Program, PATH, Seattle, Washington, 98121, United States of America
| | - Gonzalo Domingo
- Diagnostics Program, PATH, Seattle, Washington, 98121, United States of America
| | - Melissa Kapulu
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya, Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Janet Midega
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya, Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Seth Owusu-Agyei
- Institute of Health, University of Health and Allied Sciences, Hohoe, PMB 31, Ghana
| | - Cécile Nabet
- Sorbonne Université, INSERM, Institut Pierre-Louis d'Epidémiologie et de Santé Publique, AP- HP, Groupe Hospitalier Pitié-Salpêtrière, Service de Parasitologie-Mycologie, Paris, 75646, France
| | - Renaud Piarroux
- Sorbonne Université, INSERM, Institut Pierre-Louis d'Epidémiologie et de Santé Publique, AP- HP, Groupe Hospitalier Pitié-Salpêtrière, Service de Parasitologie-Mycologie, Paris, 75646, France
| | - Ogobara Doumbo
- Malaria Research and Training Centre, Parasitic Diseases Epidemiology Department, UMI 3189, University of Sciences, Technique and Technology, Bamako, Mali
| | - Safiatou Niare Doumbo
- Malaria Research and Training Centre, Parasitic Diseases Epidemiology Department, UMI 3189, University of Sciences, Technique and Technology, Bamako, Mali
| | - Kwadwo Koram
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Naomi Lucchi
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, 30030, GA, United States of America
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, 30030, GA, United States of America
| | - Jacklin Mosha
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Alfred Tiono
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Daniel Chandramohan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, 94158, CA, United States
| | - Felista Mwingira
- Biological Sciences Department, Dar es Salaam University College of Education, P. O. Box 2329, Dar es Salaam, Tanzania
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands
| | - Richard Paul
- Institut Pasteur de Dakar, Laboratoire d'Entomologie Médicale, Dakar, Senegal
| | - Eleanor M Riley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Nicholas J White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK.,Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, 63110, Thailand
| | - Mallika Imwong
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.,Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, 6525, The Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK
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Ndo C, Kopya E, Irving H, Wondji C. Exploring the impact of glutathione S-transferase (GST)-based metabolic resistance to insecticide on vector competence of Anopheles funestus for Plasmodium falciparum. Wellcome Open Res 2019; 4:52. [PMID: 31976375 PMCID: PMC6957023 DOI: 10.12688/wellcomeopenres.15061.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2019] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria control heavily relies on insecticide-based interventions against mosquito vectors. However, the increasing spread of insecticide resistance is a major threat. The extent to which such resistance, notably metabolic resistance, influences the development of the
Plasmodium parasite and its impact on overall malaria transmission remains poorly characterized. Here, we investigated whether glutathione S-transferase-based resistance could influence
Plasmodium falciparum development in
Anopheles funestus. Methods: Anopheles funestus females were infected with
P. falciparum gametocytes and midguts were dissected at day 7 post infection for detection/quantification of oocysts. Infection parameters were compared between individuals with different L119F-GSTe2 genotypes, and the polymorphism of the GSTe2 gene was analyzed in infected and uninfected mosquito groups. Results: Overall, 403
An. funestus mosquitoes were dissected and genotyped. The frequency of the L119F-GSTe2 resistance allele was significantly higher in non-infected (55.88%) compared to infected (40.99%) mosquitoes (Fisher's exact test, P<0.0001). Prevalence of infection was significantly higher in heterozygous and homozygous susceptible genotypes (P<0.001). However, homozygous resistant and heterozygous mosquitoes exhibited significantly higher infection intensity (P<0.01). No association was observed between the GSTe2 polymorphism and the infection status of mosquitoes. Conclusion: Altogether, these results suggest that GSTe2-based metabolic resistance may affect the vectorial competence of resistant
An. funestus mosquitoes to
P. falciparum infection, by possibly increasing its permissiveness to
Plasmodium infection.
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Affiliation(s)
- Cyrille Ndo
- Department of parasitology, Centre for Research in Infectious Disease (CRID), Yaoundé, P.O. Box 13591, Cameroon.,Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, P.O. Box 24157, Cameroon.,Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.,Institut de recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, P.O. Box 288, Cameroon
| | - Edmond Kopya
- Institut de recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, P.O. Box 288, Cameroon.,Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, Yaoundé, P.O. Box 337, Cameroon
| | - Helen Irving
- Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Charles Wondji
- Department of parasitology, Centre for Research in Infectious Disease (CRID), Yaoundé, P.O. Box 13591, Cameroon.,Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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38
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Ndo C, Kopya E, Irving H, Wondji C. Exploring the impact of glutathione S-transferase (GST)-based metabolic resistance to insecticide on vector competence of Anopheles funestus for Plasmodium falciparum. Wellcome Open Res 2019. [DOI: 10.12688/wellcomeopenres.15061.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background:Malaria control heavily relies on insecticide-based interventions against mosquito vectors. However, the increasing spread of insecticide resistance is a major threat. The extent to which such resistance, notably metabolic resistance, interferes with the development of thePlasmodiumparasite and its impact on overall malaria transmission remains poorly characterized. Here, we investigated whether glutathione S-transferase-based resistance could influencePlasmodium falciparumdevelopment inAnopheles funestus.Methods:Anopheles funestusfemales were infected withP. falciparumgametocytes and midguts were dissected at day 7 post infection for detection/quantification of oocysts. Infection parameters were compared between individual with different L119F-GSTe2 genotypes, and the polymorphism of the GSTe2 gene was analyzed in infected and uninfected mosquito groups.Results:Overall, 403 mosquitoes were dissected and genotyped. The frequency of the L119F-GSTe2 resistance allele was significantly higher in non-infected (55.88%) compared to infected (40.99%) mosquitoes (Fisher's exact test, P<0.0001). Prevalence of infection was significantly higher in heterozygous and homozygous susceptible genotypes (P<0.001). However, homozygous resistant and heterozygous mosquitoes exhibited significantly higher infection intensity (P<0.01). No association was observed between the GSTe2 polymorphism and the infection status of mosquitoes.Conclusion:Altogether, these results suggest that GSTe2-based metabolic resistance may affect the vectorial competence of resistantAn. funestusmosquitoes toP. falciparuminfection, by increasing its permissiveness toPlasmodiuminfection.
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39
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Assessing Plasmodium falciparum transmission in mosquito-feeding assays using quantitative PCR. Malar J 2018; 17:249. [PMID: 29976199 PMCID: PMC6034226 DOI: 10.1186/s12936-018-2382-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/09/2018] [Indexed: 12/29/2022] Open
Abstract
Background Evaluating the efficacy of transmission-blocking interventions relies on mosquito-feeding assays, with transmission typically assessed by microscopic identification of oocysts in mosquito midguts; however, microscopy has limited throughput, sensitivity and specificity. Where low prevalence and intensity mosquito infections occur, as observed during controlled human malaria infection studies or natural transmission, a reliable method for detection and quantification of low-level midgut infection is required. Here, a semi-automated, Taqman quantitative PCR (qPCR) assay sufficiently sensitive to detect a single-oocyst midgut infection is described. Results Extraction of genomic DNA from Anopheles stephensi midguts using a semi-automated extraction process was shown to have equivalent extraction efficiency to manual DNA extraction. An 18S Plasmodium falciparum qPCR assay was adapted for quantitative detection of P. falciparum midgut oocyst infection using synthetic DNA standards. The assay was validated for sensitivity and specificity, and the limit of detection was 0.7 genomes/µL (95% CI 0.4–1.6 genomes/µL). All microscopy-confirmed oocyst infected midgut samples were detected by qPCR, including all single-oocyst positive midguts. The genome number per oocyst was assessed 8–9 days after feeding assay using both qPCR and droplet digital PCR and was 3722 (IQR: 2951–5453) and 3490 (IQR: 2720–4182), respectively. Conclusions This semi-automated qPCR method enables accurate detection of low-level P. falciparum oocyst infections in mosquito midguts, and may improve the sensitivity, specificity and throughput of assays used to evaluate candidate transmission-blocking interventions. Electronic supplementary material The online version of this article (10.1186/s12936-018-2382-6) contains supplementary material, which is available to authorized users.
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40
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Esperança PM, Blagborough AM, Da DF, Dowell FE, Churcher TS. Detection of Plasmodium berghei infected Anopheles stephensi using near-infrared spectroscopy. Parasit Vectors 2018; 11:377. [PMID: 29954424 PMCID: PMC6027764 DOI: 10.1186/s13071-018-2960-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 06/18/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The proportion of mosquitoes infected with malaria is an important entomological metric used to assess the intensity of transmission and the impact of vector control interventions. Currently, the prevalence of mosquitoes with salivary gland sporozoites is estimated by dissecting mosquitoes under a microscope or using molecular methods. These techniques are laborious, subjective, and require either expensive equipment or training. This study evaluates the potential of near-infrared spectroscopy (NIRS) to identify laboratory reared mosquitoes infected with rodent malaria. METHODS Anopheles stephensi mosquitoes were reared in the laboratory and fed on Plasmodium berghei infected blood. After 12 and 21 days post-feeding mosquitoes were killed, scanned and analysed using NIRS and immediately dissected by microscopy to determine the number of oocysts on the midgut wall or sporozoites in the salivary glands. A predictive classification model was used to determine parasite prevalence and intensity status from spectra. RESULTS The predictive model correctly classifies infectious and uninfectious mosquitoes with an overall accuracy of 72%. The false negative and false positive rates were 30 and 26%, respectively. While NIRS was able to differentiate between uninfectious and highly infectious mosquitoes, differentiating between mid-range infectious groups was less accurate. Multiple scans of the same specimen, with repositioning the mosquito between scans, is shown to improve accuracy. On a smaller dataset NIRS was unable to predict whether mosquitoes harboured oocysts. CONCLUSIONS To our knowledge, we provide the first evidence that NIRS can differentiate between infectious and uninfectious mosquitoes. Currently, distinguishing between different intensities of infection is challenging. The classification model provides a flexible framework and allows for different error rates to be optimised, enabling the sensitivity and specificity of the technique to be varied according to requirements.
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Affiliation(s)
- Pedro M. Esperança
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG UK
| | - Andrew M. Blagborough
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ UK
| | - Dari F. Da
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 Avenue de la liberté, Bobo Dioulasso, 01 01 BP 545 Burkina Faso
| | - Floyd E. Dowell
- USDA, Agricultural Research Service, Center for Grain and Animal Health Research, 1515 College Avenue, Manhattan, KS 66502 USA
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG UK
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41
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Grignard L, Gonçalves BP, Early AM, Daniels RF, Tiono AB, Guelbéogo WM, Ouédraogo A, van Veen EM, Lanke K, Diarra A, Nebie I, Sirima SB, Targett GA, Volkman SK, Neafsey DE, Wirth DF, Bousema T, Drakeley C. Transmission of molecularly undetectable circulating parasite clones leads to high infection complexity in mosquitoes post feeding. Int J Parasitol 2018; 48:671-677. [PMID: 29738740 PMCID: PMC6018601 DOI: 10.1016/j.ijpara.2018.02.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 01/04/2018] [Accepted: 02/26/2018] [Indexed: 11/24/2022]
Abstract
Additional parasite alleles were consistently identified in mosquitoes compared with the human blood sample they had fed on. Assessments of Plasmodium falciparum complexity relying on single time-point collections miss transmissible clones. Low-density gametocyte – producing clones are capable of successfully establishing infections in mosquitoes.
Plasmodium falciparum malaria infections often comprise multiple distinct parasite clones. Few datasets have directly assessed infection complexity in humans and mosquitoes they infect. Examining parasites using molecular tools may provide insights into the selective transmissibility of isolates. Using capillary electrophoresis genotyping and next generation amplicon sequencing, we analysed complexity of parasite infections in human blood and in the midguts of mosquitoes that became infected in membrane feeding experiments using the same blood material in two West African settings. Median numbers of clones in humans and mosquitoes were higher in samples from Burkina Faso (4.5, interquartile range 2–8 for humans; and 2, interquartile range 1–3 for mosquitoes) than in The Gambia (2, interquartile range 1–3 and 1, interquartile range 1–3, for humans and mosquitoes, respectively). Whilst the median number of clones was commonly higher in human blood samples, not all transmitted alleles were detectable in the human peripheral blood. In both study sample sets, additional parasite alleles were identified in mosquitoes compared with the matched human samples (10–88.9% of all clones/feeding assay, n = 73 feeding assays). The results are likely due to preferential amplification of the most abundant clones in peripheral blood but confirm the presence of low density clones that produce transmissible sexual stage parasites.
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Affiliation(s)
- Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK.
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | | | - Rachel F Daniels
- Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Alfred B Tiono
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Wamdaogo M Guelbéogo
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Alphonse Ouédraogo
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Elke M van Veen
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Amidou Diarra
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issa Nebie
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Sodiomon B Sirima
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Geoff A Targett
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Sarah K Volkman
- Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA; School of Nursing and Health Sciences, Simmons College, Boston, MA, USA
| | | | - Dyann F Wirth
- Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
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Reuling IJ, van de Schans LA, Coffeng LE, Lanke K, Meerstein-Kessel L, Graumans W, van Gemert GJ, Teelen K, Siebelink-Stoter R, van de Vegte-Bolmer M, de Mast Q, van der Ven AJ, Ivinson K, Hermsen CC, de Vlas S, Bradley J, Collins KA, Ockenhouse CF, McCarthy J, Sauerwein RW, Bousema T. A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model. eLife 2018; 7:31549. [PMID: 29482720 PMCID: PMC5828662 DOI: 10.7554/elife.31549] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/14/2018] [Indexed: 12/16/2022] Open
Abstract
Background Malaria elimination strategies require a thorough understanding of parasite transmission from human to mosquito. A clinical model to induce gametocytes to understand their dynamics and evaluate transmission-blocking interventions (TBI) is currently unavailable. Here, we explore the use of the well-established Controlled Human Malaria Infection model (CHMI) to induce gametocyte carriage with different antimalarial drug regimens. Methods In a single centre, open-label randomised trial, healthy malaria-naive participants (aged 18–35 years) were infected with Plasmodium falciparum by bites of infected Anopheles mosquitoes. Participants were randomly allocated to four different treatment arms (n = 4 per arm) comprising low-dose (LD) piperaquine (PIP) or sulfadoxine-pyrimethamine (SP), followed by a curative regimen upon recrudescence. Male and female gametocyte densities were determined by molecular assays. Results Mature gametocytes were observed in all participants (16/16, 100%). Gametocytes appeared 8.5–12 days after the first detection of asexual parasites. Peak gametocyte densities and gametocyte burden was highest in the LD-PIP/SP arm, and associated with the preceding asexual parasite biomass (p=0.026). Male gametocytes had a mean estimated circulation time of 2.7 days (95% CI 1.5–3.9) compared to 5.1 days (95% CI 4.1–6.1) for female gametocytes. Exploratory mosquito feeding assays showed successful sporadic mosquito infections. There were no serious adverse events or significant differences in the occurrence and severity of adverse events between study arms (p=0.49 and p=0.28). Conclusions The early appearance of gametocytes indicates gametocyte commitment during the first wave of asexual parasites emerging from the liver. Treatment by LD-PIP followed by a curative SP regimen, results in the highest gametocyte densities and the largest number of gametocyte-positive days. This model can be used to evaluate the effect of drugs and vaccines on gametocyte dynamics, and lays the foundation for fulfilling the critical unmet need to evaluate transmission-blocking interventions against falciparum malaria for downstream selection and clinical development. Funding Funded by PATH Malaria Vaccine Initiative (MVI). Clinical trial number NCT02836002.
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Affiliation(s)
- Isaie J Reuling
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Lisanne A van de Schans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Wouter Graumans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Quirijn de Mast
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - André J van der Ven
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Karen Ivinson
- PATH Malaria Vaccine Initiative, Washington, United States
| | - Cornelus C Hermsen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Sake de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer, Brisbane, Australia
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
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43
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Modeling the genetic relatedness of Plasmodium falciparum parasites following meiotic recombination and cotransmission. PLoS Comput Biol 2018; 14:e1005923. [PMID: 29315306 PMCID: PMC5777656 DOI: 10.1371/journal.pcbi.1005923] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 01/22/2018] [Accepted: 12/12/2017] [Indexed: 11/26/2022] Open
Abstract
Unlike in most pathogens, multiple-strain (polygenomic) infections of P. falciparum are frequently composed of genetic siblings. These genetic siblings are the result of sexual reproduction and can coinfect the same host when cotransmitted by the same mosquito. The degree with which coinfecting strains are related varies among infections and populations. Because sexual recombination occurs within the mosquito, the relatedness of cotransmitted strains could depend on transmission dynamics, but little is actually known of the factors that influence the relatedness of cotransmitted strains. Part of the uncertainty stems from an incomplete understanding of how within-host and within-vector dynamics affect cotransmission. Cotransmission is difficult to examine experimentally but can be explored using a computational model. We developed a malaria transmission model that simulates sexual reproduction in order to understand what determines the relatedness of cotransmitted strains. This study highlights how the relatedness of cotransmitted strains depends on both within-host and within-vector dynamics including the complexity of infection. We also used our transmission model to analyze the genetic relatedness of polygenomic infections following a series of multiple transmission events and examined the effects of superinfection. Understanding the factors that influence the relatedness of cotransmitted strains could lead to a better understanding of the population-genetic correlates of transmission and therefore be important for public health. Genomic studies of P. falciparum reveal that multi-strain infections can include genetically related strains. P. falciparum must reproduce sexually in the mosquito vector. One consequence of sexual reproduction is that parasites cotransmitted by the same mosquito are related to one another. The degree of genetic relatedness of these parasites can be as great as that of full-siblings. However, our understanding of the cotransmission process is incomplete, and little is known of the role of cotransmission in influencing population genomic processes. To help bridge this gap, we developed a simulation model to determine which of the steps involved in transmission have the greatest impact on the relatedness of parasites cotransmitted by a mosquito vector. The primary goal of this study is to characterize the outcomes of cotransmission following single or multiple transmission events. Our model yields new insights into the cotransmission process, which we believe will be useful for understanding the results from more complicated population models and epidemiological conditions. Such an understanding is important for the use of population genomics to inform public health decisions as well as for understanding of parasite evolution.
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Dechering KJ, Duerr HP, Koolen KMJ, Gemert GJV, Bousema T, Burrows J, Leroy D, Sauerwein RW. Modelling mosquito infection at natural parasite densities identifies drugs targeting EF2, PI4K or ATP4 as key candidates for interrupting malaria transmission. Sci Rep 2017; 7:17680. [PMID: 29247222 PMCID: PMC5732164 DOI: 10.1038/s41598-017-16671-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 11/16/2017] [Indexed: 11/25/2022] Open
Abstract
Eradication of malaria requires a novel type of drug that blocks transmission from the human to the mosquito host, but selection of such a drug is hampered by a lack of translational models. Experimental mosquito infections yield infection intensities that are substantially higher than observed in natural infections and, as a consequence, underestimate the drug effect on the proportion of mosquitoes that become infected. Here we introduce a novel experimental and computational method to adequately describe drug efficacy at natural parasite densities. Parameters of a beta-binomial infection model were established and validated using a large number of experimental mosquito infections at different parasite densities. Analyses of 15 experimental and marketed drugs revealed a class-specific ability to block parasite transmission. Our results highlight the parasite's elongation factor EF2, PI4 kinase and the ATP4 sodium channel as key targets for interruption of transmission, and compounds DDD107498 and KAE609 as most advanced drug candidates.
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Affiliation(s)
- Koen J Dechering
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands.
| | | | - Karin M J Koolen
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Teun Bousema
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Jeremy Burrows
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Geneva, 15, Switzerland
| | - Didier Leroy
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Geneva, 15, Switzerland
| | - Robert W Sauerwein
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Mechanisms of Plasmodium-Enhanced Attraction of Mosquito Vectors. Trends Parasitol 2017; 33:961-973. [DOI: 10.1016/j.pt.2017.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 06/14/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022]
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Gonçalves BP, Kapulu MC, Sawa P, Guelbéogo WM, Tiono AB, Grignard L, Stone W, Hellewell J, Lanke K, Bastiaens GJH, Bradley J, Nébié I, Ngoi JM, Oriango R, Mkabili D, Nyaurah M, Midega J, Wirth DF, Marsh K, Churcher TS, Bejon P, Sirima SB, Drakeley C, Bousema T. Examining the human infectious reservoir for Plasmodium falciparum malaria in areas of differing transmission intensity. Nat Commun 2017; 8:1133. [PMID: 29074880 PMCID: PMC5658399 DOI: 10.1038/s41467-017-01270-4] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 09/05/2017] [Indexed: 12/20/2022] Open
Abstract
A detailed understanding of the human infectious reservoir is essential for improving malaria transmission-reducing interventions. Here we report a multi-regional assessment of population-wide malaria transmission potential based on 1209 mosquito feeding assays in endemic areas of Burkina Faso and Kenya. Across both sites, we identified 39 infectious individuals. In high endemicity settings, infectious individuals were identifiable by research-grade microscopy (92.6%; 25/27), whilst one of three infectious individuals in the lowest endemicity setting was detected by molecular techniques alone. The percentages of infected mosquitoes in the different surveys ranged from 0.05 (4/7716) to 1.6% (121/7749), and correlate positively with transmission intensity. We also estimated exposure to malaria vectors through genetic matching of blood from 1094 wild-caught bloodfed mosquitoes with that of humans resident in the same houses. Although adults transmitted fewer parasites to mosquitoes than children, they received more mosquito bites, thus balancing their contribution to the infectious reservoir.
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Affiliation(s)
- Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Melissa C Kapulu
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Patrick Sawa
- Human Health Division, International Centre of Insect Physiology and Ecology, PO Box 30, Mbita Point, Western Kenya, 40305, Kenya
| | - Wamdaogo M Guelbéogo
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Alfred B Tiono
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Will Stone
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Radboud Institute for Health Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Joel Hellewell
- MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Guido J H Bastiaens
- Radboud Institute for Health Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Issa Nébié
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Joyce M Ngoi
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Robin Oriango
- Human Health Division, International Centre of Insect Physiology and Ecology, PO Box 30, Mbita Point, Western Kenya, 40305, Kenya
| | - Dora Mkabili
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Maureen Nyaurah
- Human Health Division, International Centre of Insect Physiology and Ecology, PO Box 30, Mbita Point, Western Kenya, 40305, Kenya
| | - Janet Midega
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Dyann F Wirth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Kevin Marsh
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Thomas S Churcher
- MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Sodiomon B Sirima
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK.
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK.
- Radboud Institute for Health Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.
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Graumans W, Tadesse FG, Andolina C, van Gemert GJ, Teelen K, Lanke K, Gadisa E, Yewhalaw D, van de Vegte-Bolmer M, Siebelink-Stoter R, Reuling I, Sauerwein R, Bousema T. Semi-high-throughput detection of Plasmodium falciparum and Plasmodium vivax oocysts in mosquitoes using bead-beating followed by circumsporozoite ELISA and quantitative PCR. Malar J 2017; 16:356. [PMID: 28877707 PMCID: PMC5588624 DOI: 10.1186/s12936-017-2011-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/02/2017] [Indexed: 01/03/2023] Open
Abstract
Background The malaria infection status of mosquitoes is commonly determined by microscopic detection of oocysts on the dissected mosquito midgut. This method is labour-intensive, does not allow processing of large numbers of mosquitoes and can be challenging in terms of objective classification of oocysts. Here, a semi-high-throughput bead-beating ELISA method is proposed for detection of the circumsporozoite protein (CSP) followed by confirmation by quantitative PCR (qPCR). Methods Cultured Plasmodium falciparum gametocytes were offered to Anopheles stephensi mosquitoes and examined by microscopy. After bead-beating, mosquito homogenate was examined by CSP-ELISA and 18S qPCR. As negative controls, mosquitoes that were offered a heat-inactivated gametocyte blood meal were used. The CSP-ELISA/qPCR methodology was applied to high and low-intensity infections of cultured P. falciparum gametocytes. A similar methodology optimized for P. vivax was used on mosquitoes that were offered blood from Ethiopian donors who were naturally infected with P. vivax. Results There was considerable variation in CSP-ELISA signal and qPCR values in mosquitoes with low oocyst intensities. There was a strong agreement mosquito positivity by CSP-ELISA and by qPCR in mosquitoes that fed on cultured P. falciparum material (agreement 96.9%; kappa = 0.97) and naturally infected P. vivax parasite carriers [agreement 92.4% (kappa = 0.83)]. Conclusions The proposed bead-beating CSP-ELISA/qPCR methodology considerably increases throughput for the detection of mosquito infection. qPCR remains necessary to confirm infections in mosquitoes with low CSP-ELISA signal. This methodology may prove particularly useful for studies where very low mosquito infection prevalence is expected and study sites where experience with oocyst detection is limited. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2011-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wouter Graumans
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Fitsum G Tadesse
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.,Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | - Delenasaw Yewhalaw
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia.,Department of Medical Laboratory Sciences and Pathology, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Isaïe Reuling
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. .,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
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Bompard A, Da DF, Yerbanga RS, Biswas S, Kapulu M, Bousema T, Lefèvre T, Cohuet A, Churcher TS. Evaluation of two lead malaria transmission blocking vaccine candidate antibodies in natural parasite-vector combinations. Sci Rep 2017; 7:6766. [PMID: 28754921 PMCID: PMC5533793 DOI: 10.1038/s41598-017-06130-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/08/2017] [Indexed: 12/25/2022] Open
Abstract
Transmission blocking vaccines (TBV) which aim to control malaria by inhibiting human-to-mosquito transmission show considerable promise though their utility against naturally circulating parasites remains unknown. The efficacy of two lead candidates targeting Pfs25 and Pfs230 antigens to prevent onwards transmission of naturally occurring parasites to a local mosquito strain is assessed using direct membrane feeding assays and murine antibodies in Burkina Faso. The transmission blocking activity of both candidates depends on the level of parasite exposure (as assessed by the mean number of oocysts in control mosquitoes) and antibody titers. A mathematical framework is devised to allow the efficacy of different candidates to be directly compared and determine the minimal antibody titers required to halt transmission in different settings. The increased efficacy with diminishing parasite exposure indicates that the efficacy of vaccines targeting either Pfs25 or Pfs230 may increase as malaria transmission declines. This has important implications for late-stage candidate selection and assessing how they can support the drive for malaria elimination.
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Affiliation(s)
- Anais Bompard
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, United Kingdom.
| | - Dari F Da
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso.,Unité MIVEGEC, IRD 224-CNRS 5290-Université Montpellier, Montpellier, France
| | | | - Sumi Biswas
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Melissa Kapulu
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Thierry Lefèvre
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso.,Unité MIVEGEC, IRD 224-CNRS 5290-Université Montpellier, Montpellier, France.,Laboratoire mixte international sur les vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso
| | - Anna Cohuet
- Unité MIVEGEC, IRD 224-CNRS 5290-Université Montpellier, Montpellier, France
| | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, United Kingdom
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Molecular Cloning and Characterization of Babesia orientalis Rhoptry Neck 2 BoRON2 Protein. J Parasitol Res 2017; 2017:7259630. [PMID: 28775897 PMCID: PMC5523350 DOI: 10.1155/2017/7259630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 04/12/2017] [Accepted: 04/30/2017] [Indexed: 11/24/2022] Open
Abstract
Babesiosis caused by Babesia orientalis is one of the most prevalent infections of water buffalo transmitted by Rhipicephalus haemaphysaloides causing a parasitic and hemolytic disease. The organelles proteins localized in apical membrane especially rhoptries neck and microneme protein form a complex called moving junction important during invasion process of parasites belonging to apicomplexan group, including Babesia species. A truncated fragment coding a 936 bps fragment was cloned in pMD-19T and subcloned into pET32 (a)+ expression vector, expressed in E. coli BL21. Purified recombinant BoRON2 was used to produce polyclonal antibody against BoRON2. Here, we identified the full sequence of gene encoding the rhoptry neck 2 protein that we named BoRON2 which is 4035 bp in full-length open reading frame without introns, encoding a polypeptide of 1345 amino acids. Western blot of rBoRON2 probed with buffalo positive serum analysis revealed a band of around 150 kDa in parasite lysates, suggesting an active involvement during invasion process. These findings most likely are constructive in perspective of ongoing research focused particularly on water buffalo babesiosis prevention and therapeutics and globally provide new information for genes comparative analysis.
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Single dose primaquine to reduce gametocyte carriage and Plasmodium falciparum transmission in Cambodia: An open-label randomized trial. PLoS One 2017; 12:e0168702. [PMID: 28591198 PMCID: PMC5462369 DOI: 10.1371/journal.pone.0168702] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 11/26/2016] [Indexed: 12/19/2022] Open
Abstract
Background Single low dose primaquine (SLD PQ, 0.25mg/kg) is recommended in combination with artemisinin-based combination therapy (ACT) as a gametocytocide to prevent Plasmodium falciparum transmission in areas threatened by artemisinin resistance. To date, no randomized controlled trials have measured primaquine’s effect on infectiousness to Anopheline mosquitoes in Southeast Asia. Methods Cambodian adults with uncomplicated falciparum malaria were randomized to receive a single 45mg dose of primaquine (equivalent to three SLD PQ) or no primaquine after the third dose of dihydroartemisin-piperaquine (DHP) therapy. A membrane-feeding assay measured infectiousness to Anopheles dirus on days 0, 3, 7, and 14 of blood-stage therapy. Gametocytemia was evaluated by microscopy and reverse-transcriptase PCR. Results Prior to trial halt for poor DHP treatment efficacy, 101 participants were randomized and 50 received primaquine. Overall microscopic gametocyte prevalence was low (9%), but gametocytemic subjects given primaquine were gametocyte-free by day 14, and significantly less likely to harbor gametocytes by day 7 compared to those treated with DHP-alone, who remained gametocytemic for a median of two weeks. Only one infectious subject was randomized to the primaquine group, precluding assessment of transmission-blocking efficacy. However, he showed a two-fold reduction in oocyst density of infected mosquitoes less than 24 hours after primaquine dosing. In the DHP-alone group, four subjects remained infectious through day 14, infecting roughly the same number of mosquitoes pre and post-treatment. Overall, microscopic gametocytemia was an excellent predictor of infectiousness, and performed better than submicroscopic gametocytemia post-treatment, with none of 474 mosquitoes infected post-treatment arising from submicroscopic gametocytes. Conclusions In a setting of established ACT resistance, a single dose of 45mg primaquine added to DHP rapidly and significantly reduced gametocytemia, while DHP-alone failed to reduce gametocytemia and prevent malaria transmission to mosquitoes. Continued efforts to make single dose primaquine widely available are needed to help achieve malaria elimination.
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