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Connolly JB, Burt A, Christophides G, Diabate A, Habtewold T, Hancock PA, James AA, Kayondo JK, Lwetoijera DW, Manjurano A, McKemey AR, Santos MR, Windbichler N, Randazzo F. Considerations for first field trials of low-threshold gene drive for malaria vector control. Malar J 2024; 23:156. [PMID: 38773487 PMCID: PMC11110314 DOI: 10.1186/s12936-024-04952-9] [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: 11/29/2023] [Accepted: 04/15/2024] [Indexed: 05/23/2024] Open
Abstract
Sustainable reductions in African malaria transmission require innovative tools for mosquito control. One proposal involves the use of low-threshold gene drive in Anopheles vector species, where a 'causal pathway' would be initiated by (i) the release of a gene drive system in target mosquito vector species, leading to (ii) its transmission to subsequent generations, (iii) its increase in frequency and spread in target mosquito populations, (iv) its simultaneous propagation of a linked genetic trait aimed at reducing vectorial capacity for Plasmodium, and (v) reduced vectorial capacity for parasites in target mosquito populations as the gene drive system reaches fixation in target mosquito populations, causing (vi) decreased malaria incidence and prevalence. Here the scope, objectives, trial design elements, and approaches to monitoring for initial field releases of such gene dive systems are considered, informed by the successful implementation of field trials of biological control agents, as well as other vector control tools, including insecticides, Wolbachia, larvicides, and attractive-toxic sugar bait systems. Specific research questions to be addressed in initial gene drive field trials are identified, and adaptive trial design is explored as a potentially constructive and flexible approach to facilitate testing of the causal pathway. A fundamental question for decision-makers for the first field trials will be whether there should be a selective focus on earlier points of the pathway, such as genetic efficacy via measurement of the increase in frequency and spread of the gene drive system in target populations, or on wider interrogation of the entire pathway including entomological and epidemiological efficacy. How and when epidemiological efficacy will eventually be assessed will be an essential consideration before decisions on any field trial protocols are finalized and implemented, regardless of whether initial field trials focus exclusively on the measurement of genetic efficacy, or on broader aspects of the causal pathway. Statistical and modelling tools are currently under active development and will inform such decisions on initial trial design, locations, and endpoints. Collectively, the considerations here advance the realization of developer ambitions for the first field trials of low-threshold gene drive for malaria vector control within the next 5 years.
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Affiliation(s)
- John B Connolly
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK.
| | - Austin Burt
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK
| | - George Christophides
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
| | - Abdoulaye Diabate
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Tibebu Habtewold
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Penelope A Hancock
- MRC Centre for Global Infectious Disease Analysis, St. Mary's Campus, Imperial College London, London, UK
| | - Anthony A James
- Departments of Microbiology & Molecular Genetics and Molecular Biology & Biochemistry, University of California, Irvine, USA
| | - Jonathan K Kayondo
- Entomology Department, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
| | | | - Alphaxard Manjurano
- Malaria Research Unit and Laboratory Sciences, Mwanza Medical Research Centre, National Institute for Medical Research, Mwanza, Tanzania
| | - Andrew R McKemey
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK
| | - Michael R Santos
- Foundation for the National Institutes of Health, North Bethesda, MD, USA
| | - Nikolai Windbichler
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
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Kefi M, Cardoso-Jaime V, Saab SA, Dimopoulos G. Curing mosquitoes with genetic approaches for malaria control. Trends Parasitol 2024:S1471-4922(24)00092-8. [PMID: 38760256 DOI: 10.1016/j.pt.2024.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/15/2024] [Accepted: 04/15/2024] [Indexed: 05/19/2024]
Abstract
Malaria remains a persistent global public health challenge because of the limitations of current prevention tools. The use of transgenic mosquitoes incapable of transmitting malaria, in conjunction with existing methods, holds promise for achieving elimination of malaria and preventing its reintroduction. In this context, population modification involves the spread of engineered genetic elements through mosquito populations that render them incapable of malaria transmission. Significant progress has been made in this field over the past decade in revealing promising targets, optimizing genetic tools, and facilitating the transition from the laboratory to successful field deployments, which are subject to regulatory scrutiny. This review summarizes recent advances and ongoing challenges in 'curing' Anopheles vectors of the malaria parasite.
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Affiliation(s)
- Mary Kefi
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Victor Cardoso-Jaime
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Sally A Saab
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - George Dimopoulos
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
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3
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Samantsidis GR, Kwon H, Wendland M, Fonder C, Smith RC. TNF signaling mediates cellular immune function and promotes malaria parasite killing in the mosquito Anopheles gambiae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.02.592209. [PMID: 38746363 PMCID: PMC11092648 DOI: 10.1101/2024.05.02.592209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Tumor Necrosis Factor-α (TNF-α) is a proinflammatory cytokine and a master regulator of immune cell function in vertebrates. While previous studies have implicated TNF signaling in invertebrate immunity, the roles of TNF in mosquito innate immunity and vector competence have yet to be explored. Herein, we confirm the identification of a conserved TNF-α pathway in Anopheles gambiae consisting of the TNF-α ligand, Eiger, and its cognate receptors Wengen and Grindelwald. Through gene expression analysis, RNAi, and in vivo injection of recombinant TNF-α, we provide direct evidence for the requirement of TNF signaling in regulating mosquito immune cell function by promoting granulocyte midgut attachment, increased granulocyte abundance, and oenocytoid rupture. Moreover, our data demonstrate that TNF signaling is an integral component of anti-Plasmodium immunity that limits malaria parasite survival. Together, our data support the existence of a highly conserved TNF signaling pathway in mosquitoes that mediates cellular immunity and influences Plasmodium infection outcomes, offering potential new approaches to interfere with malaria transmission by targeting the mosquito host.
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Affiliation(s)
| | - Hyeogsun Kwon
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA, USA
| | - Megan Wendland
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA, USA
| | - Catherine Fonder
- Molecular, Cellular and Developmental Biology Interdepartmental Graduate Program, Iowa State University, Ames, IA, USA
| | - Ryan C. Smith
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA, USA
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Hou S, Chen J, Feng R, Xu X, Liang N, Champer J. A homing rescue gene drive with multiplexed gRNAs reaches high frequency in cage populations but generates functional resistance. J Genet Genomics 2024:S1673-8527(24)00070-5. [PMID: 38599514 DOI: 10.1016/j.jgg.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024]
Abstract
CRISPR homing gene drives have considerable potential for managing populations of medically and agriculturally significant insects. They operate by Cas9 cleavage followed by homology-directed repair, copying the drive allele to the wild-type chromosome and thus increasing in frequency and spreading throughout a population. However, resistance alleles formed by end-joining repair pose a significant obstacle. To address this, we create a homing drive targeting the essential hairy gene in Drosophila melanogaster. Nonfunctional resistance alleles are recessive lethal, while drive carriers have a recoded "rescue" version of hairy. The drive inheritance rate is moderate, and multigenerational cage studies show drive spread to 96%-97% of the population. However, the drive does not reach 100% due to the formation of functional resistance alleles, despite using four gRNAs. These alleles have a large deletion but likely utilize an alternate start codon. Thus, revised designs targeting more essential regions of a gene may be necessary to avoid such functional resistance. Replacement of the rescue element's native 3' UTR with a homolog from another species increases drive inheritance by 13%-24%. This was possibly because of reduced homology between the rescue element and surrounding genomic DNA, which could also be an important design consideration for rescue gene drives.
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Affiliation(s)
- Shibo Hou
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jingheng Chen
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China
| | - Ruobing Feng
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China
| | - Xuejiao Xu
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China
| | - Nan Liang
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jackson Champer
- Center for Bioinformatics, Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China.
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Cai JA, Christophides GK. Immune interactions between mosquitoes and microbes during midgut colonization. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101195. [PMID: 38552792 DOI: 10.1016/j.cois.2024.101195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 03/14/2024] [Accepted: 03/21/2024] [Indexed: 04/07/2024]
Abstract
Mosquitoes encounter diverse microbes during their lifetime, including symbiotic bacteria, shaping their midgut ecosystem. The organization of the midgut supports microbiota persistence while defending against potential pathogens. The influx of nutrients during blood feeding triggers bacterial proliferation, challenging host homeostasis. Immune responses, aimed at controlling bacterial overgrowth, impact blood-borne pathogens such as malaria parasites. However, parasites deploy evasion strategies against mosquito immunity. Leveraging these mechanisms could help engineer malaria-resistant mosquitoes, offering a transformative tool for malaria elimination.
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Affiliation(s)
- Julia A Cai
- Department of Life Sciences, Imperial College London, Exhibition Road, SW7 2AZ London, United Kingdom
| | - George K Christophides
- Department of Life Sciences, Imperial College London, Exhibition Road, SW7 2AZ London, United Kingdom.
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Birungi K, Mabuka DP, Balyesima V, Tripet F, Kayondo JK. Attributes of Anopheles gambiae swarms in South Central Uganda. Parasit Vectors 2024; 17:149. [PMID: 38515191 PMCID: PMC10956327 DOI: 10.1186/s13071-024-06132-9] [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: 07/18/2023] [Accepted: 01/11/2024] [Indexed: 03/23/2024] Open
Abstract
BACKGROUND Anopheles gambiae continues to be widespread and an important malaria vector species complex in Uganda. New approaches to malaria vector control are being explored including population suppression through swarm reductions and genetic modification involving gene drives. Designing and evaluating these new interventions require good understanding of the biology of the target vectors. Anopheles mosquito swarms have historically been hard to locate in Uganda and therefore have remained poorly characterized. In this study we sought to identify and characterize An. gambiae s.l mosquito swarms in three study sites of high An. gambiae s.l prevalence within Central Uganda. METHODS Nine sampling visits were made to three villages over a 2-year period. Sampling targeted both wet and dry seasons and was done for 2 days per village during each trip, using sweep nets. All swarm data were analysed using the JMP 14 software (SAS Institute, Inc., Cary, NC, USA), parametrically or non-parametrically as appropriate. RESULTS Most of the An. gambiae s.s. swarms sampled during this study were single-species swarms. However, some mixed An. gambiae s.s. and Culex spp. mosquito swarms were also observed. Swarms were larger in the wet season than in the dry season. Mean swarm height ranged from 2.16 m to 3.13 m off the ground and only varied between villages but not by season. Anopheles gambiae mosquitoes were present in all three villages, preferred to swarm over bare ground markers, and could be effectively sampled by field samplers. CONCLUSIONS This study demonstrated that An. gambiae s.l swarms could be effectively located and sampled in South Central Uganda and provided in-depth descriptions of hitherto poorly understood aspects of An. gambiae local swarm characteristics. Swarms were found close to inhabited households and were greater in size and number during the rainy season. Anopheles gambiae s.s swarms were significantly associated with bare ground markers and were sometimes at heights over 4 m above the ground, showing a necessity to develop tools suitable for swarm sampling at these heights. While mixed species swarms have been reported before elsewhere, this is the first documented instance of mixed genus swarms found in Uganda and should be studied further as it could have implications for swarm sampling explorations where multiple species of mosquitoes exist.
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Affiliation(s)
- Krystal Birungi
- Entomology Division, Uganda Virus Research Institute (UVRI), Plot 51-59, P.O. Box 49, Entebbe, Uganda
| | - Danspaid P Mabuka
- Entomology Division, Uganda Virus Research Institute (UVRI), Plot 51-59, P.O. Box 49, Entebbe, Uganda
| | - Victor Balyesima
- Entomology Division, Uganda Virus Research Institute (UVRI), Plot 51-59, P.O. Box 49, Entebbe, Uganda
| | - Frederic Tripet
- Swiss Tropical and Public Health Institute, Kreuzgasse 2, 4123, Allschwil, Switzerland
| | - Jonathan K Kayondo
- Entomology Division, Uganda Virus Research Institute (UVRI), Plot 51-59, P.O. Box 49, Entebbe, Uganda.
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Meccariello A, Hou S, Davydova S, Fawcett JD, Siddall A, Leftwich PT, Krsticevic F, Papathanos PA, Windbichler N. Gene drive and genetic sex conversion in the global agricultural pest Ceratitis capitata. Nat Commun 2024; 15:372. [PMID: 38191463 PMCID: PMC10774415 DOI: 10.1038/s41467-023-44399-1] [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: 08/22/2023] [Accepted: 12/12/2023] [Indexed: 01/10/2024] Open
Abstract
Homing-based gene drives are recently proposed interventions promising the area-wide, species-specific genetic control of harmful insect populations. Here we characterise a first set of gene drives in a tephritid agricultural pest species, the Mediterranean fruit fly Ceratitis capitata (medfly). Our results show that the medfly is highly amenable to homing-based gene drive strategies. By targeting the medfly transformer gene, we also demonstrate how CRISPR-Cas9 gene drive can be coupled to sex conversion, whereby genetic females are transformed into fertile and harmless XX males. Given this unique malleability of sex determination, we modelled gene drive interventions that couple sex conversion and female sterility and found that such approaches could be effective and tolerant of resistant allele selection in the target population. Our results open the door for developing gene drive strains for the population suppression of the medfly and related tephritid pests by co-targeting female reproduction and shifting the reproductive sex ratio towards males. They demonstrate the untapped potential for gene drives to tackle agricultural pests in an environmentally friendly and economical way.
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Affiliation(s)
- Angela Meccariello
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.
| | - Shibo Hou
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Serafima Davydova
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | | | - Alexandra Siddall
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Philip T Leftwich
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Flavia Krsticevic
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Philippos Aris Papathanos
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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Green EI, Jaouen E, Klug D, Proveti Olmo R, Gautier A, Blandin S, Marois E. A population modification gene drive targeting both Saglin and Lipophorin impairs Plasmodium transmission in Anopheles mosquitoes. eLife 2023; 12:e93142. [PMID: 38051195 PMCID: PMC10786457 DOI: 10.7554/elife.93142] [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: 10/02/2023] [Accepted: 11/14/2023] [Indexed: 12/07/2023] Open
Abstract
Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the Anopheles coluzzii Lipophorin gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite Plasmodium falciparum. The resulting transgenic mosquitoes show a markedly decreased ability to transmit Plasmodium berghei expressing the P. falciparum circumsporozoite protein to mice. To force the spread of this antimalarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene Saglin and also cleaves wild-type Lipophorin, causing the anti-malarial modified Lipophorin version to replace the wild type and hitch-hike together with the Saglin drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the Saglin-based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial Lipophorin::Sc2A10 allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.
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Affiliation(s)
- Emily I Green
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
| | - Etienne Jaouen
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
| | - Dennis Klug
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
| | | | - Amandine Gautier
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
| | - Stéphanie Blandin
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
| | - Eric Marois
- Inserm U1257, CNRS UPR9022, University of StrasbourgStrasbourgFrance
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Pescod P, Bevivino G, Anthousi A, Shelton R, Shepherd J, Lombardo F, Nolan T. Measuring the Impact of Genetic Heterogeneity and Chromosomal Inversions on the Efficacy of CRISPR-Cas9 Gene Drives in Different Strains of Anopheles gambiae. CRISPR J 2023; 6:419-429. [PMID: 37702604 DOI: 10.1089/crispr.2023.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023] Open
Abstract
The human malaria vector Anopheles gambiae is becoming increasingly resistant to insecticides, spurring the development of genetic control strategies. CRISPR-Cas9 gene drives can modify a population by creating double-stranded breaks at highly specific targets, triggering copying of the gene drive into the cut site ("homing"), ensuring its inheritance. The DNA repair mechanism responsible requires homology between the donor and recipient chromosomes, presenting challenges for the invasion of laboratory-developed gene drives into wild populations of target species An. gambiae species complex, which show high levels of genome variation. Two gene drives (vas2-5958 and zpg-7280) were introduced into three An. gambiae strains collected across Africa with 5.3-6.6% variation around the target sites, and the effect of this variation on homing was measured. Gene drive homing across different karyotypes of the 2La chromosomal inversion was also assessed. No decrease in gene drive homing was seen despite target site heterology, demonstrating the applicability of gene drives to wild populations.
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Affiliation(s)
- Poppy Pescod
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Giulia Bevivino
- Division of Parasitology, Department of Public Health and Infectious Diseases, University of Rome "la Sapienza," Rome, Italy; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Amalia Anthousi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Crete, Greece; and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Insects and Vector Borne Diseases, Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Ruth Shelton
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Josephine Shepherd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Fabrizio Lombardo
- Division of Parasitology, Department of Public Health and Infectious Diseases, University of Rome "la Sapienza," Rome, Italy; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Tony Nolan
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
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Ouologuem DT, Dara A, Kone A, Ouattara A, Djimde AA. Plasmodium falciparum Development from Gametocyte to Oocyst: Insight from Functional Studies. Microorganisms 2023; 11:1966. [PMID: 37630530 PMCID: PMC10460021 DOI: 10.3390/microorganisms11081966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/06/2023] [Accepted: 07/14/2023] [Indexed: 08/27/2023] Open
Abstract
Malaria elimination may never succeed without the implementation of transmission-blocking strategies. The transmission of Plasmodium spp. parasites from the human host to the mosquito vector depends on circulating gametocytes in the peripheral blood of the vertebrate host. Once ingested by the mosquito during blood meals, these sexual forms undergo a series of radical morphological and metabolic changes to survive and progress from the gut to the salivary glands, where they will be waiting to be injected into the vertebrate host. The design of effective transmission-blocking strategies requires a thorough understanding of all the mechanisms that drive the development of gametocytes, gametes, sexual reproduction, and subsequent differentiation within the mosquito. The drastic changes in Plasmodium falciparum shape and function throughout its life cycle rely on the tight regulation of stage-specific gene expression. This review outlines the mechanisms involved in Plasmodium falciparum sexual stage development in both the human and mosquito vector, and zygote to oocyst differentiation. Functional studies unravel mechanisms employed by P. falciparum to orchestrate the expression of stage-specific functional products required to succeed in its complex life cycle, thus providing us with potential targets for developing new therapeutics. These mechanisms are based on studies conducted with various Plasmodium species, including predominantly P. falciparum and the rodent malaria parasites P. berghei. However, the great potential of epigenetics, genomics, transcriptomics, proteomics, and functional genetic studies to improve the understanding of malaria as a disease remains partly untapped because of limitations in studies using human malaria parasites and field isolates.
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Affiliation(s)
- Dinkorma T. Ouologuem
- Malaria Research and Training Center, Faculty of Pharmacy, Faculty of Medicine and Dentistry, University of Sciences, Techniques, and Technologies of Bamako, Bamako 1805, Mali
| | - Antoine Dara
- Malaria Research and Training Center, Faculty of Pharmacy, Faculty of Medicine and Dentistry, University of Sciences, Techniques, and Technologies of Bamako, Bamako 1805, Mali
| | - Aminatou Kone
- Malaria Research and Training Center, Faculty of Pharmacy, Faculty of Medicine and Dentistry, University of Sciences, Techniques, and Technologies of Bamako, Bamako 1805, Mali
| | - Amed Ouattara
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Abdoulaye A. Djimde
- Malaria Research and Training Center, Faculty of Pharmacy, Faculty of Medicine and Dentistry, University of Sciences, Techniques, and Technologies of Bamako, Bamako 1805, Mali
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Carballar-Lejarazú R, Dong Y, Pham TB, Tushar T, Corder RM, Mondal A, Sánchez C. HM, Lee HF, Marshall JM, Dimopoulos G, James AA. Dual effector population modification gene-drive strains of the African malaria mosquitoes, Anopheles gambiae and Anopheles coluzzii. Proc Natl Acad Sci U S A 2023; 120:e2221118120. [PMID: 37428915 PMCID: PMC10629562 DOI: 10.1073/pnas.2221118120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/05/2023] [Indexed: 07/12/2023] Open
Abstract
Proposed genetic approaches for reducing human malaria include population modification, which introduces genes into vector mosquitoes to reduce or prevent parasite transmission. We demonstrate the potential of Cas9/guide RNA (gRNA)-based gene-drive systems linked to dual antiparasite effector genes to spread rapidly through mosquito populations. Two strains have an autonomous gene-drive system coupled to dual anti-Plasmodium falciparum effector genes comprising single-chain variable fragment monoclonal antibodies targeting parasite ookinetes and sporozoites in the African malaria mosquitoes Anopheles gambiae (AgTP13) and Anopheles coluzzii (AcTP13). The gene-drive systems achieved full introduction within 3 to 6 mo after release in small cage trials. Life-table analyses revealed no fitness loads affecting AcTP13 gene-drive dynamics but AgTP13 males were less competitive than wild types. The effector molecules reduced significantly both parasite prevalence and infection intensities. These data supported transmission modeling of conceptual field releases in an island setting that shows meaningful epidemiological impacts at different sporozoite threshold levels (2.5 to 10 k) for human infection by reducing malaria incidence in optimal simulations by 50 to 90% within as few as 1 to 2 mo after a series of releases, and by ≥90% within 3 mo. Modeling outcomes for low sporozoite thresholds are sensitive to gene-drive system fitness loads, gametocytemia infection intensities during parasite challenges, and the formation of potentially drive-resistant genome target sites, extending the predicted times to achieve reduced incidence. TP13-based strains could be effective for malaria control strategies following validation of sporozoite transmission threshold numbers and testing field-derived parasite strains. These or similar strains are viable candidates for future field trials in a malaria-endemic region.
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Affiliation(s)
| | - Yuemei Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Malaria Research Institute, Johns Hopkins University, Baltimore, MD21205
| | - Thai Binh Pham
- Department of Microbiology & Molecular Genetics, University of California, Irvine, CA92697-4025
| | - Taylor Tushar
- Department of Microbiology & Molecular Genetics, University of California, Irvine, CA92697-4025
| | - Rodrigo M. Corder
- Divisions of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA94720
| | - Agastya Mondal
- Divisions of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA94720
| | - Héctor M. Sánchez C.
- Divisions of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA94720
| | - Hsu-Feng Lee
- Department of Microbiology & Molecular Genetics, University of California, Irvine, CA92697-4025
| | - John M. Marshall
- Divisions of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA94720
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Malaria Research Institute, Johns Hopkins University, Baltimore, MD21205
| | - Anthony A. James
- Department of Microbiology & Molecular Genetics, University of California, Irvine, CA92697-4025
- Department of Molecular Biology & Biochemistry, University of California, Irvine, CA92697-3900
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Jones S. How genetically modified mosquitoes could eradicate malaria. Nature 2023; 618:S29-S31. [PMID: 37380677 DOI: 10.1038/d41586-023-02051-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
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Loaiza JR, Bennett KL, Miller MJ, De León LF. Unraveling the genomic complexity of sylvatic mosquitoes in changing Neotropical environments. Curr Opin Biotechnol 2023; 81:102944. [PMID: 37099930 DOI: 10.1016/j.copbio.2023.102944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/10/2023] [Accepted: 03/20/2023] [Indexed: 04/28/2023]
Abstract
Sylvatic New World mosquitoes (e.g. Old-growth Forest species) can transmit viruses among non-human primates. This could be a continuous source of viral cycling and spillover events from animals to humans, particularly in changing environments. However, most species of Neotropical sylvatic mosquitoes (genera Aedes, Haemagogus, and Sabethes), which include vector and non-vector species, currently lack genomic resources because there is no reliable and accurate approach for creating de novo reference genomes for these insects. This is a major knowledge gap in the biology of these mosquitoes, restricting our ability to predict and mitigate the emergence and spread of novel arboviruses in Neotropical regions. We discuss recent advances and potential solutions for generating hybrid de novo assemblies from vector and non-vector species using pools of consanguineous offspring. We also discussed research opportunities likely to emerge from these genomic resources.
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Affiliation(s)
- Jose R Loaiza
- Centro de Biodiversidad y Descubrimiento de Drogas, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Clayton 0843-01103, Republic of Panama.
| | - Kelly L Bennett
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Matthew J Miller
- RENECO International Wildlife Consultants LLC, Al Reem Island, Abu Dhabi, UAE
| | - Luis F De León
- Centro de Biodiversidad y Descubrimiento de Drogas, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Clayton 0843-01103, Republic of Panama; Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
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Klug D, Blandin SA. Activation of complement-like antiparasitic responses in Anopheles mosquitoes. Curr Opin Microbiol 2023; 72:102280. [PMID: 36841199 DOI: 10.1016/j.mib.2023.102280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/13/2023] [Accepted: 01/19/2023] [Indexed: 02/25/2023]
Abstract
During their development in mosquitoes, malaria parasites undergo massive losses that are in part due to a potent antiparasitic response mounted by the vector. The most efficient and best-characterized response relies on a complement-like system particularly effective against parasites as they cross the mosquito midgut epithelium. While our vision of the molecular and cellular events that lead to parasite elimination is still partial, our understanding of the steps triggering complement activation at the surface of invading parasites has considerably progressed, not only through the identification of novel contributing genes, but also with the recent in-depth characterization of the different mosquito blood cell types, and the ability to track them in live mosquitoes. Here, we propose a simple model based on the time of invasion to explain how parasites may escape complement-like responses during midgut infection.
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Affiliation(s)
- Dennis Klug
- Université de Strasbourg, CNRS, Inserm, UPR9022/U1257, Mosquito Immune Responses (MIR), F-67000 Strasbourg, France
| | - Stephanie A Blandin
- Université de Strasbourg, CNRS, Inserm, UPR9022/U1257, Mosquito Immune Responses (MIR), F-67000 Strasbourg, France.
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James S, Santos M. The Promise and Challenge of Genetic Biocontrol Approaches for Malaria Elimination. Trop Med Infect Dis 2023; 8:201. [PMID: 37104327 PMCID: PMC10140850 DOI: 10.3390/tropicalmed8040201] [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: 02/22/2023] [Revised: 03/15/2023] [Accepted: 03/23/2023] [Indexed: 04/03/2023] Open
Abstract
Malaria remains an ongoing public health challenge, with over 600,000 deaths in 2021, of which approximately 96% occurred in Africa. Despite concerted efforts, the goal of global malaria elimination has stalled in recent years. This has resulted in widespread calls for new control methods. Genetic biocontrol approaches, including those focused on gene-drive-modified mosquitoes (GDMMs), aim to prevent malaria transmission by either reducing the population size of malaria-transmitting mosquitoes or making the mosquitoes less competent to transmit the malaria parasite. The development of both strategies has advanced considerably in recent years, with successful field trials of several biocontrol methods employing live mosquito products and demonstration of the efficacy of GDMMs in insectary-based studies. Live mosquito biocontrol products aim to achieve area-wide control with characteristics that differ substantially from current insecticide-based vector control methods, resulting in some different considerations for approval and implementation. The successful field application of current biocontrol technologies against other pests provides evidence for the promise of these approaches and insights into the development pathway for new malaria control agents. The status of technical development as well as current thinking on the implementation requirements for genetic biocontrol approaches are reviewed, and remaining challenges for public health application in malaria prevention are discussed.
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Affiliation(s)
- Stephanie James
- Foundation for the National Institutes of Health, North Bethesda, MD 20852, USA
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Wong ML, Zulzahrin Z, Vythilingam I, Lau YL, Sam IC, Fong MY, Lee WC. Perspectives of vector management in the control and elimination of vector-borne zoonoses. Front Microbiol 2023; 14:1135977. [PMID: 37025644 PMCID: PMC10070879 DOI: 10.3389/fmicb.2023.1135977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/28/2023] [Indexed: 04/08/2023] Open
Abstract
The complex transmission profiles of vector-borne zoonoses (VZB) and vector-borne infections with animal reservoirs (VBIAR) complicate efforts to break the transmission circuit of these infections. To control and eliminate VZB and VBIAR, insecticide application may not be conducted easily in all circumstances, particularly for infections with sylvatic transmission cycle. As a result, alternative approaches have been considered in the vector management against these infections. In this review, we highlighted differences among the environmental, chemical, and biological control approaches in vector management, from the perspectives of VZB and VBIAR. Concerns and knowledge gaps pertaining to the available control approaches were discussed to better understand the prospects of integrating these vector control approaches to synergistically break the transmission of VZB and VBIAR in humans, in line with the integrated vector management (IVM) developed by the World Health Organization (WHO) since 2004.
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Affiliation(s)
- Meng Li Wong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Zulhisham Zulzahrin
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - I-Ching Sam
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Wenn-Chyau Lee
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- *Correspondence: Wenn-Chyau Lee,
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Bottino-Rojas V, James AA. Use of Insect Promoters in Genetic Engineering to Control Mosquito-Borne Diseases. Biomolecules 2022; 13:biom13010016. [PMID: 36671401 PMCID: PMC9855440 DOI: 10.3390/biom13010016] [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: 12/03/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Mosquito transgenesis and gene-drive technologies provide the basis for developing promising new tools for vector-borne disease prevention by either suppressing wild mosquito populations or reducing their capacity from transmitting pathogens. Many studies of the regulatory DNA and promoters of genes with robust sex-, tissue- and stage-specific expression profiles have supported the development of new tools and strategies that could bring mosquito-borne diseases under control. Although the list of regulatory elements available is significant, only a limited set of those can reliably drive spatial-temporal expression. Here, we review the advances in our ability to express beneficial and other genes in mosquitoes, and highlight the information needed for the development of new mosquito-control and anti-disease strategies.
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Affiliation(s)
- Vanessa Bottino-Rojas
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
| | - Anthony A. James
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
- Correspondence:
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