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New insights into antimalarial chemopreventive activity of antifolates. Antimicrob Agents Chemother 2021; 66:e0153821. [PMID: 34930029 DOI: 10.1128/aac.01538-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antifolates targeting dihydrofolate reductase (DHFR) are antimalarial compounds that have long been used for malaria treatment and chemoprevention (inhibition of infection from mosquitoes to humans). Despite their extensive applications, the thorough understanding of antifolate activity against hepatic malaria parasites, especially resistant parasites, have yet to be achieved. Using a transgenic P. berghei harboring quadruple mutant dhfr from P. falciparum (Pb::Pfdhfr-4M), we demonstrate that quadruple mutations on Pfdhfr confer complete chemoprevention resistance to pyrimethamine, the previous generation of antifolate, but not to a new class of antifolate designed to overcome the resistance such as P218. Detailed investigation to pin-point stage-specific chemoprevention further demonstrated that it is unnecessary for the drug to be present throughout hepatic development. The drug is most potent against the developmental stages from early hepatic trophozoite to late hepatic trophozoite, but is not effective at inhibiting sporozoite and early hepatic stage development from sporozoite to early trophozoite. Our data shows that P218 also inhibited the late hepatic stage development, from trophozoite to mature schizonts to a lesser extent. With a single dose of 15 mg/kg, P218 prevented infection from up to 25,000 pyrimethamine-resistant sporozoites, a number equal to thousands of infectious mosquito bites. Additionally, the hepatic stage of malaria parasite is much more susceptible to antifolates than the asexual blood stage. This study provides important insights into the activity of antifolates, as a chemopreventive therapeutic which could lead to a more efficient and cost effective treatment regime.
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Carlton JM. A cornucopia of research resources for the fourth rodent malaria parasite species. BMC Biol 2021; 19:82. [PMID: 33888109 PMCID: PMC8063385 DOI: 10.1186/s12915-021-01019-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/01/2021] [Indexed: 11/10/2022] Open
Abstract
The study of human malaria caused by species of Plasmodium has undoubtedly been enriched by the use of model systems, such as the rodent malaria parasites originally isolated from African thicket rats. A significant gap in the arsenal of resources of the species that make up the rodent malaria parasites has been the lack of any such tools for the fourth of the species, Plasmodium vinckei. This has recently been rectified by Abhinay Ramaprasad and colleagues, whose pivotal paper published in BMC Biology describes a cornucopia of new P. vinckei 'omics datasets, mosquito transmission experiments, transfection protocols, and virulence phenotypes, to propel this species firmly into the twenty-first century.
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Affiliation(s)
- Jane M Carlton
- Center for Genomics & Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY, 10003, USA.
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3
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O'Donnell AJ, Reece SE. Ecology of asynchronous asexual replication: the intraerythrocytic development cycle of Plasmodium berghei is resistant to host rhythms. Malar J 2021; 20:105. [PMID: 33608011 PMCID: PMC7893937 DOI: 10.1186/s12936-021-03643-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 02/10/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Daily periodicity in the diverse activities of parasites occurs across a broad taxonomic range. The rhythms exhibited by parasites are thought to be adaptations that allow parasites to cope with, or exploit, the consequences of host activities that follow daily rhythms. Malaria parasites (Plasmodium) are well-known for their synchronized cycles of replication within host red blood cells. Whilst most species of Plasmodium appear sensitive to the timing of the daily rhythms of hosts, and even vectors, some species present no detectable rhythms in blood-stage replication. Why the intraerythrocytic development cycle (IDC) of, for example Plasmodium chabaudi, is governed by host rhythms, yet seems completely independent of host rhythms in Plasmodium berghei, another rodent malaria species, is mysterious. METHODS This study reports a series of five experiments probing the relationships between the asynchronous IDC schedule of P. berghei and the rhythms of hosts and vectors by manipulating host time-of-day, photoperiod and feeding rhythms. RESULTS The results reveal that: (i) a lack coordination between host and parasite rhythms does not impose appreciable fitness costs on P. berghei; (ii) the IDC schedule of P. berghei is impervious to host rhythms, including altered photoperiod and host-feeding-related rhythms; (iii) there is weak evidence for daily rhythms in the density and activities of transmission stages; but (iv), these rhythms have little consequence for successful transmission to mosquitoes. CONCLUSIONS Overall, host rhythms do not affect the performance of P. berghei and its asynchronous IDC is resistant to the scheduling forces that underpin synchronous replication in closely related parasites. This suggests that natural variation in the IDC schedule across species represents different parasite strategies that maximize fitness. Thus, subtle differences in the ecological interactions between parasites and their hosts/vectors may select for the evolution of very different IDC schedules.
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Affiliation(s)
- Aidan J O'Donnell
- Institute of Evolutionary Biology, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK.
| | - Sarah E Reece
- Institute of Evolutionary Biology, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
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Conteh S, Kolasny J, Robbins YL, Pyana P, Büscher P, Musgrove J, Butler B, Lambert L, Gorres JP, Duffy PE. Dynamics and Outcomes of Plasmodium Infections in Grammomys surdaster ( Grammomys dolichurus) Thicket Rats versus Inbred Mice. Am J Trop Med Hyg 2020; 103:1893-1901. [PMID: 32815499 DOI: 10.4269/ajtmh.20-0183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Investigations of malaria infection are often conducted by studying rodent Plasmodium species in inbred laboratory mice, but the efficacy of vaccines or adjunctive therapies observed in these models often does not translate to protection in humans. This raises concerns that mouse malaria models do not recapitulate important features of human malaria infections. African woodland thicket rats (Grammomys surdaster) are the natural host for the rodent malaria parasite Plasmodium berghei and the suspected natural host for Plasmodium vinckei vinckei. Previously, we reported that thicket rats are highly susceptible to diverse rodent parasite species, including P. berghei, Plasmodium yoelii, and Plasmodium chabaudi chabaudi, and are a more stringent model to assess the efficacy of whole-sporozoite vaccines than laboratory mice. Here, we compare the course of infection and virulence with additional rodent Plasmodium species, including various strains of P. berghei, P. yoelii, P. chabaudi, and P. vinckei, in thicket rats versus laboratory mice. We present evidence that rodent malaria parasite growth typically differs between the natural versus nonnatural host; G. surdaster limit infection by multiple rodent malaria strains, delaying and reducing peak parasitemia compared with laboratory mice. The course of malaria infection in thicket rats varied depending on parasite species and strain, resulting in self-cure, chronic parasitemia, or rapidly lethal infection, thus offering a variety of rodent malaria models to study different clinical outcomes in the natural host.
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Affiliation(s)
- Solomon Conteh
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Jacqueline Kolasny
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Yvette L Robbins
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Pati Pyana
- Department of Parasitology, Institut National de Recherche Biomedicale (INRB), Kinshasa, Democratic Republic of the Congo
| | - Philippe Büscher
- Department of Biomedical Sciences, Unit of Parasite Diagnostics, Institute of Tropical Medicine, Antwerp, Belgium
| | - Javonn Musgrove
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Brandi Butler
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Lynn Lambert
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - John Patrick Gorres
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology (LMIV), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland
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Kurtovic L, Boyle MJ, Opi DH, Kennedy AT, Tham WH, Reiling L, Chan JA, Beeson JG. Complement in malaria immunity and vaccines. Immunol Rev 2019; 293:38-56. [PMID: 31556468 PMCID: PMC6972673 DOI: 10.1111/imr.12802] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/20/2022]
Abstract
Developing efficacious vaccines for human malaria caused by Plasmodium falciparum is a major global health priority, although this has proven to be immensely challenging over the decades. One major hindrance is the incomplete understanding of specific immune responses that confer protection against disease and/or infection. While antibodies to play a crucial role in malaria immunity, the functional mechanisms of these antibodies remain unclear as most research has primarily focused on the direct inhibitory or neutralizing activity of antibodies. Recently, there is a growing body of evidence that antibodies can also mediate effector functions through activating the complement system against multiple developmental stages of the parasite life cycle. These antibody‐complement interactions can have detrimental consequences to parasite function and viability, and have been significantly associated with protection against clinical malaria in naturally acquired immunity, and emerging findings suggest these mechanisms could contribute to vaccine‐induced immunity. In order to develop highly efficacious vaccines, strategies are needed that prioritize the induction of antibodies with enhanced functional activity, including the ability to activate complement. Here we review the role of complement in acquired immunity to malaria, and provide insights into how this knowledge could be used to harness complement in malaria vaccine development.
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Affiliation(s)
- Liriye Kurtovic
- Burnet Institute, Melbourne, Vic., Australia.,Central Clinical School, Monash University, Melbourne, Vic., Australia
| | | | | | - Alexander T Kennedy
- Walter and Eliza Hall Institute, Melbourne, Vic., Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Vic., Australia
| | - Wai-Hong Tham
- Walter and Eliza Hall Institute, Melbourne, Vic., Australia
| | | | - Jo-Anne Chan
- Burnet Institute, Melbourne, Vic., Australia.,Central Clinical School, Monash University, Melbourne, Vic., Australia
| | - James G Beeson
- Burnet Institute, Melbourne, Vic., Australia.,Central Clinical School, Monash University, Melbourne, Vic., Australia.,Department of Microbiology, Monash University, Clayton, Vic., Australia.,Department of Medicine, The University of Melbourne, Parkville, Vic., Australia
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DEHGHAN H, OSHAGHI MA, MOSA-KAZEMI SH, ABAI MR, RAFIE F, NATEGHPOUR M, MOHAMMADZADEH H, FARIVAR L, MOHAMMADI BAVANI M. Experimental Study on Plasmodium berghei, Anopheles Stephensi, and BALB/c Mouse System: Implications for Malaria Transmission Blocking Assays. IRANIAN JOURNAL OF PARASITOLOGY 2018; 13:549-559. [PMID: 30697308 PMCID: PMC6348208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 01/16/2018] [Indexed: 10/25/2022]
Abstract
BACKGROUND Plasmodium berghei is a rodent malaria parasite and has been very valuable means in the progress of our understanding of the essential molecular and cellular biology of the malaria parasites. Availability of hosts such as mice and vectors such as Anopheles stephensi has made this parasite a suitable system to study the parasite-host and vector-parasite relationships. METHODS This study was performed at Medical Entomology and Parasitology laboratories of the School of Public Health, Tehran University of Medical Sciences, Iran in 2016. The investigation was carried out to describe life cycle and parameters influencing maintenance of the parasite within the mice or the mosquito. RESULTS Results have revealed details and addressed some parameters and points influence maintenance of various life stages of the parasite including merozoites, macrogametocytes, ookinetes, oocysts and sporozoites in the laboratory model P. berghei-A. stephensi-BALB/c mouse. Injection of fresh infected blood results in higher gametocytemia in the animals. The more injected parasites result in earlier and higher parasitemia and exfelagellation centers in the mice blood. However, the highest number of infected mosquitoes and oocysts formation were observed when the parasitemia and exflagellation centers per microscopic field were 9% and 3.6 in the infected mice respectively. The infected mosquitoes should be maintained on 8% (w/v) fructose, 0.05% (w/v) PABA at 20±1 °C and 50%-80% relative humidity. CONCLUSION This study helps to understand the biology of vertebrate-parasite and mosquito-malaria interactions that may aid in the development of a new generation of drug/vaccine and vector-based measures for malaria control.
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Affiliation(s)
- Hossein DEHGHAN
- Dept. of Medical Entomology & Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali OSHAGHI
- Dept. of Medical Entomology & Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Hassan MOSA-KAZEMI
- Dept. of Medical Entomology & Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza ABAI
- Dept. of Medical Entomology & Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Fatemeh RAFIE
- Dept. of Medical Entomology & Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi NATEGHPOUR
- Dept. of Parasitology and Medical Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Habib MOHAMMADZADEH
- Cellular and Molecular Research Center, Urmia University of Medical Sciences, Urmia, Iran
- Dept. of Medical Parasitology and Mycology, School of Health, Urmia University of Medical Sciences, Urmia, Iran
| | - Leila FARIVAR
- Dept. of Parasitology and Medical Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mulood MOHAMMADI BAVANI
- Dept. of Medical Entomology, School of Health, Urmia University of Medical Sciences, Urmia, Iran
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Kreutzfeld O, Müller K, Matuschewski K. Engineering of Genetically Arrested Parasites (GAPs) For a Precision Malaria Vaccine. Front Cell Infect Microbiol 2017; 7:198. [PMID: 28620583 PMCID: PMC5450620 DOI: 10.3389/fcimb.2017.00198] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/04/2017] [Indexed: 01/08/2023] Open
Abstract
Continuous stage conversion and swift changes in the antigenic repertoire in response to acquired immunity are hallmarks of complex eukaryotic pathogens, including Plasmodium species, the causative agents of malaria. Efficient elimination of Plasmodium liver stages prior to blood infection is one of the most promising malaria vaccine strategies. Here, we describe different genetically arrested parasites (GAPs) that have been engineered in Plasmodium berghei, P. yoelii and P. falciparum and compare their vaccine potential. A better understanding of the immunological mechanisms of prime and boost by arrested sporozoites and experimental strategies to enhance vaccine efficacy by further engineering existing GAPs into a more immunogenic form hold promise for continuous improvements of GAP-based vaccines. A critical hurdle for vaccines that elicit long-lasting protection against malaria, such as GAPs, is safety and efficacy in vulnerable populations. Vaccine research should focus on solutions toward turning malaria into a vaccine-preventable disease, which would offer an exciting new path of malaria control.
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Affiliation(s)
- Oriana Kreutzfeld
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Katja Müller
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt UniversityBerlin, Germany
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Antibody-independent mechanisms regulate the establishment of chronic Plasmodium infection. Nat Microbiol 2017; 2:16276. [PMID: 28165471 DOI: 10.1038/nmicrobiol.2016.276] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 12/22/2016] [Indexed: 01/15/2023]
Abstract
Malaria is caused by parasites of the genus Plasmodium. All human-infecting Plasmodium species can establish long-lasting chronic infections1-5, creating an infectious reservoir to sustain transmission1,6. It is widely accepted that the maintenance of chronic infection involves evasion of adaptive immunity by antigenic variation7. However, genes involved in this process have been identified in only two of five human-infecting species: Plasmodium falciparum and Plasmodium knowlesi. Furthermore, little is understood about the early events in the establishment of chronic infection in these species. Using a rodent model we demonstrate that from the infecting population, only a minority of parasites, expressing one of several clusters of virulence-associated pir genes, establishes a chronic infection. This process occurs in different species of parasites and in different hosts. Establishment of chronicity is independent of adaptive immunity and therefore different from the mechanism proposed for maintenance of chronic P. falciparum infections7-9. Furthermore, we show that the proportions of parasites expressing different types of pir genes regulate the time taken to establish a chronic infection. Because pir genes are common to most, if not all, species of Plasmodium10, this process may be a common way of regulating the establishment of chronic infections.
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