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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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2
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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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3
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Kina UY, Kamil M, Deveci G, Rafiqi AM, Matuschewski K, Aly ASI. A Candidate Bacterial-Type Amino Acid Decarboxylase Is Essential for Male Gamete Exflagellation and Mosquito Transmission of the Malaria Parasite. Infect Immun 2023; 91:e0016723. [PMID: 37260388 PMCID: PMC10353352 DOI: 10.1128/iai.00167-23] [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: 05/03/2023] [Accepted: 05/07/2023] [Indexed: 06/02/2023] Open
Abstract
A frequent side effect of chemotherapy against malaria parasite blood infections is a dramatic induction of the sexual blood stages, thereby enhancing the risk of future malaria transmissions. The polyamine biosynthesis pathway has been suggested as a candidate target for transmission-blocking anti-malarial drug development. Herein, we describe the role of a bacterial-type amino acid decarboxylase (AAD) in the life cycle of the malaria model parasite Plasmodium yoelii. Hallmarks of AAD include a conserved catalytic lysine residue and high-level homology to arginine/lysine/ornithine decarboxylases of pathogenic bacteria. By targeted gene deletion, we show that AAD plays an essential role in the exflagellation of microgametes, resulting in complete absence of sporozoites in the mosquito vector. These data highlight the central role of the biosysthesis of polyamines in the final steps of male gamete sexual development of the malaria parasite and, hence, onward transmission to mosquitoes.
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Affiliation(s)
- Umit Y. Kina
- Aly lab, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey
- Department of Biotechnology, Institute of Health Sciences, Bezmialem Vakif University, Istanbul, Turkey
| | - Mohd Kamil
- Aly lab, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Gozde Deveci
- Aly lab, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey
| | - Ab. Matteen Rafiqi
- Aly lab, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Ahmed S. I. Aly
- Aly lab, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University, Istanbul, Turkey
- School of Science and Engineering, Al Akhawayn University, Ifrane, Morocco
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4
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Klug D, Gautier A, Calvo E, Marois E, Blandin SA. The salivary protein Saglin facilitates efficient midgut colonization of Anopheles mosquitoes by malaria parasites. PLoS Pathog 2023; 19:e1010538. [PMID: 36862755 PMCID: PMC10013899 DOI: 10.1371/journal.ppat.1010538] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 03/14/2023] [Accepted: 02/08/2023] [Indexed: 03/03/2023] Open
Abstract
Malaria is caused by the unicellular parasite Plasmodium which is transmitted to humans through the bite of infected female Anopheles mosquitoes. To initiate sexual reproduction and to infect the midgut of the mosquito, Plasmodium gametocytes are able to recognize the intestinal environment after being ingested during blood feeding. A shift in temperature, pH change and the presence of the insect-specific compound xanthurenic acid have been shown to be important stimuli perceived by gametocytes to become activated and proceed to sexual reproduction. Here we report that the salivary protein Saglin, previously proposed to be a receptor for the recognition of salivary glands by sporozoites, facilitates Plasmodium colonization of the mosquito midgut, but does not contribute to salivary gland invasion. In mosquito mutants lacking Saglin, Plasmodium infection of Anopheles females is reduced, resulting in impaired transmission of sporozoites at low infection densities. Interestingly, Saglin can be detected in high amounts in the midgut of mosquitoes after blood ingestion, possibly indicating a previously unknown host-pathogen interaction between Saglin and midgut stages of Plasmodium. Furthermore, we were able to show that saglin deletion has no fitness cost in laboratory conditions, suggesting this gene would be an interesting target for gene drive approaches.
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Affiliation(s)
- Dennis Klug
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
- * E-mail:
| | - Amandine Gautier
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Eric Calvo
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Eric Marois
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Stéphanie A. Blandin
- Université de Strasbourg, CNRS UPR9022, INSERM U1257, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
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Russell AJC, Sanderson T, Bushell E, Talman AM, Anar B, Girling G, Hunziker M, Kent RS, Martin JS, Metcalf T, Montandon R, Pandey V, Pardo M, Roberts AB, Sayers C, Schwach F, Choudhary JS, Rayner JC, Voet T, Modrzynska KK, Waters AP, Lawniczak MKN, Billker O. Regulators of male and female sexual development are critical for the transmission of a malaria parasite. Cell Host Microbe 2023; 31:305-319.e10. [PMID: 36634679 PMCID: PMC7616090 DOI: 10.1016/j.chom.2022.12.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/04/2022] [Accepted: 12/12/2022] [Indexed: 01/13/2023]
Abstract
Malaria transmission to mosquitoes requires a developmental switch in asexually dividing blood-stage parasites to sexual reproduction. In Plasmodium berghei, the transcription factor AP2-G is required and sufficient for this switch, but how a particular sex is determined in a haploid parasite remains unknown. Using a global screen of barcoded mutants, we here identify genes essential for the formation of either male or female sexual forms and validate their importance for transmission. High-resolution single-cell transcriptomics of ten mutant parasites portrays the developmental bifurcation and reveals a regulatory cascade of putative gene functions in the determination and subsequent differentiation of each sex. A male-determining gene with a LOTUS/OST-HTH domain as well as the protein interactors of a female-determining zinc-finger protein indicate that germ-granule-like ribonucleoprotein complexes complement transcriptional processes in the regulation of both male and female development of a malaria parasite.
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Affiliation(s)
| | - Theo Sanderson
- Wellcome Sanger Institute, Hinxton CB10 1SA, UK; Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Ellen Bushell
- Wellcome Sanger Institute, Hinxton CB10 1SA, UK; Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå 90187, Sweden; Department of Molecular Biology, Umeå University, Umeå 90187, Sweden
| | - Arthur M Talman
- Wellcome Sanger Institute, Hinxton CB10 1SA, UK; MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Burcu Anar
- Wellcome Sanger Institute, Hinxton CB10 1SA, UK
| | | | - Mirjam Hunziker
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå 90187, Sweden; Department of Molecular Biology, Umeå University, Umeå 90187, Sweden
| | - Robyn S Kent
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, VT 05405, USA
| | - Julie S Martin
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow G12 8TA, UK
| | - Tom Metcalf
- Wellcome Sanger Institute, Hinxton CB10 1SA, UK
| | | | - Vikash Pandey
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå 90187, Sweden; Department of Molecular Biology, Umeå University, Umeå 90187, Sweden
| | | | - A Brett Roberts
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow G12 8TA, UK
| | - Claire Sayers
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå 90187, Sweden; Department of Molecular Biology, Umeå University, Umeå 90187, Sweden
| | | | | | - Julian C Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Thierry Voet
- Department of Human Genetics, University of Leuven, KU Leuven, B-3000 Leuven, Belgium; KU Leuven Institute for Single Cell Omics, LISCO, KU Leuven, 3000 Leuven, Belgium
| | - Katarzyna K Modrzynska
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow G12 8TA, UK
| | - Andrew P Waters
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow G12 8TA, UK.
| | | | - Oliver Billker
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå 90187, Sweden; Department of Molecular Biology, Umeå University, Umeå 90187, Sweden.
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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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The Impact of Temperature on the Sporogonic Development of the Tropical Avian Malaria Parasite Plasmodium relictum (Genetic Lineage pGRW4) in Culex pipiens Form molestus Mosquitoes. Microorganisms 2021; 9:microorganisms9112240. [PMID: 34835365 PMCID: PMC8620208 DOI: 10.3390/microorganisms9112240] [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: 08/04/2021] [Revised: 10/12/2021] [Accepted: 10/25/2021] [Indexed: 12/02/2022] Open
Abstract
The avian malaria parasite Plasmodium relictum (genetic lineage pGRW4) is known to cause severe pathology in nonadapted vertebrate hosts. This parasite is prevalent in some bird species in Northern Europe, however the records obtained are only from adult long-distance migrant birds after their return from the wintering grounds. A recent experimental study showed that this parasite completes sporogonic development in the local European vector Culex pipiens at a controlled mean temperature of 19 °C. Thereby, temperature limits for the transmission of this parasite in Northern Europe remain unknown. In this study, we took a step further and tested the impact of different temperature conditions, including some extreme fluctuations between 23 °C down to 7 °C, on the sporogonic development of P. relictum (pGRW4) in the vector Culex pipiens form molestus. Mosquitoes were exposed to infection and kept under different air-temperature conditions: (i) constant warm temperature, (ii) natural outdoor temperatures and (iii) temporary exposure to low temperatures. Plasmodium relictum (pGRW4) completed sporogony in mosquitoes of all experimental groups, however different patterns of the sporogonic development depending on temperature conditions were observed. Based on these results, we conclude that the cool air temperature of Northern Europe in summer is not a limiting factor in successful development of the parasite. However, delayed sporogony caused by low summer temperatures may have a detrimental impact on the active transmission of this parasite in Northern Europe.
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Whitlock AOB, Juliano JJ, Mideo N. Immune selection suppresses the emergence of drug resistance in malaria parasites but facilitates its spread. PLoS Comput Biol 2021; 17:e1008577. [PMID: 34280179 PMCID: PMC8321109 DOI: 10.1371/journal.pcbi.1008577] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/29/2021] [Accepted: 06/04/2021] [Indexed: 12/23/2022] Open
Abstract
Although drug resistance in Plasmodium falciparum typically evolves in regions of low transmission, resistance spreads readily following introduction to regions with a heavier disease burden. This suggests that the origin and the spread of resistance are governed by different processes, and that high transmission intensity specifically impedes the origin. Factors associated with high transmission, such as highly immune hosts and competition within genetically diverse infections, are associated with suppression of resistant lineages within hosts. However, interactions between these factors have rarely been investigated and the specific relationship between adaptive immunity and selection for resistance has not been explored. Here, we developed a multiscale, agent-based model of Plasmodium parasites, hosts, and vectors to examine how host and parasite dynamics shape the evolution of resistance in populations with different transmission intensities. We found that selection for antigenic novelty (“immune selection”) suppressed the evolution of resistance in high transmission settings. We show that high levels of population immunity increased the strength of immune selection relative to selection for resistance. As a result, immune selection delayed the evolution of resistance in high transmission populations by allowing novel, sensitive lineages to remain in circulation at the expense of the spread of a resistant lineage. In contrast, in low transmission settings, we observed that resistant strains were able to sweep to high population prevalence without interference. Additionally, we found that the relationship between immune selection and resistance changed when resistance was widespread. Once resistance was common enough to be found on many antigenic backgrounds, immune selection stably maintained resistant parasites in the population by allowing them to proliferate, even in untreated hosts, when resistance was linked to a novel epitope. Our results suggest that immune selection plays a role in the global pattern of resistance evolution. Drug resistance in the malaria parasite, Plasmodium falciparum, presents an ongoing public health challenge, but aspects of its evolution are poorly understood. Although antimalarial resistance is common worldwide, it can typically be traced to just a handful of evolutionary origins. Counterintuitively, although Sub Saharan Africa bears 90% of the global malaria burden, resistance typically originates in regions where transmission intensity is low. In high transmission regions, infections are genetically diverse, and hosts have significant standing adaptive immunity, both of which are known to suppress the frequency of resistance within infections. However, interactions between immune-driven selection, transmission intensity, and resistance have not been investigated. Using a multiscale, agent-based model, we found that high transmission intensity slowed the evolution of resistance via its effect on host population immunity. High host immunity strengthened selection for antigenic novelty, interfering with selection for resistance and allowing sensitive lineages to suppress resistant lineages in untreated hosts. However, once resistance was common in the circulating parasite population, immune selection maintained it in the population at a high prevalence. Our findings provide a novel explanation for observations about the origin of resistance and suggest that adaptive immunity is a critical component of selection.
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Affiliation(s)
| | - Jonathan J. Juliano
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Nicole Mideo
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Canada
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9
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Sekar V, Rivero A, Pigeault R, Gandon S, Drews A, Ahren D, Hellgren O. Gene regulation of the avian malaria parasite Plasmodium relictum, during the different stages within the mosquito vector. Genomics 2021; 113:2327-2337. [PMID: 34023365 DOI: 10.1016/j.ygeno.2021.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/26/2021] [Accepted: 05/18/2021] [Indexed: 10/21/2022]
Abstract
The malaria parasite Plasmodium relictum is one of the most widespread species of avian malaria. As in the case of its human counterparts, bird Plasmodium undergoes a complex life cycle infecting two hosts: the arthropod vector and the vertebrate host. In this study, we examined transcriptomes of P. relictum (SGS1) during crucial timepoints within its vector, Culex pipiens quinquefasciatus. Differential gene-expression analyses identified genes linked to the parasites life-stages at: i) a few minutes after the blood meal is ingested, ii) during peak oocyst production phase, iii) during peak sporozoite phase and iv) during the late-stages of the infection. A large amount of genes coding for functions linked to host-immune invasion and multifunctional genes was active throughout the infection cycle. One gene associated with a conserved Plasmodium membrane protein with unknown function was upregulated throughout the parasite development in the vector, suggesting an important role in the successful completion of the sporogonic cycle. Gene expression analysis further identified genes, with unknown functions to be significantly differentially expressed during the infection in the vector as well as upregulation of reticulocyte-binding proteins, which raises the possibility of the multifunctionality of these RBPs. We establish the existence of highly stage-specific pathways being overexpressed during the infection. This first study of gene-expression of a non-human Plasmodium species in its vector provides a comprehensive insight into the molecular mechanisms of the common avian malaria parasite P. relictum and provides essential information on the evolutionary diversity in gene regulation of the Plasmodium's vector stages.
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Affiliation(s)
| | - Ana Rivero
- MIVEGEC (CNRS - Université de Montpellier - IRD), 34394 Montpellier, France; CREES (Centre de Recherche en Ecologie et Evolution de la Santé), 34394 Montpellier, France
| | - Romain Pigeault
- Department of Biology, Lund University, Sweden; Department of Ecology and Evolution, CH-1015 Lausanne, Switzerland
| | - Sylvain Gandon
- CEFE (CNRS - Université de Montpellier - Université Paul-Valéry - EPHE - IRD), Montpellier, France
| | - Anna Drews
- MEMEG, Department of Biology, Lund University, Sweden
| | - Dag Ahren
- National Bioinformatics Infrastructure Sweden (NBIS), SciLifeLab, Department of Biology, Lund, Sweden
| | - Olof Hellgren
- MEMEG, Department of Biology, Lund University, Sweden.
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10
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Moita D, Nunes-Cabaço H, Mendes AM, Prudêncio M. A guide to investigating immune responses elicited by whole-sporozoite pre-erythrocytic vaccines against malaria. FEBS J 2021; 289:3335-3359. [PMID: 33993649 DOI: 10.1111/febs.16016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/19/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022]
Abstract
In the last few decades, considerable efforts have been made toward the development of efficient vaccines against malaria. Whole-sporozoite (Wsp) vaccines, which induce efficient immune responses against the pre-erythrocytic (PE) stages (sporozoites and liver forms) of Plasmodium parasites, the causative agents of malaria, are among the most promising immunization strategies tested until present. Several Wsp PE vaccination approaches are currently under evaluation in the clinic, including radiation- or genetically-attenuated Plasmodium sporozoites, live parasites combined with chemoprophylaxis, or genetically modified rodent Plasmodium parasites. In addition to the assessment of their protective efficacy, clinical trials of Wsp PE vaccine candidates inevitably involve the thorough investigation of the immune responses elicited by vaccination, as well as the identification of correlates of protection. Here, we review the main methodologies employed to dissect the humoral and cellular immune responses observed in the context of Wsp PE vaccine clinical trials and discuss future strategies to further deepen the knowledge generated by these studies, providing a toolbox for the in-depth analysis of vaccine-induced immunogenicity.
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Affiliation(s)
- Diana Moita
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - Helena Nunes-Cabaço
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - António M Mendes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - Miguel Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
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11
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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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12
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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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13
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Isaïa J, Rivero A, Glaizot O, Christe P, Pigeault R. Last-come, best served? Mosquito biting order and Plasmodium transmission. Proc Biol Sci 2020; 287:20202615. [PMID: 33234076 PMCID: PMC7739503 DOI: 10.1098/rspb.2020.2615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A pervasive characteristic of parasite infections is their tendency to be overdispersed. Understanding the mechanisms underlying this overdispersed distribution is of key importance as it may impact the transmission dynamics of the pathogen. Although multiple factors ranging from environmental stochasticity to inter-individual heterogeneity may explain parasite overdispersion, parasite infection is also overdispersed in an inbred host population maintained under laboratory conditions, suggesting that other mechanisms are at play. Here, we show that the aggregated distribution of malaria parasites within mosquito vectors is partially explained by a temporal heterogeneity in parasite infectivity triggered by the bites of mosquitoes. Parasite transmission tripled between the mosquito's first and last blood feed in a period of only 3 h. Surprisingly, the increase in transmission is not associated with an increase in parasite investment in production of the transmissible stage. Overall, we highlight that Plasmodium is capable of responding to the bites of mosquitoes to increase its own transmission at a much faster pace than initially thought and that this is partly responsible for overdispersed distribution of infection. We discuss the underlying mechanisms as well as the broader implications of this plastic response for the epidemiology of malaria.
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Affiliation(s)
- J Isaïa
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - A Rivero
- MIVEGEC (UMR CNRS 5290), Montpellier, France.,CREES (Centre de Recherche en Ecologie et Evolution de la Santé), Montpellier, France
| | - O Glaizot
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.,Musée Cantonal de Zoologie, Lausanne, Switzerland
| | - P Christe
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - R Pigeault
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
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14
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Hajkazemian M, Bossé C, Mozūraitis R, Emami SN. Battleground midgut: The cost to the mosquito for hosting the malaria parasite. Biol Cell 2020; 113:79-94. [PMID: 33125724 DOI: 10.1111/boc.202000039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/31/2020] [Accepted: 10/12/2020] [Indexed: 12/27/2022]
Abstract
In eco-evolutionary studies of parasite-host interactions, virulence is defined as a reduction in host fitness as a result of infection relative to an uninfected host. Pathogen virulence may either promote parasite transmission, when correlated with higher parasite replication rate, or decrease the transmission rate if the pathogen quickly kills the host. This evolutionary mechanism, referred to as 'trade-off' theory, proposes that pathogen virulence evolves towards a level that most benefits the transmission. It has been generally predicted that pathogens evolve towards low virulence in their insect vectors, mainly due to the high dependence of parasite transmission on their vector survival. Therefore, the degree of virulence which malaria parasites impose on mosquito vectors may depend on several external and internal factors. Here, we review briefly (i) the role of mosquito in parasite development, with a particular focus on mosquito midgut as the battleground between Plasmodium and the mosquito host. We aim to point out (ii) the histology of the mosquito midgut epithelium and its role in host defence against parasite's countermeasures in the three main battle sites, namely (a) the lumen (microbiota and biochemical environment), (b) the peritrophic membrane (physical barrier) and (c) the tubular epithelium including the basal membrane (physical and biochemical barrier). Lastly, (iii) we describe the impact which malaria parasite and its virulence factors have on mosquito fitness.
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Affiliation(s)
- Melika Hajkazemian
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Clément Bossé
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,François Rabelais University, Tours, France
| | - Raimondas Mozūraitis
- Laboratory of Chemical and Behavioural Ecology, Institute of Ecology, Nature Research Centre, Vilnius, Lithuania.,Department of Zoology, Stockholm University, Stockholm, Sweden
| | - S Noushin Emami
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,Molecular Attraction AB, Hägersten, Stockholm, Sweden.,Natural Resources Institute, FES, University of Greenwich, London, UK
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15
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Childs LM, Prosper OF. The impact of within-vector parasite development on the extrinsic incubation period. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192173. [PMID: 33204441 PMCID: PMC7657899 DOI: 10.1098/rsos.192173] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Mosquito-borne diseases, in particular malaria, have a significant burden worldwide leading to nearly half a million deaths each year. The malaria parasite requires a vertebrate host, such as a human, and a vector host, the Anopheles mosquito, to complete its full life cycle. Here, we focus on the parasite dynamics within the vector to examine the first appearance of sporozoites in the salivary glands, which indicates a first time of infectiousness of mosquitoes. The timing of this period of pathogen development in the mosquito until transmissibility, known as the extrinsic incubation period, remains poorly understood. We develop compartmental models of within-mosquito parasite dynamics fitted with experimental data on oocyst and sporozoite counts. We find that only a fraction of oocysts burst to release sporozoites and bursting must be delayed either via a time-dependent function or a gamma-distributed set of compartments. We use Bayesian inference to estimate distributions of parameters and determine that bursting rate is a key epidemiological parameter. A better understanding of the factors impacting the extrinsic incubation period will aid in the development of interventions to slow or stop the spread of malaria.
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Affiliation(s)
- Lauren M. Childs
- Department of Mathematics, Virginia Tech, 225 Stanger St, Blacksburg, VA 24060, USA
| | - Olivia F. Prosper
- Department of Mathematics, University of Tennessee, 1403 Circle Dr, Knoxville, TN 37996, USA
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16
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High Plasmodium infection intensity in naturally infected malaria vectors in Africa. Int J Parasitol 2020; 50:985-996. [PMID: 32681932 DOI: 10.1016/j.ijpara.2020.05.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/14/2020] [Accepted: 05/17/2020] [Indexed: 01/18/2023]
Abstract
The population dynamics of human to mosquito malaria transmission in the field has important implications for the genetics, epidemiology and control of malaria. The number of oocysts in oocyst-positive mosquitoes developing from a single, naturally acquired infectious blood meal (herein referred to as a single-feed infection load) greatly influences the efficacy of transmission blocking interventions but still remains poorly documented. During a year-long analysis of malaria parasite transmission in Burkina Faso we caught and dissected wild malaria vectors to assess Plasmodium oocyst prevalence and load (the number of oocysts counted in mosquitoes with detectable oocysts) and the prevalence of salivary gland sporozoites. This was compared with malaria endemicity in the human population, assessed in cross-sectional surveys. Data were analysed using a novel transmission mathematical model to estimate the per bite transmission probability and the average single-feed infection load for each location. The observed oocyst load and the estimated single-feed infection load in naturally infected mosquitoes were substantially higher than previous estimates (means ranging from 3.2 to 24.5 according to seasons and locations) and indicate a strong positive association between the single-feed infection load and parasite prevalence in humans. This work suggests that highly infected mosquitoes are not rare in the field and might have a greater influence on the epidemiology and genetics of the parasite, and on the efficacy of novel transmission blocking interventions.
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17
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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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18
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Soré H, Lopatriello A, Ebstie YA, Tenoh Guedoung AR, Hilou A, Pereira JA, Kijjoa A, Habluetzel A, Taglialatela-Scafati O. Plasmodium stage-selective antimalarials from Lophira lanceolata stem bark. PHYTOCHEMISTRY 2020; 174:112336. [PMID: 32192964 DOI: 10.1016/j.phytochem.2020.112336] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 02/26/2020] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
Targeting the transmissible stages of the Plasmodium parasite that develop in the human and mosquito host is a crucial strategy for malaria control and elimination. Medicinal plants offer a prolific source for the discovery of new antimalarial compounds. The recent identification of the gametocytocidal activity of lophirone E, obtained from the African plant Lophira lanceolata (Ochnaceae), inspired the evaluation of the plant also against early sporogonic stages of the parasite development. The bioassay-guided phytochemical study led to the isolation of two known lanceolins and of a new glycosylated bichalcone, named glucolophirone C. Its stereostructure, including absolute configuration of the bichalcone moiety, was elucidated by means of NMR, HRMS, ECD and computational calculations. Lanceolin B proved to be a potent inhibitor of the development of Plasmodium early sporogonic stages indicating that the plant produces two different stage-specific antimalarial agents acting on transmissible stages in the human and mosquito host.
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Affiliation(s)
- Harouna Soré
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, 01 BP 2208, Burkina Faso; Laboratoire de Biochimie et Chimie Appliquées (LABIOCA), Université Joseph Ki Zerbo de Ouagadougou, 03 BP: 7021, Burkina Faso
| | - Annalisa Lopatriello
- Department of Pharmacy, School of Medicine and Surgery, University of Naples Federico II, Via D. Montesano 49, 80131, Naples, Italy
| | - Yehenew A Ebstie
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università di Camerino Macerata, Via Madonna delle Carceri 9, 62032, Camerino, Italy
| | - Alain R Tenoh Guedoung
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università di Camerino Macerata, Via Madonna delle Carceri 9, 62032, Camerino, Italy
| | - Adama Hilou
- Laboratoire de Biochimie et Chimie Appliquées (LABIOCA), Université Joseph Ki Zerbo de Ouagadougou, 03 BP: 7021, Burkina Faso
| | - José A Pereira
- ICBAS-Instituto de Ciencias Biomedicas Abel Salazar and CIIMAR, Rua de Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Anake Kijjoa
- ICBAS-Instituto de Ciencias Biomedicas Abel Salazar and CIIMAR, Rua de Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Annette Habluetzel
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università di Camerino Macerata, Via Madonna delle Carceri 9, 62032, Camerino, Italy; Centro Interuniversitario di Ricerca Sulla Malaria / Italian Malaria Network, University of Milan, Milan, Italy.
| | - Orazio Taglialatela-Scafati
- Department of Pharmacy, School of Medicine and Surgery, University of Naples Federico II, Via D. Montesano 49, 80131, Naples, Italy; Centro Interuniversitario di Ricerca Sulla Malaria / Italian Malaria Network, University of Milan, Milan, Italy.
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19
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Kenthirapalan S, Tran PN, Kooij TWA, Ridgway MC, Rauch M, Brown SHJ, Mitchell TW, Matuschewski K, Maier AG. Distinct adaptations of a gametocyte ABC transporter to murine and human Plasmodium parasites and its incompatibility in cross-species complementation. Int J Parasitol 2020; 50:511-522. [PMID: 32445722 DOI: 10.1016/j.ijpara.2020.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 11/18/2022]
Abstract
Parasites of the genus Plasmodium infect a wide range of mammalian hosts including humans, primates, bats and arboreal rodents. A hallmark of Plasmodium spp. is the very narrow host range, indicative of matching parasite-host coevolution. Accordingly, their respective genomes harbour many unique genes and gene families that typically encode proteins involved in host cell recognition and remodelling. Whether and to what extent conserved proteins that are shared across Plasmodium spp. also exert distinct species-specific roles remains largely untested. Here, we present detailed functional profiling of the female gametocyte-specific ATP-binding cassette transporter gABCG2 in the murine parasite Plasmodium berghei and compare our findings with data from the orthologous gene in the human parasite Plasmodium falciparum. We show that P. berghei gABCG2 is female-specific and continues to be expressed in zygotes and ookinetes. In contrast to a distinct localization to Iipid-rich gametocyte-specific spots as observed in P. falciparum, the murine malaria parasite homolog is found at the parasite plasma membrane. Plasmodium berghei lacking gABCG2 displays fast asexual blood-stage replication and increased proportions of female gametocytes, consistent with the corresponding P. falciparum knock-out phenotype. Strikingly, cross-species replacement of gABCG2 in either the murine or the human parasite did not restore normal growth rates. The lack of successful complementation despite high conservation across Plasmodium spp. is an indicator of distinct adaptations and tight parasite-host coevolution. Hence, incompatibility of conserved genes in closely related Plasmodium spp. might be more common than previously anticipated.
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Affiliation(s)
| | - Phuong N Tran
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Taco W A Kooij
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Melanie C Ridgway
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Manuel Rauch
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Dept. of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Simon H J Brown
- School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Todd W Mitchell
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia; School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Kai Matuschewski
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany; Dept. of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany.
| | - Alexander G Maier
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
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20
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Kirkman LA, Deitsch KW. Vive la Différence: Exploiting the Differences between Rodent and Human Malarias. Trends Parasitol 2020; 36:504-511. [PMID: 32407681 DOI: 10.1016/j.pt.2020.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/23/2020] [Accepted: 03/23/2020] [Indexed: 12/14/2022]
Abstract
Experimental research into malaria biology and pathogenesis has historically focused on two model systems, in vitro culture of the human parasite Plasmodium falciparum and in vivo infections of laboratory animals using rodent parasites. While there is clear value in having a manipulatable animal model for studying malaria, there have occasionally been controversies around how representative the rodent model is of the human disease, and therefore significant emphasis has been placed on the similarities between the two biological systems. By focusing on basic nuclear functions, we wish to highlight that identifying key differences in the parasites and their interactions with their mammalian hosts can be equally informative and provide remarkable insights into the biology and evolution of these important infectious organisms.
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Affiliation(s)
- Laura A Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA; Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, USA
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
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21
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Wells MB, Andrew DJ. Anopheles Salivary Gland Architecture Shapes Plasmodium Sporozoite Availability for Transmission. mBio 2019; 10:e01238-19. [PMID: 31387905 PMCID: PMC6686039 DOI: 10.1128/mbio.01238-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/11/2019] [Indexed: 12/18/2022] Open
Abstract
Plasmodium sporozoites (SPZs) must traverse the mosquito salivary glands (SGs) to reach a new vertebrate host and continue the malaria disease cycle. Although SGs can harbor thousands of sporozoites, only 10 to 100 are deposited into a host during probing. To determine how the SGs might function as a bottleneck in SPZ transmission, we have characterized Anopheles stephensi SGs infected with the rodent malaria parasite Plasmodium berghei using immunofluorescence confocal microscopy. Our analyses corroborate findings from previous electron microscopy studies and provide new insights into the invasion process. We identified sites of SPZ accumulation within SGs across a range of infection intensities. Although SPZs were most often seen in the distal lateral SG lobes, they were also observed in the medial and proximal lateral lobes. Most parasites were associated with either the basement membrane or secretory cavities. SPZs accumulated at physical barriers, including fused salivary ducts and extensions of the chitinous salivary duct wall into the distal lumen. SPZs were observed only rarely within salivary ducts. SPZs appeared to contact each other in many different quantities, not just in the previously described large bundles. Within parasite bundles, all of the SPZs were oriented in the same direction. We found that moderate levels of infection did not necessarily correlate with major SG disruptions or abundant SG cell death. Altogether, our findings suggest that SG architecture largely acts as a barrier to SPZ transmission.IMPORTANCE Malaria continues to have a devastating impact on human health. With growing resistance to insecticides and antimalarial drugs, as well as climate change predictions indicating expansion of vector territories, the impact of malaria is likely to increase. Additional insights regarding pathogen migration through vector mosquitoes are needed to develop novel methods to prevent transmission to new hosts. Pathogens, including the microbes that cause malaria, must invade the salivary glands (SGs) for transmission. Since SG traversal is required for parasite transmission, SGs are ideal targets for transmission-blocking strategies. The work presented here highlights the role that mosquito SG architecture plays in limiting parasite traversal, revealing how the SG transmission bottleneck is imposed. Further, our data provide unprecedented detail about SG-sporozoite interactions and gland-to-gland variation not provided in previous studies.
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Affiliation(s)
- Michael B Wells
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Deborah J Andrew
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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22
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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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23
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Espinosa A, Paz-Y-Miño-C G. Discrimination Experiments in Entamoeba and Evidence from Other Protists Suggest Pathogenic Amebas Cooperate with Kin to Colonize Hosts and Deter Rivals. J Eukaryot Microbiol 2019; 66:354-368. [PMID: 30055104 PMCID: PMC6349510 DOI: 10.1111/jeu.12673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/27/2018] [Accepted: 07/25/2018] [Indexed: 01/06/2023]
Abstract
Entamoeba histolytica is one of the least understood protists in terms of taxa, clone, and kin discrimination/recognition ability. However, the capacity to tell apart same or self (clone/kin) from different or nonself (nonclone/nonkin) has long been demonstrated in pathogenic eukaryotes like Trypanosoma and Plasmodium, free-living social amebas (Dictyostelium, Polysphondylium), budding yeast (Saccharomyces), and in numerous bacteria and archaea (prokaryotes). Kin discrimination/recognition is explained under inclusive fitness theory; that is, the reproductive advantage that genetically closely related organisms (kin) can gain by cooperating preferably with one another (rather than with distantly related or unrelated individuals), minimizing antagonism and competition with kin, and excluding genetic strangers (or cheaters = noncooperators that benefit from others' investments in altruistic cooperation). In this review, we rely on the outcomes of in vitro pairwise discrimination/recognition encounters between seven Entamoeba lineages to discuss the biological significance of taxa, clone, and kin discrimination/recognition in a range of generalist and specialist species (close or distantly related phylogenetically). We then focus our discussion on the importance of these laboratory observations for E. histolytica's life cycle, host infestation, and implications of these features of the amebas' natural history for human health (including mitigation of amebiasis).
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Affiliation(s)
- Avelina Espinosa
- Department of Biology, Roger Williams University, Bristol, Rhode Island
- New England Center for the Public Understanding of Science, Roger Williams University, Bristol, Rhode Island
| | - Guillermo Paz-Y-Miño-C
- New England Center for the Public Understanding of Science, Roger Williams University, Bristol, Rhode Island
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24
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Obrova K, Cyrklaff M, Frank R, Mair GR, Mueller AK. Transmission of the malaria parasite requires ferlin for gamete egress from the red blood cell. Cell Microbiol 2019; 21:e12999. [PMID: 30597708 DOI: 10.1111/cmi.12999] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 11/15/2018] [Accepted: 12/09/2018] [Indexed: 02/02/2023]
Abstract
Ferlins mediate calcium-dependent vesicular fusion. Although conserved throughout eukaryotic evolution, their function in unicellular organisms including apicomplexan parasites is largely unknown. Here, we define a crucial role for a ferlin-like protein (FLP) in host-to-vector transmission of the rodent malaria parasite Plasmodium berghei. Infection of the mosquito vectors requires the formation of free gametes and their fertilisation in the mosquito midgut. Mature gametes will only emerge upon secretion of factors that stimulate the disruption of the red blood cell membrane and the parasitophorous vacuole membrane. Genetic depletion of FLP in sexual stages leads to a complete life cycle arrest in the mosquito. Although mature gametes form normally, mutants lacking FLP remain trapped in the red blood cell. The egress defect is rescued by detergent-mediated membrane lysis. In agreement with ferlin vesicular localisation, HA-tagged FLP labels intracellular speckles, which relocalise to the cell periphery during gamete maturation. Our data define FLP as a novel critical factor for Plasmodium fertilisation and transmission and suggest an evolutionarily conserved example of ferlin-mediated exocytosis.
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Affiliation(s)
- Klara Obrova
- Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Marek Cyrklaff
- Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Roland Frank
- Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Gunnar R Mair
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, USA
| | - Ann-Kristin Mueller
- Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany.,German Center for Infectious Diseases (DZIF), Universitätsklinikum Heidelberg, Heidelberg, Germany
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25
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Kooistra RL, David R, Ruiz AC, Powers SW, Haselton KJ, Kiernan K, Blagborough AM, Solamen L, Olsen KW, Putonti C, Kanzok SM. Characterization of a protozoan Phosducin-like protein-3 (PhLP-3) reveals conserved redox activity. PLoS One 2019; 13:e0209699. [PMID: 30596727 PMCID: PMC6312279 DOI: 10.1371/journal.pone.0209699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/09/2018] [Indexed: 11/18/2022] Open
Abstract
We recently identified three novel thioredoxin-like genes in the genome of the protozoan parasite Plasmodium that belong to the Phosducin-like family of proteins (PhLP). PhLPs are small cytosolic proteins hypothesized to function in G-protein signaling and protein folding. Although PhLPs are highly conserved in eukaryotes from yeast to mammals, only a few representatives have been experimentally characterized to date. In addition, while PhLPs contain a thioredoxin domain, they lack a CXXC motif, a strong indicator for redox activity, and it is unclear whether members of the PhLP family are enzymatically active. Here, we describe PbPhLP-3 as the first phosducin-like protein of a protozoan organism, Plasmodium berghei. Initial transcription analysis revealed continuous low-level expression of pbphlp-3 throughout the complex Plasmodium life cycle. Attempts to knockout pbphlp-3 in P. berghei did not yield live parasites, suggesting an essential role for the gene in Plasmodium. We cloned, expressed and purified PbPhLP-3 and determined that the recombinant protein is redox active in vitro in a thioredoxin-coupled redox assay. It also has the capacity to reduce the organic compound tert-Butyl hydroperoxide (TBHP) in vitro, albeit at low efficiency. Sequence analysis, structural modeling, and site-directed mutagenesis revealed a conserved cysteine in the thioredoxin domain to be the redox active residue. Lastly, we provide evidence that recombinant human PhLP-3 exhibits redox activity similar to that of PbPhLP-3 and suggest that redox activity may be conserved in PhLP-3 homologs of other species. Our data provide new insight into the function of PhLP-3, which is hypothesized to act as co-chaperones in the folding and regulation of cytoskeletal proteins. We discuss the potential implications of PhLP-3 as a thioredoxin-target protein and possible links between the cellular redox network and the eukaryotic protein folding machinery.
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Affiliation(s)
- Rachel L. Kooistra
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Robin David
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Ana C. Ruiz
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Sean W. Powers
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Kyle J. Haselton
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Kaitlyn Kiernan
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Andrew M. Blagborough
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Ligin Solamen
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- Bioinformatics Program, Loyola University Chicago, Chicago, IL, United States of America
| | - Kenneth W. Olsen
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States of America
| | - Catherine Putonti
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- Bioinformatics Program, Loyola University Chicago, Chicago, IL, United States of America
- Department of Computer Science, Loyola University Chicago, Chicago, IL, United States of America
| | - Stefan M. Kanzok
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- Bioinformatics Program, Loyola University Chicago, Chicago, IL, United States of America
- * E-mail:
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26
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Sherrard-Smith E, Sala KA, Betancourt M, Upton LM, Angrisano F, Morin MJ, Ghani AC, Churcher TS, Blagborough AM. Synergy in anti-malarial pre-erythrocytic and transmission-blocking antibodies is achieved by reducing parasite density. eLife 2018; 7:35213. [PMID: 29914622 PMCID: PMC6008048 DOI: 10.7554/elife.35213] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 05/18/2018] [Indexed: 01/05/2023] Open
Abstract
Anti-malarial pre-erythrocytic vaccines (PEV) target transmission by inhibiting human infection but are currently partially protective. It has been posited, but never demonstrated, that co-administering transmission-blocking vaccines (TBV) would enhance malaria control. We hypothesized a mechanism that TBV could reduce parasite density in the mosquito salivary glands, thereby enhancing PEV efficacy. This was tested using a multigenerational population assay, passaging Plasmodium berghei to Anopheles stephensi mosquitoes. A combined efficacy of 90.8% (86.7-94.2%) was observed in the PEV +TBV antibody group, higher than the estimated efficacy of 83.3% (95% CrI 79.1-87.0%) if the two antibodies acted independently. Higher PEV efficacy at lower mosquito parasite loads was observed, comprising the first direct evidence that co-administering anti-sporozoite and anti-transmission interventions act synergistically, enhancing PEV efficacy across a range of TBV doses and transmission intensities. Combining partially effective vaccines of differing anti-parasitic classes is a pragmatic, powerful way to accelerate malaria elimination efforts.
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Affiliation(s)
- Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Katarzyna A Sala
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Leanna M Upton
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Fiona Angrisano
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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27
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Dehghan H, Oshaghi MA, Moosa-Kazemi SH, Yakhchali B, Vatandoost H, Maleki-Ravasan N, Rassi Y, Mohammadzadeh H, Abai MR, Mohtarami F. Dynamics of Transgenic Enterobacter cloacae Expressing Green Fluorescent Protein Defensin (GFP-D) in Anopheles stephensi Under Laboratory Condition. J Arthropod Borne Dis 2017; 11:515-532. [PMID: 29367928 PMCID: PMC5775158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/23/2017] [Indexed: 10/29/2022] Open
Abstract
BACKGROUND Enterobacter cloacae bacterium is a known symbiont of the most Anopheles gut microflora and nominated as a good candidate for paratransgenic control of malaria. However, the population dynamics of this bacterium within An. stephensi and its introduction methods to the mosquitoes have not yet been explored. METHODS Enterobacter cloacae subsp. dissolvens expressing green fluorescent protein and defensin (GFP-D) was used to study transstadial transmission and the course of time, larval habitat, sugar, and blood meal on dynamics of the bacterium in the mosquito life stages in the laboratory condition. The bacterial quantities were measured by plating samples and counting GFP expressing colonies on the Tet-BHI agar medium. RESULTS The E. cloacae population remained stable in sugar bait at least for eleven days whereas it was lowered in the insectary larval habitat where the bacteria inadequately recycled. The bacterium was weakly transmitted transstadially from larval to adult stage. The bacterial populations increased smoothly and then dramatically in the guts of An. stephensi following sugar and blood meal respectively followed by a gradual reduction over the time. CONCLUSION Enterobacter cloacae was highly stable in sugar bait and increased tremendously in the gut of female adult An. stephensi within 24h post blood meal. Sugar bait stations can be used for introduction of the transgenic bacteria in a paratransgenic approach. It is recommended to evaluate the attraction of sugar bait in combination with attractive kairomones as well as its stability and survival rate in the semi-field or field conditions.
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Affiliation(s)
- Hossein Dehghan
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Oshaghi
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Corresponding Authors: Dr Mohammad Ali Oshaghi, E-mail: , Dr Seyed Hassan Moosa-Kazemi,
| | - Seyed Hassan Moosa-Kazemi
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Corresponding Authors: Dr Mohammad Ali Oshaghi, E-mail: , Dr Seyed Hassan Moosa-Kazemi,
| | - Bagher Yakhchali
- Department Industrial and of Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Hassan Vatandoost
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran
| | - Naseh Maleki-Ravasan
- Malaria and Vector Research Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Yavar Rassi
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Habib Mohammadzadeh
- Department of Parasitology and Mycology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Mohammad Reza Abai
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Mohtarami
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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28
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Lefevre T, Ohm J, Dabiré KR, Cohuet A, Choisy M, Thomas MB, Cator L. Transmission traits of malaria parasites within the mosquito: Genetic variation, phenotypic plasticity, and consequences for control. Evol Appl 2017; 11:456-469. [PMID: 29636799 PMCID: PMC5891056 DOI: 10.1111/eva.12571] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 10/23/2017] [Indexed: 12/16/2022] Open
Abstract
Evaluating the risk of emergence and transmission of vector‐borne diseases requires knowledge of the genetic and environmental contributions to pathogen transmission traits. Compared to the significant effort devoted to understanding the biology of malaria transmission from vertebrate hosts to mosquito vectors, the strategies that malaria parasites have evolved to maximize transmission from vectors to vertebrate hosts have been largely overlooked. While determinants of infection success within the mosquito host have recently received attention, the causes of variability for other key transmission traits of malaria, namely the duration of parasite development and its virulence within the vector, as well as its ability to alter mosquito behavior, remain largely unknown. This important gap in our knowledge needs to be bridged in order to obtain an integrative view of the ecology and evolution of malaria transmission strategies. Associations between transmission traits also need to be characterized, as they trade‐offs and constraints could have important implications for understanding the evolution of parasite transmission. Finally, theoretical studies are required to evaluate how genetic and environmental influences on parasite transmission traits can shape malaria dynamics and evolution in response to disease control.
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Affiliation(s)
- Thierry Lefevre
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France.,Institut de Recherche en Sciences de la Santé (IRSS) Bobo Dioulasso Burkina Faso.,Laboratoire Mixte International sur les Vecteurs (LAMIVECT) Bobo Dioulasso Burkina Faso
| | - Johanna Ohm
- Department of Entomology and Center for Infectious Disease Dynamics Penn State University University Park PA USA
| | - Kounbobr R Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS) Bobo Dioulasso Burkina Faso.,Laboratoire Mixte International sur les Vecteurs (LAMIVECT) Bobo Dioulasso Burkina Faso
| | - Anna Cohuet
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France
| | - Marc Choisy
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France.,Oxford University Clinical Research Unit Hanoi Vietnam
| | - Matthew B Thomas
- Department of Entomology and Center for Infectious Disease Dynamics Penn State University University Park PA USA
| | - Lauren Cator
- Grand Challenges in Ecosystems and Environment Imperial College London Ascot UK
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29
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Modulation of transmission success of Plasmodium falciparum gametocytes (sexual stages) in various species of Anopheles by erythrocytic asexual stage parasites. Acta Trop 2017; 176:263-269. [PMID: 28859956 DOI: 10.1016/j.actatropica.2017.08.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/23/2017] [Accepted: 08/26/2017] [Indexed: 12/15/2022]
Abstract
During malaria infection, a small proportion of erythrocytic asexual stages undergo sexual differentiation. Male and female gametocytes ingested in the blood meal initiate the sexual development of malaria parasites in the mosquito midgut. During blood feeding on a host, a mosquito ingests, in addition to mature gametocytes, host immune factors present in the blood, as well as large excess of erythrocytic asexual stages. In the current study we addressed the impact of the presence of large excess of asexual stages, hitherto not known or even suspected to influence, on the infectivity of gametocytes in the mosquito. Asexual stages resulted in a dose-dependent inhibition of infectiousness of gametocytes, and some of this could be explained by the presumed effect of hemozoin and other unknown asexual-stage components on the mosquito immune system, affecting survival and maturation of parasites in the mosquito midgut. Interactions between asexual and sexual stages, maturity and ratio of male and female gametocytes, host immune factors and mosquito innate immune factors are some of the variables that determine the infectiousness of gametocytes in the mosquitoes and ultimately malaria transmission success. Understanding of determinants affecting malaria transmission will be critical to approaches directly targeting the transmission process for malaria elimination.
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30
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Hopp CS, Bennett BL, Mishra S, Lehmann C, Hanson KK, Lin JW, Rousseau K, Carvalho FA, van der Linden WA, Santos NC, Bogyo M, Khan SM, Heussler V, Sinnis P. Deletion of the rodent malaria ortholog for falcipain-1 highlights differences between hepatic and blood stage merozoites. PLoS Pathog 2017; 13:e1006586. [PMID: 28922424 PMCID: PMC5602738 DOI: 10.1371/journal.ppat.1006586] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 08/16/2017] [Indexed: 01/10/2023] Open
Abstract
Proteases have been implicated in a variety of developmental processes during the malaria parasite lifecycle. In particular, invasion and egress of the parasite from the infected hepatocyte and erythrocyte, critically depend on protease activity. Although falcipain-1 was the first cysteine protease to be characterized in P. falciparum, its role in the lifecycle of the parasite has been the subject of some controversy. While an inhibitor of falcipain-1 blocked erythrocyte invasion by merozoites, two independent studies showed that falcipain-1 disruption did not affect growth of blood stage parasites. To shed light on the role of this protease over the entire Plasmodium lifecycle, we disrupted berghepain-1, its ortholog in the rodent parasite P. berghei. We found that this mutant parasite displays a pronounced delay in blood stage infection after inoculation of sporozoites. Experiments designed to pinpoint the defect of berghepain-1 knockout parasites found that it was not due to alterations in gliding motility, hepatocyte invasion or liver stage development and that injection of berghepain-1 knockout merosomes replicated the phenotype of delayed blood stage growth after sporozoite inoculation. We identified an additional role for berghepain-1 in preparing blood stage merozoites for infection of erythrocytes and observed that berghepain-1 knockout parasites exhibit a reticulocyte restriction, suggesting that berghepain-1 activity broadens the erythrocyte repertoire of the parasite. The lack of berghepain-1 expression resulted in a greater reduction in erythrocyte infectivity in hepatocyte-derived merozoites than it did in erythrocyte-derived merozoites. These observations indicate a role for berghepain-1 in processing ligands important for merozoite infectivity and provide evidence supporting the notion that hepatic and erythrocytic merozoites, though structurally similar, are not identical. Malaria affects hundreds of millions of people and is the cause of hundreds of thousands of deaths each year. Infection begins with the inoculation of sporozoites into the skin during the bite of an infected mosquito. Sporozoites subsequently travel to the liver, where they invade and replicate in hepatocytes, eventually releasing the stage of the parasite that is infectious for red blood cells, termed merozoites. Hepatic merozoites initiate blood stage infection, the stage that is responsible for the clinical symptoms of malaria. The blood stage of the parasite grows through repeated rounds of invasion, development and egress of blood stage merozoites, which then continue the cycle. Proteases are among the enzymes that are essential for parasite survival and their functions range from invasion of red blood cells, to the breakdown of red cell hemoglobin, to the release of parasites from red cells. As the function of the cysteine protease falcipain-1 in the lifecycle of the human malaria parasite Plasmodium falciparum remains poorly understood, we decided to study berghepain-1, the orthologue of the rodent malaria parasite P. berghei by generating a berghepain-1 deletion parasite. Using this mutant, we demonstrate that berghepain-1 has a critical role in both hepatic and erythrocytic merozoite infectivity. Little is known about differences between these two types of merozoites and our data leads us to conclude that these merozoites are not identical.
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Affiliation(s)
- Christine S. Hopp
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail: (CSH); (BLB); (PS)
| | - Brandy L. Bennett
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (CSH); (BLB); (PS)
| | - Satish Mishra
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | | | - Kirsten K. Hanson
- Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Jing-wen Lin
- Department of Parasitology, Leiden Malaria Research Group, Leiden University Medical Center, Leiden ZA, The Netherlands
| | - Kimberly Rousseau
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Filomena A. Carvalho
- Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Wouter A. van der Linden
- Departments of Pathology and Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Nuno C. Santos
- Instituto de Medicina Molecular, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Matthew Bogyo
- Departments of Pathology and Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Shahid M. Khan
- Department of Parasitology, Leiden Malaria Research Group, Leiden University Medical Center, Leiden ZA, The Netherlands
| | - Volker Heussler
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Photini Sinnis
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (CSH); (BLB); (PS)
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31
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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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32
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Affiliation(s)
- Robert E. Sinden
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail:
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33
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Yurayart N, Kaewthamasorn M, Tiawsirisup S. Vector competence of Aedes albopictus (Skuse) and Aedes aegypti (Linnaeus) for Plasmodium gallinaceum infection and transmission. Vet Parasitol 2017; 241:20-25. [DOI: 10.1016/j.vetpar.2017.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 05/03/2017] [Accepted: 05/06/2017] [Indexed: 10/19/2022]
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34
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Habtewold T, Groom Z, Christophides GK. Immune resistance and tolerance strategies in malaria vector and non-vector mosquitoes. Parasit Vectors 2017; 10:186. [PMID: 28420446 PMCID: PMC5395841 DOI: 10.1186/s13071-017-2109-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 03/24/2017] [Indexed: 11/10/2022] Open
Abstract
Background The Anopheles gambiae complex consists of species that vary greatly in their capacity to transmit malaria. The mosquito immune system has been identified as a key factor that can influence whether Plasmodium infection establishes within the mosquito vector. This study was designed to investigate the immune responses of An. coluzzii, An. arabiensis and An. quadriannulatus mosquitoes. The first two mosquito species are major vectors of malaria in sub-Saharan Africa, while the third is thought to be a non-vector. Methods All three mosquito species were reared in mixed cultures. Their capacity to eliminate P. berghei and regulate midgut bacteria was examined. Results Our results revealed large differences in mosquito resistance to P. berghei. In all three mosquito species, immune reactions involving the complement system were triggered when the number of parasites that mosquitoes were challenged with exceeded a certain level, i.e. immune tolerance threshold. This threshold was markedly lower in An. quadriannulatus compared to An. coluzzii and An. arabiensis. We also demonstrated that the level of immune tolerance to P. berghei infection in the haemolymph is inversely correlated with the level of immune tolerance to microbiota observed in the midgut lumen after a blood meal. The malaria non-vector mosquito species, An. quadriannulatus was shown to have a much higher level of tolerance to microbiota in the midgut than An. coluzzii. Conclusions We propose a model whereby an increased tolerance to microbiota in the mosquito midgut results in lower tolerance to Plasmodium infection. In this model, malaria non-vector mosquito species are expected to have increased immune resistance in the haemocoel, possibly due to complement priming by microbiota elicitors. We propose that this strategy is employed by the malaria non-vector mosquito, An. quadriannulatus, while An. coluzzii has reduced tolerance to bacterial infection in the midgut and consequently reduced immune resistance to Plasmodium infection at the haemocoel level. An in-depth understanding of the molecular mechanisms regulating immune tolerance versus resistance in different mosquito vectors of malaria could guide the design of new vector and disease control strategies. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2109-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tibebu Habtewold
- Department of Life Sciences, Imperial College London, London, UK. .,Department of Comparative Physiology and Biometrics, University of Ghent, Ghent, Belgium.
| | - Zoe Groom
- Department of Life Sciences, Imperial College London, London, UK.,Costello Medical Consulting, Cambridge, UK
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Sherrard-Smith E, Churcher TS, Upton LM, Sala KA, Zakutansky SE, Slater HC, Blagborough AM, Betancourt M. A novel model fitted to multiple life stages of malaria for assessing efficacy of transmission-blocking interventions. Malar J 2017; 16:137. [PMID: 28376897 PMCID: PMC5379616 DOI: 10.1186/s12936-017-1782-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/17/2017] [Indexed: 11/15/2022] Open
Abstract
Background Transmission-blocking interventions (TBIs) aim to eliminate malaria by reducing transmission of the parasite between the host and the invertebrate vector. TBIs include transmission-blocking drugs and vaccines that, when given to humans, are taken up by mosquitoes and inhibit parasitic development within the vector. Accurate methodologies are key to assess TBI efficacy to ensure that only the most potent candidates progress to expensive and time-consuming clinical trials. Measuring intervention efficacy can be problematic because there is substantial variation in the number of parasites in both the host and vector populations, which can impact transmission even in laboratory settings. Methods A statistically robust empirical method is introduced for estimating intervention efficacy from standardised population assay experiments. This method will be more reliable than simple summary statistics as it captures changes in parasite density in different life-stages. It also allows efficacy estimates at a finer resolution than previous methods enabling the impact of the intervention over successive generations to be tracked. A major advantage of the new methodology is that it makes no assumptions on the population dynamics of infection. This enables both host-to-vector and vector-to-host transmission to be density-dependent (or other) processes and generates easy-to-understand estimates of intervention efficacy. Results This method increases the precision of intervention efficacy estimates and demonstrates that relying on changes in infection prevalence (the proportion of infected hosts) alone may be insufficient to capture the impact of TBIs, which also suppress parasite density in secondarily infected hosts. Conclusions The method indicates that potentially useful, partially effective TBIs may require multiple infection cycles before substantial reductions in prevalence are observed, despite more rapidly suppressing parasite density. Accurate models to quantify efficacy will have important implications for understanding how TBI candidates might perform in field situations and how they should be evaluated in clinical trials. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1782-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ellie Sherrard-Smith
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK.
| | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Leanna M Upton
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Katarzyna A Sala
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Sara E Zakutansky
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Hannah C Slater
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Andrew M Blagborough
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, UK
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Smith TA, Chitnis N, Penny M, Tanner M. Malaria Modeling in the Era of Eradication. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a025460. [PMID: 28003280 DOI: 10.1101/cshperspect.a025460] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mathematical models provide the essential basis of rational research and development strategies in malaria, informing the choice of which technologies to target, which deployment strategies to consider, and which populations to focus on. The Internet and remote sensing technologies also enable assembly of ever more relevant field data. Together with supercomputing technology, this has made available timely descriptions of the geography of malaria transmission and disease across the world and made it possible for policy and planning to be informed by detailed simulations of the potential impact of intervention programs. These information technology advances do not replace the basic understanding of the dynamics of malaria transmission that should be embedded in the thinking of anyone planning malaria interventions. The appropriate use of modeling may determine whether we are living in an era of hubris or indeed in an age of eradication.
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Affiliation(s)
- Thomas A Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel CH 4002, Switzerland; and University of Basel, Basel CH 4001, Switzerland
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel CH 4002, Switzerland; and University of Basel, Basel CH 4001, Switzerland
| | - Melissa Penny
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel CH 4002, Switzerland; and University of Basel, Basel CH 4001, Switzerland
| | - Marcel Tanner
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel CH 4002, Switzerland; and University of Basel, Basel CH 4001, Switzerland
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Churcher TS, Sinden RE, Edwards NJ, Poulton ID, Rampling TW, Brock PM, Griffin JT, Upton LM, Zakutansky SE, Sala KA, Angrisano F, Hill AVS, Blagborough AM. Probability of Transmission of Malaria from Mosquito to Human Is Regulated by Mosquito Parasite Density in Naïve and Vaccinated Hosts. PLoS Pathog 2017; 13:e1006108. [PMID: 28081253 PMCID: PMC5230737 DOI: 10.1371/journal.ppat.1006108] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/02/2016] [Indexed: 11/19/2022] Open
Abstract
Over a century since Ronald Ross discovered that malaria is caused by the bite of an infectious mosquito it is still unclear how the number of parasites injected influences disease transmission. Currently it is assumed that all mosquitoes with salivary gland sporozoites are equally infectious irrespective of the number of parasites they harbour, though this has never been rigorously tested. Here we analyse >1000 experimental infections of humans and mice and demonstrate a dose-dependency for probability of infection and the length of the host pre-patent period. Mosquitoes with a higher numbers of sporozoites in their salivary glands following blood-feeding are more likely to have caused infection (and have done so quicker) than mosquitoes with fewer parasites. A similar dose response for the probability of infection was seen for humans given a pre-erythrocytic vaccine candidate targeting circumsporozoite protein (CSP), and in mice with and without transfusion of anti-CSP antibodies. These interventions prevented infection more efficiently from bites made by mosquitoes with fewer parasites. The importance of parasite number has widespread implications across malariology, ranging from our basic understanding of the parasite, how vaccines are evaluated and the way in which transmission should be measured in the field. It also provides direct evidence for why the only registered malaria vaccine RTS,S was partially effective in recent clinical trials. Malaria is transmitted to humans by the bite of an infectious mosquito though it is unclear whether a mosquito with a high number of parasites is more infectious than one with only a few. Here we show that the greater the number of parasites within the salivary gland of the mosquito following blood-feeding the more likely it is to have transmitted the disease. A clear dose-response is seen with highly infected mosquitoes being more likely to have caused infection (and to have done so quicker) than lightly infected mosquitoes. This suggesting that mosquito-based methods for measuring transmission in the field need to be refined as they currently only consider whether a mosquito is infected or not (and not how heavily infected the mosquito is). Novel transmission reducing drugs and vaccines are tested by experimentally infecting people using infectious mosquitoes. This work indicates that it is important to further standardise infectious dose in malaria experimental infections to enable the efficacy of new interventions to be accurately compared. The work also provides direct evidence to suggest that the world’s first licenced malaria vaccine may be partially effective because it fails to provide protection against highly infected mosquitoes.
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Affiliation(s)
- Thomas S. Churcher
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- * E-mail:
| | - Robert E. Sinden
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Nick J. Edwards
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Ian D. Poulton
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Thomas W. Rampling
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Patrick M. Brock
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jamie T. Griffin
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Leanna M. Upton
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Sara E. Zakutansky
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Katarzyna A. Sala
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Fiona Angrisano
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Adrian V. S. Hill
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Andrew M. Blagborough
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
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Abstract
This article attempts to draw together current knowledge on the biology of Plasmodium and experience gained from past control campaigns to interpret and guide current efforts to discover and develop exciting new strategies targeting the parasite with the objective of interrupting transmission. Particular note is made of the advantages of targeting often unappreciated small, yet vital, bottleneck populations to enhance both the impact and the useful lifetime of hard-won interventions. A case is made for the standardization of methods to measure transmission blockade to permit the rational comparison of how diverse interventions (drugs, vaccines, insecticides, Genetically Modified technologies) targeting disparate aspects of parasite biology may impact upon the commonly used parameter of parasite prevalence in the human population.
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Affiliation(s)
- R E Sinden
- The Jenner Institute, Oxford, United Kingdom.
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Molina-Cruz A, Zilversmit MM, Neafsey DE, Hartl DL, Barillas-Mury C. Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria. Annu Rev Genet 2016; 50:447-465. [PMID: 27732796 DOI: 10.1146/annurev-genet-120215-035211] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.
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Affiliation(s)
- Alvaro Molina-Cruz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852;
| | - Martine M Zilversmit
- Richard Guilder Graduate School and Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY 10024
| | - Daniel E Neafsey
- Genome Sequencing and Analysis Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Daniel L Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Carolina Barillas-Mury
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852;
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Lawniczak MKN, Eckhoff PA. A computational lens for sexual-stage transmission, reproduction, fitness and kinetics in Plasmodium falciparum. Malar J 2016; 15:487. [PMID: 27653663 PMCID: PMC5031309 DOI: 10.1186/s12936-016-1538-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/14/2016] [Indexed: 11/10/2022] Open
Abstract
Background The burden of falciparum malaria remains unacceptably high in much of sub-Saharan Africa and massive efforts are underway to eliminate the parasite. While symptoms of malaria are caused by asexual reproduction of the parasite, transmission to new human hosts relies entirely on male and female sexual-stage parasites, known as gametocytes. Successful transmission can be observed at very low gametocyte densities, which raises the question of whether transmission-enhancing mechanisms exist in the human host, the mosquito, or both. Methods A new computational model was developed to investigate the probability of fertilization over a range of overdispersion parameters and male gamete exploration rates. Simulations were used to fit a likelihood surface for data on rates of mosquito infection across a wide range of host gametocyte densities. Results The best fit simultaneously requires very strong overdispersion and faster gamete exploration than is possible with random swimming in order to explain typical prevalence levels in mosquitoes. Gametocyte overdispersion or clustering in the human host and faster gamete exploration of the mosquito blood meal are highly probably given these results. Conclusions Density-dependent gametocyte clustering in the human host, and non-random searching (e.g., chemotaxis) in the mosquito are probable. Future work should aim to discover these mechanisms, as disrupting parasite development in the mosquito will play a critical role in eliminating malaria. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1538-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Philip A Eckhoff
- Institute for Disease Modeling, 3150 139th Avenue SE, Bellevue, WA, 98005, USA.
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Chaurio RA, Pacheco MA, Cornejo OE, Durrego E, Stanley CE, Castillo AI, Herrera S, Escalante AA. Evolution of the Transmission-Blocking Vaccine Candidates Pvs28 and Pvs25 in Plasmodium vivax: Geographic Differentiation and Evidence of Positive Selection. PLoS Negl Trop Dis 2016; 10:e0004786. [PMID: 27347876 PMCID: PMC4922550 DOI: 10.1371/journal.pntd.0004786] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/28/2016] [Indexed: 11/23/2022] Open
Abstract
Transmission-blocking (TB) vaccines are considered an important tool for malaria control and elimination. Among all the antigens characterized as TB vaccines against Plasmodium vivax, the ookinete surface proteins Pvs28 and Pvs25 are leading candidates. These proteins likely originated by a gene duplication event that took place before the radiation of the known Plasmodium species to primates. We report an evolutionary genetic analysis of a worldwide sample of pvs28 and pvs25 alleles. Our results show that both genes display low levels of genetic polymorphism when compared to the merozoite surface antigens AMA-1 and MSP-1; however, both ookinete antigens can be as polymorphic as other merozoite antigens such as MSP-8 and MSP-10. We found that parasite populations in Asia and the Americas are geographically differentiated with comparable levels of genetic diversity and specific amino acid replacements found only in the Americas. Furthermore, the observed variation was mainly accumulated in the EGF2- and EGF3-like domains for P. vivax in both proteins. This pattern was shared by other closely related non-human primate parasites such as Plasmodium cynomolgi, suggesting that it could be functionally important. In addition, examination with a suite of evolutionary genetic analyses indicated that the observed patterns are consistent with positive natural selection acting on Pvs28 and Pvs25 polymorphisms. The geographic pattern of genetic differentiation and the evidence for positive selection strongly suggest that the functional consequences of the observed polymorphism should be evaluated during development of TBVs that include Pvs25 and Pvs28. Plasmodium vivax is the most prevalent human malarial parasite outside Africa. The fact that patients can relapse due to the parasite dormant liver stages, among other biologic and epidemiologic characteristics of vivax malaria, facilitates the persistence of the disease in many endemic areas. These challenges have fueled the search for new control tools, including transmission blocking (TB) vaccines targeting the parasite sexual stages. Here we study the genetic diversity of two major TB vaccine antigens, Pvs25 and Pvs28. We show that these genes are relatively conserved worldwide but still harbor diversity that is not evenly distributed across the genes. These patterns are shared by the same proteins in closely related parasite species suggesting their functional importance. We also identify strong geographic differentiation between the circulating variants found in Asia and the Americas. Finally, evolutionary genetic analyses indicate that the observed variation in both genes could be maintained by natural selection. Thus, these polymorphisms may confer an adaptive advantage to the parasite. These results indicate that the genetic variation found in these genes and their geographic distribution should be considered by vaccine developers.
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Affiliation(s)
- Ricardo A Chaurio
- Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - M Andreína Pacheco
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Omar E Cornejo
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Ester Durrego
- Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Craig E Stanley
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Andreína I Castillo
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | | | - Ananias A Escalante
- Institute for Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Temple University, Philadelphia, Pennsylvania, United States of America
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Lecona-Valera AN, Tao D, Rodríguez MH, López T, Dinglasan RR, Rodríguez MC. An antibody against an Anopheles albimanus midgut myosin reduces Plasmodium berghei oocyst development. Parasit Vectors 2016; 9:274. [PMID: 27165123 PMCID: PMC4863318 DOI: 10.1186/s13071-016-1548-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/27/2016] [Indexed: 11/13/2022] Open
Abstract
Background Malaria parasites are transmitted by Anopheles mosquitoes. Although several studies have identified mosquito midgut surface proteins that are putatively important for Plasmodium ookinete invasion, only a few have characterized these protein targets and demonstrated transmission-blocking activity. Molecular information about these proteins is essential for the development of transmission-blocking vaccines (TBV). The aim of the present study was to test three monoclonal antibodies (mAbs), A-140, A-78 and A-10, for their ability to recognize antigens and block oocyst infection of the midgut of Anopheles albimanus, a major malaria vector in Latin America. Method Western-blot of mAbs on antigens from midgut brush border membrane vesicles was used to select antibodies. Three mAbs were tested by membrane feeding assays to evaluate their potential transmission-blocking activity against Plasmodium berghei. The cognate antigens recognized by mAbs with oocyst-reducing activity were determined by immunoprecipitation followed by liquid chromatography tandem mass spectrometry. Results Only one mAb, A-140, significantly reduced oocyst infection intensity. Hence, its probable protein target in the Anopheles albimanus midgut was identified and characterized. It recognized three high-molecular mass proteins from a midgut brush border microvilli vesicle preparation. Chemical deglycosylation assays confirmed the peptide nature of the epitope recognized by mAb A-140. Immunoprecipitation followed by proteomic identification with tandem mass spectrometry revealed five proteins, presumably extracted together as a complex. Of these, AALB007909 had the highest mascot score and corresponds to a protein with a myosin head motor domain, indicating that the target of mAb A-140 is probably myosin located on the microvilli of the mosquito midgut. Conclusion These results provide support for the participation of myosin in mosquito midgut invasion by Plasmodium ookinetes. The potential inclusion of this protein in the design of new multivalent vaccine strategies for blocking Plasmodium transmission is discussed. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1548-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alba N Lecona-Valera
- Center of Research on Infectious Diseases, National Institute of Public Health, Av. Universidad 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, C. P. 62508, Mexico
| | - Dingyin Tao
- W. Harry Feinstone Department of Molecular Microbiology & Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland, 21205, USA
| | - Mario H Rodríguez
- Center of Research on Infectious Diseases, National Institute of Public Health, Av. Universidad 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, C. P. 62508, Mexico
| | - Tomás López
- Instituto de Biotecnología, Universidad Nacional Autónoma de Méxic006F, Av. Universidad 2001, Colonia Chamilpa, Cuernavaca, Morelos, 62210, Mexico
| | - Rhoel R Dinglasan
- W. Harry Feinstone Department of Molecular Microbiology & Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland, 21205, USA
| | - María C Rodríguez
- Center of Research on Infectious Diseases, National Institute of Public Health, Av. Universidad 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, C. P. 62508, Mexico.
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Parham PE, Waldock J, Christophides GK, Hemming D, Agusto F, Evans KJ, Fefferman N, Gaff H, Gumel A, LaDeau S, Lenhart S, Mickens RE, Naumova EN, Ostfeld RS, Ready PD, Thomas MB, Velasco-Hernandez J, Michael E. Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2013.0551. [PMID: 25688012 DOI: 10.1098/rstb.2013.0551] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems.
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Affiliation(s)
- Paul E Parham
- Department of Public Health and Policy, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3GL, UK Grantham Institute for Climate Change, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Joanna Waldock
- The Cyprus Institute, Nicosia, Cyprus Imperial College London, London SW7 2AZ, UK
| | | | - Deborah Hemming
- Meteorological Office Hadley Centre, UK Meteorological Office, Fitzroy Road, Exeter, EX1 3PB, UK
| | - Folashade Agusto
- Department of Mathematics, Austin Peay State University, Clarksville, TN 37044, USA
| | - Katherine J Evans
- Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Nina Fefferman
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA
| | - Holly Gaff
- Department of Biological Sciences, Old Dominium University, Norfolk, VA 23529, USA
| | - Abba Gumel
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1904, USA School of Mathematical and Natural Sciences, Arizona State University, Phoenix, AZ 85069-7100, USA
| | - Shannon LaDeau
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996-1300, USA
| | - Ronald E Mickens
- Department of Physics, Clark Atlanta University, PO Box 172, Atlanta, GA 30314, USA
| | - Elena N Naumova
- Department of Civil and Environmental Engineering, Tufts University School of Engineering, Medford, MA 02155, USA
| | - Richard S Ostfeld
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Paul D Ready
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jorge Velasco-Hernandez
- Universidad Nacional Autnoma de Mexico Institute of Mathematics Mexico City, Distrito Federal, Mexico
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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Abstract
Mathematical modelling provides an effective way to challenge conventional wisdom about
parasite evolution and investigate why parasites ‘do what they do’ within the host. Models
can reveal when intuition cannot explain observed patterns, when more complicated biology
must be considered, and when experimental and statistical methods are likely to mislead.
We describe how models of within-host infection dynamics can refine experimental design,
and focus on the case study of malaria to highlight how integration between models and
data can guide understanding of parasite fitness in three areas: (1) the adaptive
significance of chronic infections; (2) the potential for tradeoffs between virulence and
transmission; and (3) the implications of within-vector dynamics. We emphasize that models
are often useful when they highlight unexpected patterns in parasite evolution, revealing
instead why intuition yields the wrong answer and what combination of theory and data are
needed to advance understanding.
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Pollitt LC, Bram JT, Blanford S, Jones MJ, Read AF. Existing Infection Facilitates Establishment and Density of Malaria Parasites in Their Mosquito Vector. PLoS Pathog 2015; 11:e1005003. [PMID: 26181518 PMCID: PMC4504473 DOI: 10.1371/journal.ppat.1005003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 06/04/2015] [Indexed: 02/06/2023] Open
Abstract
Very little is known about how vector-borne pathogens interact within their vector and how this impacts transmission. Here we show that mosquitoes can accumulate mixed strain malaria infections after feeding on multiple hosts. We found that parasites have a greater chance of establishing and reach higher densities if another strain is already present in a mosquito. Mixed infections contained more parasites but these larger populations did not have a detectable impact on vector survival. Together these results suggest that mosquitoes taking multiple infective bites may disproportionally contribute to malaria transmission. This will increase rates of mixed infections in vertebrate hosts, with implications for the evolution of parasite virulence and the spread of drug-resistant strains. Moreover, control measures that reduce parasite prevalence in vertebrate hosts will reduce the likelihood of mosquitoes taking multiple infective feeds, and thus disproportionally reduce transmission. More generally, our study shows that the types of strain interactions detected in vertebrate hosts cannot necessarily be extrapolated to vectors.
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Affiliation(s)
- Laura C. Pollitt
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
- * E-mail:
| | - Joshua T. Bram
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Simon Blanford
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Matthew J. Jones
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, State College, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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Wu Y, Sinden RE, Churcher TS, Tsuboi T, Yusibov V. Development of malaria transmission-blocking vaccines: from concept to product. ADVANCES IN PARASITOLOGY 2015; 89:109-52. [PMID: 26003037 DOI: 10.1016/bs.apar.2015.04.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Despite decades of effort battling against malaria, the disease is still a major cause of morbidity and mortality. Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. In the 1950s, Huff et al. first demonstrated the induction of transmission-blocking immunity in chickens by repeated immunizations with Plasmodium gallinaceum-infected red blood cells. Since then, significant progress has been made in identification of parasite antigens responsible for transmission-blocking activity. Recombinant technologies accelerated evaluation of these antigens as vaccine candidates, and it is possible to induce effective transmission-blocking immunity in humans both by natural infection and now by immunization with recombinant vaccines. This chapter reviews the efforts to produce TBVs, summarizes the current status and advances and discusses the remaining challenges and approaches.
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Affiliation(s)
- Yimin Wu
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
| | | | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Takafumi Tsuboi
- Division of Malaria Research, Ehime University, Matsuyama, Ehime, Japan
| | - Vidadi Yusibov
- Fraunhofer USA Center for Molecular Biotechnology, Newark, DE, USA
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Žiegytė R, Bernotienė R, Bukauskaitė D, Palinauskas V, Iezhova T, Valkiūnas G. Complete sporogony of Plasmodium relictum (lineages pSGS1 and pGRW11) in mosquito Culex pipiens pipiens form molestus, with implications to avian malaria epidemiology. J Parasitol 2015; 100:878-82. [PMID: 24979183 DOI: 10.1645/13-469.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Plasmodium parasites (Plasmodiidae) cause malaria in many species of terrestrial vertebrates and are transmitted mainly by mosquitoes (Culicidae). Avian malaria is often caused by Plasmodium relictum , a cosmopolitan hemosporidian infection. Numerous genetic lineages of P. relictum have been described. However, it remains unclear if these lineages can be transmitted by Culex pipiens pipiens form molestus, which is widespread but has been insufficiently investigated as a possible vector of avian malaria. The aim of this study was to test experimentally if 2 common P. relictum lineages complete sporogony in the experimentally infected insects. The mosquitoes were cultivated under laboratory conditions. Unfed females were allowed to take blood meals on domestic canaries experimentally infected with the lineages pSGS1 and pGRW11 of P. relictum . These lineages are widespread and cause malaria in many species of birds. Infected female flies were examined for sporogonic development of each parasite lineage. Both exposed groups were maintained under the same laboratory conditions. Mosquitoes were dissected at intervals, and the midguts and salivary glands were prepared in order to detect sporogonic stages. Numerous ookinetes, oocysts, and sporozoites of both parasite lineages were observed. Polymerase chain reaction confirmed the presence of corresponding parasite lineages in the experimentally infected insects. Sporogonic stages of both lineages were morphologically similar and developed synchronously in this mosquito; however, the lineage pGRW11 developed a significantly greater number of oocysts than did the lineage pSGS1. This study shows that Culex p. pipiens f. molestus is susceptible to 2 widespread lineages of P. relictum and worth more attention in avian malaria epidemiology. We recommend C. p. pipiens f. molestus for experimental research of avian malaria parasites, principally because it willingly takes blood meals on birds and because it is easy to establish and maintain new colonies of this insect under laboratory conditions using wild-sampled eggs, larvae, or imago.
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Affiliation(s)
- Rita Žiegytė
- Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 21, LT-08412, Lithuania
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48
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Pimenta PFP, Orfano AS, Bahia AC, Duarte APM, Ríos-Velásquez CM, Melo FF, Pessoa FAC, Oliveira GA, Campos KMM, Villegas LM, Rodrigues NB, Nacif-Pimenta R, Simões RC, Monteiro WM, Amino R, Traub-Cseko YM, Lima JBP, Barbosa MGV, Lacerda MVG, Tadei WP, Secundino NFC. An overview of malaria transmission from the perspective of Amazon Anopheles vectors. Mem Inst Oswaldo Cruz 2015; 110:23-47. [PMID: 25742262 PMCID: PMC4371216 DOI: 10.1590/0074-02760140266] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 12/18/2014] [Indexed: 02/07/2023] Open
Abstract
In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Anopheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.
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Affiliation(s)
- Paulo FP Pimenta
- Centro de Pesquisas René Rachou-Fiocruz, Belo Horizonte, MG,
Brasil
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
| | | | - Ana C Bahia
- Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil
| | - Ana PM Duarte
- Centro de Pesquisas René Rachou-Fiocruz, Belo Horizonte, MG,
Brasil
| | | | - Fabrício F Melo
- Centro de Pesquisas René Rachou-Fiocruz, Belo Horizonte, MG,
Brasil
| | | | | | - Keillen MM Campos
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
| | | | | | | | - Rejane C Simões
- Instituto Nacional de Pesquisas da Amazônia, Manaus, AM, Brasil
| | - Wuelton M Monteiro
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
| | - Rogerio Amino
- Unité de Biologie et Génétique du Paludisme, Institut Pasteur, Paris,
France
| | | | - José BP Lima
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
- Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil
| | - Maria GV Barbosa
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
| | - Marcus VG Lacerda
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, AM,
Brasil
- Instituto Leônidas e Maria Deane-Fiocruz, Manaus, AM, Brasil
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Ganter M, Rizopoulos Z, Schüler H, Matuschewski K. Pivotal and distinct role for Plasmodium actin capping protein alpha during blood infection of the malaria parasite. Mol Microbiol 2015; 96:84-94. [PMID: 25565321 PMCID: PMC4413046 DOI: 10.1111/mmi.12922] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2015] [Indexed: 11/28/2022]
Abstract
Accurate regulation of microfilament dynamics is central to cell growth, motility and response to environmental stimuli. Stabilizing and depolymerizing proteins control the steady-state levels of filamentous (F-) actin. Capping protein (CP) binds to free barbed ends, thereby arresting microfilament growth and restraining elongation to remaining free barbed ends. In all CPs characterized to date, alpha and beta subunits form the active heterodimer. Here, we show in a eukaryotic parasitic cell that the two CP subunits can be functionally separated. Unlike the beta subunit, the CP alpha subunit of the apicomplexan parasite Plasmodium is refractory to targeted gene deletion during blood infection in the mammalian host. Combinatorial complementation of Plasmodium berghei CP genes with the orthologs from Plasmodium falciparum verified distinct activities of CP alpha and CP alpha/beta during parasite life cycle progression. Recombinant Plasmodium CP alpha could be produced in Escherichia coli in the absence of the beta subunit and the protein displayed F-actin capping activity. Thus, the functional separation of two CP subunits in a parasitic eukaryotic cell and the F-actin capping activity of CP alpha expand the repertoire of microfilament regulatory mechanisms assigned to CPs.
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Affiliation(s)
- Markus Ganter
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany; Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, MA, 02115, USA
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50
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Da DF, Churcher TS, Yerbanga RS, Yaméogo B, Sangaré I, Ouedraogo JB, Sinden RE, Blagborough AM, Cohuet A. Experimental study of the relationship between Plasmodium gametocyte density and infection success in mosquitoes; implications for the evaluation of malaria transmission-reducing interventions. Exp Parasitol 2014; 149:74-83. [PMID: 25541384 DOI: 10.1016/j.exppara.2014.12.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 12/10/2014] [Accepted: 12/15/2014] [Indexed: 11/29/2022]
Abstract
The evaluation of transmission reducing interventions (TRI) to control malaria widely uses membrane feeding assays. In such assays, the intensity of Plasmodium infection in the vector might affect the measured efficacy of the candidates to block transmission. Gametocyte density in the host blood is a determinant of the infection success in the mosquito, however, uncertain estimates of parasite densities and intrinsic characteristics of the infected blood can induce variability. To reduce this variation, a feasible method is to dilute infectious blood samples. We describe the effect of diluting samples of Plasmodium-containing blood samples to allow accurate relative measures of gametocyte densities and their impact on mosquito infectivity and TRI efficacy. Natural Plasmodium falciparum samples were diluted to generate a wide range of parasite densities, and fed to Anopheles coluzzii mosquitoes. This was compared with parallel dilutions conducted on Plasmodium berghei infections. We examined how blood dilution influences the observed blocking activity of anti-Pbs28 monoclonal antibody using the P. berghei/Anopheles stephensi system. In the natural species combination P. falciparum/An. coluzzii, blood dilution using heat-inactivated, infected blood as diluents, revealed positive near linear relationships, between gametocyte densities and oocyst loads in the range tested. A similar relationship was observed in the P. berghei/An. stephensi system when using a similar dilution method. In contrast, diluting infected mice blood with fresh uninfected blood dramatically increases the infectiousness. This suggests that highly infected mice blood contains inhibitory factors or reduced blood moieties, which impede infection and may in turn, lead to misinterpretation when comparing individual TRI evaluation assays. In the lab system, the transmission blocking activity of an antibody specific for Pbs28 was confirmed to be density-dependent. This highlights the need to carefully interpret evaluations of TRI candidates, regarding gametocyte densities in the P. berghei/An. stephensi system.
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Affiliation(s)
- 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; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France
| | - Thomas S Churcher
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Rakiswendé S Yerbanga
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Bienvenue Yaméogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Ibrahim Sangaré
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France
| | - Jean Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso
| | - Robert E Sinden
- Division of Cell and Molecular Biology, Imperial College London, London, United Kingdom; The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Andrew M Blagborough
- Division of Cell and Molecular Biology, Imperial College London, London, United Kingdom
| | - Anna Cohuet
- Institut de Recherche en Sciences de la Santé, Direction Régionale, 399 avenue de la liberté, Bobo Dioulasso 01 01 BP 545, Burkina Faso; Institut de Recherche pour le Développement, unité MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), 911 avenue Agropolis, Montpellier Cedex 5 34394, France.
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