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Salazar Alvarez LC, Carneiro Barbosa V, Vera Lizcano O, Baia da Silva DC, Gonçalves Santana RA, Fabbri C, Paoluci Pimenta PF, Monteiro WM, Albrecht L, Guimarães de Lacerda MV, Trindade Maranhão Costa F, Costa Pinto Lopes S. Rosette formation by Plasmodium vivax gametocytes favors the infection in Anopheles aquasalis. Front Cell Infect Microbiol 2023; 13:1108348. [PMID: 36875524 PMCID: PMC9975573 DOI: 10.3389/fcimb.2023.1108348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/23/2023] [Indexed: 02/17/2023] Open
Abstract
Plasmodium vivax is a public health problem and the most common type of malaria outside sub-Saharan Africa. The capacity of cytoadhesion, rosetting, and liver latent phase development could impact treatment and disease control. Although the ability to P. vivax gametocyte develop rosetting is known, it is not yet clear which role it plays during the infection and transmission process to the mosquito. Here, we used ex vivo approaches for evaluate the rosetting P. vivax gametocytes capacity and we have investigated the effect of this adhesive phenotype on the infection process in the vector Anopheles aquasalis mosquito. Rosette assays were performed in 107 isolates, and we have observed an elevated frequency of cytoadhesive phenomena (77,6%). The isolates with more than 10% of rosettes have presented a higher infection rate in Anopheles aquasalis (p=0.0252). Moreover, we found a positive correlation between the frequency of parasites in rosetting with the infection rate (p=0.0017) and intensity (p=0.0387) in the mosquito. The disruption of P. vivax rosette formation through mechanical rupture assay confirmed the previously findings, since the paired comparison showed that isolates with disrupted rosettes have a lower infection rate (p<0.0001) and intensity (p=0.0003) compared to the control group (no disruption). Herein we have demonstrated for the first time a potential effect of the rosette phenomenon on the infection process in the mosquito vector An. aquasalis, favoring its capacity and intensity of infection, thus allowing the perpetuation of the parasite cycle life.
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Affiliation(s)
- Luis Carlos Salazar Alvarez
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, Brazil
| | - Vanessa Carneiro Barbosa
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
| | - Omaira Vera Lizcano
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, Brazil
- Grupo de investigación en Química y Biotecnología (QUIBIO), Facultad de Ciencias Básicas, Universidad Santiago de Cali, Cali, Colombia
| | - Djane Clarys Baia da Silva
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
- Departamento de Saúde Coletiva, Universidade Federal do Amazonas, Manaus, Brazil
- Universidade Nilton Lins, Manaus, Brazil
| | - Rosa Amélia Gonçalves Santana
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
| | - Camila Fabbri
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
| | - Paulo Filemon Paoluci Pimenta
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto de Pesquisas René Rachou (IRR/ Fiocruz Minas), FIOCRUZ, Belo Horizonte, Brazil
| | - Wuelton Marcelo Monteiro
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
| | - Letusa Albrecht
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, Brazil
- Instituto Carlos Chagas (ICC/ Fiocruz Paraná), FIOCRUZ, Curitiba, Brazil
| | - Marcus Vinicius Guimarães de Lacerda
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
| | - Fabio Trindade Maranhão Costa
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
- *Correspondence: Stefanie Costa Pinto Lopes, ; Fabio Trindade Maranhão Costa,
| | - Stefanie Costa Pinto Lopes
- Centro Internacional de Pesquisa Clínica em Malária – CIPCliM, Fundação de Medicina Tropical - Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil
- Instituto Leônidas & Maria Deane (ILMD/Fiocruz Amazônia), Fundação Oswaldo Cruz (FIOCRUZ), Manaus, Brazil
- *Correspondence: Stefanie Costa Pinto Lopes, ; Fabio Trindade Maranhão Costa,
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Rodríguez‐Pastor R, Shafran Y, Knossow N, Gutiérrez R, Harrus S, Zaman L, Lenski RE, Barrick JE, Hawlena H. A road map for in vivo evolution experiments with blood-borne parasitic microbes. Mol Ecol Resour 2022; 22:2843-2859. [PMID: 35599628 PMCID: PMC9796859 DOI: 10.1111/1755-0998.13649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 03/14/2022] [Accepted: 05/13/2022] [Indexed: 01/07/2023]
Abstract
Laboratory experiments in which blood-borne parasitic microbes evolve in their animal hosts offer an opportunity to study parasite evolution and adaptation in real time and under natural settings. The main challenge of these experiments is to establish a protocol that is both practical over multiple passages and accurately reflects natural transmission scenarios and mechanisms. We provide a guide to the steps that should be considered when designing such a protocol, and we demonstrate its use via a case study. We highlight the importance of choosing suitable ancestral genotypes, treatments, number of replicates per treatment, types of negative controls, dependent variables, covariates, and the timing of checkpoints for the experimental design. We also recommend specific preliminary experiments to determine effective methods for parasite quantification, transmission, and preservation. Although these methodological considerations are technical, they also often have conceptual implications. To this end, we encourage other researchers to design and conduct in vivo evolution experiments with blood-borne parasitic microbes, despite the challenges that the work entails.
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Affiliation(s)
- Ruth Rodríguez‐Pastor
- Jacob Blaustein Center for Scientific Cooperation, The Jacob Blaustein Institutes for Desert ResearchBen‐Gurion University of the NegevMidreshet Ben‐GurionIsrael
| | - Yarden Shafran
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, The Jacob Blaustein Institutes for Desert ResearchBen‐Gurion University of the NegevMidreshet Ben‐GurionIsrael
| | - Nadav Knossow
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, The Jacob Blaustein Institutes for Desert ResearchBen‐Gurion University of the NegevMidreshet Ben‐GurionIsrael
| | - Ricardo Gutiérrez
- Koret School of Veterinary Medicine, Faculty of Agricultural, Nutritional and Environmental SciencesThe Hebrew University of JerusalemRehovotIsrael
| | - Shimon Harrus
- Koret School of Veterinary Medicine, Faculty of Agricultural, Nutritional and Environmental SciencesThe Hebrew University of JerusalemRehovotIsrael
| | - Luis Zaman
- Department of Ecology and Evolutionary Biology, The Center for the Study of Complex Systems (CSCS)University of MichiganAnn ArborMichiganUSA
| | - Richard E. Lenski
- Department of Microbiology and Molecular GeneticsMichigan State UniversityEast LansingMichiganUSA
| | - Jeffrey E. Barrick
- Department of Molecular BiosciencesThe University of Texas AustinAustinTexasUSA
| | - Hadas Hawlena
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, The Jacob Blaustein Institutes for Desert ResearchBen‐Gurion University of the NegevMidreshet Ben‐GurionIsrael
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Heterologous Infection of Pregnant Mice Induces Low Birth Weight and Modifies Offspring Susceptibility to Malaria. PLoS One 2016; 11:e0160120. [PMID: 27467392 PMCID: PMC4965193 DOI: 10.1371/journal.pone.0160120] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/12/2016] [Indexed: 11/20/2022] Open
Abstract
Pregnancy malaria (PM) is associated with poor pregnancy outcomes, and can arise due to relapse, recrudescence or a re-infection with heterologous parasites. We have used the Plasmodium chabaudi model of pregnancy malaria in C57BL/6 mice to examine recrudescence and heterologous infection using CB and AS parasite strains. After an initial course of patent parasitemia and first recrudescence, CB but not AS parasites were observed to recrudesce again in most animals that became pregnant. Pregnancy exacerbated heterologous CB infection of AS-experienced mice, leading to mortality and impaired post-natal growth of pups. Parasites were detected in placental blood without evidence of sequestration, unlike P. falciparum but similar to other malaria species that infect pregnant women. Inflammatory cytokine levels were elevated in pregnant females during malaria, and associated with intensity of infection and with poor outcomes. Pups born to dams during heterologous infection were more resistant to malaria infections at 6–7 weeks of age, compared to pups born to malaria-experienced but uninfected dams or to malaria-naïve dams. In summary, our mouse model reproduces several features of human PM, including recrudescences, heterologous infections, poor pregnancy outcomes associated with inflammatory cytokines, and modulation of offspring susceptibility to malaria. This model should be further studied to explore mechanisms underlying PM pathogenesis.
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Barclay VC, Kennedy DA, Weaver VC, Sim D, Lloyd-Smith JO, Read AF. The Effect of Immunodeficiency on the Evolution of Virulence: An Experimental Test with the Rodent MalariaPlasmodium chabaudi. Am Nat 2014; 184 Suppl 1:S47-57. [DOI: 10.1086/676887] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Mackinnon MJ. The role of immunity in mosquito-induced attenuation of malaria virulence. Malar J 2014; 13:25. [PMID: 24443873 PMCID: PMC3904012 DOI: 10.1186/1475-2875-13-25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/19/2014] [Indexed: 11/10/2022] Open
Abstract
A recent study found that mosquito-transmitted (MT) lines of rodent malaria parasites elicit a more effective immune response than non-transmitted lines maintained by serial blood passage (non-MT), thereby causing lower parasite densities in the blood and less pathology to the host. The authors attribute these changes to higher diversity in expression of antigen-encoding genes in MT cf. non-MT lines. Alternative explanations that are equally parsimonious with these new data, and results from previous studies, suggest that this conclusion may be premature.
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Plasmodium berghei sporozoites acquire virulence and immunogenicity during mosquito hemocoel transit. Infect Immun 2013; 82:1164-72. [PMID: 24379288 DOI: 10.1128/iai.00758-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Malaria is a vector-borne disease caused by the single-cell eukaryote Plasmodium. The infectious parasite forms are sporozoites, which originate from midgut-associated oocysts, where they eventually egress and reach the mosquito hemocoel. Sporozoites actively colonize the salivary glands in order to be transmitted to the mammalian host. Whether residence in the salivary glands provides distinct and vital cues for the development of infectivity remains unsolved. In this study, we systematically compared the infectivity of Plasmodium berghei sporozoites isolated from the mosquito hemocoel and salivary glands. Hemocoel sporozoites display a lower proportion of gliding motility but develop into liver stages when added to cultured hepatoma cells or after intravenous injection into mice. Mice infected by hemocoel sporozoites had blood infections similar to those induced by sporozoites liberated from salivary glands. These infected mice display indistinguishable systemic inflammatory cytokine responses and develop experimental cerebral malaria. When used as metabolically active, live attenuated vaccine, hemocoel sporozoites elicit substantial protection against sporozoite challenge infections. Collectively, these findings show that salivary gland colonization does not influence parasite virulence in the mammalian host when sporozoites are administered intravenously. This conclusion has important implications for in vitro sporozoite production and manufacturing of whole-sporozoite vaccines.
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Mosquito transmission, growth phenotypes and the virulence of malaria parasites. Malar J 2013; 12:440. [PMID: 24314024 PMCID: PMC3924181 DOI: 10.1186/1475-2875-12-440] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/04/2013] [Indexed: 11/10/2022] Open
Abstract
Background A series of elegant experiments was recently published which demonstrated that transmission of malaria parasites through mosquitoes elicited an attenuated growth phenotype, whereby infections grew more slowly and reached peak parasitaemia at least five-fold lower than parasites which had not been mosquito transmitted. To assess the implications of these results it is essential to understand whether the attenuated infection phenotype is a general phenomenon across parasites genotypes and conditions. Methods Using previously published data, the impact of mosquito transmission on parasite growth rates and virulence of six Plasmodium chabaudi lines was analysed. Results The effect of mosquito transmission varied among strains, but did not lead to pronounced or consistent reductions in parasite growth rate. Conclusions Mosquito-induced attenuated growth phenotype is sensitive to experimental conditions.
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Read AF, Mideo N. The vector as protector. Nature 2013; 498:177-8. [DOI: 10.1038/nature12252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Spence PJ, Jarra W, Lévy P, Reid AJ, Chappell L, Brugat T, Sanders M, Berriman M, Langhorne J. Vector transmission regulates immune control of Plasmodium virulence. Nature 2013; 498:228-31. [PMID: 23719378 PMCID: PMC3784817 DOI: 10.1038/nature12231] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 04/26/2013] [Indexed: 01/15/2023]
Abstract
Defining mechanisms by which Plasmodium virulence is regulated is central to understanding the pathogenesis of human malaria. Serial blood passage of Plasmodium through rodents1-3, primates4 or humans5 increases parasite virulence, suggesting that vector transmission regulates Plasmodium virulence within the mammalian host. In agreement, disease severity can be modified by vector transmission6-8, which is assumed to ‘reset’ Plasmodium to its original character3. However, direct evidence that vector transmission regulates Plasmodium virulence is lacking. Here we utilise mosquito transmission of serially blood passaged (SBP) Plasmodium chabaudi chabaudi9 to interrogate regulation of parasite virulence. Analysis of SBP P.c. chabaudi before and after mosquito transmission demonstrates that vector transmission intrinsically modifies the asexual blood-stage parasite, which in turn, modifies the elicited mammalian immune response, which in turn, attenuates parasite growth and associated pathology. Attenuated parasite virulence associates with modified expression of the pir multi-gene family. Vector transmission of Plasmodium therefore regulates gene expression of probable variant antigens in the erythrocytic cycle, modifies the elicited mammalian immune response, and thus regulates parasite virulence. These results place the mosquito at the centre of our efforts to dissect mechanisms of protective immunity to malaria for the development of an effective vaccine.
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Affiliation(s)
- Philip J Spence
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Understanding barriers to Borrelia burgdorferi dissemination during infection using massively parallel sequencing. Infect Immun 2013; 81:2347-57. [PMID: 23608706 DOI: 10.1128/iai.00266-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Borrelia burgdorferi is an invasive spirochete that can cause acute and chronic infections in the skin, heart, joints, and central nervous system of infected mammalian hosts. Little is understood about where the bacteria encounter the strongest barriers to infection and how different components of the host immune system influence the population as the infection progresses. To identify population bottlenecks in a murine host, we utilized Tn-seq to monitor the composition of mixed populations of B. burgdorferi during infection. Both wild-type mice and mice lacking the Toll-like receptor adapter molecule MyD88 were infected with a pool of infectious B. burgdorferi transposon mutants with insertions in the same gene. At multiple time points postinfection, bacteria were isolated from the mice and the compositions of the B. burgdorferi populations at the injection site and in distal tissues determined. We identified a population bottleneck at the site of infection that significantly altered the composition of the population. The magnitude of this bottleneck was reduced in MyD88(-/-) mice, indicating a role for innate immunity in limiting early establishment of B. burgdorferi infection. There is not a significant bottleneck during the colonization of distal tissues, suggesting that founder effects are limited and there is not a strict limitation on the number of organisms able to initiate populations at distal sites. These findings further our understanding of the interactions between B. burgdorferi and its murine host in the establishment of infection and dissemination of the organism.
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Spence PJ, Jarra W, Lévy P, Nahrendorf W, Langhorne J. Mosquito transmission of the rodent malaria parasite Plasmodium chabaudi. Malar J 2012; 11:407. [PMID: 23217144 PMCID: PMC3528485 DOI: 10.1186/1475-2875-11-407] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/03/2012] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Serial blood passage of Plasmodium increases virulence, whilst mosquito transmission inherently regulates parasite virulence within the mammalian host. It is, therefore, imperative that all aspects of experimental malaria research are studied in the context of the complete Plasmodium life cycle. METHODS Plasmodium chabaudi chabaudi displays many characteristics associated with human Plasmodium infection of natural mosquito vectors and the mammalian host, and thus provides a unique opportunity to study the pathogenesis of malaria in a single infection setting. An optimized protocol that permits efficient and reproducible vector transmission of P. c. chabaudi via Anopheles stephensi was developed. RESULTS AND CONCLUSIONS This protocol was utilized for mosquito transmission of genetically distinct P. c. chabaudi isolates, highlighting differential parasite virulence within the mosquito vector and the spectrum of host susceptibility to infection initiated via the natural route, mosquito bite. An apposite experimental system in which to delineate the pathogenesis of malaria is described in detail.
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Affiliation(s)
- Philip J Spence
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - William Jarra
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Prisca Lévy
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Wiebke Nahrendorf
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Jean Langhorne
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Cameron A, Reece SE, Drew DR, Haydon DT, Yates AJ. Plasticity in transmission strategies of the malaria parasite,
P
lasmodium chabaudi
: environmental and genetic effects. Evol Appl 2012; 6:365-76. [PMID: 23467678 PMCID: PMC3586624 DOI: 10.1111/eva.12005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/30/2012] [Indexed: 12/31/2022] Open
Abstract
Parasites may alter their behaviour to cope with changes in the within-host environment. In particular, investment in transmission may alter in response to the availability of parasite resources or host immune responses. However, experimental and theoretical studies have drawn conflicting conclusions regarding parasites' optimal (adaptive) responses to deterioration in habitat quality. We analyse data from acute infections with six genotypes of the rodent malaria species Plasmodium chabaudi to quantify how investment in transmission (gametocytes) is influenced by the within-host environment. Using a minimum of modelling assumptions, we find that proportional investment in gametocytogenesis increases sharply with host anaemia and also increases at low parasite densities. Further, stronger dependence of investment on parasite density is associated with greater virulence of the parasite genotype. Our study provides a robust quantitative framework for studying parasites' responses to the host environment and whether these responses are adaptive, which is crucial for predicting the short-term and evolutionary impact of transmission-blocking treatments for parasitic diseases.
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Affiliation(s)
- Angus Cameron
- Boyd Orr Centre for Population and Ecosystem Health Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
- Department of Systems and Computational Biology Albert Einstein College of Medicine Bronx NY USA
| | - Sarah E. Reece
- Centre for Immunity, Infection & Evolution Institutes of Evolution, Immunology and Infection Research School of Biological Sciences University of Edinburgh Edinburgh UK
| | - Damien R. Drew
- Centre for Immunity, Infection & Evolution Institutes of Evolution, Immunology and Infection Research School of Biological Sciences University of Edinburgh Edinburgh UK
- Burnet Institute Melbourne Vic. Australia
| | - Daniel T. Haydon
- Boyd Orr Centre for Population and Ecosystem Health Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
| | - Andrew J. Yates
- Department of Systems and Computational Biology Albert Einstein College of Medicine Bronx NY USA
- Department of Microbiology and Immunology Albert Einstein College of Medicine Bronx NY USA
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The evolutionary consequences of blood-stage vaccination on the rodent malaria Plasmodium chabaudi. PLoS Biol 2012; 10:e1001368. [PMID: 22870063 PMCID: PMC3409122 DOI: 10.1371/journal.pbio.1001368] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 06/19/2012] [Indexed: 02/04/2023] Open
Abstract
A candidate malaria vaccine promoted the evolution of more virulent malaria parasites in mice. Malaria vaccine developers are concerned that antigenic escape will erode vaccine efficacy. Evolutionary theorists have raised the possibility that some types of vaccine could also create conditions favoring the evolution of more virulent pathogens. Such evolution would put unvaccinated people at greater risk of severe disease. Here we test the impact of vaccination with a single highly purified antigen on the malaria parasite Plasmodium chabaudi evolving in laboratory mice. The antigen we used, AMA-1, is a component of several candidate malaria vaccines currently in various stages of trials in humans. We first found that a more virulent clone was less readily controlled by AMA-1-induced immunity than its less virulent progenitor. Replicated parasites were then serially passaged through control or AMA-1 vaccinated mice and evaluated after 10 and 21 rounds of selection. We found no evidence of evolution at the ama-1 locus. Instead, virulence evolved; AMA-1-selected parasites induced greater anemia in naïve mice than both control and ancestral parasites. Our data suggest that recombinant blood stage malaria vaccines can drive the evolution of more virulent malaria parasites. Vaccination can drive the evolution of pathogens. Most obviously, molecules targeted by vaccine-induced immunity can change. Such evolution makes vaccines less effective. A different possibility is that more virulent pathogens are favored in vaccinated hosts. In that case, vaccination would create pathogens that cause more harm to unvaccinated individuals. To test this idea, we studied a rodent malaria parasite in laboratory mice immunized with a component of malaria vaccines currently in human trials. We found that a more virulent parasite clone was less well controlled by vaccine-induced immunity than was its less virulent ancestor. We then passaged parasites through sham- or vaccinated mice to study how the parasites might evolve after multiple rounds of infection of mouse hosts. The parasite molecule targeted by the vaccine did not change during this process. Instead, the parasites became more virulent if they evolved in vaccinated hosts. Our data suggest that some vaccines can drive the evolution of more virulent parasites.
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Abstract
Trypanosomes are protozoan parasites of medical and veterinary importance. It is well established that different species, subspecies and strains of trypanosome can cause very different disease in the mammalian host, exemplified by the two human-infective subspecies of Trypanosoma brucei that cause either acute or chronic disease. We are beginning to understand how the host response shapes the course of the disease and how genetic variation in the host can be a factor in disease severity, particularly in the mouse model, but until recently the role of parasite genetic variation that determines differential disease outcome has been a neglected area. This review will discuss the recent advances in this field, covering both our current knowledge of the T. brucei genes involved and the approaches that are leading towards the identification of T. brucei virulence genes. Finally, the potential for using parasite genotype variation to examine the evolutionary context of virulence will be discussed.
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Affiliation(s)
- L J Morrison
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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Oberle M, Balmer O, Brun R, Roditi I. Bottlenecks and the maintenance of minor genotypes during the life cycle of Trypanosoma brucei. PLoS Pathog 2010; 6:e1001023. [PMID: 20686656 PMCID: PMC2912391 DOI: 10.1371/journal.ppat.1001023] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 06/30/2010] [Indexed: 11/18/2022] Open
Abstract
African trypanosomes are digenetic parasites that undergo part of their developmental cycle in mammals and part in tsetse flies. We established a novel technique to monitor the population dynamics of Trypanosoma brucei throughout its life cycle while minimising the confounding factors of strain differences or variation in fitness. Clones derived from a single trypanosome were tagged with short synthetic DNA sequences in a non-transcribed region of the genome. Infections were initiated with mixtures of tagged parasites and a combination of polymerase chain reaction and deep sequencing were used to monitor the composition of populations throughout the life cycle. This revealed that a minimum of several hundred parasites survived transmission from a tsetse fly to a mouse, or vice versa, and contributed to the infection in the new host. In contrast, the parasites experienced a pronounced bottleneck during differentiation and migration from the midgut to the salivary glands of tsetse. In two cases a single tag accounted for > or =99% of the population in the glands, although minor tags could be also detected. Minor tags were transmitted to mice together with the dominant tag(s), persisted during a chronic infection, and survived transmission to a new insect host. An important outcome of the bottleneck within the tsetse is that rare variants can be amplified in individual flies and disseminated by them. This is compatible with the epidemic population structure of T. brucei, in which clonal expansion of a few genotypes in a region occurs against a background of frequent recombination between strains.
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Affiliation(s)
- Michael Oberle
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- Institut für Zellbiologie, Universität Bern, Bern, Switzerland
| | - Oliver Balmer
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Reto Brun
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Isabel Roditi
- Institut für Zellbiologie, Universität Bern, Bern, Switzerland
- * E-mail:
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17
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Abstract
Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.
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Affiliation(s)
- Benjamin M Bolker
- Department of Biology, University of Florida, Gainesville, FL 32611, USA.
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Modifying insect population age structure to control vector-borne disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 627:126-40. [PMID: 18510020 DOI: 10.1007/978-0-387-78225-6_11] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Age is a critical determinant of the ability of most arthropod vectors to transmit a range of human pathogens. This is due to the fact that most pathogens require a period of extrinsic incubation in the arthropod host before pathogen transmission can occur. This developmental period for the pathogen often comprises a significant proportion of the expected lifespan of the vector. As such, only a small proportion of the population that is oldest contributes to pathogen transmission. Given this, strategies that target vector age would be expected to obtain the most significant reductions in the capacity of a vector population to transmit disease. The recent identification of biological agents that shorten vector lifespan, such as Wolbachia, entomopathogenic fungi and densoviruses, offer new tools for the control of vector-borne diseases. Evaluation of the efficacy of these strategies under field conditions will be possible due to recent advances in insect age-grading techniques. Implementation of all of these strategies will require extensive field evaluation and consideration of the selective pressures that reductions in vector longevity may induce on both vector and pathogen.
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Abstract
One theory of why some pathogens are virulent (i.e., they damage their host) is that they need to extract resources from their host in order to compete for transmission to new hosts, and this resource extraction can damage the host. Here we describe our studies in malaria that test and support this idea. We go on to show that host immunity can exacerbate selection for virulence and therefore that vaccines that reduce pathogen replication may select for more virulent pathogens, eroding the benefits of vaccination and putting the unvaccinated at greater risk. We suggest that in disease contexts where wild-type parasites can be transmitted through vaccinated hosts, evolutionary outcomes need to be considered.
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Affiliation(s)
- M J Mackinnon
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
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20
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Bell AS, Roode JC, Sim D, Read AF. WITHIN-HOST COMPETITION IN GENETICALLY DIVERSE MALARIA INFECTIONS: PARASITE VIRULENCE AND COMPETITIVE SUCCESS. Evolution 2006. [DOI: 10.1111/j.0014-3820.2006.tb01215.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Bell AS, de Roode JC, Sim D, Read AF. WITHIN-HOST COMPETITION IN GENETICALLY DIVERSE MALARIA INFECTIONS: PARASITE VIRULENCE AND COMPETITIVE SUCCESS. Evolution 2006. [DOI: 10.1554/05-611.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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