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Peters MAE, King AA, Wale N. Red blood cell dynamics during malaria infection challenge the assumptions of mathematical models of infection dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575051. [PMID: 38260611 PMCID: PMC10802624 DOI: 10.1101/2024.01.10.575051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
For decades, mathematical models have been used to understand the course and outcome of malaria infections (i.e., infection dynamics) and the evolutionary dynamics of the parasites that cause them. A key conclusion of these models is that red blood cell (RBC) availability is a fundamental driver of infection dynamics and parasite trait evolution. The extent to which this conclusion holds will in part depend on model assumptions about the host-mediated processes that regulate RBC availability i.e., removal of uninfected RBCs and supply of RBCs. Diverse mathematical functions have been used to describe host-mediated RBC supply and clearance, but it remains unclear whether they adequately capture the dynamics of RBC supply and clearance during infection. Here, we use a unique dataset, comprising time-series measurements of erythrocyte (i.e., mature RBC) and reticulocyte (i.e., newly supplied RBC) densities during Plasmodium chabaudi malaria infection, and a quantitative data-transformation scheme to elucidate whether RBC dynamics conform to common model assumptions. We found that RBC clearance and supply are not well described by mathematical functions commonly used to model these processes. Furthermore, the temporal dynamics of both processes vary with parasite growth rate in a manner again not captured by existing models. Together, these finding suggest that new model formulations are required if we are to explain and ultimately predict the within-host population dynamics and evolution of malaria parasites.
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2
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Pak D, Kamiya T, Greischar MA. Proliferation in malaria parasites: How resource limitation can prevent evolution of greater virulence. Evolution 2024; 78:1287-1301. [PMID: 38581661 DOI: 10.1093/evolut/qpae057] [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: 12/15/2023] [Revised: 03/28/2024] [Accepted: 04/04/2024] [Indexed: 04/08/2024]
Abstract
For parasites, robust proliferation within hosts is crucial for establishing the infection and creating opportunities for onward transmission. While faster proliferation enhances transmission rates, it is often assumed to curtail transmission duration by killing the host (virulence), a trade-off constraining parasite evolution. Yet in many diseases, including malaria, the preponderance of infections with mild or absent symptoms suggests that host mortality is not a sufficient constraint, raising the question of what restrains evolution toward faster proliferation. In malaria infections, the maximum rate of proliferation is determined by the burst size, the number of daughter parasites produced per infected red blood cell. Larger burst sizes should expand the pool of infected red blood cells that can be used to produce the specialized transmission forms needed to infect mosquitoes. We use a within-host model parameterized for rodent malaria parasites (Plasmodium chabaudi) to project the transmission consequences of burst size, focusing on initial acute infection where resource limitation and risk of host mortality are greatest. We find that resource limitation restricts evolution toward higher burst sizes below the level predicted by host mortality alone. Our results suggest resource limitation could represent a more general constraint than virulence-transmission trade-offs, preventing evolution towards faster proliferation.
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Affiliation(s)
- Damie Pak
- Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, United States
| | - Tsukushi Kamiya
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Paris, France
- HRB Clinical Research Facility, University of Galway, Ireland
| | - Megan A Greischar
- Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, United States
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3
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Carrillo-Bustamante P, Costa G, Lampe L, Levashina EA. Evolutionary modelling indicates that mosquito metabolism shapes the life-history strategies of Plasmodium parasites. Nat Commun 2023; 14:8139. [PMID: 38097582 PMCID: PMC10721866 DOI: 10.1038/s41467-023-43810-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
Within-host survival and between-host transmission are key life-history traits of single-celled malaria parasites. Understanding the evolutionary forces that shape these traits is crucial to predict malaria epidemiology, drug resistance, and virulence. However, very little is known about how Plasmodium parasites adapt to their mosquito vectors. Here, we examine the evolution of the time Plasmodium parasites require to develop within the vector (extrinsic incubation period) with an individual-based model of malaria transmission that includes mosquito metabolism. Specifically, we model the metabolic cascade of resource allocation induced by blood-feeding, as well as the influence of multiple blood meals on parasite development. Our model predicts that successful vector-to-human transmission events are rare, and are caused by long-lived mosquitoes. Importantly, our results show that the life-history strategies of malaria parasites depend on the mosquito's metabolic status. In our model, additional resources provided by multiple blood meals lead to selection for parasites with slow or intermediate developmental time. These results challenge the current assumption that evolution favors fast developing parasites to maximize their chances to complete their within-mosquito life cycle. We propose that the long sporogonic cycle observed for Plasmodium is not a constraint but rather an adaptation to increase transmission potential.
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Affiliation(s)
| | - Giulia Costa
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany
| | - Lena Lampe
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany
- Physiology and Metabolism Laboratory, The Francis Crick Institute, NW11AT, London, UK
| | - Elena A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117, Berlin, Germany.
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4
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Pike VL, Stevens EJ, Griffin AS, King KC. Within- and between-host dynamics of producer and non-producer pathogens. Parasitology 2023; 150:805-812. [PMID: 37394480 PMCID: PMC10478067 DOI: 10.1017/s0031182023000586] [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: 02/13/2023] [Revised: 05/25/2023] [Accepted: 05/28/2023] [Indexed: 07/04/2023]
Abstract
For infections to be maintained in a population, pathogens must compete to colonize hosts and transmit between them. We use an experimental approach to investigate within-and-between host dynamics using the pathogen Pseudomonas aeruginosa and the animal host Caenorhabditis elegans. Within-host interactions can involve the production of goods that are beneficial to all pathogens in the local environment but susceptible to exploitation by non-producers. We exposed the nematode host to ‘producer’ and two ‘non-producer’ bacterial strains (specifically for siderophore production and quorum sensing), in single infections and coinfections, to investigate within-host colonization. Subsequently, we introduced infected nematodes to pathogen-naive populations to allow natural transmission between hosts. We find that producer pathogens are consistently better at colonizing hosts and transmitting between them than non-producers during coinfection and single infection. Non-producers were poor at colonizing hosts and between-host transmission, even when coinfecting with producers. Understanding pathogen dynamics across these multiple levels will ultimately help us predict and control the spread of infections, as well as contribute to explanations for the persistence of cooperative genotypes in natural populations.
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Affiliation(s)
| | | | | | - Kayla C. King
- Department of Biology, University of Oxford, Oxford, UK
- Department of Zoology, University of British Columbia, Vancouver, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
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5
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Greischar MA, Childs LM. Extraordinary parasite multiplication rates in human malaria infections. Trends Parasitol 2023; 39:626-637. [PMID: 37336700 DOI: 10.1016/j.pt.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/21/2023]
Abstract
For pathogenic organisms, faster rates of multiplication promote transmission success, the potential to harm hosts, and the evolution of drug resistance. Parasite multiplication rates (PMRs) are often quantified in malaria infections, given the relative ease of sampling. Using modern and historical human infection data, we show that established methods return extraordinarily - and implausibly - large PMRs. We illustrate how inflated PMRs arise from two facets of malaria biology that are far from unique: (i) some developmental ages are easier to sample than others; (ii) the distribution of developmental ages changes over the course of infection. The difficulty of accurately quantifying PMRs demonstrates a need for robust methods and a subsequent re-evaluation of what is known even in the well-studied system of malaria.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA.
| | - Lauren M Childs
- Department of Mathematics, Virginia Tech, Blacksburg, VA, USA
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6
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Declines in prevalence alter the optimal level of sexual investment for the malaria parasite Plasmodium falciparum. Proc Natl Acad Sci U S A 2022; 119:e2122165119. [PMID: 35867831 PMCID: PMC9335338 DOI: 10.1073/pnas.2122165119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Like most human pathogens, the malaria parasite Plasmodium falciparum experiences strong selection pressure from public health interventions such as drug treatment. While most commonly studied in the context of drug targets and related pathways, parasite adaptation to control measures likely extends to phenotypes beyond drug resistance. Here, we use modeling to explore how control measures can reduce levels of within-host competition between P. falciparum genotypes and favor higher rates of sexual investment. We validate these predictions with longitudinally sampled genomic data from French Guiana during a period of malaria decline and find that the most strongly selected genes are enriched for transcription factors involved in commitment to and development of the parasite’s sexual gametocyte form. Successful infectious disease interventions can result in large reductions in parasite prevalence. Such demographic change has fitness implications for individual parasites and may shift the parasite’s optimal life history strategy. Here, we explore whether declining infection rates can alter Plasmodium falciparum’s investment in sexual versus asexual growth. Using a multiscale mathematical model, we demonstrate how the proportion of polyclonal infections, which decreases as parasite prevalence declines, affects the optimal sexual development strategy: Within-host competition in multiclone infections favors a greater investment in asexual growth whereas single-clone infections benefit from higher conversion to sexual forms. At the same time, drug treatment also imposes selection pressure on sexual development by shortening infection length and reducing within-host competition. We assess these models using 148 P. falciparum parasite genomes sampled in French Guiana over an 18-y period of intensive intervention (1998 to 2015). During this time frame, multiple public health measures, including the introduction of new drugs and expanded rapid diagnostic testing, were implemented, reducing P. falciparum malaria cases by an order of magnitude. Consistent with this prevalence decline, we see an increase in the relatedness among parasites, but no single clonal background grew to dominate the population. Analyzing individual allele frequency trajectories, we identify genes that likely experienced selective sweeps. Supporting our model predictions, genes showing the strongest signatures of selection include transcription factors involved in the development of P. falciparum’s sexual gametocyte form. These results highlight how public health interventions impose wide-ranging selection pressures that affect basic parasite life history traits.
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7
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SONG TIANQI, WANG CHUNCHENG, TIAN BOPING. MULTIPLE PERIODIC SOLUTIONS OF A WITHIN-HOST MALARIA INFECTION MODEL WITH TIME DELAY. J BIOL SYST 2021. [DOI: 10.1142/s0218339021500108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, we study a within-host malaria infection model recently proposed by Schneider et al. in 2018. The stability and Hopf bifurcation analysis at the interior equilibrium are carried out, finding that the basic reproduction number plays a key role in the dynamics of the model, and incrementing the time delay will induce Hopf bifurcation at this equilibrium. The global extension of the local Hopf branch is further tracked numerically by the MatLab package DDE-BIFTOOL. Neimark-Sacker bifurcation of Poincaré map and period-doubling bifurcation of the bifurcated periodic solution are also detected, resulting in the existence of quasi-periodic and multiple periodic solutions, respectively. These results reveal that Hopf bifurcation will indeed bring about the rich dynamics of the model.
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Affiliation(s)
- TIANQI SONG
- School of Economics and Management, Shanghai Maritime University, Shanghai, P. R. China
- School of Mathematics, Harbin Institute of Technology, Harbin, Heilongjiang, P. R. China
| | - CHUNCHENG WANG
- School of Mathematics, Harbin Institute of Technology, Harbin, Heilongjiang, P. R. China
| | - BOPING TIAN
- School of Mathematics, Harbin Institute of Technology, Harbin, Heilongjiang, P. R. China
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Schneider P, Reece SE. The private life of malaria parasites: Strategies for sexual reproduction. Mol Biochem Parasitol 2021; 244:111375. [PMID: 34023299 PMCID: PMC8346949 DOI: 10.1016/j.molbiopara.2021.111375] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 12/22/2022]
Abstract
Malaria parasites exhibit a complex lifecycle, requiring extensive asexual replication in the liver and blood of the vertebrate host, and in the haemocoel of the insect vector. Yet, they must also undergo a single round of sexual reproduction, which occurs in the vector's midgut upon uptake of a blood meal. Sexual reproduction is obligate for infection of the vector and thus, is essential for onwards transmission to new hosts. Sex in malaria parasites involves several bottlenecks in parasite number, making the stages involved attractive targets for blocking disease transmission. Malaria parasites have evolved a suite of adaptations ("strategies") to maximise the success of sexual reproduction and transmission, which could undermine transmission-blocking interventions. Yet, understanding parasite strategies may also reveal novel opportunities for such interventions. Here, we outline how evolutionary and ecological theories, developed to explain reproductive strategies in multicellular taxa, can be applied to explain two reproductive strategies (conversion rate and sex ratio) expressed by malaria parasites within the vertebrate host.
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Affiliation(s)
- Petra Schneider
- Institute of Evolutionary Biology, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
| | - Sarah E Reece
- Institute of Evolutionary Biology, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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9
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Sondo P, Bihoun B, Tahita MC, Derra K, Rouamba T, Nakanabo Diallo S, Kazienga A, Ilboudo H, Valea I, Tarnagda Z, Sorgho H, Lefèvre T, Tinto H. Plasmodium falciparum gametocyte carriage in symptomatic patients shows significant association with genetically diverse infections, anaemia, and asexual stage density. Malar J 2021; 20:31. [PMID: 33413393 PMCID: PMC7791700 DOI: 10.1186/s12936-020-03559-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/18/2020] [Indexed: 11/17/2022] Open
Abstract
Background Multi-genotype malaria infections are frequent in endemic area, and people commonly harbour several genetically distinct Plasmodium falciparum variants. The influence of genetic multiplicity and whether some specific genetic variants are more or less likely to invest into gametocyte production is not clearly understood. This study explored host and parasite-related risk factors for gametocyte carriage, and the extent to which some specific P. falciparum genetic variants are associated with gametocyte carriage. Methods Gametocytes and asexual forms were detected by light microscopy on thick smears collected between 2010 and 2012 in Nanoro, Burkina Faso. Merozoite surface protein 1 and 2 were genotyped by nested PCR on clinical samples. Associations between gametocyte carriage and factors, including multiplicity of infection, parasite density, patient age, gender, haemoglobin (Hb) level, and body temperature were assessed. The relationship between the presence of a particular msp1 and msp2 genetic variants and gametocyte carriage was also explored. Results Of the 724 samples positive to P. falciparum and successfully genotyped, gametocytes were found in 48 samples (6.63%). There was no effect of patient gender, age and body temperature on gametocyte carriage. However, the probability of gametocyte carriage significantly increased with increasing values of multiplicity of infection (MOI). Furthermore, there was a negative association between parasite density and gametocyte carriage. MOI decreased with parasite density in gametocyte-negative patients, but increased in gametocyte carriers. The probability of gametocyte carriage decreased with Hb level. Finally, the genetic composition of the infection influenced gametocyte carriage. In particular, the presence of RO33 increased the odds of developing gametocytes by 2 while the other allelic families K1, MAD20, FC27, and 3D7 had no significant impact on the occurrence of gametocytes in infected patients. Conclusion This study provides insight into potential factors influencing gametocyte production in symptomatic patients. The findings contribute to enhance understanding of risk factors associated with gametocyte carriage in humans. Trial registration NCT01232530.
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Affiliation(s)
- Paul Sondo
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso.
| | - Biebo Bihoun
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Marc Christian Tahita
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Karim Derra
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Toussaint Rouamba
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Seydou Nakanabo Diallo
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso.,Institut National de Santé Publique/Centre Muraz de Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| | - Adama Kazienga
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hamidou Ilboudo
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Innocent Valea
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso.,Institut National de Santé Publique/Centre Muraz de Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| | - Zekiba Tarnagda
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Thierry Lefèvre
- Laboratoire Mixte International Sur Les Vecteurs (LAMIVECT), Bobo Dioulasso, Burkina Faso.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.,Centre de Recherche en Écologie Et Évolution de La Santé (CREES), Montpellier, France
| | - Halidou Tinto
- Institut de Recherche en Sciences de La Santé/ Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
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10
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Garabed RB, Jolles A, Garira W, Lanzas C, Gutierrez J, Rempala G. Multi-scale dynamics of infectious diseases. Interface Focus 2019. [DOI: 10.1098/rsfs.2019.0118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
To address the challenge of multiscale dynamics of infectious diseases, the Mathematical Biosciences Institute organized a workshop at The Ohio State University to bring together scientists from a variety of disciplines to share expertise gained through looking at infectious diseases across different scales. The researchers at the workshop, held in April 2018, were specifically looking at three model systems: foot-and-mouth disease, vector-borne diseases and enteric diseases. Although every multiscale model must be necessarily derived from a multiscale system, not every multiscale system has to lead to multiscale models. These three model systems seem to have produced a variety of both multiscale and integrated single-scale mechanistic models that have developed their own strengths and particular challenges. Here, we present papers from some of the workshop participants to show the breadth of the field.
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Affiliation(s)
- Rebecca B. Garabed
- College of Veterinary Medicine–Preventive Medicine, The Ohio State University, Columbus, OH, USA
| | - Anna Jolles
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
- Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Winston Garira
- Mathematics and Applied Mathematics, University of Venda, Thohoyandou, Limpopo, South Africa
| | | | - Juan Gutierrez
- Department of Mathematics, University of Texas at San Antonio, San Antonio, TX, USA
| | - Grzegorz Rempala
- College of Public Health–Biostatistics, The Ohio State University, Columbus, OH, USA
- College of Arts and Sciences–Mathematics, The Ohio State University, Columbus, OH, USA
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11
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Greischar MA, Beck-Johnson LM, Mideo N. Partitioning the influence of ecology across scales on parasite evolution. Evolution 2019; 73:2175-2188. [PMID: 31495911 DOI: 10.1111/evo.13840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/31/2019] [Indexed: 11/30/2022]
Abstract
Vector-borne parasites must succeed at three scales to persist: they must proliferate within a host, establish in vectors, and transmit back to hosts. Ecology outside the host undergoes dramatic seasonal and human-induced changes, but predicting parasite evolutionary responses requires integrating their success across scales. We develop a novel, data-driven model to titrate the evolutionary impact of ecology at multiple scales on human malaria parasites. We investigate how parasites invest in transmission versus proliferation, a life-history trait that influences disease severity and spread. We find that transmission investment controls the pattern of host infectiousness over the course of infection: a trade-off emerges between early and late infectiousness, and the optimal resolution of that trade-off depends on ecology outside the host. An expanding epidemic favors rapid proliferation, and can overwhelm the evolutionary influence of host recovery rates and mosquito population dynamics. If transmission investment and recovery rate are positively correlated, then ecology outside the host imposes potent selection for aggressive parasite proliferation at the expense of transmission. Any association between transmission investment and recovery represents a key unknown, one that is likely to influence whether the evolutionary consequences of interventions are beneficial or costly for human health.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | | | - Nicole Mideo
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
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12
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Greischar MA, Reece SE, Savill NJ, Mideo N. The Challenge of Quantifying Synchrony in Malaria Parasites. Trends Parasitol 2019; 35:341-355. [PMID: 30952484 DOI: 10.1016/j.pt.2019.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/21/2022]
Abstract
Malaria infection is often accompanied by periodic fevers, triggered by synchronous cycles of parasite replication within the host. The degree of synchrony in parasite development influences the efficacy of drugs and immune defenses and is therefore relevant to host health and infectiousness. Synchrony is thought to vary over the course of infection and across different host-parasite genotype or species combinations, but the evolutionary significance - if any - of this diversity remains elusive. Standardized methods are lacking, but the most common metric for quantifying synchrony is the percentage of parasites in a particular developmental stage. We use a heuristic model to show that this metric is often unacceptably biased. Methodological challenges must be addressed to characterize diverse patterns of synchrony and their consequences for disease severity and spread.
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Affiliation(s)
- Megan A Greischar
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
| | - Sarah E Reece
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Nicholas J Savill
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Nicole Mideo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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13
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Adaptive plasticity in the gametocyte conversion rate of malaria parasites. PLoS Pathog 2018; 14:e1007371. [PMID: 30427935 PMCID: PMC6261640 DOI: 10.1371/journal.ppat.1007371] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 11/28/2018] [Accepted: 10/02/2018] [Indexed: 11/30/2022] Open
Abstract
Sexually reproducing parasites, such as malaria parasites, experience a trade-off between the allocation of resources to asexual replication and the production of sexual forms. Allocation by malaria parasites to sexual forms (the conversion rate) is variable but the evolutionary drivers of this plasticity are poorly understood. We use evolutionary theory for life histories to combine a mathematical model and experiments to reveal that parasites adjust conversion rate according to the dynamics of asexual densities in the blood of the host. Our model predicts the direction of change in conversion rates that returns the greatest fitness after perturbation of asexual densities by different doses of antimalarial drugs. The loss of a high proportion of asexuals is predicted to elicit increased conversion (terminal investment), while smaller losses are managed by reducing conversion (reproductive restraint) to facilitate within-host survival and future transmission. This non-linear pattern of allocation is consistent with adaptive reproductive strategies observed in multicellular organisms. We then empirically estimate conversion rates of the rodent malaria parasite Plasmodium chabaudi in response to the killing of asexual stages by different doses of antimalarial drugs and forecast the short-term fitness consequences of these responses. Our data reveal the predicted non-linear pattern, and this is further supported by analyses of previous experiments that perturb asexual stage densities using drugs or within-host competition, across multiple parasite genotypes. Whilst conversion rates, across all datasets, are most strongly influenced by changes in asexual density, parasites also modulate conversion according to the availability of red blood cell resources. In summary, increasing conversion maximises short-term transmission and reducing conversion facilitates in-host survival and thus, future transmission. Understanding patterns of parasite allocation to reproduction matters because within-host replication is responsible for disease symptoms and between-host transmission determines disease spread. Malaria parasites in the host replicate asexually and, during each replication cycle, some asexuals transform into sexual stages that enable between-host transmission. It is not understood why the rate of conversion to sexual stages varies during infections despite its importance for the severity and spread of the disease. We combined a mathematical model and experiments to show that parasites adjust conversion rates depending on changes in their in-host population size. When population sizes plummet, between-host transmission is prioritised. However, smaller losses in number elicit reproductive restraint, which facilitates in-host survival and future transmission. We show that increased and decreased conversion in response to a range of in-host environments are actually part of one continuum: a sophisticated reproductive strategy similar to that of multicellular organisms.
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14
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Pigeault R, Caudron Q, Nicot A, Rivero A, Gandon S. Timing malaria transmission with mosquito fluctuations. Evol Lett 2018; 2:378-389. [PMID: 30283689 PMCID: PMC6122125 DOI: 10.1002/evl3.61] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/22/2018] [Accepted: 05/22/2018] [Indexed: 12/12/2022] Open
Abstract
Temporal variations in the activity of arthropod vectors can dramatically affect the epidemiology and evolution of vector‐borne pathogens. Here, we explore the “Hawking hypothesis”, which states that these pathogens may evolve the ability to time investment in transmission to match the activity of their vectors. First, we use a theoretical model to identify the conditions promoting the evolution of time‐varying transmission strategies in pathogens. Second, we experimentally test the “Hawking hypothesis” by monitoring the within‐host dynamics of Plasmodium relictum throughout the acute and the chronic phases of the bird infection. We detect a periodic increase of parasitemia and mosquito infection in the late afternoon that coincides with an increase in the biting activity of its natural vector. We also detect a positive effect of mosquito bites on Plasmodium replication in the birds both in the acute and in the chronic phases of the infection. This study highlights that Plasmodium parasites use two different strategies to increase the match between transmission potential and vector availability. We discuss the adaptive nature of these unconditional and plastic transmission strategies with respect to the time scale and the predictability of the fluctuations in the activity of the vector.
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Affiliation(s)
- Romain Pigeault
- MIVEGEC (UMR CNRS 5290); University of Montpellier; Montpellier France
- Department of Ecology and Evolution; University of Lausanne; Lausanne Switzerland
| | | | - Antoine Nicot
- CEFE (UMR CNRS 5175); University of Montpellier; Montpellier France
| | - Ana Rivero
- MIVEGEC (UMR CNRS 5290); University of Montpellier; Montpellier France
| | - Sylvain Gandon
- CEFE (UMR CNRS 5175); University of Montpellier; Montpellier France
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15
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Simam J, Rono M, Ngoi J, Nyonda M, Mok S, Marsh K, Bozdech Z, Mackinnon M. Gene copy number variation in natural populations of Plasmodium falciparum in Eastern Africa. BMC Genomics 2018; 19:372. [PMID: 29783949 PMCID: PMC5963192 DOI: 10.1186/s12864-018-4689-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 04/17/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Gene copy number variants (CNVs), which consist of deletions and amplifications of single or sets of contiguous genes, contribute to the great diversity in the Plasmodium falciparum genome. In vitro studies in the laboratory have revealed their important role in parasite fitness phenotypes such as red cell invasion, transmissibility and cytoadherence. Studies of natural parasite populations indicate that CNVs are also common in the field and thus may facilitate adaptation of the parasite to its local environment. RESULTS In a survey of 183 fresh field isolates from three populations in Eastern Africa with different malaria transmission intensities, we identified 94 CNV loci using microarrays. All CNVs had low population frequencies (minor allele frequency < 5%) but each parasite isolate carried an average of 8 CNVs. Nine CNVs showed high levels of population differentiation (FST > 0.3) and nine exhibited significant clines in population frequency across a gradient in transmission intensity. The clearest example of this was a large deletion on chromosome 9 previously reported only in laboratory-adapted isolates. This deletion was present in 33% of isolates from a population with low and highly seasonal malaria transmission, and in < 9% of isolates from populations with higher transmission. Subsets of CNVs were strongly correlated in their population frequencies, implying co-selection. CONCLUSIONS These results support the hypothesis that CNVs are the target of selection in natural populations of P. falciparum. Their environment-specific patterns observed here imply an important role for them in conferring adaptability to the parasite thus enabling it to persist in its highly diverse ecological environment.
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Affiliation(s)
| | - Martin Rono
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Joyce Ngoi
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Mary Nyonda
- Department of Microbiology and Molecular Medicine, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Sachel Mok
- Department of Microbiology and Immunology, Columbia University, New York, USA
| | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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16
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Early AM, Lievens M, MacInnis BL, Ockenhouse CF, Volkman SK, Adjei S, Agbenyega T, Ansong D, Gondi S, Greenwood B, Hamel M, Odero C, Otieno K, Otieno W, Owusu-Agyei S, Asante KP, Sorgho H, Tina L, Tinto H, Valea I, Wirth DF, Neafsey DE. Host-mediated selection impacts the diversity of Plasmodium falciparum antigens within infections. Nat Commun 2018; 9:1381. [PMID: 29643376 PMCID: PMC5895824 DOI: 10.1038/s41467-018-03807-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/14/2018] [Indexed: 12/28/2022] Open
Abstract
Host immunity exerts strong selective pressure on pathogens. Population-level genetic analysis can identify signatures of this selection, but these signatures reflect the net selective effect of all hosts and vectors in a population. In contrast, analysis of pathogen diversity within hosts provides information on individual, host-specific selection pressures. Here, we combine these complementary approaches in an analysis of the malaria parasite Plasmodium falciparum using haplotype sequences from thousands of natural infections in sub-Saharan Africa. We find that parasite genotypes show preferential clustering within multi-strain infections in young children, and identify individual amino acid positions that may contribute to strain-specific immunity. Our results demonstrate that natural host defenses to P. falciparum act in an allele-specific manner to block specific parasite haplotypes from establishing blood-stage infections. This selection partially explains the extreme amino acid diversity of many parasite antigens and suggests that vaccines targeting such proteins should account for allele-specific immunity. Host immune responses exert selective pressure on Plasmodium falciparum. Here, the authors show that allele-specific immunity impacts the antigenic diversity of individual malaria infections. This process partially explains the extreme amino acid diversity of many parasite antigens and suggests that vaccines should account for allele-specific immunity.
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Affiliation(s)
- Angela M Early
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA. .,Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
| | | | - Bronwyn L MacInnis
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.,Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | | | - Sarah K Volkman
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.,Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.,Simmons College, School of Nursing and Health Sciences, Boston, MA, 02115, USA
| | - Samuel Adjei
- School of Medical Sciences, Kwame Nkrumah University of Science and Technology, KNUST - Kumasi, Ghana
| | - Tsiri Agbenyega
- School of Medical Sciences, Kwame Nkrumah University of Science and Technology, KNUST - Kumasi, Ghana
| | - Daniel Ansong
- School of Medical Sciences, Kwame Nkrumah University of Science and Technology, KNUST - Kumasi, Ghana
| | - Stacey Gondi
- KEMRI-Walter Reed Project, Kombewa, 40102, Kenya
| | - Brian Greenwood
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Mary Hamel
- KEMRI/CDC Research and Public Health Collaboration, Kisumu, 40100, Kenya
| | - Chris Odero
- KEMRI/CDC Research and Public Health Collaboration, Kisumu, 40100, Kenya
| | - Kephas Otieno
- KEMRI/CDC Research and Public Health Collaboration, Kisumu, 40100, Kenya
| | | | - Seth Owusu-Agyei
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Kintampo Health Research Centre, Kintampo, 200, Ghana.,University of Health and Allied Science, PMB 31, Ho, Volta Region, Ghana
| | | | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso/Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - Lucas Tina
- KEMRI-Walter Reed Project, Kombewa, 40102, Kenya
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso/Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - Innocent Valea
- Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso/Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - Dyann F Wirth
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.,Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Daniel E Neafsey
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA. .,Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
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17
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Birget PLG, Greischar MA, Reece SE, Mideo N. Altered life history strategies protect malaria parasites against drugs. Evol Appl 2018; 11:442-455. [PMID: 29636798 PMCID: PMC5891063 DOI: 10.1111/eva.12516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/30/2017] [Indexed: 11/26/2022] Open
Abstract
Drug resistance has been reported against all antimalarial drugs, and while parasites can evolve classical resistance mechanisms (e.g., efflux pumps), it is also possible that changes in life history traits could help parasites evade the effects of treatment. The life history of malaria parasites is governed by an intrinsic resource allocation problem: specialized stages are required for transmission, but producing these stages comes at the cost of producing fewer of the forms required for within-host survival. Drug treatment, by design, alters the probability of within-host survival, and so should alter the costs and benefits of investing in transmission. Here, we use a within-host model of malaria infection to predict optimal patterns of investment in transmission in the face of different drug treatment regimes and determine the extent to which alternative patterns of investment can buffer the fitness loss due to drugs. We show that over a range of drug doses, parasites are predicted to adopt "reproductive restraint" (investing more in asexual replication and less in transmission) to maximize fitness. By doing so, parasites recoup some of the fitness loss imposed by drugs, though as may be expected, increasing dose reduces the extent to which altered patterns of transmission investment can benefit parasites. We show that adaptation to drug-treated infections could result in more virulent infections in untreated hosts. This work emphasizes that in addition to classical resistance mechanisms, drug treatment generates selection for altered parasite life history. Understanding how any shifts in life history will alter the efficacy of drugs, as well as any limitations on such shifts, is important for evaluating and predicting the consequences of drug treatment.
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Affiliation(s)
- Philip L. G. Birget
- Institutes of Evolutionary Biology, Immunology and Infection ResearchUniversity of EdinburghEdinburghUK
| | - Megan A. Greischar
- Department of Ecology & Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Sarah E. Reece
- Institutes of Evolutionary Biology, Immunology and Infection ResearchUniversity of EdinburghEdinburghUK
| | - Nicole Mideo
- Department of Ecology & Evolutionary BiologyUniversity of TorontoTorontoONCanada
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18
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Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
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Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
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19
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Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
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Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
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20
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Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.4] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2018] [Indexed: 01/05/2023] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
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Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
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21
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Brancucci NMB, De Niz M, Straub TJ, Ravel D, Sollelis L, Birren BW, Voss TS, Neafsey DE, Marti M. Probing Plasmodium falciparum sexual commitment at the single-cell level. Wellcome Open Res 2018; 3:70. [PMID: 30320226 PMCID: PMC6143928 DOI: 10.12688/wellcomeopenres.14645.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
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Affiliation(s)
- Nicolas M B Brancucci
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mariana De Niz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Timothy J Straub
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Deepali Ravel
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Bruce W Birren
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel E Neafsey
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Matthias Marti
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
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22
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Rono MK, Nyonda MA, Simam JJ, Ngoi JM, Mok S, Kortok MM, Abdullah AS, Elfaki MM, Waitumbi JN, El-Hassan IM, Marsh K, Bozdech Z, Mackinnon MJ. Adaptation of Plasmodium falciparum to its transmission environment. Nat Ecol Evol 2017; 2:377-387. [PMID: 29255304 DOI: 10.1038/s41559-017-0419-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/20/2017] [Indexed: 12/19/2022]
Abstract
Success in eliminating malaria will depend on whether parasite evolution outpaces control efforts. Here, we show that Plasmodium falciparum parasites (the deadliest of the species causing human malaria) found in low-transmission-intensity areas have evolved to invest more in transmission to new hosts (reproduction) and less in within-host replication (growth) than parasites found in high-transmission areas. At the cellular level, this adaptation manifests as increased production of reproductive forms (gametocytes) early in the infection at the expense of processes associated with multiplication inside red blood cells, especially membrane transport and protein trafficking. At the molecular level, this manifests as changes in the expression levels of genes encoding epigenetic and translational machinery. Specifically, expression levels of the gene encoding AP2-G-the transcription factor that initiates reproduction-increase as transmission intensity decreases. This is accompanied by downregulation and upregulation of genes encoding HDAC1 and HDA1-two histone deacetylases that epigenetically regulate the parasite's replicative and reproductive life-stage programmes, respectively. Parasites in reproductive mode show increased reliance on the prokaryotic translation machinery found inside the plastid-derived organelles. Thus, our dissection of the parasite's adaptive regulatory architecture has identified new potential molecular targets for malaria control.
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Affiliation(s)
- Martin K Rono
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Mary A Nyonda
- Department of Microbiology and Molecular Medicine, Medical Faculty, University of Geneva, Geneva, Switzerland
| | | | - Joyce M Ngoi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sachel Mok
- Columbia University Medical Center, New York, NY, USA
| | - Moses M Kortok
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Mohammed M Elfaki
- Department of Microbiology and Parasitology, Faculty of Medicine, Jazan University, Gizan, Jazan, Saudi Arabia
| | - John N Waitumbi
- Walter Reed Army Institute of Research/Kenya Medical Research Institute, Kisumu, Kenya
| | - Ibrahim M El-Hassan
- Faculty of Public Health and Tropical Medicine, Jazan University, Gizan, Jazan, Saudi Arabia
| | - Kevin Marsh
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore
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23
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Birget PLG, Repton C, O'Donnell AJ, Schneider P, Reece SE. Phenotypic plasticity in reproductive effort: malaria parasites respond to resource availability. Proc Biol Sci 2017; 284:20171229. [PMID: 28768894 PMCID: PMC5563815 DOI: 10.1098/rspb.2017.1229] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 06/28/2017] [Indexed: 12/11/2022] Open
Abstract
The trade-off between survival and reproduction is fundamental in the life history of all sexually reproducing organisms. This includes malaria parasites, which rely on asexually replicating stages for within-host survival and on sexually reproducing stages (gametocytes) for between-host transmission. The proportion of asexual stages that form gametocytes (reproductive effort) varies during infections-i.e. is phenotypically plastic-in response to changes in a number of within-host factors, including anaemia. However, how the density and age structure of red blood cell (RBC) resources shape plasticity in reproductive effort and impacts upon parasite fitness is controversial. Here, we examine how and why the rodent malaria parasite Plasmodium chabaudi alters its reproductive effort in response to experimental perturbations of the density and age structure of RBCs. We show that all four of the genotypes studied increase reproductive effort when the proportion of RBCs that are immature is elevated during host anaemia, and that the responses of the genotypes differ. We propose that anaemia (counterintuitively) generates a resource-rich environment in which parasites can afford to allocate more energy to reproduction (i.e. transmission) and that anaemia also exposes genetic variation to selection. From an applied perspective, adaptive plasticity in parasite reproductive effort could explain the maintenance of genetic variation for virulence and why anaemia is often observed as a risk factor for transmission in human infections.
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Affiliation(s)
- Philip L G Birget
- Institutes of Evolutionary Biology, and Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Charlotte Repton
- Institutes of Evolutionary Biology, and Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Aidan J O'Donnell
- Institutes of Evolutionary Biology, and Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Petra Schneider
- Institutes of Evolutionary Biology, and Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Sarah E Reece
- Institutes of Evolutionary Biology, and Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
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24
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Wilson AJ, Morgan ER, Booth M, Norman R, Perkins SE, Hauffe HC, Mideo N, Antonovics J, McCallum H, Fenton A. What is a vector? Philos Trans R Soc Lond B Biol Sci 2017; 372:20160085. [PMID: 28289253 PMCID: PMC5352812 DOI: 10.1098/rstb.2016.0085] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2016] [Indexed: 11/18/2022] Open
Abstract
Many important and rapidly emerging pathogens of humans, livestock and wildlife are 'vector-borne'. However, the term 'vector' has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the 'haematophagous arthropod' and 'mobility' definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the 'micropredator' and 'sequential' definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
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Affiliation(s)
- Anthony James Wilson
- Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK
| | - Eric René Morgan
- School of Veterinary Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Mark Booth
- School of Medicine, Pharmacy and Health, Durham University, Thornaby TS17 6BH, UK
| | - Rachel Norman
- School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
| | - Sarah Elizabeth Perkins
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
- Department of Biodiversity and Molecular Ecology, Centre for Research and Innovation, Fondazione Edmund Mach, Via E. Mach 1, 38010 S Michele all'Adige (TN), Italy
| | - Heidi Christine Hauffe
- Department of Biodiversity and Molecular Ecology, Centre for Research and Innovation, Fondazione Edmund Mach, Via E. Mach 1, 38010 S Michele all'Adige (TN), Italy
| | - Nicole Mideo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Janis Antonovics
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Hamish McCallum
- Environmental Futures Research Institute, Griffith University, Nathan 4111, Queensland, Australia
| | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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