Evolution of parasite reproductive strategies in natural infections
Lead Research Organisation:
University of Edinburgh
Department Name: Inst of Evolutionary Biology
Abstract
Predicting how parasites adapt to their environment is becoming increasingly important. For example, changes to: the climate, composition of host-parasite-vector communities, and habitat, are implicated in the emergence of new infectious diseases of wildlife, crop species, livestock, and humans. More broadly, the in-host environment experienced by parasites also varies rapidly and extensively. Understanding how parasites cope with a variable in-host environment is central to understanding disease and infectiousness, as well as providing a framework for predicting parasite evolution in response to other changes in their ecology. We will use evolutionary theory to ask fundamental questions in evolutionary biology and infectious disease research: how do reproductive (transmission) strategies of protozoan parasites evolve? This group includes malaria (Plasmodium) parasites and cause some of the most serious pathogens of livestock, companion animals, wildlife, and humans. Despite the economic, medical, and veterinary importance of understanding the transmission strategies of malaria parasites, over a century of research has yielded remarkably little understanding of their basic reproductive biology. However, rapid progress has been made in recent years: new molecular tools have been developed and applied in an evolutionary framework to ask questions about parasite transmission. Data from this new approach are overturning the conventional wisdom: from the epidemiology of parasites to their behaviour during infections. For example, we have discovered that parasites fine-tune the production and sex ratio of transmission stages in remarkably sophisticated ways; according to their density within hosts, competition with other parasite strains, and whether their hosts are anaemic, mounting an immune response, or receiving drug treatment. These 'plastic family planning strategies' enable parasites to maximise transmission by matching their behaviour to the changing conditions they face during infections. However, these studies have focused on model parasites in laboratory experiments - whether these 'sophisticated' strategies occur in natural infections is controversial. We will address this by developing sensitive methods to quantify the production and sex ratio of transmission (reproductive) stages of human malaria (P. falciparum) parasites in the wild and testing whether evolutionary theory can explain their strategies. We have already developed these methods for a related species of malaria parasite and laid the groundwork for translating this assay to human parasites. Evolutionary theory predicts that parasite reproductive strategies will be shaped by the variation in their in-host environment that they encounter during infections. Most studies on parasite transmission have focused on either the number or sex ratio of transmission stages but evolutionary theory predicts these traits are simultaneously optimised - therefore they need to be investigated together and can only be understood in the context of each other. Explaining variation in the life-history traits exhibited by individuals is a major aim in evolutionary biology. There is also increasing interest in using an evolutionary approach to understand how parasite life-history traits shape within-infection dynamics and contribute to virulence and transmission. Given the sophisticated parasite strategies recently observed in lab experiments, investigating the behaviour of parasites in natural infections is timely and important. Understanding plasticity in the reproductive strategies of parasites is also central to predicting their short- and long-term responses to changes in their ecology: such as how habitat change, host shifts, or control measures influence the spread of disease.
People |
ORCID iD |
Sarah Reece (Principal Investigator) | |
Petra Schneider (Researcher) |
Publications
Cameron A
(2013)
Plasticity in transmission strategies of the malaria parasite, Plasmodium chabaudi: environmental and genetic effects.
in Evolutionary applications
Carter LM
(2013)
Stress and sex in malaria parasites: Why does commitment vary?
in Evolution, medicine, and public health
Carter LM
(2014)
Information use and plasticity in the reproductive decisions of malaria parasites.
in Malaria journal
Gadalla AA
(2016)
Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections.
in PloS one
Greischar MA
(2016)
The role of models in translating within-host dynamics to parasite evolution.
in Parasitology
Khan SM
(2013)
Why are male malaria parasites in such a rush?: Sex-specific evolution and host-parasite interactions.
in Evolution, medicine, and public health
Mideo N
(2013)
Life in cells, hosts, and vectors: parasite evolution across scales.
in Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases
Mideo N
(2012)
Plasticity in parasite phenotypes: evolutionary and ecological implications for disease.
in Future microbiology
Pollitt LC
(2012)
The problem of auto-correlation in parasitology.
in PLoS pathogens
Title | ASCUS art exhibition |
Description | ASCUS-CIIE microresidencies. 4 artsists created an exhibition based on science from the department including ours. Various lab members were involved. The exhibition "transmissions" was presented in various Scottish venues. The exhibition included artwork as well as film (featuring several lab members) |
Type Of Art | Artwork |
Year Produced | 2014 |
Impact | Inspiring collaboration with the artists involved, plus reaching a large audience through the exhibition of their work. |
URL | http://www.ascus.org.uk/the-micro-residency-begins/ |
Description | Malaria parasites replicate asexually in their hosts, enabling in-host survival, but must reproduce sexually to be transmitted between hosts. Despite the importance of malaria parasites, their reproductive strategies remain poorly understood. Previous data suggest that malaria parasites can adjust their investment in asexual vs. sexual stages, and females vs. males in response to their environment (e.g. competition with other strains of malaria, resource availability, anti-malarial drugs, and the inbreeding rate). Until now, studies have focused on model malaria systems: rodent parasites in vivo and human parasites in vitro. In this project, we tested the predictions of life history theory to explain the variation in reproductive effort and sex allocation of human malaria parasites from a natural population. During the project we have: 1) Developed RT-qPCR assays to separately quantify male and female transmission stages of Plasmodium falciparum in field samples. Assays are published in Schneider et al (2015; DOI: 10.1016/j.molbiopara.2015.03.006). The manuscript is listed no. 6 of most downloaded articles for the journal, and the assay is currently in use by collaborators in a.o. the Gambia, Italy, the Netherlands, Oman, Sudan, Tanzania, UK and USA. 2) Provided proof-of-principle for the utility of an evolutionary framework to explain parasite traits in natural infections. As the same general principles underlie adaptation across taxa, understanding how reproductive strategies underlie transmission in this population will be applicable to areas with different endemic settings. 3) Applied the newly developed methods to complete a large dataset on natural P. falciparum infections in a markedly seasonal setting in the Sudan. We are in the process of completing papers based on the generated data including a) epidemiological analyses: effects of drug resistance, infection genetic diversity and seasonality on gametocytes; b) testing hypotheses for reproductive decisions: how variation in the in-host environment shapes the Plasmodium falciparum sex ratios in natural infections. |
Exploitation Route | We undertake engagement with groups spanning from evolutionary theoreticians, to parasitologists and clinicians, to immunologists. We expanded our engagement network aiming to include policy makers. Communication with these groups is central to using an evolutionary framework to inform disease treatment policy. Policy makers are often interested in the evolutionary framework developed for parasites, but a link between experimental data and epidemiology - achieved by this project - is required to turn this interest into knowledge transfer. Knowledge transfer was achieved as follows: - http://reecelab.science now contains lay summaries of all papers and contributions to the media. - We expanded our collaboration with field researchers, as evident from use of the developed techniques in several countries, allowing us to develop this project by testing key findings in other natural populations. - We have strong track records in communication with the media and contribute press releases on our work. - Local science festivals, engagement events and online discussions. - Schools: A visit by 6th form Biology students to our lab, communicating the value of evolutionary biology to all biological disciplines. A science session about mosquitoes was developed for nursery/primary schools. - We supported an international postgraduate student, who has learned new skills (laboratory and data-analysis) and since completed her PhD. -The RA on the project has learned many new skills and will start a PhD in September. |
Sectors | Education,Healthcare,Pharmaceuticals and Medical Biotechnology,Other |
URL | http://reecelab.science |
Description | presentations at Edinburgh Science Festival, School of Biological Sciences open days, exhibitions at schools, ASCUS 'transmissions' art exhibition, and media coverage. |
First Year Of Impact | 2011 |
Sector | Education,Leisure Activities, including Sports, Recreation and Tourism,Culture, Heritage, Museums and Collections |
Impact Types | Cultural,Societal |
Description | NERC - standard grant |
Amount | £732,000 (GBP) |
Funding ID | NE/K006029/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 04/2013 |
End | 04/2016 |
Description | RoySoc - URF |
Amount | £465,000 (GBP) |
Organisation | The Royal Society |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start |
Title | sex-specific P. falciparum assays |
Description | Assays to quantify male and female transmission stages of the human malaria parasite Plasmodium falciparum. Published in Schneider et al 2015. Quantification of male and female Plasmodium falciparum gametocytes by reverse transcriptase quantitative PCR. Mol Biochem Parasit 199: 29-33. DOI: 10.1016/j.molbiopara.2015.03.006. |
Type Of Material | Technology assay or reagent |
Year Produced | 2014 |
Provided To Others? | Yes |
Impact | It is now possible to accurately quantify male and females transmission stages separately, facilitating the study of sex ratios as described in the project output for NERC NE/I015329/1 |
URL | http://dx.doi.org/10.1016/j.molbiopara.2015.03.006 |
Description | NERC short grant 2011 collaborations |
Organisation | Radboud University Nijmegen Medical Center |
Country | Netherlands |
Sector | Academic/University |
PI Contribution | Collaborators benefited from early access to the methods developed, and are co-authors on the resulting manuscript. |
Collaborator Contribution | The research methods developed during the project benefited from scientific input from our collaborators / co-authors. |
Impact | Development of assay to quantify male and female transmission stages of the human malaria parasite P. falciparum (molecular parasitology, published: http://dx.doi.org/10.1016/j.molbiopara.2015.03.006); application of these assays to datasets from natural parasite populations (epidemiology, paper in preparation; evolutionary ecology, paper in preparation). Outcomes as for the overall project: including knowledge transfer, media coverage, school activities, training of staff and students, science festivals and art projects |
Start Year | 2011 |
Description | NERC short grant 2011 collaborations |
Organisation | Sultan Qaboos University |
Department | College of Medicine and Health Sciences |
Country | Oman |
Sector | Academic/University |
PI Contribution | Collaborators benefited from early access to the methods developed, and are co-authors on the resulting manuscript. |
Collaborator Contribution | The research methods developed during the project benefited from scientific input from our collaborators / co-authors. |
Impact | Development of assay to quantify male and female transmission stages of the human malaria parasite P. falciparum (molecular parasitology, published: http://dx.doi.org/10.1016/j.molbiopara.2015.03.006); application of these assays to datasets from natural parasite populations (epidemiology, paper in preparation; evolutionary ecology, paper in preparation). Outcomes as for the overall project: including knowledge transfer, media coverage, school activities, training of staff and students, science festivals and art projects |
Start Year | 2011 |
Description | NERC short grant 2011 collaborations |
Organisation | University of Glasgow |
Department | School of Life Sciences Glasgow |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Collaborators benefited from early access to the methods developed, and are co-authors on the resulting manuscript. |
Collaborator Contribution | The research methods developed during the project benefited from scientific input from our collaborators / co-authors. |
Impact | Development of assay to quantify male and female transmission stages of the human malaria parasite P. falciparum (molecular parasitology, published: http://dx.doi.org/10.1016/j.molbiopara.2015.03.006); application of these assays to datasets from natural parasite populations (epidemiology, paper in preparation; evolutionary ecology, paper in preparation). Outcomes as for the overall project: including knowledge transfer, media coverage, school activities, training of staff and students, science festivals and art projects |
Start Year | 2011 |
Description | ASCUS art exhibition |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | ASCUS-CIIE microresidencies. 4 artsists created an exhibition based on science from the department including ours. Various lab members were involved. The exhibition "transmissions" was presented in various Scottish venues. |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.ascus.org.uk/the-micro-residency-begins/ |
Description | Conference-BSP-Amal |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics. British Society for Parasitology Cambridge. Poster by Amal Gadalla |
Year(s) Of Engagement Activity | 2014 |
Description | Conference-BSP2011-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics |
Year(s) Of Engagement Activity | 2011 |
Description | Conference-BSP2015-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics |
Year(s) Of Engagement Activity | 2015 |
Description | Conference-Biomalpar2012-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics, Biomalpar conference in Heidelberg Germany. Poster |
Year(s) Of Engagement Activity | 2012 |
Description | Conference-Biomalpar2013-Amal |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics, Biomalpar conference Heidelberg, poster by Amal Gadalla |
Year(s) Of Engagement Activity | 2013 |
Description | Conference-Biomalpar2013-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics, Biomalpar conference in Heidelberg Germany. Poster |
Year(s) Of Engagement Activity | 2013 |
Description | Departmental seminar invitations |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Other audiences |
Results and Impact | Invited departmental seminar presentations (1-3 per year). Presentation of scientific results to academics. |
Year(s) Of Engagement Activity | 2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019 |
Description | Dept.talk-Liverpool2013-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Other audiences |
Results and Impact | invited presentation of research to academics |
Year(s) Of Engagement Activity | 2013 |
Description | Dept.talk-Paisley2014-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Other audiences |
Results and Impact | invited presentation of research to academics |
Year(s) Of Engagement Activity | 2014 |
Description | Edinburgh International Science Festival |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Research exhibition at the Edinburgh science festival. |
Year(s) Of Engagement Activity | 2015 |
Description | Intl_Keynotes_SR |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Invited keynote presentations _ international (1-3 per year). Presentation of scientific results to academics. |
Year(s) Of Engagement Activity | 2010,2011,2012,2013,2014,2015,2017,2018,2019 |
Description | Natl_Keynotes_SR |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | Invited keynote presentations _ national (1-3 per year). Presentation of scientific results to academics. |
Year(s) Of Engagement Activity | 2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019 |
Description | conference-BSP2013-PS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | presentation of research to academics |
Year(s) Of Engagement Activity | 2013 |
Description | press coverage |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | We have strong track records in communication with the media and contribute press releases on our work. |
Year(s) Of Engagement Activity | 2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018 |