Exploring the adaptive role of genomic instability in Trypanosoma cruzi.
Lead Research Organisation:
University of Glasgow
Department Name: College of Medical, Veterinary, Life Sci
Abstract
Trypanosoma cruzi is a protozoan that causes Chagas disease, a fatal parasitic disease spread by an insect vector called a kissing bug. T. cruzi infects seven million people in Latin America and seventeen million are thought to be at risk of infection. Migration of infected individuals to Europe and North America has transferred Chagas disease outside its traditional range, accounting for c.500,000 additional cases globally. In Europe and America, a risk of congenital and transfusional transmission exists, and infected individuals represent a significant challenge for public health services.
Chagas disease is the most important parasitic in Latin America, killing 12,000 people every year. To provide context, malaria in the region kills a fraction of that number (200-400 annually). Infection with T. cruzi in Chagas disease patients is life-long. Drug treatments are limited, often ineffective at clearing parasite infection, and almost always ineffective at alleviating debilitating chronic symptoms (heart disease, GI tract abnormalities). Despite the impact of Chagas disease on human health, relatively little is known about its biology by comparison to other related human parasites - T. brucei (agent of sleeping sickness) and Leishmania (agent of Leishmaniasis). Important knowledge gaps exist around how T. cruzi adapts to environmental stressors. Addressing theses gaps could shed light on how the parasite avoids host immunity to establish persistent infections in its host, as well as how it survives drug treatment.
DNA sequencing of T. cruzi isolates by members of our consortium and others reveals a genome in a constant state of re-arrangement. The number, sizes, copy number and composition of T. cruzi chromosomes can vary substantially between closely related isolates, as well as, based on pilot data we now present, from individual human infections sampled at different time points. The adaptive value of such genomic re-arrangements may hold the key to understanding, and addressing, many intractable aspects of T. cruzi biology. In this proposal we leverage advances in genomics, genetic manipulation, animal disease models, as well as a world-class research team to understand how T. cruzi genomic re-arrangements may underpin long term survival in the mammalian host as well as parasite resistance to frontline and next generation drugs. Using single cell genomics, we will link genomic re-arrangements to drug resistance and then, via genetic manipulation, attempt to interrupt the machinery that enables such re-arrangements to occur. We will then undertake a series of incisive experiments to link parasite genomic re-arrangements to survival under immune pressure in mouse models and confirm these via observations in a cohort of Ecuadorian Chagas disease patients. Experiments in mammals will focus on re-arrangements among families of genes expressed on the parasite cell surface. The temporal dynamics of parasite genomic changes within immune-competent hosts will be followed and compared to the those in the absence of a functioning immune system to detect signatures of immune avoidance via antigenic shift.
The experiments proposed in this research program are vital basic science precursors to improved drug design and the lab groundwork for future T. cruzi vaccine development, ultimately improving health outcomes for the millions affected by Chagas disease.
Chagas disease is the most important parasitic in Latin America, killing 12,000 people every year. To provide context, malaria in the region kills a fraction of that number (200-400 annually). Infection with T. cruzi in Chagas disease patients is life-long. Drug treatments are limited, often ineffective at clearing parasite infection, and almost always ineffective at alleviating debilitating chronic symptoms (heart disease, GI tract abnormalities). Despite the impact of Chagas disease on human health, relatively little is known about its biology by comparison to other related human parasites - T. brucei (agent of sleeping sickness) and Leishmania (agent of Leishmaniasis). Important knowledge gaps exist around how T. cruzi adapts to environmental stressors. Addressing theses gaps could shed light on how the parasite avoids host immunity to establish persistent infections in its host, as well as how it survives drug treatment.
DNA sequencing of T. cruzi isolates by members of our consortium and others reveals a genome in a constant state of re-arrangement. The number, sizes, copy number and composition of T. cruzi chromosomes can vary substantially between closely related isolates, as well as, based on pilot data we now present, from individual human infections sampled at different time points. The adaptive value of such genomic re-arrangements may hold the key to understanding, and addressing, many intractable aspects of T. cruzi biology. In this proposal we leverage advances in genomics, genetic manipulation, animal disease models, as well as a world-class research team to understand how T. cruzi genomic re-arrangements may underpin long term survival in the mammalian host as well as parasite resistance to frontline and next generation drugs. Using single cell genomics, we will link genomic re-arrangements to drug resistance and then, via genetic manipulation, attempt to interrupt the machinery that enables such re-arrangements to occur. We will then undertake a series of incisive experiments to link parasite genomic re-arrangements to survival under immune pressure in mouse models and confirm these via observations in a cohort of Ecuadorian Chagas disease patients. Experiments in mammals will focus on re-arrangements among families of genes expressed on the parasite cell surface. The temporal dynamics of parasite genomic changes within immune-competent hosts will be followed and compared to the those in the absence of a functioning immune system to detect signatures of immune avoidance via antigenic shift.
The experiments proposed in this research program are vital basic science precursors to improved drug design and the lab groundwork for future T. cruzi vaccine development, ultimately improving health outcomes for the millions affected by Chagas disease.
Technical Summary
Major gaps in understanding exist around the biology of T. cruzi that must be addressed to enable sustainable CD treatment and control. These gaps centre around how T. cruzi adapts and survives different environmental stressors such as host immune pressure, transfer between host and vector, and how it survives drug treatment.
A core observation from our work and that of others is the high level of genomic plasticity in T. cruzi in vivo and in vitro, both in terms of organisation and ploidy. Regions of the T. cruzi genome that encode surface-expressed molecules are particularly variable in their organisation, even among closely related clones. The aim of this proposal is to discover the drivers and adaptive significance of the genomic structural plasticity in T. cruzi, both in terms of coping with environmental stressors as well as the ability of this organism to establish life-long infection in immunocompetent mammalian hosts.
Via assessment of aneuploidy and copy number variation at the single cell level, the role of genome structural plasticity in enabling the adaptation of T. cruzi to frontline and next generation drugs will be defined. Transgenic disruption of the genetic machinery of genome structural plasticity will then be undertaken to attenuate genome structural plasticity and limit emergence of resistance phenotypes. The role of genome structural instability in underpinning transcriptional changes involve in between transit between host and vector will also be assessed.
In immunocompromised and immunocompetent mouse models we will track intra-host temporal dynamics of surface gene family structural stability to link antigenic shift with avoidance of host immunity. These findings will be followed up via longitudinal parasite genomic surveillance in a cohort of Chagas disease patients.
Our findings will lay the groundwork for improved drug treatments and, potentially, vaccine design.
A core observation from our work and that of others is the high level of genomic plasticity in T. cruzi in vivo and in vitro, both in terms of organisation and ploidy. Regions of the T. cruzi genome that encode surface-expressed molecules are particularly variable in their organisation, even among closely related clones. The aim of this proposal is to discover the drivers and adaptive significance of the genomic structural plasticity in T. cruzi, both in terms of coping with environmental stressors as well as the ability of this organism to establish life-long infection in immunocompetent mammalian hosts.
Via assessment of aneuploidy and copy number variation at the single cell level, the role of genome structural plasticity in enabling the adaptation of T. cruzi to frontline and next generation drugs will be defined. Transgenic disruption of the genetic machinery of genome structural plasticity will then be undertaken to attenuate genome structural plasticity and limit emergence of resistance phenotypes. The role of genome structural instability in underpinning transcriptional changes involve in between transit between host and vector will also be assessed.
In immunocompromised and immunocompetent mouse models we will track intra-host temporal dynamics of surface gene family structural stability to link antigenic shift with avoidance of host immunity. These findings will be followed up via longitudinal parasite genomic surveillance in a cohort of Chagas disease patients.
Our findings will lay the groundwork for improved drug treatments and, potentially, vaccine design.
