Completed Genetics & Molecular Biology Infection & Immunity

Molecular mechanisms mediating immune evasion in African trypanosomes.

In plain English

AI plain-English summary

African trypanosomes—single-celled parasites that cause sleeping sickness—switch their surface coats like a fugitive changing disguises, and this project aims to expose exactly how they do it. The parasite evades the human immune system by periodically swapping out a dense protein layer called VSG on its surface, allowing it to stay one step ahead of antibody attacks. Researchers already know that only one VSG gene is active at a time, but the molecular machinery that controls this strict on/off switching—and that ensures the coat is properly made before the cell divides—remains poorly understood. This project will dissect the roles of specific proteins (TbISWI, NLP, FACT, NAP1, and histone H1) in regulating VSG expression, and investigate how the parasite senses whether VSG synthesis is complete before it commits to cell division. If successful, this fundamental science will reveal the basic biology of a major human pathogen. Understanding these immune evasion mechanisms could eventually point toward new drug targets—for example, by disrupting the coat-switching process or by triggering the cell-cycle checkpoint that kills the parasite when VSG production fails. There is no immediate practical application, but similar work on parasite surface proteins has historically opened routes to vaccines and therapies for diseases like malaria.

View original technical description
1. Our main aim is to elucidate transcriptional control in African trypanosomes, including how VSG expression sites (ESs) are regulated. What is the role of chromatin remodeling in T. brucei? How are ESs activated in a strictly monoallelic fashion? Which proteins mediate life-cycle specific differences in ES transcriptional control in bloodstream and insect form T. brucei? We will answer these questions through a functional analysis of T. brucei proteins which we have recently disc overed are involved in transcriptional control, including TbISWI, NLP, FACT, NAP1 and histone H1 in the first instance. We will also investigate the functional architecture of ESs, including potential regulatory roles for flanking regions of simple sequence repeats. 2. Our second aim is to understand how VSG protects the trypanosome from the mammalian immune system, and determine how VSG synthesis is monitored during the T. brucei cell cycle. We have found that VSG is essential, an d blocking its synthesis triggers an abrupt cell cycle arrest immediately before cytokinesis. We will dissect the mechanism behind this cell cycle checkpoint. What aspect of VSG is sensed during trypanosome cell cycle progression? We will investigate how VSG protects the trypanosome from the mammalian complement system.

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Researchers

Gloria Rudenko (EPMC Awardee)

Related Research

Grants with similar aims, by meaning.

Molecular mechanisms mediating immune evasion in African trypanosomes
Decoding mechanisms of gene regulation in African trypanosomes
Investigation of control of Variant Surface Glycoprotein gene expression sites in the African trypanosome Trypanosoma brucei
Telomeric chromatin and VSG allelic exclusion in African trypanosomes
The role of nuclear architecture in transcriptional regulation in the African Trypanosome, Trypanosoma brucei

Original classification

Senior Research Fellowship Basic Renewal

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