Stealth is a well-known concept in military tactics. Almost since the invention of radar, the hunt began for counter-technologies to hide aircraft and missiles from detection – most successfully by modifying the composition and shape of surfaces to confound detection. In a biological parallel, the African sleeping sickness parasite Trypanosoma brucei also has a stealth-like trick for altering its surface to confound recognition by the human immune system.
Trypanosomes are covered in some 10 million identical proteins called variant surface glycoproteins (VSGs). Although VSGs are well recognised by the immune system, trypanosomes can rapidly and repeatedly change every single one of these coat proteins, just as the rumblings of an immune response against the first coat have begun. In this way, the parasite can effectively ‘disappear’ again and again, deflecting the immune response to something that has essentially become an echo.
A complex mechanism of gene control underlies the process that allows trypanosomes to switch coats. Part of this mechanism has now been revealed in recent research by Cambridge parasitologist Professor Mark Field and colleagues from the USA, UK and Europe.
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Image: Trypanosoma brucei use a changing cloak of VSG coat proteins to confound recognition by the human immune system
Credit: Mark Field
Reproduced courtesy of the University of Cambridge
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Sleeping sickness by stealth
5 February 2013
New research is helping to unveil how the parasite that causes sleeping sickness uses stealth tactics to escape detection by the human immune system.