Trypanosoma brucei
2019
Romero-Meza, Gabriela | Mugnier, Monica
Trypanosoma brucei causes African trypanosomiasis in humans and nagana in domestic animals. This vector-borne disease, transmitted by the tsetse fly, affects rural areas in sub-Saharan Africa. When injected by the fly, metacyclic form parasites are introduced into the host dermis and then disseminate into the bloodstream as replicative long slender forms. Throughout its life cycle, T. brucei is entirely extracellular. To evade host antibody recognition, the parasite uses antigenic variation: it periodically changes a dense coat of only one kind of variant surface glycoprotein (VSG), drawing from a genomic repertoire of about 2000 VSG-encoding genes. Using quorum sensing mechanisms, slender forms develop into stumpy forms that are pre-adapted to the insect environment. Once taken up by the fly, the parasite replaces its VSG coat with procyclins and progresses through procyclic and epimastigote stages. Finally, the parasites become VSG-expressing metacyclic trypomastigotes.
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