Article

Bloodstream form Trypanosome plasma membrane proteins: antigenic variation and invariant antigens.

Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB21GA, UK.
Parasitology (Impact Factor: 2.35). 12/2010; 137(14):2029-39. DOI: 10.1017/S0031182009992034
Source: PubMed

ABSTRACT Trypanosoma brucei is exposed to the adaptive immune system and complement in the blood of its mammalian hosts. The aim of this review is to analyse the role and regulation of the proteins present on the external face of the plasma membrane in the long-term persistence of an infection and transmission. In particular, the following are addressed: (1) antigenic variation of the variant surface glycoprotein (VSG), (2) the formation of an effective VSG barrier shielding invariant surface proteins, and (3) the rapid uptake of VSG antibody complexes combined with degradation of the immunoglobulin and recycling of the VSG.

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    • "In some forms of the parasite found in the host, the dense surface coat, composed mainly of a homogeneous layer of the parasite's variable surface protein, triggers an efficient antibody response. The continuous and complete replacement of these molecules by another immunologically distinct variable surface protein leads to prolonged infection (Prucca and Lujan 2009; Schwede and Carrington 2010; Tembo and Montgomery 2010; Recker et al. 2011). Here, we observed that VSG, VSP, and VAR are significantly enriched with repeats compared with the proteomes (fig. "
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    • "It has been estimated that only 30% of nascent VSG 221 attains the native state; the remainder is recognised to be the ER quality control system and is degraded by the proteosome (Field et al. 2007). The trypanosome has monoallelic expression of VSGs and switches the identity of the expressed VSG occasionally, usually as a result of a gene conversion event (reviewed in Schwede and Carrington 2010). It is likely that different VSGs fold at different rates, but the absence of a UPR would indicate that the trypanosome cannot compensate for slow-folding VSGs by increasing chaperone concentrations. "
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