Endocytosis by Trypanosoma Brucei: Proteases and Their Possible Role in the Degradation of Anti-VSG Antibodies

African trypanosomes can evade the immune system of their host by changing their variable surface glycoproteins (VSGs). Although healthy parasites do not normally release VSG (Black et al. 1982; Lonsdale-Eccles & Grab, 1986), they can remove surface-bound, VSG-specific antibodies (Seyfang, 1990). We have, therefore, looked for alternative explanations for the disappearance of antibody-VSG complexes such as their possible uptake into the endocytic network of the parasites (Webster, 1989).