title: Antigenic variation in its biological context.
abstract: The biology of antigenic variation is discussed, and the problems that must be solved to provide a full understanding of antigenic variation are considered. These are (i) the induction of v.s.g. synthesis in the salivary glands of the tsetse fly; (ii) the nature of the restriction on v.s.g. genes that allows only some of them to be expressed in the salivary glands; (iii) the nature of 'predominance' in v.s.g. expression in the mammalian host, and the mechanism by which it operates; (iv) the repression of v.s.g. synthesis in the insect midgut; (v) the anamnestic response that produces expression of the ingested variant in the first patent parasitaemia in the mammalian host; (vi) the mechanism by which only one v.s.g. gene at a time is expressed; (vii) the relationship if any of v.s.g. structure to v.s.g.-associated differences in growth rate and host range; (viii) the role of v.s.g. release within the life cycle and to pathogenesis.
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics*; D014644:Genetic Variation; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D014345:Trypanosoma / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D014370:Tsetse Flies / Q000469:parasitology; D014643:Variant Surface Glycoproteins, Trypanosoma
chemical_list: D000953:Antigens, Protozoan; D006023:Glycoproteins; D014643:Variant Surface Glycoproteins, Trypanosoma