Conservation of a variant-specific surface antigen gene in different trypanosome species and sub-species.

In Trypanosoma brucie brucie, T. b. rhodesiense, T. b. gambiense and T. evansi, the variant-specific antigen (VSA) genes are organized in families of related sequences, one of which is duplicated when expressed. Some of these VSA sequences appear to be conserved in the different species and sub-species: restriction mapping of isotypic genes of AnTat 1.8 VSA (from T. b. brucei) reveals extensive homology in T. b. rhodesiense, T. b. gambiense and T. evansi, although the genetic surrounding differs in each case. By contrast, the AnTat 1.1 sequence (also from T. b. brucei) appears to be absent from T. b. gambiense DNA.