BOVINE T-CELLS SPECIFIC FOR TRYPANOSOMA-BRUCEI-BRUCEI VARIANT SURFACEGLYCOPROTEIN RECOGNIZE NONCONSERVED AREAS OF THE MOLECULE

The specificity of bovine CD4(+) T-cell responses to Trypanosoma bruce i variant surface glycoprotein (VSG) has been examined by using a pane l of seven T-cell clones and nested deletions of the ILTat 1.3 VSG gen e expressed in Escherichia coli. All clones recognized the polymorphic N-terminal domain of the antigen, and the recognition sites of five o f the clones were resolved to three areas with lengths of 14, 18, and 21 amino acids. Comparison of these regions with corresponding areas o f other VSG molecules, including those derived from the same trypanoso mal serodeme, has shown that the sites are not conserved. In the light of recent observations that VSG-specific T-cell responses are induced in mice infected with T. brucei, these results conform with the belie f that immune pressure from T cells may contribute to the generation o f antigenic diversity on the surface of African trypanosomes.