Variant-specific trypanolytic antibodies in sera from patients infected with Trypanosoma brucei rhodesiense.

Infections with salivarian trypanosomes are characterized by the successive development of parasite populations of distinct variable antigen types (VATs), the corresponding antibodies accumulating in the blood of the host. Sixty VATs had been cloned during previous studies on variable antigen repertoires of Trypanosoma brucei rhodesiense; 12 of these were selected for immunolysis tests against 85 sera from T.b. rhodesiense patients in Busoga (Uganda). One variant, ETat 1/1, reacted with 59 out of 65 sera that contained detectable lytic antibodies. ETat 1/1 in combination with two other variants ETat 1/14 and Utat 1/1, covered all the seropositive sera; other VATs showed varying degrees of reactivity. The results suggest that sera from T.b. rhodesiense patients contain easily detectable VAT-specific antibodies and that their corresponding antigens might be used in the preparation of serodiagnostic reagents for the disease.