Identification of an antigen specific to Trypanosoma congolense by using monoclonal antibodies

Using indirect immunofluorescence assays on acetone-fixed smears of a series of different parasites, we have shown that two monoclonal antibodies bind specifically to Trypanosoma congolense organisms. The antibodies bind to both bloodstream trypomastigotes and procyclic culture forms of the parasite and are thus not stage specific. Immunoprecipitation and immunoblot analysis showed that both monoclonal reagents bound a protein of approximately 31,000 m.w. This antigen appeared to be located on the plasma membrane of T. congolense, but the epitope was not exposed on the surface of living bloodstream or procyclic organisms. The antigen was detectable on acetone-fixed organisms or in trypanosome lysates in enzyme-linked immunosorbent assays and may therefore by useful as a species-specific marker in field assays for epidemiologic and clinical investigations.