Characterization of Trypanosoma cruzi antigens recognized by sera from patients with chronic Chagas' disease.

The aim of this work was to study the Trypanosoma cruzi antigens more reactive with antibodies from chagasic patients. For this purpose, the polypeptidic spectrum of cytosol was analyzed by isoelectric focusing. It showed about thirty bands distributed along a pH gradient of 3-10. In order to study the antigenicity of these polypeptides, four fractions from the focused cytosol were eluted and then analyzed by ELISA with chagasic and control sera. The more acidic and homogeneous fraction (FIV, pI 4-5,5) was the most reactive with antibodies from Chagas' disease patients. The 125I-labeled FIV was immunoprecipitated with chagasic and control human sera and subjected to SDS-PAGE analysis. The autoradiography revealed the presence of 4 major antigens, with apparent molecular weights of 49, 80, 86 and 110 kilodaltons only reactive with sera from chagasic patients. Two antigens with molecular weights of 34 and 21 kilodaltons were reactive with both chagasic and control sera.