Serodiagnosis of American trypanosomosis by using nonpathogenic trypanosomatid antigen.

Crithidia luciliae, a nonpathogenic trypanosomatid, could provide a good alternative source of antigen for serodiagnosis of Chagas' disease. An enzyme-linked immunosorbent assay showed 100% sensitivity and 83% specificity when 91 human serum samples from Chagas' disease patients and 127 human serum samples from people suffering from toxoplasmosis (21 samples), leishmaniasis (32 samples), systemic rheumatic diseases (33 samples), and heart diseases (41 samples) were tested simultaneously with Trypanosoma cruzi and C. luciliae crude extracts. By Western blotting, an immunodominant band (30 kDa) was recognized by chagasic sera on the C. luciliae crude extract; specificity reached 97% with respect to this protein band. The carbohydrate moieties were not antigenic.