New enzyme immunoassays for specific assay and general detection of Trypanosoma cruzi, epimastigotes.

A highly specific competitive enzyme-linked immunosorbent assay for the epimastigote of Tulahuen strain was developed by using the usual 3 immunological reagents, a rabbit antiserum specific for T. cruzi, epimastigote of Tulahuen strain, beta-D-galactosidase-labeled goat anti-rabbit immunoglobulin G and the solid-phase cell fragments of the epimastigote of Tulahuen strain. A new method, the selected antibody enzyme immunoassay (SAEIA) which generally detected all strains of the epimastigote tested with the same working range, was developed by changing only the solid-phase antigen to the epimastigote of Y strain among the 3 immunological reagents. Both assays permitted us to measure accurately as little as 1,000 parasites per assay tube. Scope of the SAEIA was limited to the epimastigote. Both life-cycle forms of T. cruzi which appear in mammals, amastigote and trypomastigote, and other kinetoplastids showed low cross-reaction values by the assay. The assay principle of the new method and a preliminary study to apply the SAEIA for finding the field T. cruzi-infected insect vectors were also reported.