Detection of circulating antigens ofTrypanosoma cruziby enzyme immunoassay

Abstract

An enzyme-linked immunosorbent assay (ELISA) was developed to detect antigens of Trypanosoma cruzi in plasma during infection with the parasite. In experiments in mice and rabbits, T. cruzi antigens were detected at a time during infection when parasitaemia was very low or not detectable by microscopy. The ELISA method also detected antigens in plasma from immuno- suppressed, infected mice that had survived the initial phase of the infection with T. cruzi and which had low parasitaemia detectable by microscopy. Antigens were also demonstrated in the supernatant from cultures of cells infected with T. cruzi. Immunofluorescence revealed that antigens of T. cruzi may bind to the surface of the membranes of normal cells, which suggests that these antigens may serve as sites of recognition by cytotoxic T cells and/or antibody and thereby may play an important role in the destruction of host cells. In experiments in which the antigens in the supernatant from cell cultures infected with T. cruzi were compared with antigens in plasma from infected mice, at least four antigenic components detected in the supernatant were not demonstrable in the plasma.