GLYCOCONJUGATES OF TRYPANOSOMA-CRUZI - A 74 KD ANTIGEN OF TRYPOMASTIGOTES SPECIFICALLY REACTS WITH LYTIC ANTI-ALPHA-GALACTOSYL ANTIBODIES FROM PATIENTS WITH CHRONIC CHAGAS-DISEASE

Protective, lytic antibodies are believed to be correlated with active Trypanosoma cruzi infection. In patients with chronic infection, anti bodies lysing trypomastigote forms recognize chiefly alpha-galactosyl structures at the parasite surface. The target molecules on cell-deriv ed trypomastigotes that react with anti-alpha-galactosyl antibodies (a nti-Gal) from patients with chronic Chagas disease were investigated. Glycoconjugates were isolated from trypomastigotes and shown to absorb purified Chagasic (Ch) anti-Gal effectively as well as lytic antibodi es from Ch sera. Active fractions were F2 (74 kD and 95.6 kD) and F3 ( 120-200 kD). A differential reactivity with antibodies from untreated Ch patients (trypanolytic) and from treated. presumably cured. individ uals (not trypanolytic) was evident using F2 and F3 antigenic fraction s. No cross-reactivity with heterologous sera (other infections) was o bserved. The F2 glycoconjugate (mostly 74 kD) can be used in the diagn osis of active Chagas infection, replacing the quantitative determinat ion of complement-mediated lysis. With the present sample of patients' sera and normal human sera, it showed 100% sensitivity and specificit y. (C) 1993 Wiley-Liss. Inc.