Differences in antigenic constitution of strains of Trypanosoma cruzi

Abstract

The antigenic constitution of strains of Trypanosoma cruzi isolated from man (Y, L), bat (M), triatoma bug (T), opossums (OPF, 8857) and a wild rodent (8717) has been compared through agglutination and precipitation tests in agar gel. Rabbit antisera against a single strain agglutinated every strain tested. However, after specific absorption of an anti-Y immune serum with cultural forms of the various strains, it has been possible to separate these into two immunological types: one that includes flagellates capable of completely absorbing agglutinins from the anti-Y serum (type A—strains Y, L, M and T), and another with flagellates absorbing only part of the agglutinins from said serum (type B—strains OPF, 8857 and 8717). The presence of type- and group-specific substances in aqueous extracts of cultural forms of the various strains was verified through precipitation tests in agar gel and immunoelectrophoresis performed with antiserum from a horse immunized against human strains of the parasite. The type-specific antigens from types A and B cross react, which indicates their structural similarity. They are present in the flagellates' membrane and some observations suggest their polysaccharide nature. The authors discuss the epidemiological implications of these findings and suggest the possibility that the existence of distinct immunological types of T. cruzi might explain the clinical diversity observed in Chagas' disease.