The identification of two main-groups of Trypanosoma cruzi stocks from Brazil by their isoenzyme patterns of isoelectrofocusing.

The isoelectrofocusing of seven enzymes was studied using extracts of 40 Brazilian stocks of T. cruzi culture forms. Four enzymes showed intraspecific variation in enzyme profiles and were selected for characterization of T. cruzi. These enzymes are: nonspecific esterase (E.C.3.1.1), phosphoglucomutase (E.C. 2.7.5.1), glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) and glucosephosphate isomerase (E.C. 5.3.1.9). The parasite stocks were isolated from endemic areas in the States: Rio Grande do Sul, Sao Paulo, Espirito Santo, Minas Gerais and Bahia. By combining the electrophoretic patterns of the four enzymes concerned the stocks have been classified into two main-groups. Stocks of group I were exclusively isolated from wild animal reservoirs, whereas group II was mainly composed of stocks from human cases and domestic hosts. Only three "sylvatic" stocks have been found in group II. The enzymes glucose-6-phosphate dehydrogenase and glucosephosphate isomerase showed further subtypes within both groups I and II; their significance is not yet clear. The results are in support of the existence of a domestic and a sylvatic transmission cycles in Brazil which are either clearly distinct or overlapping in some areas.