title: The identification by isoenzyme patterns of two distinct strain-groups of Trypanosoma cruzi, circulating independently in a rural area of Brazil.
abstract: Culture forms of 17 Trypanosoma cruzi stocks, primarily isolated from a rural area of endemic Chagas disease at São Felipe, Bahia, Brazil, were compared by the electrophoretic patterns of six enzymes: aspartate aminotransferase, alanine aminotransferase, glucose-6-phosphate dehydrogenase, malate dehydrogenase (decarb-oxylating) (NADP+), glucosephosphate isomerase and phosphoglucomutase. Two markedly distinct combinations of isoenzyme patterns were seen, justifying the arrangement of the 17 stocks into two strain-groups, each of which was enzymically homogeneous. One combination was characteristic of the 11 domestic stocks of T. cruzi derived from both human infections and domiciliated animals; the second was characteristic of the six sylvatic stocks derived from opossums and a sylvatic triatomine species. The enzyme patterns were independent of the original host and the type of culture medium used. Distinction of the two strain-groups accords with epidemiological evidence that the domestic and sylvatic transmission cycles in São Felipe do not overlap. It is suggested that the diverse enzyme characters of the two strain-groups circulating in São Felipe reflect diverse origins; the domestic form of T. cruzi probably invaded the area from the south of Brazil with the domestic triatomine vector, Panstrongylus megistus.
mesh_terms: D000818:Animals; D001938:Brazil; D014355:Chagas Disease / Q000469:parasitology; D004592:Electrophoresis, Starch Gel; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D014349:Trypanosoma cruzi / Q000145:classification / Q000201:enzymology*
chemical_list: D007527:Isoenzymes