Trypanosoma cruzi Chagas, 1909: genetic variability of isolates from chronic chagasic patients in the Paraná state, Brazil

Abstract

The present work had as objective to verify the genetic diversity among strains of Trypanosoma cruzi isolated in chronic chagasic patients in the Paraná state. Fifty patients with compatible clinical symptoms were selected (cardiopathy, megacolon and/or megaesophagus) and that presented positive serological reaction to T. cruzi. Six strains of the protozoan were isolated in hemoculture and identified by electrophoresis in starch thick gel with aid of 14 isoenzymes (6PGD; G6PD; ME¹; ME²; ICD; PGM; GPI; GOT¹; GOT²; NP¹; NP²; DIA; MPI and FH). The statistical analysis were accomplished by the softwares NTSYs and UPGMA. Eighty-four electromorphs were individualized and four isoenzymes (ICD, GPI, 6PGD, e PGM) showed compatibility for heterozygosis. The phenetic analysis evidenced the hypothesis of constant evolution (genetic distances = 0.0536 to 0.1429, Hardy-Weinberg = 1.0000 to 0.0769 and differentiation for exact tests = 1.0000 to 0.0658). A great intra-specific genetic diversity in T. cruzi was verified in the isolates obtained in humans and it indicates that the clonet II is associated to the domestic cycle of transmission.