ARE GENOTYPES OF TRYPANOSOMA-CRUZI INVOLVED IN THE CHALLENGE OF CHAGASIC CARDIOMYOPATHY

Myocardial damage in Chagas' disease differs, depending on the particu lar Trypanosoma cruzi stock. It is reasonable to expect that the exten t of phylogenetic divergence between lineages will have an impact on t he biological properties of the parasite. The aim of the present work was to evaluate this impact on the cardiac damage produced by this pro tozoan. Heart histopathologic lesions were studied in mice infected wi th 15 cloned stocks of T. cruzi of various origins pertaining to 3 maj or clones or genotypes (19, 20, and 39) that share 3 different profile s for a given set of genetic markers. Sets of mice were infected intra peritoneally with 10(6) blood trypomastigotes of each of the T. cruzi clones. The macroscopy study showed a cardiac index (CI) higher than 0 .6 (cardiomegaly) in 5 of the 15 stocks studied (33.33%). Inflammatory infiltrates appeared in stocks pertaining to the three genotypes stud ied without relation to the genetic pattern. Pseudocysts were present at higher levels (83%) in stocks pertaining to genotype 39. A lower ra te could be seen in stocks pertaining to genotype 19 (50%). Only one s tock pertaining to genotype 20 presented myocardial parasites (20%). H earts were also studied for lesions in the different cardiac chambers. Inflammatory foci as well as pseudocysts appeared mainly in ventricle s, with the left ventricle sharing the highest percentage of pathologi c findings. In summary, in spite of the similar inflammatory pattern d emonstrated for all stocks studied, the parasite's presence seemed to be related to the genotype of reference, but no relation could be demo nstrated with the genetic distances.