Probing population dynamics of trypanosoma cruzi during progression of the chronic phase in chagasic patients

Resumo

Our research aimed to characterize the genetic profiles of 102 Trypanosoma cruzi isolates recently obtained from 44 chronic chagasic patients from different regions of the states of Minas Gerais and Goiás in Brazil. At least two isolates were obtained from each patient at different times in order to study the parasite population dynamics during disease progression in the chronic phase. The isolates were characterized molecularly by genotyping the 3ⴕ region of the 24S␣ rRNA, the mitochondrial cytochrome oxidase subunit 2 (COII) gene, and the intergenic region of the spliced leader intergenic region (SL-IR) gene. Seventy-seven isolates were analyzed for nine microsatellite loci. The data presented here show a strong correlation between the T. cruzi lineage II (T. cruzi II) and human infection in these regions of Brazil. Interestingly, isolates from two patients were initially characterized (by rRNA genotyping) as T. cruzi I and hybrid strains, but subsequent analyses of the COII and SL-IR genes confirmed that those isolates belonged to T. cruzi III and a hybrid group, respectively. Our results confirm the risk of misclassifying T. cruzi isolates on the basis of analysis of a single molecular marker. The microsatellite profiles showed that different isolates obtained from the same patient were genet- ically identical and monoclonal. Exceptions were observed for T. cruzi isolates from two patients who presented differences for the SCLE11 locus and also from two other patients who showed amplification of three peaks for a microsatellite locus (TcAAAT6), implying that they were multiclonal. On the basis of the findings of the studies described here, we were not able to establish a correlation between the clinical forms of Chagas’ disease and the genetic profiles of the T. cruzi isolates.

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Citação

D'ÁVILA, Daniella Alchaar; MACEDO, Andréa Mara; VALADARES, Helder Magno Silva; GONTIJO, Eliane Dias; CASTRO, Ana Maria de; MACHADO, Carlos Renato; CHIARI, Egler; GALVÃO, Lúcia Maria Cunha. Probing population dynamics of trypanosoma cruzi during progression of the chronic phase in chagasic patients. Journal of Clinical Microbiology, Washington, v. 47, n. 6, p. 1718-1725, June 2009.