[Genetic variability of Trypanosoma cruzi in blood and organs of infected mice determined by LSSP-PCR].

BACKGROUND: Chagas' disease, caused by Trypanosoma cruzi, has a variable clinical course, ranging from asymptomatic infection to chronic disease. Trypanosoma cruzi has a clonal population structure, although infecting strains are often multiclonal. Genetic variability of T. cruzi may be one of the determinant factors in differential tissue tropism and consequently of the clinical forms of the disease.

OBJECTIVE: To examine this possibility, mice were infected with two Colombian T. cruzi strains to determine the distribution of genetic variants in blood and organs. The sensitivity of three molecular markers was evaluated, and the genetic variability of the clones was determined. The latter was attained by means of low-stringency single specific primer polymerase chain reaction (LSSP-PCR) using a kinetoplast DNA (kDNA) marker. The kDNA signatures obtained with the LSSP-PCR were analyzed by neighbor-joining.

RESULTS AND CONCLUSION: The presence of the two lineages of T. cruzi was confirmed, as well as the multiclonal character of the two strains. The most sensitive marker was the kDNA. The most affected organ was the heart, which showed the greatest number of positive results with the three markers. Genetic differences were noted between the clones from the blood and organs of infected mice. These results support the value of the LSSP-PCR technique for the study of the molecular epidemiology of Chagas' disease.