Mini-exon gene sequence polymorphism among Trypanosoma rangeli strains isolated from distinct geographical regions

Trypanosoma rangeli can infect humans and the same domestic and wild animal s and triatomine vectors infected by T. cruzi in Central and South America. This overlapping distribution complicates the epidemiology of Chagas disea se because of the cross-reactivity between T. rangeli and T. cruzi antigens . We have studied T. rangeli strains isolated from different geographical r egions using the mini-exon gene as a genetic marker. Two pairs of oligonucl eotides directed to this gene were designed in order to detect specifically T. rangeli DNA by PCR assays. This assay was highly sensitive, able to amp lify the target sequence using the equivalent DNA content of a single paras ite as template, and demonstrated no cross-reactivity with T. cruzi DNA. T. rangeli SC-58 strain, isolated in southern Brazil, showed a distinct elect rophoretic pattern from the other T. rangeli strains tested. Low stringency single specific primer-PCR (LSSP) assays were able to detect sequence poly morphisms at the mini-exon gene among T. rangeli strains. Sequence comparis ons of this gene revealed that the SC-58 strain was genetically distinct fr om strains isolated in Central America and northern South America. In addit ion to insertion/deletion events, the presence of microsatellite repeats in the non-transcribed region of the gene contribute to the intra-species var iability.