Identification of Leishmania spp. by molecular amplification and DNA sequencing analysis of a fragment of rRNA internal transcribed spacer 2.

Isoenzyme analysis of cultured parasites is the conventional approach for Leishmania species identification. Molecular approaches have the potential to be more sensitive and rapid. We designed PCR generic primers to amplify a segment of the rRNA internal transcribed spacer 2 (ITS2) from multiple Leishmania species. To validate the selected ITS2 fragment, we tested clinical specimens and compared the species results obtained by the molecular approach (PCR followed by DNA sequencing analysis) with those from the parasitologic approach (in vitro culture followed by isoenzyme analysis). Among the 159 patients with clinical specimens positive by both approaches, a total of eight Leishmania species were identified. The species results were concordant for all but two patients: for one patient, the results were Leishmania (Viannia) guyanensis by the molecular approach versus L. (V.) braziliensis by the parasitologic approach; for the other patient, the results were L. (Leishmania) tropica versus L. (L.) major, respectively. ITS2 PCR, followed by sequencing analysis, can be used to detect and discriminate among Leishmania species. The results confirmed our hypothesis that a region of the ITS2 gene can complement the characterization of Leishmania parasites at the species level. The approach we developed can be used as a diagnostic tool in reference laboratories with adequate infrastructure to perform molecular characterization of pathogens.