Trypanosoma rangeli: discrimination from Trypanosoma cruzi based on a variable domain from the large subunit ribosomal RNA gene

306-314. Three synthetic oligonucleotides corresponding to sequences within the D7a divergent domain of the large subunit ribosomal RNA gene have been used to amplify the total DNA of Trypanosoma rangeli and Trypanosoma cruzi, two morphologically similar protozoa with overlapping geographical distribution and hosts. The two organisms may be distinguished by the electrophoretic mobilities of their respective amplification products. For T. rangeli a 210-bp product was obtained. The presence of this fragment was confirmed in 14 T. rangeli strains. For T. cruzi two possible amplification products were originated: a 265-bp DNA fragment for strains typed as lineage 1 and a 250-bp fragment for lineage 2 strains. Eleven unidentified trypanosome stocks, recently isolated from Amazonian vectors, could be discriminated using the proposed assay. The potential field application of multiplex PCR was further demonstrated by identification of the two parasite species in samples containing intestinal tract and feces of triatomines. In the present study we have also amplified the D7a domain of several trypanosomatids employing primers complementary to the conserved flanking regions. Size and sequence polymorphisms were observed, indicating that this region could also be explored as a target for specific detection of other members of the Trypanosomatidae family.