PCR amplification of mini-exon genes differentiates Trypanosoma cruzi from Trypanosoma rangeli.

Synthetic oligonucleotides corresponding to a conserved 22 nucleotide sequence within the tandemly repeated mini-exon gene have been used to amplify a single gene-containing repeat from Trypanosoma cruzi and Trypanosoma rangeli, two morphologically similar organisms with overlapping hosts and geographical distribution but different pathogenicity in humans. The T. cruzi repeat is 582 nucleotides long and the T. rangeli repeat is 858 nucleotides. The two organisms may therefore be distinguished primarily by the electrophoretic mobilities of their respective amplification products. Confirmation of the diagnosis can be obtained by Southern blot analysis using species-specific DNA probes from the unique intergenic regions. We also present a diagnostic assay in which the unique intergenic regions are immobilized on nylon membranes and differentiation is based on hybridization with a digoxigenin-labelled PCR product.