TRYPANOSOMA-CRUZI - EVALUATION OF A RAPD SYNAPOMORPHIC FRAGMENT AS A SPECIES-SPECIFIC DNA-PROBE

A methodological approach is proposed to select rapidly DNA sequences characterized by a well defined specificity and potentially interestin g to be used as diagnostic probes or as taxonomic phylogenetic markers . A fragment amplified from a diversified sample of Trypanosoma cruzi stocks by the RAPD (random amplified polymorphic DNA) method with the A8 primer, previously found to be monomorphic in all stocks, was separ ated in 2 fragments using polyacrylamide electrophoresis. RFLP (restri ction fragment length polymorphism) analysis of the 750-bp fragment co mmon to all stocks revealed some sequence heterogeneity within the T. cruzi species, whereas hybridization experiments showed a high homolog y between fragments amplified from different T. cruzi stocks. These re sults suggest that sequence analysis will allow the design of internal primers to be used as probes to target specific taxonomic levels (clo ne, family of related clones, or species) and for diagnosis.