RESUMEN
In American man can be infected with two trypanosomes: Trypanosoma cruzi, the etiological agent of Chagas' disease and Trypanosoma rangeli, a suspected nonpathogenic parasite. In this communication are presented 4 methods in order to improve the current knowledge about the specific identification of these parasites. Using the SDS-PAGE technique it was possible to differentiate between T. rangeli. and T. cruzi based in at less 4 protein bands with a relative molecular weights of 93, 77-73, 63 and 54-52 KDa. These polypeptides were found only in T. rangeli electrophoretic profiles. An ELISA test showed that the antigenic composition found in the enzyme cisteine proteinase (cruzipain) is specific for T. cruzi epimastigotes. Antigenic analysis by Western blot assay, proved that T. rangeli and not T. cruzi present antigenic bands with a Mr of 142, 63, 54, 51, 49, 43, 39 and 24 KDa. Finally, using the Southern blot procedure, it was confirmed that SAPA, a DNA sequence originally identified in the T. cruzi, genome, is absent in T. rangeli nuclear DNA. These initial observations revealed that it is possible to identify both parasites using the described methods, however further works are required to clarify the biochemical, immunological and molecular relationship between T. rangeli and T. cruzi