T. cruzi is a flagellate protozoon, agent of Chagas disease. Analysis of electrophoretic zymograms for a set of 6 enzymes allowed characterization of 12 "isozymic strains" or "zymodemes" in Argentina. Two of those zymodemes (Z1 and Z12) are widely distributed and are the most frequently found in human patients (De Luca d´Oro et al. Parasitology 107: 405, 1993). A significant correlation was observed between the zymodeme of the infecting parasite and the clinical picture. Most of the patients (81.1%) harboring Z1 were asymptomatic, while 72.7% of patients with Z12 presented cardiomiopathies (Montamat et al. Am.J.Trop.Med.Hyg. 55 (6), 1996). Thus, strain-identification of the infecting parasite during the intermediate phase of the disease would be useful for the prognosis. But zymodeme characterization is not practical for clinical use. Given the correlalion between groupings obtained by studying enzymes and kinetoplast DNA (Macina et al. Molec. Biochem. Parasit. 25: 45, 1987) it is possible to identify zymodemes by analyzing DNA. Kinetoplast DNA was studied by: a) RAPDs: most of the amplified DNA segments were common to Z1 and Z12, but some were zymodeme-specific. b) Probes: using primers for the sequences flanking segments of the hypervariable regions , these segments were amplified, digested with Sca 1 and Sau 961 to eliminale conserved regions, and labeled with alfa32 PdATP. After denaturation and transfer of DNA from diferent isolates, hybridization with the labeled probes allowed identification. This technique, applied to blood samples, offers a mean to predict the most probable course of the disease in a given patient.
