BIOLOGICAL CHARACTERIZATION AND GENETIC DIVERSITY OF MEXICAN ISOLATESOF TRYPANOSOMA-CRUZI

The present work reports the in vitro biological characterization of 1 7 Trypanosoma cruzi isolates from southern and central Mexico, and com pares these results to those of four South American strains and one cl one from Brazil. The parameters evaluated were growth rates, percentag e of parasites undergoing transformation from epimastigotes to trypoma stigotes, infectivity to, and in vitro killing of cultured Vero and P3 88 cells. Isoenzyme patterns of 11 enzymatic systems and 16 loci were also determined for the Mexican isolates. The parasites showed differe nces in growth, depending if they were cultured in LIT with hemin or i n Grace's media. Transformation was obtained only in Grace's medium an d differences were observed between the stocks. Stocks Z10 and Z21 sho wed the highest percentage of transformation within the Mexican isolat es (39 and 41%, respectively). A second group showed percentages of tr ansformation between 15 and 28%. In contrast, the South American strai ns showed higher rates of transformation (36-65%). Infection of cultur ed cells by isolates Z10 and H5 was evaluated in both Vero and P388 ce lls. Differences were observed both in the percentage of infected cell s as well as in the number of amastigotes per cell. Differences in the ability to cause in vitro killing of P388 cells were also observed am ong the isolates. Isoenzyme analysis revealed genetic variation betwee n the isolates, each of them with an unique zymodeme. This genetic ana lysis revealed, in general, a clustering based on the geographical ori gin of the isolates. Finally, correlation with clinical symptoms is di scussed. (C) 1998 Elsevier Science B.V. All rights reserved.