An isoenzyme survey of Trypanosoma cruzi genetic variability in sylvatic cycles from French Guiana

Twenty-seven trypanosomatidae stocks isolated from various hosts in French Guiana have been surveyed by Multilocus Enzyme Electrophoresis on cellulose acetate plates. The variability observed at 22 different enzyme systems was considerable, since 21 different enzyme profiles (zymodemes) could be distinguished. Clustering analysis and comparison with four laboratory reference stocks showed clearly that three stocks were distantly related from the rest and most probably cannot be included in the species Trypanosoma cruzi. All the other stocks were more related to the formerly described zymodeme I than to the formerly described zymodemes II and III. Genotype variability in this T. cruzi sylvatic population was notably higher than in domestic populations of the same parasite. This could suggest more frequent genetic exchange occurring in sylvatic cycles. Nevertheless, a population genetic analysis of the data showed a considerable linkage disequilibrium, which rather favors the hypothesis that T. cruzi has a basically clonal population structure in this ecosystem too.