TRYPANOSOMA-CRUZI - IMPACT OF CLONAL EVOLUTION OF THE PARASITE ON ITSBIOLOGICAL AND MEDICAL PROPERTIES

Trypanosoma cruzi populations are subdivided into natural clones that can exhibit considerable genetic differences. It has been proposed tha t T. cruzi clonal structure has a major impact on this parasite's biol ogical properties. The present work aims at testing this hypothesis. T wenty-one stocks isolated from various ecological cycles, places, and hosts were characterized by multilocus enzyme electrophoresis (MLEE) w ith 22 genetic loci and random amplification of polymorphic DNA (RAPD) with 10 primers on the one hand and by 14 different biological parame ters on the other hand. These parameters were related to: (i) growth k inetics of epimastigotes and amastigotes; (ii) infection of culture ce lls by amastigotes; (iii) viability of extracellular trypomastigotes; or (iv) sensitivity of epimastigotes, trypomastigotes, and amastigotes to Benznidazole and Nifurtimox. MLEE and RAPD results exhibited parit y to each other, as previously noted (M. Tibayrenc, K. Neubauer, C. Ba rnabe, F. Guerrini, D. Skarecky, and F. J. Ayala, 1993, Proceedings of the National Academy of Sciences of the US4 90, 1335-1339), and showe d that the 21 stocks were distributed into three main genetic groups, 19/20, 32, and 39, corresponding to the major clones 19, 20, 32, and 3 9 previously described on the basis of 15 isozyme loci. Most biologica l parameters showed a strong correlation to the genetic distances eval uated from either MLEE or RAPD, which favors the working hypothesis. T he only exception came from drug sensitivity estimated on trypomastigo te forms. The overall results made it possible to firmly reject the nu ll hypothesis that there is no relationships between evolutionary dist ances and biological differences in T. cruzi natural clones. (C) 1998 Academic Press.