Identification of Trypanosoma cruzi genotypes circulating in Chilean chagasic patients

Parasite DNA amplified by PCR from blood of 73 chagasic children and adults of two endemic areas of Chile were studied by Southern blot and/or dot blo t hybridization analysis with a panel of three minicircle probes correspond ing to the parasite genotypes (clonets 19, 33 and 39). The hybridization pa ttern of the PCR positive samples identified clonets 39, 19/20, and 32/33 w ith frequencies of 0.84, 0.32 and 0.26, respectively. A total of 31 samples corresponded to mixed infections. The most fre quently found mixtures were : clonets 39 and 19/20(14 cases), followed by clonets 39 and 32/33 (8 cases ), clonets 39, 32/33 and 19/20 (8 cases), and clonets 32/33 and 19/20 (1 ca se). Amplified DNA from 9 cases showed no hybridization signal with none of the three studied probes indicating that other genotypes different to the ones mentioned are circulating in humans, but that the clonets used as prob es are the most prevalent ones in terms of transmission in the endemic area s studied. A biological characterization of 34 T. cruzi populations isolate d from the xenodiagnosis of the patients was performed on an experimental m urine model. The biochemical characterization of the parasite populations b y molecular karyotype determined that the most frequent parasite isolated f rom patients belongs to clonet 39. (C) 2001 Academic Press.