Selection of Trypanosoma cruzi clonal genotypes (clonet 20 and 39) isolated from Bolivian triatomines following subculture in liquid medium

Previous studies showed that two groups of Trypanosoma cruzi clonal genotyp es named clonet 20 and clonet 39 were predominant in Triatoma infestans, th e unique vector of Chagas disease in Bolivia. These groups of clones corres pond to distinct genetic clusters. These clonets were! detected in T. infes tans and Rhodnius pictipes fecal samples before isolation and after culture by kDNA PCR (polymerase chain rreaction) and hybridization of the amplifie d products with clonet specific kDNA probes named 20 and 39 as previously r eported. Forty eight T. infestans and three R. pictipes infected insects ca ptured at random in different Bolivian departments were proceeded. As previ ously reported the dir-eel identification of the two major clonets in fecal samples allowed the detection of abundant mixed infections. 41% in the ori ginal sample, however after culture, only 6% of mixed infection:; were dete cted. Among the 21 parasite stocks isolated from digestive tracts there mix ed infections were initially detected (clonet 20 + 39) clonet 20 alone was detected in 81% of them. This result clearly showed that the culture step s elected clonet 20 parasites over those belonging to clonet 39. The taxonomi c status of the isolated stocks was also confirmed by isoenzyme typing, and correlation was observed between clustering topology and hybridization pat terns with the probes 20 and 39.