TRYPANOSOMA-CRUZI - COMPARED VECTORIAL TRANSMISSIBILITY OF 3 MAJOR CLONAL GENOTYPES BY TRIATOMA-INFESTANS

Twenty Trypanosoma cruzi stocks attributed to the 19/20, 32, and 39 ma jor clones (Tibayrenc et al. 1986) were used to infect experimentally third instar larvae of Triatoma infestans. Three variables were consid ered: (i) percentage of infected insects; (ii) number of flagellates p er insect (NFI); and (iii) percentage of metacyclic trypomastigotes pe r insect. Differences between the genotypes under study for all parame ters considered were detected. These differences were statistically si gnificant (P < 10(-3)), except between the 39 and 32 clonal genotypes for the NFI parameter. The correlation coefficient between the genetic distance and the biological parameters determined by the nonparametri c Mantel's test was strongly significant (P < 10(-4)). Data obtained s uggest clearly that populations of parasites belonging to the 19/20 ge notype are more efficiently transmitted thigh transmissibility genotyp e) by the vector than the 32 genotype (low transmissibility genotype), while the 39 genotype presents intermediary characteristic. Results c onfirm the working hypothesis that the subdivision of T. cruzi into di screte clonal lineages has an impact on the vectorial competence of T. infestans, the most important vector of the chagasic infection in Sou th America, and that different clonal lineages do not exhibit the same vectorial transmissibility. This fact is relevant both for Chagas' di sease epidemiology and for the use of xenodiagnosis. (C) 1998 Academic Press.