Trypanosoma cruzi: Compared Vectorial Transmissibility of Three Major Clonal Genotypes byTriatoma infestans

Abstract

de Lana, M., da Silveira Pinto, A., Barnabé, C., Quesney, V., Noël, S., and Tibayrenc, M. 1998.Trypanosoma cruzi: Compared vectorial transmissibility of three major clonal genotypes byTriatoma infestans.Experimental Parasitology90, 20–25. TwentyTrypanosoma cruzistocks attributed to the 19/20, 32, and 39 major clones (Tibayrencet al.1986) were used to infect experimentally third instar larvae ofTriatoma infestans.Three variables were considered: (i) percentage of infected insects; (ii) number of flagellates per insect (NFI); and (iii) percentage of metacyclic trypomastigotes per insect. Differences between the genotypes under study for all parameters considered were detected. These differences were statistically significant (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 nonparametric Mantel's test was strongly significant (P< 10−4). Data obtained suggest clearly that populations of parasites belonging to the 19/20 genotype are more efficiently transmitted (high transmissibility genotype) by the vector than the 32 genotype (low transmissibility genotype), while the 39 genotype presents intermediary characteristic. Results confirm the working hypothesis that the subdivision ofT. cruziinto discrete clonal lineages has an impact on the vectorial competence ofT. infestans, the most important vector of the chagasic infection in South America, and that different clonal lineages do not exhibit the same vectorial transmissibility. This fact is relevant both for Chagas' disease epidemiology and for the use of xenodiagnosis.