title: Putative panmixia in restricted populations of Trypanosoma cruzi isolated from wild Triatoma infestans in Bolivia.
abstract: Trypanosoma cruzi, the causative agent of Chagas disease, is subdivided into six discrete typing units (DTUs; TcI-TcVI) of which TcI is ubiquitous and genetically highly variable. While clonality is the dominant mode of propagation, recombinant events play a significant evolutive role. Recently, foci of wild Triatoma infestans have been described in Bolivia, mainly infected by TcI. Hence, for the first time, we evaluated the level of genetic exchange within TcI natural potentially panmictic populations (single DTU, host, area and sampling time). Seventy-nine TcI stocks from wild T. infestans, belonging to six populations were characterized at eight microsatellite loci. For each population, Hardy-Weinberg equilibrium (HWE), linkage disequilibrium (LD), and presence of repeated multilocus genotypes (MLG) were analyzed by using a total of seven statistics, to test the null hypothesis of panmixia (H0). For three populations, none of the seven statistics allowed to rejecting H0; for another one the low size did not allow us to conclude, and for the two others the tests have given contradictory results. Interestingly, apparent panmixia was only observed in very restricted areas, and was not observed when grouping populations distant of only two kilometers or more. Nevertheless it is worth stressing that for the statistic tests of "HWE", in order to minimize the type I error (i. e. incorrect rejection of a true H0), we used the Bonferroni correction (BC) known to considerably increase the type II error ( i. e. failure to reject a false H0). For the other tests (LD and MLG), we did not use BC and the risk of type II error in these cases was acceptable. Thus, these results should be considered as a good indicator of the existence of panmixia in wild environment but this must be confirmed on larger samples to reduce the risk of type II error.
authors: MIVEGEC (Université de Montpellier 1 et 2 - CNRS 5290 - IRD 224), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Institut de recherche pour le développement (IRD), Representation in Bolivia, La Paz, Bolivia ; Instituto Nacional de Laboratorios de Salud (INLASA), Department of Entomology, La Paz, Bolivia.
authors: Christian
authors: C
authors: Barnabe
authors: Rosio
authors: R
authors: Buitrago
authors: Philippe
authors: P
authors: Bremond
authors: Claudia
authors: C
authors: Aliaga
authors: Renata
authors: R
authors: Salas
authors: Pablo
authors: P
authors: Vidaurre
authors: Claudia
authors: C
authors: Herrera
authors: Frédérique
authors: F
authors: Cerqueira
authors: Marie-France
authors: MF
authors: Bosseno
authors: Etienne
authors: E
authors: Waleckx
authors: Simone Frédérique
authors: SF
authors: Breniere
mesh_terms: D000818:Animals; D001838:Bolivia; D014644:Genetic Variation; D006790:Host-Parasite Interactions; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats / Q000235:genetics; D014224:Triatoma / Q000235:genetics / Q000469:parasitology*; D014349:Trypanosoma cruzi / Q000302:isolation & purification*