Microsatellite marker analysis shows differentiation among Trypanosoma cruzi populations of peripheral blood and dejections of Triatoma infestans fed on the same chronic chagasic patients

Abstract

To investigate whether Trypanosoma cruzi populations found in chagasic cardiopathic and non-cardiopathic patients are genetically differentiated, three molecular microsatellite markers were analysed. This analysis was also applied to compare T. cruzi samples from peripheral blood or dejections of Triatoma infestans fed on the blood of the same patients. In order to obtain the first objective, analyses of predominant T. cruzi genotypes were conducted using three approaches: a locus-by-locus analysis; a Fisher method across three loci; and analysis of molecular variance by Genepop and Arlequin programs. Only with one locus and on the blood samples was a significant differentiation detected among non-cardiopathic and cardiopathic groups, which was not confirmed by the other two methods. On the contrary, with the three approaches, it was found that T. cruzi clones present in the blood of patients are genetically differentiated from those detected in dejections of T. infestans fed on the same patients. Our results showed that the most frequent lineage both in blood as well as in triatomine dejection samples was TcI. No significant difference in T. cruzi lineage distribution was observed among chagasic cardiopathic and non-cardiopathic patients. The majority of the samples (50-60%) had only one T. cruzi clone (uniclonal) either in blood or dejection samples.

Microsatellite loci-based distribution of Trypanosoma cruzi genotypes from Chilean chronic Chagas disease patients and Triatoma infestans is concordant with a specific host-parasite association hypothesis

“…Another example, the lineages TcI and TcIII from the triatomine group (G1) differs significantly from the NB sample (G1/NB). As expected, according to previously published analyzes (Venegas et al 2010), no significant differences were detected when comparing non-cardiopathic patients with cardiopathic patients both in blood as xenodiagnosis samples (NB / CB and NX / CX).…”

“…b Determined using the Geneclass program using simultaneously the methods of: Goldstein et al (1995), Paetkau et al (1995) and Rannala and Mountain (1997) (see Materials and Methods). The lineage nomenclature used corresponds to the recent agreement (Zingales et al 2009 (29) 12 ( results in which the genetic characteristics of the same kind of sample were more similar to each other than to the type of patient (Venegas et al 2010), the NX and CX clustered together, as well as NB and CB. Finally, the topology of the tree produced from the foreign T. cruzi clones is concordant with the previous published topology ( De Freitas et al 2006); the hybrid clones clustered together in a node located between the TcII and TcIII lineages and the TcI lineage was furthest from TcII.…”

“…These three population samples will be called the "triatomine group" (G1). The second group will be called "Chagas disease group" (G2), is composed of samples from non-cardiopathic and cardiopathic T. cruzi infected patients, data obtained earlier by our laboratory with the same three microsatellite markers (Venegas et al 2010).…”

“…Peripheral blood samples were obtained from Chagas disease Chilean patients classified as non-cardiopathic (NB, 29 individuals) and cardiopathic (CB, 24 individuals), according to criteria described before (Venegas et al 2010). The patients were inhabitants from the IV region (between parallels 29°10´and 32°10´).…”

“…These samples were boiled, centrifuged and the supernatants were used to obtain DNA for PCR, as described (Venegas et al 2010). …”