Probing the genetic population structure of Trypanosoma cruzi with polymorphic microsatellites

Abstract

We describe here the identification of eight polymorphic microsatellite loci with (CA) n repeats in the Trypanosoma cruzi genome based on the affinity capture of fragments using biotinylated (CA) 12 attached to streptavidincoated magnetic beads. The presence of two peaks in PCR amplification products from individual clones confirmed that T. cruzi is diploid. Hardy-Weinberg and linkage disequilibrium analyses suggested that sexual reproduction is rare or absent and that the population structure is clonal. Several strains, especially those isolated from nonhuman sources, showed more than two alleles in many loci demonstrating that they were multiclonal. The phylogenetic analysis of T. cruzi based on microsatellites revealed a great genetic distance among strains, although the strain dispersion profile in the Wagner network was in general agreement with the species dimorphism found by PCR amplification of the divergent region of the rRNA 24S␣ gene.

The population structure of Trypanosoma cruzi: expanded analysis of 54 strains using eight polymorphic CA-repeat microsatellites

“…1B), implying that they were multiclonal. In our previous study with microsatellites (Oliveira et al 1998) we had only observed more than two peaks in strains obtained from insect vectors, wild mammals or human patients in the acute phase of Chagas disease. Now, with the expanded number of strains from chronic patients we could now observe several cases of more than two peaks, although still at a smaller proportion (Table II).…”

“…Primers sequences have been published previously (Oliveira et al 1998). One primer of each pair was 5'-labeled with fluorescein.…”

“…Recently, we cloned and sequenced the first eight T. cruzi polymorphic microsatellite loci and studied 31 clones and strains to obtain valuable information about the population structure of the parasite (Oliveira et al 1998). We have now studied 23 further strains, increasing from 11 to 31 the number of strains obtained from patients with chronic Chagas disease.…”

Caracterización biológica y genética de dos clones pertenecientes a los grupos I y II de Trypanosoma cruzi de Colombia

“…En esta fase el parasitismo en tejidos es muy alto y restringido a algunos órganos como corazón, músculo esquelético, hígado, esófago, bazo y recto (5,6). La habilidad del parásito para sobrevivir a la fase aguda y avanzar hacia la fase crónica e invadir determinados órganos depende tanto de factores genéticos del parásito como del hospedero (7)(8)(9)(10)(11). Por esto, diversas investigaciones han estudiado la variabilidad genética del parásito y su posible relación con las manifestaciones clínicas de la enfermedad (7).…”

Análisis por LSSP-PCR de la variabilidad genética de Trypanosoma cruzi en sangre y órganos de ratones.

“…cruzi es considerado como un organismo diploide, aunque su reproducción es básicamente clonal (5,6); su interacción sexual se restringe a algunas poblaciones selváticas (7). Mediante ensayos con isoenzimas y microsatélites se encontró que las cepas de este protozoo son frecuentemente multiclonales (6,8) y, posiblemente, los pacientes y los vectores se infectan al menos con dos clones genéticamente diferentes (9,10).…”