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Infectio ; 15(4): 227-234, oct.-dic. 2011. ilus, graf, tab
Article in Spanish | LILACS, COLNAL | ID: lil-649978

ABSTRACT

Introducción. La enfermedad de Chagas, cuyo agente causal es Trypanosoma cruzi, constituye una antropozoonosis ampliamente distribuida en América Latina. Los estudios moleculares y los perfiles genéticos han demostrado que el parásito presenta una gran variabilidad y han permitido la clasificación de T. cruzi en seis unidades discretas de tipificación (I-VI), de las cuales, TcII a TcVI han sido ampliamente caracterizadas por distintos marcadores moleculares. Objetivo. Evaluar la variabilidad genética de TcI, mediante el uso de marcadores de microsatélites. Materiales y métodos. Se evaluaron siete microsatélites en quince aislamientos colombianos obtenidos mediante PCR a partir de reservorios, vectores y humanos, y se analizaron en un gel para desnaturalizar de poliacrilamida de un secuenciador láser fluorescente automático (ALF). Los datos se analizaron en un software para análisis de genética de poblaciones (Arlequin® 3.1 y Microsat®). Resultados. Los resultados demostraron variabilidad dentro de TcI al obtener 24 alelos, de los cuales, 12 se reportan por primera vez. Aunque se encontraron genotipos asociados a la infección humana y al ciclo selvático de transmisión, ningún locus permitió comprobar la presencia de los genotipos previamente reportados. Los parámetros de heterocigocidad observada y esperada, permitieron determinar la presencia de dos poblaciones (aislamientos domésticos y selváticos); asimismo, el desequilibrio de ligamento facilitó la creación de dos mapas físicos para los loci analizados. Conclusiones. Se corrobora la gran variabilidad genética presente en TcI, lo que sugiere un patrón de variación intraespecífica en Colombia.


Introduction: Chagas disease which is caused by the protozoan Trypanosoma cruzi, is a major public health problem in Latin American countries with a different distribution of the parasite across the continent in which nearly 15 million people are infected and 28 million are at risk. Genetic profiling of T. cruzi has shown great diversity and variability of the parasite allowing its classification into six discrete typing units (DTUs I-VI) in which TcII to TcVI are well characterized by different molecular markers. However, the presence of four subgroups according to the transmission cycle has only been reported in DTU T. cruzi I. Objective: To evaluate the genetic variability evidenced within TCI by the use of microsatellite markers. Materials and methods: Seven microsatellite loci were tested in fifteen Colombian isolates from vectors, reservoirs, and humans by means of PCR and automatic laser fluorescent sequencer (ALF). Data were analyzed using a population genetic data analysis software (Arlequin® 3.1 and Microsat®). Results: Variability among the isolates was demonstrated with 24 alleles, from which twelve had never been reported before. However, none of the microsatellite loci were able to support the idea of genotypes within TcI strains. The parameters of expected and observed heterozygocity allowed us to determine presence of two populations (domestic and sylvatic isolates); likewise, the linkage disequilibrium helped with the construction of two physical maps for the loci analyzed. Conclusions: We corroborated the high genetic variability displayed by TcI populations suggesting a pattern of intraspecific variation in Colombia.


Subject(s)
Humans , Trypanosoma cruzi , Polymerase Chain Reaction , Chagas Disease , Genetics , Software , Genetic Markers , Linkage Disequilibrium , Risk , Colombia , Rosaceae , Alleles , Lasers
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