Trypanosoma cruzi: ancestral genomes and population structure

Memórias do Instituto Oswaldo Cruz

Sérgio Dj Pena¹  Carlos Renato Machado¹  Andréa Mara Macedo¹ 

[1] ,Universidade Federal de Minas Gerais Departamento de Bioquímica e Imunologia Belo Horizonte MG ,Brasil

关键词: Trypanosoma cruzi;    Chagas disease;    genome;    sex;    evolution;    pathogenesis;   

DOI  :  10.1590/S0074-02762009000900016

来源: SciELO

【 摘 要 】

Although the genome of Trypanosoma cruzi has been completely sequenced, little is known about its population structure and evolution. Since 1999, two major evolutionary lineages presenting distinct epidemiological characteristics have been recognised: T. cruzi I and T. cruzi II. We describe new and important aspects of the population structure of the parasite, and unequivocally characterise a third ancestral lineage that we propose to name T. cruzi III. Through a careful analysis of haplotypes (blocks of genes that are stably transmitted from generation to generation of the parasite), we inferred at least two hybridisation events between the parental lineages T. cruzi II and T. cruzi III. The strain CL Brener, whose genome was sequenced, is one such hybrid. Based on these results, we propose a simple evolutionary model based on three ancestral genomes, T. cruzi I, T. cruzi II and T. cruzi III. At least two hybridisation events produced evolutionarily viable progeny, and T. cruzi III was the cytoplasmic donor for the resulting offspring (as identified by the mitochondrial clade of the hybrid strains) in both events. This model should be useful to inform evolutionary and pathogenetic hypotheses regarding T. cruzi.

【 授权许可】

CC BY   
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