Extraordinary Trypanosoma cruzi diversity within single mammalian reservoir hosts implies a mechanism of diversifying selection

Abstract

Graphical abstract

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Research highlights

► We report extraordinary genetic diversity within single reservoir hosts of Trypanosoma cruzi. ► Two hundred and thirty-three biological clones were taken from eight mammals. ► Nine polymorphic microsatellite markers were amplified. ► Forty-nine distinct multilocus genotypes were defined. ► Widespread multiclonality contrasts with the precarious nature of T. cruzi vectorial transmission. ► We propose that non-neutral processes could account for the diversity observed.

Abstract

Trypanosoma cruzi is an evolutionarily ancient parasitic protozoan endemic to the Americas. Multiple genetic and phenotypic markers indicate that this parasite is highly diverse, with several divergent and discrete major genotypes reported. Infection multiclonality has been observed among numerous metazoan and unicellular endoparasitic species. However, few studies report the complexity of mixed infections within an individual host in any detail or consider their ecological and biological implications. Here we report extraordinary genetic diversity within single reservoir hosts of T. cruzi I using nine polymorphic microsatellite markers across 211 clones from eight mammals from three different sylvatic foci in South America. Forty-nine distinct multilocus genotypes were defined, with as many as 10 isolated from the same host. We discuss our data in the light of previous population genetic studies of this and related parasitic protozoa and contrast high levels of diversity within each host with the precarious nature of T. cruzi contaminative vectorial transmission. Finally, we propose that non-neutral processes could easily account for the diversity we observe and suggest a functional link with survival in the host.