Genetic Variation and Exchange in Trypanosoma cruzi Isolates from the United States

Abstract

Trypanosoma cruzi, the causative agent of Chagas disease, is a multiclonal parasite with high levels of genetic diversity and broad host and geographic ranges. Molecular characterization of South American isolates of T. cruzi has demonstrated homologous recombination and nuclear hybridization, as well as the presence of 6 main genetic clusters or “discrete typing units” (DTUs). Few studies have extensively investigated such exchange events and genetic diversity in North American isolates. In the current study, we genetically characterized over 50 US isolates from wildlife reservoirs (e.g., raccoons, opossums, armadillos, skunks), domestic dogs, humans, nonhuman primates, and reduviid vectors from nine states (TX, CA, OK, SC, FL, GA, MD, LA, TN) using a multilocus sequencing method. Single nucleotide polymorphisms were identified in sequences of the mismatch-repair class 2 (MSH2) and Tc52 genes. Typing based on the two genes often paralleled genotyping by classic methodologies using mini-exon and 18S and 24Sα rRNA genes. Evidence for genetic exchange was obtained by comparing sequence phylogenies of nuclear and mitochondrial gene targets, dihydrofolate reductase-thymidylate synthase (DHFR-TS) and the cytochrome oxidase subunit II- NADH dehydrogenase subunit I region (COII-ND1), respectively. We observed genetic exchange in several US isolates as demonstrated by incongruent mitochondrial and nuclear genes phylogenies, which confirms a previous finding of a single genetic exchange event in a Florida isolate. The presence of SNPs and evidence of genetic exchange illustrates that strains from the US are genetically diverse, even though only two phylogenetic lineages have been identified in this region.

Landscape ecology of Trypanosoma cruzi in the southern Yucatan Peninsula

“…Previous studies have reported detection of mixed TcI and TcVI in human samples in Rio (Sangenis et al, 2015) and in dogs and bugs in northwestern Argentina and the Atlantic forest of Brazil (Marcet et al, 2006;Lima et al, 2014a). Other DTU mixes of TcI and TcIV have been identified in the Brazilian Amazon (Lima et al, 2014b), the United States (Roellig et al, 2013), andin Venezuela (Carrasco et al, 2012); TcI and TcII or TcV have also been reported in mixed infections in Amazonia (Lima et al, 2012). These few studies suggest, however, only minor structuring of T. cruzi on broad geographic scales.…”

Comparison of the Bacterial Gut Microbiome of North American Triatoma spp. With and Without Trypanosoma cruzi

“…T. cruzi infection prevalence in triatomines collected in Texas is greater than 50% in some Triatoma spp. (Kjos et al, 2008;Curtis-Robles et al, 2018a), with discrete typing units (DTU) TcI and TcIV most commonly represented (Roellig et al, 2013;Brenière et al, 2016;Curtis-Robles et al, 2018a). Although triatomines found in the United States are generally considered sylvatic, these vectors are regularly encountered in and around human dwellings (Kjos et al, 2008;Wozniak et al, 2015;Curtis-Robles et al, 2018b).…”

Ecological host fitting of Trypanosoma cruzi TcI in Bolivia: mosaic population structure, hybridization and a role for humans in Andean parasite dispersal

“…The majority of field evidence indicates T. cruzi does not conform to strict clonality or panmixia and that recombination is common, nonobligatory and idiosyncratic, potentially involving independent exchange of kinetoplastid and nuclear genetic material and both canonical meiotic and parasexual mechanisms (Carrasco et al 1996;Machado & Ayala 2001;Ocaña-Mayorga et al 2010;Lewis et al 2011;Messenger et al 2012;Ram ırez et al 2012;Roellig et al 2013;Baptista Rde et al 2014). The relative contributions of alternate mating strategies to T. cruzi population structures are as yet unclear and strongly debated (Tibayrenc & Ayala 2012Ram ırez & Llewellyn 2014).…”