title: 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.
authors: Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America. iyd4@cdc.gov
authors: Dawn M
authors: DM
authors: Roellig
authors: Mason Y
authors: MY
authors: Savage
authors: A Wendy
authors: AW
authors: Fujita
authors: Christian
authors: C
authors: Barnabé
authors: Michel
authors: M
authors: Tibayrenc
authors: Frank J
authors: FJ
authors: Steurer
authors: Michael J
authors: MJ
authors: Yabsley
mesh_terms: D000818:Animals; D001483:Base Sequence; D014355:Chagas Disease / Q000469:parasitology*; D003576:Electron Transport Complex IV / Q000235:genetics; D050259:Genes, Mitochondrial; D020459:Genes, rRNA; D014644:Genetic Variation; D006801:Humans; D006824:Hybridization, Genetic; D009097:Multienzyme Complexes / Q000235:genetics; D009245:NADH Dehydrogenase / Q000235:genetics; D010802:Phylogeny; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics; D013940:Thymidylate Synthase / Q000235:genetics; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification*; D014481:United States
chemical_list: D009097:Multienzyme Complexes; C056930:thymidylate synthase-dihydrofolate reductase; D013762:Tetrahydrofolate Dehydrogenase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D013940:Thymidylate Synthase