title: Evidence for multiple hybrid groups in Trypanosoma cruzi.
abstract: A role for parasite genetic variability in the spectrum of Chagas disease is emerging but not yet evident, in part due to an incomplete understanding of the population structure of Trypanosoma cruzi. To investigate further the observed genotypic variation at the sequence and chromosomal levels in strains of standard and field-isolated T. cruzi we have undertaken a comparative analysis of 10 regions of the genome from two isolates representing T. cruzi I (Dm28c and Silvio X10) and two from T. cruzi II (CL Brener and Esmeraldo). Amplified regions contained intergenic (non-coding) sequences from tandemly repeated genes. Multiple nucleotide polymorphisms correlated with the T. cruzi I/T. cruzi II classification. Two intergenic regions had useful polymorphisms for the design of classification probes to test on genomic DNA from other known isolates. Two adjacent nucleotide polymorphisms in HSP 60 correlated with the T. cruzi I and T. cruzi II distinction. 1F8 nucleotide polymorphisms revealed multiple subdivisions of T. cruzi II: subgroups IIa and IIc displayed the T. cruzi I pattern; subgroups IId and IIe possessed both the I and II patterns. Furthermore, isolates from subgroups IId and IIe contained the 1F8 polymorphic markers on different chromosome bands supporting a genetic exchange event that resulted in chromosomes V and IX of T. cruzi strain CL Brener. Based on these analyses, T. cruzi I and subgroup IIb appear to be pure lines, while subgroups IIa/IIc and IId/IIe are hybrid lines. These data demonstrate for the first time that IIa/IIc are hybrid, consistent with the hypothesis that genetic recombination has occurred more than once within the T. cruzi lines.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California at Los Angeles, 609 Charles E. Young Drive East, Los Angeles, CA 90095-1489, USA.
authors.forename: Nancy R
authors.initials: NR
authors.lastname: Sturm
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Vargas
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Westenberger
authors.forename: Bianca
authors.initials: B
authors.lastname: Zingales
authors.forename: David A
authors.initials: DA
authors.lastname: Campbell
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern / Q000379:methods; D014355:Chagas Disease / Q000469:parasitology*; D002874:Chromosome Mapping; D018503:Genome, Protozoan; D006824:Hybridization, Genetic; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D014349:Trypanosoma cruzi / Q000235:genetics*
chemical_list: D015800:Protozoan Proteins