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Comparative Study
. 2005 Oct;171(2):527-43.
doi: 10.1534/genetics.104.038745. Epub 2005 Jul 5.

Two hybridization events define the population structure of Trypanosoma cruzi

Affiliations
Comparative Study

Two hybridization events define the population structure of Trypanosoma cruzi

Scott J Westenberger et al. Genetics. 2005 Oct.

Abstract

Genetic variation in Trypanosoma cruzi is likely a key determinant in transmission and pathogenesis of Chagas disease. We have examined nine loci as markers for the extant T. cruzi strains. Four distinct alleles were found for each locus, corresponding to the sequence classes present in the homozygous discrete typing units (DTUs) I, IIa, IIb, and IIc. The alleles in DTUs IIa and IIc showed a spectrum of polymorphism ranging from DTU I-like to DTU IIb-like, in addition to DTU-specific sequence variation. DTUs IId and IIe were indistinguishable, showing DTU homozygosity at one locus and heterozygosity with DTU IIb and IIc allelic sequences at eight loci. Recombination between the DTU IIb and IIc alleles is evidenced from mosaic polymorphisms. These data imply that two discrete hybridization events resulted in the formation of the current DTUs. We propose a model in which a fusion between ancestral DTU I and IIb strains gave rise to a heterozygous hybrid that homogenized its genome to become the homozygous progenitor of DTUs IIa and IIc. The second hybridization between DTU IIb and IIc strains that generated DTUs IId and IIe resulted in extensive heterozygosity with subsequent recombination of parental genotypes.

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Figures

Figure 1.
Figure 1.
Loci in T. cruzi where DTU IIa/IIc alleles are more similar to DTU I. (A) Unrooted neighbor-joining trees of the HSP70 and histone H2B intergenic- and MSH2 partial coding-region sequences reveal four DNA sequence classes. **, CL Brener sequences from TIGR. Additional MSH2 sequences were taken from Gaunt et al. (2003). (B) Agarose gel electrophoresis of HSP70, GPI, and MSH2 PCR-RFLP products. The DNA was stained with ethidium bromide. Size markers (M) are either the BRL 1-kb ladder or the 25-bp ladder. (♦) 1-kb bands, (•) 0.5-kb bands, (○しろまる) 0.1-kb bands. The SNPs that create the AclI restriction site polymorphism in the HSP70 IIb allele are positions 362 and 363; a SNP at position 173 creates the HhaI polymorphism in the GPI locus; and a SNP at position 2294 creates the NlaIII polymorphism in the MSH2 locus (Table 2).
Figure 2.
Figure 2.
Loci in T. cruzi where the similarity of DTU IIa/IIc alleles are split between DTU I and DTU IIb. (A) Unrooted neighbor-joining trees of histone H1 and histone H3 intergenic sequences reveal four DNA sequence classes. *, the sequence of the uncut allele sequence of IIa strains; **, the CL Brener sequences from TIGR. (B) Agarose gel electrophoresis of PCR-RFLP products from the histone H1 and histone H3 loci of 25 strains. The DNA was stained with ethidium bromide. Size markers (M) are either the BRL 1-kb ladder or the 25-bp ladder. • and ○しろまる represent 0.5- and 0.1-kb bands, respectively. SNPs at positions 116 and 118 create the AatII polymorphism in the H1 locus, and a SNP at position 216 creates the AluI polymorphism in the histone H3 locus (Table 2).
Figure 3.
Figure 3.
Loci in T. cruzi where DTU IIa/IIc alleles are more similar to DTU IIb. (A) Unrooted neighbor-joining trees of HSP60 and 1F8 intergenic sequences reveal four DNA sequence classes. Superscript b or c represent DTU IIb or DTU IIc sequence types, respectively. **, sequence from CL Brener genomic read TCKCA96TR. (B) Agarose gel electrophoresis of PCR-RFLP products from the HSP60 locus of 25 strains. The DNA was stained with ethidium bromide. Size markers (M) are the BRL 1-kb ladders. • and ○しろまる represent 0.5-kb and 0.1-kb bands, respectively. A SNP at position 125 creates the EcoRV polymorphism in the HSP60 locus (Table 2).
Figure 4.
Figure 4.
Mosaicism of DTU IIb and IIc alleles within a multicopy locus for heterozygous DTU IId and IIe strains. Neighbor-joining phylogenetic tree of histone H2A intergenic sequences reveals five sequence classes. Mosaic IIb/IIc sequences from CL Brener and Tula strains form their own class.
Figure 5.
Figure 5.
A schematic of the evolution of T. cruzi groups. Boxes represent extant groups and their ancestral progenitors. The lines connecting boxes represent periods of clonal reproduction. Arrows represent contributions of various DTUs to form new hybrid strains. From a common ancestral universal genotype, two different genotypes arose that are represented today as DTUs I and IIb. Strains from these DTUs subsequently hybridized to produce DTUs IIa and IIc. A second hybridization between strains from DTUs IIb and IIc produced DTUs IId and IIe.

References

    1. Anonymous, 1999. Recommendations from a satellite meeting. Mem. Inst. Oswaldo Cruz 94 (Suppl. 1): 429–432. - PubMed
    1. Åslund, L., L. Carlsson, J. Henriksson, M. Rydåker, G. C. Toro et al., 1994. A gene family encoding heterogenous histone H1 proteins in Trypanosoma cruzi. Mol. Biochem. Parasitol. 65: 317–330. - PubMed
    1. Augusto-Pinto, L., S. M. R. Teixeira, S. D. J. Pena and C. R. Machado, 2003. Single-nucleotide polymorphisms of the Trypanosoma cruzi MSH2 gene support the existence of three phylogenetic lineages presenting differences in mismatch-repair efficiency. Genetics 164: 117–126. - PMC - PubMed
    1. Barnabé, C., S. Brisse and M. Tibayrenc, 2000. Population structure and genetic typing of Trypanosoma cruzi, the agent of Chagas disease: a multilocus enzyme electrophoresis approach. Parasitology 120: 513–526. - PubMed
    1. Barnabé, C., K. Neibauer, A. Solari and M. Tibayrenc, 2001. a Trypanosoma cruzi: presence of the two major phylogenetic lineages and of several lesser discrete typing units (DTUs) in Chile and Paraguay. Acta Tropica 78: 127–137. - PubMed

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