Journal Article

Globally diverse Toxoplasma gondii isolates comprise six major clades originating from a small number of distinct ancestral lineages

Dubey, Jitender P., Su, Chunlei, Khan, Asis, Majumdar, Debashree, Ajzenberg, Daniel, Rosenthal, Benjamin M., Zhu, Xing-Quan, Ajioka, James W., Sibley, L. David, Zhou, Peng, Dardé, Marie-Laure

2012

Overview

Marked phenotypic variation characterizes isolates of Toxoplasma gondii, a ubiquitous zoonotic parasite that serves as an important experimental model for studying apicomplexan parasites. Progress in identifying the heritable basis for clinically and epidemiologically significant differences requires a robust system for describing and interpreting evolutionary subdivisions in this prevalent pathogen. To develop such a system, we have examined more than 950 isolates collected from around the world and genotyped them using three independent sets of polymorphic DNA markers, sampling 30 loci distributed across all nuclear chromosomes as well as the plastid genome. Our studies reveal a biphasic pattern consisting of regions in the Northern Hemisphere where a few, highly clonal and abundant lineages predominate; elsewhere, and especially in portions of South America are characterized by a diverse assemblage of less common genotypes that show greater evidence of recombination. Clustering methods were used to organize the marked genetic diversity of 138 unique genotypes into 15 haplogroups that collectively define six major clades. Analysis of gene flow indicates that a small number of ancestral lineages gave rise to the existing diversity through a process of limited admixture. Identification of reference strains for these major groups should facilitate future studies on comparative genomics and identification of genes that control important biological phenotypes including pathogenesis and transmission.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Base Sequence / Biological Sciences / Chromosomes / Datasets / Evolution / Gene flow / genes / Genetic diversity / Genetic Loci / Genetic Loci - genetics / Genetic Markers / genetic recombination / Genetic Variation / Genetics, Population / Genomics / genotype / Genotype & phenotype / Genotypes / Geography / Haplotypes / Haplotypes - genetics / Human genetics / Introns / Introns - genetics / Life Sciences / loci / Medical genetics / Microsatellite Repeats / Microsatellite Repeats - genetics / Molecular Sequence Data / Parasites / Parasitism / Pathogens / phenotype / phenotypic variation / Phenotypic variations / Phylogeny / plastid DNA / Plastids / Polymorphism, Restriction Fragment Length / Population Dynamics / Population structure / Recombination / Sampling / Santé publique et épidémiologie / South America / Toxoplasma / Toxoplasma - classification / Toxoplasma - genetics / Toxoplasma - isolation & purification / Toxoplasma gondii