Toxoplasma gondii comprises three clonal lineages: Correlation of parasite genotype with human disease

Daniel K. Howe, L. David Sibley

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1091 Scopus citations


The population genetic structure of Toxoplasma gondii was determined by multilocus restriction fragment length polymorphism analysis at 6 loci in 106 independent isolates from humans and animals. Phylogenetic and statistical analyses indicated a highly unusual population structure consisting of 3 widespread clonal lineages. Extensively mixed genotypes were only apparent in 4 strains, which indicated that, while not separate species, sexual recombination between the 3 lineages is exceedingly rare in natural populations. T. gondii is a major cause of subclinical human infection and an important opportunistic pathogen that causes severe disease in immunocompromised patients. While strains from all 3 lineages were isolated from humans, the majority of human toxoplasmosis cases were associated with strains of a type II genotype. The correlation of specific clonal lineages with human toxoplasmosis has important implications for development of vaccines, drug treatments, and diagnostic protocols.

Original languageEnglish
Pages (from-to)1561-1566
Number of pages6
JournalJournal of Infectious Diseases
Issue number6
StatePublished - Dec 1995

Bibliographical note

Funding Information:
Grant support: American Foundation for AIDS Research (02058-15-RGR), National Institutes of Health (AI-36629, AI-07ln), and Burroughs Wellcome Fund.

ASJC Scopus subject areas

  • General Medicine


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