Toxoplasma Gondii Comprises Three Clonal Lineages: Correlation of Parasite Genotype With Human Disease

J Infect Dis. 1995 Dec;172(6):1561-6. doi: 10.1093/infdis/172.6.1561.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Genotype
  • Humans
  • Molecular Sequence Data
  • Phylogeny
  • Polymerase Chain Reaction
  • Polymorphism, Restriction Fragment Length
  • Toxoplasma / genetics*
  • Toxoplasmosis / etiology*