title: Genotyping of Toxoplasma gondii strains from immunocompromised patients reveals high prevalence of type I strains.
abstract: Toxoplasma gondii is an important food- and waterborne opportunistic pathogen that causes severe disease in immunocompromised patients. T. gondii has an unusual clonal population structure consisting of three widespread lineages known as I, II, and III. To establish the genotypes of strains of T. gondii associated with human toxoplasmosis, we have developed a set of four highly sensitive and polymorphic nested PCR markers. Multiplex nested PCR analysis was used to genotype parasites in cerebral spinal fluid samples from 8 of 10 human immunodeficiency virus-positive patients. Remarkably, a majority of these patients had infections with type I strains or strains containing type I alleles, despite the fact that this lineage is normally uncommon in humans and animals. Multiplex analysis of these four unlinked makers was able to distinguish all three common genotypes and also detected two strains with mixed genotypes. Further analysis based on sequencing of a polymorphic intron revealed that one of these recombinant strains was an exotic lineage distinct from the archetypal clonal lineages. The multiplex nested PCR analysis described here will be useful for analyzing the contribution of parasite genotype to toxoplasmosis.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: A
authors.initials: A
authors.lastname: Khan
authors.forename: C
authors.initials: C
authors.lastname: Su
authors.forename: M
authors.initials: M
authors.lastname: German
authors.forename: G A
authors.initials: GA
authors.lastname: Storch
authors.forename: D B
authors.initials: DB
authors.lastname: Clifford
authors.forename: L David
authors.initials: LD
authors.lastname: Sibley
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology; D000818:Animals; D001483:Base Sequence; D002555:Cerebrospinal Fluid / Q000469:parasitology; D005838:Genotype; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D016867:Immunocompromised Host; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D015800:Protozoan Proteins / Q000235:genetics; D014122:Toxoplasma / Q000145:classification* / Q000235:genetics; D014123:Toxoplasmosis / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology
chemical_list: D015800:Protozoan Proteins