title: Extensive genetic diversity, unique population structure and evidence of genetic exchange in the sexually transmitted parasite Trichomonas vaginalis.
abstract: BACKGROUND
  Trichomonas vaginalis is the causative agent of human trichomoniasis, the most common non-viral sexually transmitted infection world-wide. Despite its prevalence, little is known about the genetic diversity and population structure of this haploid parasite due to the lack of appropriate tools. The development of a panel of microsatellite makers and SNPs from mining the parasite's genome sequence has paved the way to a global analysis of the genetic structure of the pathogen and association with clinical phenotypes.
  
  
  RESULTS
  Here we utilize a panel of T. vaginalis-specific genetic markers to genotype 235 isolates from Mexico, Chile, India, Australia, Papua New Guinea, Italy, Africa and the United States, including 19 clinical isolates recently collected from 270 women attending New York City sexually transmitted disease clinics. Using population genetic analysis, we show that T. vaginalis is a genetically diverse parasite with a unique population structure consisting of two types present in equal proportions world-wide. Parasites belonging to the two types (type 1 and type 2) differ significantly in the rate at which they harbor the T. vaginalis virus, a dsRNA virus implicated in parasite pathogenesis, and in their sensitivity to the widely-used drug, metronidazole. We also uncover evidence of genetic exchange, indicating a sexual life-cycle of the parasite despite an absence of morphologically-distinct sexual stages.
  
  
  CONCLUSIONS
  Our study represents the first robust and comprehensive evaluation of global T. vaginalis genetic diversity and population structure. Our identification of a unique two-type structure, and the clinically relevant phenotypes associated with them, provides a new dimension for understanding T. vaginalis pathogenesis. In addition, our demonstration of the possibility of genetic exchange in the parasite has important implications for genetic research and control of the disease.
authors.affiliation: Department of Biology, Center for Genomics and Systems Biology, New York University, New York, New York, USA.
authors.forename: Melissa D
authors.initials: MD
authors.lastname: Conrad
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Gorman
authors.forename: Julia A
authors.initials: JA
authors.lastname: Schillinger
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Fiori
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.forename: Nancy
authors.initials: N
authors.lastname: Malla
authors.forename: Mohan Lal
authors.initials: ML
authors.lastname: Dubey
authors.forename: Jorge
authors.initials: J
authors.lastname: Gonzalez
authors.forename: Susan
authors.initials: S
authors.lastname: Blank
authors.forename: William E
authors.initials: WE
authors.lastname: Secor
authors.forename: Jane M
authors.initials: JM
authors.lastname: Carlton
mesh_terms: D000328:Adult; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D016000:Cluster Analysis; D004351:Drug Resistance; D005260:Female; D014644:Genetic Variation; D014943:Global Health; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012749:Sexually Transmitted Diseases / Q000469:parasitology*; D014245:Trichomonas Infections / Q000469:parasitology*; D014246:Trichomonas vaginalis / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000981:Antiprotozoal Agents; D008795:Metronidazole