The protozoan parasite Trichomonas vaginalis is the causative agent of trichomoniasis, an extremely common, but non-life-threatening, sexually-transmitted disease throughout the world. Recent population genetics studies of T. vaginalis have detected high genetic diversity and revealed a two-type population structure, associated with phenotypic differences in sensitivity to metronidazole, the drug commonly used for treatment, and presence of T. vaginalis virus. There is currently a lack of data on UK isolates; most isolates examined to date are from the US. Here we used a recently described system for multilocus sequence typing (MLST) of T. vaginalis to study diversity of clinical isolates from Bristol, UK. We used MLST to characterise 23 clinical isolates of T. vaginalis collected from female patients during 2013. Seven housekeeping genes were PCR-amplified for each isolate and sequenced. The concatenated sequences were then compared with data from other MLST-characterised isolates available from http://tvaginalis.mlst.net/ to analyse the population structure and construct phylogenetic trees. Among the 23 isolates from the Bristol population of T. vaginalis, we found 23 polymorphic nucleotide sites, 25 different alleles and 19 sequence types (genotypes). Most isolates had a unique genotype, in agreement with the high levels of heterogeneity observed elsewhere in the world. A two-type population structure was evident from population genetic analysis and phylogenetic reconstruction split the isolates into two major clades. Tests for recombination in the Bristol population of T. vaginalis gave conflicting results, suggesting overall a clonal pattern of reproduction. We conclude that the Bristol population of T. vaginalis parasites conforms to the two-type population structure found in most other regions of the world. We found the MLST scheme to be an efficient genotyping method. The online MLST database provides a useful repository and resource that will prove invaluable in future studies linking the genetics of T. vaginalis with the clinical manifestation of trichomoniasis.
Bibliographical noteFunding Information:
We warmly thank Karen Gough and colleagues of the PHE Bristol Public Health Bacteriology Laboratory at Bristol Royal Infirmary for the parasite material used here. We are grateful to Mark Beaumont and Gary Barker, University of Bristol for advice on population genetics analysis, and Manal Natto, University of Glasgow, for kindly supplying the G3 isolate and advising on culture methods. The work was partly funded by University of Bristol . AW received a Wellcome Trust vacation scholarship and we are very grateful to Barry Vipond, PHE for his contribution to training. The funders had no role in study design, execution or preparation of the work for publication.
© 2015 Elsevier B.V.
- Multilocus genotyping
- Multilocus sequence typing
- Population genetics
- Population structure
- Sexually transmitted disease
- Sexually transmitted infection
- Trichomonas vaginalis