Molecular typing of Trichomonas vaginalis isolates by actin gene sequence analysis and carriage of T. vaginalis viruses

Simon C Masha,Mario Vaneechoutte,Tania Crucitti,Eduard J Sanders,Piet Cools

doi:10.1186/s13071-017-2496-7

Abstract

BackgroundThe protozoan parasite Trichomonas vaginalis is the most common non-viral, sexually transmitted pathogen. Although T. vaginalis is highly prevalent among women in Kenya, there is lack of data regarding genetic diversity of isolates currently in circulation in Kenya.MethodsTyping was performed on 22 clinical isolates of T. vaginalis collected from women attending the antenatal care clinic at Kilifi County Hospital, Kenya, in 2015. Genotyping followed a previously proposed restriction fragment length polymorphism (RFLP) scheme, which involved in silico cleavage of the amplified actin gene by HindII, MseI and RsaI restriction enzymes. Phylogenetic analysis of all the sequences was performed to confirm the results obtained by RFLP-analysis and to assess the diversity within the RFLP genotypes. Additionally, we determined carriage of the four different types of Trichomonas vaginalis viruses (TVVs) by polymerase chain reaction.ResultsIn silico RFLP-analysis revealed five actin genotypes; 50.0% of the isolates were of actin genotype E, 27.3% of actin genotype N, 13.6% of actin genotype G and 4.5% of actin genotypes I and P. Phylogenetic analysis was in agreement with the RFLP-analysis, with the different actin genotypes clustering together. Prevalence of TVVs was 43.5% (95% confidence interval, CI: 23.2–65.5). TVV1 was the most prevalent, present in 39.1% of the strains and 90% of the T. vaginalis isolates which harbored TVVs had more than one type of TVV. None of the isolates of actin genotype E harbored any TVV.ConclusionThe presence of five actin genotypes in our study suggests notable diversity among T. vaginalis isolates occurring among pregnant women in Kilifi, Kenya. Isolates of the most prevalent actin genotype E lacked TVVs. We found no association between T. vaginalis genotype, carriage of TVVs and symptoms. Further studies with higher number of strains should be conducted in order to corroborate these results.

Highlights

The protozoan parasite Trichomonas vaginalis is the most common non-viral, sexually transmitted pathogen
We identified single actin genotypes in all T. vaginalis cultures, which is indicative for the presence of only 1 T. vaginalis strain per culture, we cannot rule out that the presence of the multiple Trichomonas vaginalis viruses (TVV) may be the result of a mixture of T. vaginalis strains, each infected with a different TVV
Our study was limited by the small number of isolates, which rendered it difficult to investigate the implication of TVV carriage on clinical signs and symptoms

Summary

Introduction

The protozoan parasite Trichomonas vaginalis is the most common non-viral, sexually transmitted pathogen. T. vaginalis is highly prevalent among women in Kenya, there is lack of data regarding genetic diversity of isolates currently in circulation in Kenya. Trichomonas vaginalis is a flagellated protozoan parasite that infects the human urogenital tract, causing the most common non-viral, sexually transmitted infectious disease worldwide [1]. In about half of the infected women, T. vaginalis causes a malodorous vaginal discharge, vulval irritation and. The global prevalence of T. vaginalis and the health sequelae associated with it have necessitated the need to understand its genetic make-up. Carriage of TVVs has been suggested to upregulate pro-inflammatory host responses [12] and T. vaginalis immunogenic protein P270 [13] and is associated with differential qualitative and quantitative expression of cysteine proteinases [14]. No method has been adapted as a standard clinical diagnostic test for TVVs [15]

Methods

Results

Discussion

Conclusion