Trichomoniasis, caused by Trichomonas vaginalis (T. vaginalis, TV), is the most common non-viral sexually transmitted infection (STI) among women worldwide. However, the correlation between TV genetic diversity and pathogenicity remains unclear. We sought to achieve simple and effective differentiation of the pathogenicity of TV clinical isolates based on nucleotide variations in key genes associated with parasite colonization. A comparison of genetic structure between China and various other countries was conducted. Haplotype diversity analysis identified that a total of 40 haplotypes (including a novel haplotype, Hap₄0) among 291 isolates. STRUCTURE software clustered all isolates into two populations, which was consistent with the result of principal component analysis (PCA) and phylogenetic tree. FST and AMOVA analyses revealed that genetic type, rather than geographic isolation, acts as the primary driver of population differentiation. The two genetic types showed extremely high differentiation and nearly complete genetic isolation within Chinese populations. Phenotypic experiments of representative isolates revealed that JZ16 (Type II) had significantly higher proliferation capacity, viability, and drug resistance than JZ19 (Type I). In contrast, JZ19 had a substantially greater adhesive capacity to the plate surface and higher cytotoxicity. Type II is the dominant genotype in China, and its low pathogenicity may facilitate its widespread dissemination and high prevalence. This finding suggests a potential correlation between genetic evolutionary typing and pathogenicity of T. vaginalis. Our results contribute to a deeper understanding of TV pathogenicity and may provide insights into the development of novel therapeutic strategies. • The existence of two population structures of T. vaginalis. • Type II predominates in China, and the two genetic types showed extremely high differentiation and nearly complete genetic isolation. • Genetic type is the primary driver of population differentiation, exceeding the effect of geographic isolation. • Significant differences were observed in the phenotypic experiments among the representative strains, which was consistent with the laws of genetic evolution.
Yang et al. (Thu,) studied this question.