TvCP39 is a key molecule in the pathogenicity and the synergy with human papillomavirus infection of Trichomonas vaginalis.

Cysteine proteinase-39 from Trichomonas vaginalis (T. vaginalis, TvCP39) is an important pathogenic molecule involved in the parasite's virulence. Herein, TvCP39 was found in the cytoplasm, surface and flagella of trophozoites. Knocking down TvCP39 significantly reduced T. vaginalis viability, attachment to VK2/E6E7 cells, and its ability to inhibit cell proliferation and induce apoptosis. In contrast, the recombinant TvCP39 notably enhanced the attachment of T. vaginalis to host cells, promoted cell apoptosis, and inhibited cell proliferation. Mouse infection experiments demonstrated that Anti-rTvCP39 polyclonal antibody blockade or passive immunization effectively reduced T. vaginalis infection and vagina damage. TvCP39 knockdown also diminished T. vaginalis's promotion of human papillomavirus (HPV) infection. Immunofluorescence staining revealed that TvCP39 was able to bind to host cells, while a yeast two-hybrid assay identified 17 molecules that interact with TvCP39. Additional studies are required to clarify whether TvCP39 contributes to the pathogenesis of T. vaginalis and enhances HPV infection through interactions with these molecules. This study offers a more thorough investigation of TvCP39's role in T. vaginalis infection, providing not only a potential target for novel therapeutic strategies against T. vaginalis but also a foundation for further exploration of its pathogenic mechanisms.