Reversible association of tetraspanin with Trichomonas vaginalis flagella upon adherence to host cells

The parasite Trichomonas vaginalis is the causative agent of trichomoniasis, a prevalent sexually transmitted infection. Here, we report the cellular analyses of T.?vaginalis tetraspanin 6 (TvTSP6). This family of membrane proteins has been implicated in cell adhesion, migration and proliferation in vertebrates. We observed that TvTSP6 expression is upregulated upon contact with vaginal ectocervical cells (VECs) and that parasite strains that are highly adherent to VECs express higher levels of TvTSP6 mRNA relative to poorly adherent strains. TvTSP6 is localized predominantly on the flagella of parasites cultured in the absence of host cells; however, adherence of the parasite to VECs initially results in a redistribution of the protein to intracellular vesicles and the plasma membrane of the main body of the cell. We found that a 16-amino-acid C-terminal intracellular tail of TvTSP6 is necessary and sufficient for flagellar localization and protein redistribution when the parasite is in contact with VECs. Additionally, deletion of the C-terminal tail reduced parasite migration through Matrigel, a mimic of the extracellular matrix. Together, our data support roles for TvTSP6 in parasite migration in the host and sensory reception during infection.