Surface expression of TV44 on trichomonads decreases after contact with VECs. FITC-conjugated goat anti-IgA antibody bound to IgA mAb 6B8 on the surface of non permeabilized T. vaginalis organisms as evident by uniform fluorescence seen in panel B1. In contrast, parasites isolated after contact with MS-74 VECs and handled identically had little or no detectable fluorescence as seen in panel B2. Brightfield pictures show the integrity of parasites used for the assay. No fluorescence was detectable in the absence of the mAb 6B8 as negative controls (not shown).