CP30, a cysteine proteinase involved in Trichomonas vaginalis cytoadherence

We describe here the participation of a Trichomonas vaginalis 30-kDa protei nase (CP30) with affinity to the HeLa cell surface in attachment of this pa rasite to host epithelial cells. The CP30 band is a cysteine proteinase bec ause its activity was inhibited by E-64, a thiol proteinase inhibitor. In t wo-dimensional substrate gel electrophoresis of total extracts of the trich omonad isolate CNCD 147, three spots with proteolytic activity were detecte d in the 30-kDa region, in the pI range from 4.5 to 5.5. Two Of the spots ( pI 4.5 and 5.0) bound to the surfaces of fixed HeLa cells corresponding to the CP30 band. The immunoglobulin G fraction of the rabbit anti-CP30 antise rum that recognized a 30-kDa band by Western blotting and immunoprecipitate d CP30 specifically inhibited trichomonal cytoadherence to HeLa cell monola yers in a concentration-dependent manner and reacted with CP30 at the paras ite surface. CP30 degraded proteins found on the female urogenital tract, i ncluding fibronectin, collagen IV and hemoglobin. Interestingly, CP30 diges ted fibronectin and collagen IV only at pH levels between 4.5 and 5.0. More over, trichomonosis patients whose diagnosis was confirmed by in vitro cult ure possessed antibody to CP30 in both sera and vaginal washes, and CP30 ac tivity was found in vaginal washes. Our results suggest that surface CP30 i s a cysteine proteinase necessary for trichomonal adherence to human epithe lial cells.