Isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with acrylamide copolymerized with gelatin (substrate-SDS-PAGE) were combined to evaluate the proteinases of both long-term-grown and fresh isolates of Trichomonas vaginalis. This two-dimensional substrate-SDS-PAGE resolved as many as 23 distinct proteinase activities in several isolates, and proteinases had relative molecular masses between 23 and 110 kilodaltons (kDa). Isoelectric points (pl) of proteinases ranged from 5.7 to 7.0. Overall, the various representative proteinase profiles were similar among those of long-term-grown and fresh isolates, although heterogeneity existed among several cysteine proteinase activities. Pattern changes were detected in fresh isolates passaged over several weeks, showing the ability of proteinases to be differentially * Corresponding author.

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Solubilization of live Trichomonas vaginalis organisms with detergent caused the release of cysteine proteinases in the detergent extract which were inhibitable with N-a-p-tosyl-L-lysine chloromethyl ketone. The detergent extracts of all isolates tested possessed similar cysteine proteinase activities. These parasite proteinases rapidly degraded a prominent immunogen whose surface disposition undergoes phenotypic variation in some isolates. The relatedness of the forms of this immunogen among all isolates tested was confirmed by identical immunoblot patterns of autolysed immunogen, and data suggest the presence of repeating units or at least equidistant sites for proteinase cleavage within the immunogen molecule.

(Infect Immun 1987;55:1037). Finally, the MAb or VW Ab was never cytolytic for immunoreactive (fluorescent) parasites, even in the presence of complement. This study identifies the most important trichomonad surface immunogen on the basis of the vaginal Ab response, and data underscore the significance ofimmune evasion strategies of this sexually transmitted disease agent.