Abstract: Objective To prepare and characterize the monoclonal antibodies （McAbs） against recombinant adhesion protein 33 （AP33） of Trichomonas vaginalis. Methods The purified recombinant fusion protein AP33 was used as antigen to immunize BALB/c mice. Sp2/0 myeloma cells were fused with the splenocytes from immunized BALB/c mice. After ELISA screening and 4 times of limited dilution， 5 positive hybridoma cell lines were obtained， and the biological properties of the McAbs were identified by Western blotting. Indirect immunofluorescent antibody test （IFAT） was performed and the inhibition effect of McAbs on the cytoadherence of T.richomonas vaginalis to HeLa cell was assayed. Results Western blotting demonstrated that 5 McAbs， designated as 4A2， 4F11， 4F8， 4E7 and 4H11， specifically combined with the recombinant AP33 of T.vaginalis. The McAbs were IgG1 isotypes. Four of them （4F11， 4F8， 4E7 and 4H11） showed parasite recognition by IFAT. Parasite cytoadherence to a monolayer of HeLa cells was inhibited in vitro with a inhibition rate of 50.08%， 65.03%， 50.70% and 49.08% by the 4 McAbs under a concentration of 200， 200， 400 and 200 μg/ml， respectively. Conclusions The prepared McAbs against the recombinant AP33 show a protective inhibition on cytoadherence of Trichomonas vaginalis in vitro.

Key words: Trichomonas vaginalis, AP33, Monoclonal antibody