Identification of a surface antigen of Trichomonas vaginalis.

A major surface antigen of Trichomonas vaginalis was purified by using three independently derived monoclonal antibodies (two immunoglobulin M and one immunoglobulin G1) prepared against T. vaginalis PHS-2J. A 115,000-molecular-weight antigen and one or more components with a molecular weight of 58,000 to 64,000 were recovered when any of the three antibodies was used as an immunoadsorbent. The purified antigen reacted with all three monoclonal antibodies in an enzyme-linked immunosorbent assay, indicating that the antibodies recognized the same antigen but not necessarily the same determinant. The purified antigen was sensitive to both pronase digestion and periodate oxidation. The antigen was shown to be on the external surface of some but not all T. vaginalis isolates by agglutination of live organisms with the monoclonal antibodies.