IDENTIFICATION AND CHARACTERIZATION OF A MYCOPLASMA-SYNOVIAE 55,000-MOLECULAR-WEIGHT ANTIGEN ASSOCIATED WITH HEMAGGLUTINATION

Serological studies have shown that some antigenic determinants are co nserved among several pathogenic Mycoplasma species, including Mycopla sma pneumoniae, M. genitalium, and M. gallisepticum. M. synoviae, an a vian pathogen that shares certain morphological and biological feature s with the above-mentioned mycoplasmas, was examined by the protein im munoblot procedure for its reactivity with hyperimmune rabbit antiseru m specific for the major (190,000 molecular-weight [MW]) adhesion Pl p rotein of M. pneumoniae. A single polypeptide of M. synoviae of approx imately 55,000 MW was recognized by the anti-P1 antiserum. The 55,000- MW antigen was electroeluted following electrophoretic separation of M . synoviae polypeptides, and the eluted protein was used for immunizat ion of mice for the production of monoclonal antibodies (MAbs) and pol yclonal antiserum. Immunoelectron microscopy with MAbs and gold-conjug ated secondary antibodies showed that the 55,000-MW antigen was locate d at the cell surface and was more densely clustered around the bleb-l ike protuberance of the cell. Immuno-affinity-purified 55,000-MW antig en, as well as the antibodies produced against it, blocked the hemaggl utination by M. synoviae.