Protein Antigens of Genital Mycoplasmas

are relatively poorly defined. In this study, an unusual antigen complex of U urealyticum consisting of multiple bands forming a "ladder" pattern after electrophoretic separation was noted. It is similar to the variable V-l surface antigen of Mycoplasmapulmonis. Data on U urealyticum are only preliminary, but the ureaplasma antigen, if it proves to be analogous to V-I, may provide the antigenic determinants for distinguishing among serovars or serogroups and correlating them with pathogenicity. Surface proteins of M. hominis were identified with use of 125I surface labeling, [35S]methionine metabolic labeling, and immunoadsorption of rabbit antiserum. Comparison of M. hominis reference strains PG-21 and 4195 showed little homology between surface proteins, although with metabolic labeling they appeared essentially identical. Immunoblotting with patients' sera, using PG-21 as antigen, showed that most reactions were directed to surface proteins and that a 102K antigen (MH1) was recognized by 94%o of the sera. MH1 was one of the few surface proteins of PG-21 that appeared to have counterparts in the other six reference strains, making MH1 a prime candidate for reliable and specific detection of M. hominis infection.