Serotype 8- and serocluster-specific surface-expressed antigens of Ureaplasma urealyticum

The polypeptides of all 14 serotypes of Ureaplasma urealyticum were analyzed by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. The electrophoretic patterns did not allow ready discrimination of individual serotypes or seroclusters. The analysis of the antigens of serotype 8 was reported previously (B. L. Precious, D. Thirkell, and W. C. Russell, J. Gen. Microbiol. 133:2659-2676, 1987). In this study, three of the surface-expressed membrane antigens of 16, 17, and 96 kilodaltons were further investigated, and monoclonal antibodies were raised against these three polypeptides. The major 96-kilodalton polypeptide was serotype 8 specific, and the 16-kilodalton polypeptide was present only in the larger serocluster. We describe monoclonal antibody probes that unequivocally differentiate serotype 8 from the other serotypes and that separate the two seroclusters of the organism.