Common antigens of streptococcal and nonstreptococcal oral bacteria: characterization of wall-associated protein and comparison with extracellular protein antigen.

A soluble wall-associated common protein (WAP) has been isolated from cell wall-extracted antigens of exponentially growing cells of Streptococcus sanguis OMZ9, two serotypes (a and e), of Streptococcus mutans and Actinomyces viscosus OMZ104. The WAP antigens from the different strains were obtained by chromatography on an anti-rabbit immunoglobulin column of sodium dodecyl sulfate-dissociated immunoprecipitates. The affinity-isolated WAP antigens from the different oral bacteria were identical, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (showing an apparent molecular weight of 80,000) and amino acid and sugar compositions. This WAP antigen, common to all bacterial strains tested, consisted of 90% protein and 10% sugar. A comparison of the chemical properties of this WAP antigen and of the soluble extracellular common protein antigen showed that, although having similar amino acid and sugar compositions, the two proteins are different. Electron micrographs developed after immunocytological labeling of the WAP antigen on whole cells confirmed that it is located on the cell wall.