Protein antigens of Streptococcus mutans: purification and properties of a double antigen and its protease-resistant component

Abstract

A surface protein antigen [Ag] of S. mutans having 2 sets of antigenic determinants (Ag I and II) was purified by column chromatography from culture supernatants of S. mutans serotype c. The protease-resistant component, Ag II, was purified from pronase-digested antigen I/II. The Ag were analyzed chemically and immunologically and their physicochemical properties were investigated. Ag I/II consisted of more than 80% protein and its peptide chain MW was estimated to be about 185,000. Ag II consisted of approximately 60% protein, with a peptide chain MW of 48,000. Antisera of Ag I/II and II were raised in rabbits and used to investigate the presence of the Ag in cells of other streptococci. Serotypes c, e and f apparently possessed Ag I and II determinants, whereas serotypes a, d and g possessed a determinant related to Ag I but none related to Ag II. [This may be important in the development of a vaccine against dental caries].