Chemical Composition of Streptococcus mutans Type c Antigen: Comparison to Type a, b, and d Antigens

Abstract

Studies of the serotype a, b, and d antigens of S mutans were extended to include the serotype c antigen. Type c antigen was extracted from cells of strain Ingbritt and purified by repeated column chromatography. Two type c antigens fractions were separated by chromatography on DEAE-Sephadex and were designated I and II. On agar gel diffusion, the major components of antigens I and II were serologically identical with the major component of the crude Ingbritt extract. Rhamnose and glucose were present in a 2.4:1 ratio and comprised 98 and 93% of the purified antigens, respectively. The compositions of the c antigens were directly related to the carbohydrate content of the serotype c cell wall. In contrast, purified a, b-II, and d antigens, which are also cell wall polysaccharides contain only trace amounts of rhamnose, a major wall carbohydrate. Studies which used comparative immunoelectrophoresis demonstrated that the purified a, b-I, and d antigens were serologically identical to the antigen preparations that have been used for the immunological classification of these serotypes.