Antigens of Streptococcus mutans. I. Characterization of a serotype-specific determinant from Streptococcus mutans

A membrane-associated glycerol teichoic acid antigen has been isolated from Streptococcus mutans AHT and a similar antigen has been demonstrated to be present in each of the other Bratthall serotype a organisms studied. Trichloroacetic acid-extracted material was resolved into two phosphorus-containing antigenic fractions (B and C) by agarose chromatography. Fraction B was preliminarily identified as a phospholipid moiety with a glycerol-to-phosphorus ratio of 2:1, and fraction C showed a ratio of 1:1 indicative of a glycerol teichoic acid. This latter fraction also was associated with glucose, galactose, alanine, and fatty acids. Diglycerol triphosphate, the compound characteristically released from 1-3 phosphodiester-linked glycerol teichoic acids by alkaline hydrolysis, was isolated and characterized. Alanine was identified as its alkaline-labile, ester-linked D-isomer. A glyceride was isolated containing a disaccharide of glucose and galactose attached to the 2-hydroxyl group of glycerol. Hapten inhibition analysis demonstrated that beta-galactosides were the greatest inhibitors of the precipitin reaction (>75%), whereas glucose and its derivatives inhibited to a much lesser extent (<30%). Comparative immunodiffusion and immuno-electrophoresis analyses demonstrated that all six Bratthall serotype a organisms tested contained this antigenic determinant and that it was absent in serotypes b, c, and d. It is suggested that the common antigenic determinant of this serotype within S. mutans may be a beta-galactoside associated with a glycerol teichoic acid and possibly other polymers.