Antigens of Streptococcus mutans I. Characterization of a Serotype-Specific Determinant from Streptococcus mutans

Abstract

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 β-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 β-galactoside associated with a glycerol teichoic acid and possibly other polymers.