[Chemical analysis and immunochemical characterization of serotype-specific antigens from the strains of Actinobacillus actinomycetemcomitans which were frequently found in the periodontal pockets of the patients of localized juvenile periodontitis].

Serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving. The extracts were purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. The purified polysaccharide antigens formed a single precipitin band with the corresponding anti-a, b or c serum on immunodiffusion. Analysis of component sugars by GLC, HPLC, GLC-MS, NMR together with specific optical rotation data showed that the serotype a antigen consisted of 6-Deoxy-D-talose, the serotype b antigen consisted of L-rhamnose and D-fucose, and the serotype c antigen consisted of 6-Deoxy-L-talose. Structural analysis indicated that these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1- (serotype a), -3)-alpha-D-Fucp-(1-2)-beta-L-Rhap-(1- (serotype b) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1- (serotype c). 13C and 1H-NMR analyses suggested that the serotype a and c polysaccharides carried approximately one acetyl group per two sugar residues, although the acetylated position was not identified. In quantitative precipitin inhibition tests, the component sugars showed very low inhibition, whereas the partial hydrolysates of these antigens were effective inhibitors. These results suggest that the serotype-specific antisera recognize larger oligosaccharide units.