IMMUNOCHEMICAL CHARACTERIZATION OF THE CARBOHYDRATE ANTIGENS OF SEROTYPE-C LANCEFIELD GROUP-C STREPTOCOCCUS-MILLERI

Carbohydrate antigens of the serotype c/Lancefield group C ''Streptoco ccus milleri'' were extracted by autoclaving whole cells of the type c reference strain K51Y. The type c and group C antigen molecules were separated and partially purified by a DEAE-Sephadex A-25 column chroma tography followed by Sephadex G-100 gel filtration. The purified type c antigen and group C antigen were homogeneous in the double diffusion and in the immunoelectrophoresis. The type c antigen was composed pri ncipally of glycerol, rhamnose, glucose and N-acetylglucosamine in a m olar ratio of 0.22:0.27:1.00:0.48. The quantitative precipitin inhibit ion test indicated that N-acetylglucosamine played a major role in imm unodeterminant structure. Thus, the type c antigen of ''S. milleri'' i s a new carbohydrate type antigen and is immunochemically different fr om the Ottens-type antigen III found occasionally in group C streptoco cci. In contrast, the group C antigen preparation contained a high pro portion of N-acetylgalactosamine in addition to glycerol, rhamnose, gl ucose and N-acetylglucosamine, and the N-acetylgalactosamine residue w as involved in the immunodominant epitope, being in good agreement wit h the previously proposed chemical structure of the group antigen. N-a cetylgalactosamine was detected in the autoclaved extracts of a nontyp eable/group C strain but not of a type c/ungroupable strain.