K. Kitada et al., IMMUNOCHEMICAL CHARACTERIZATION OF THE CARBOHYDRATE ANTIGENS OF SEROTYPE-C LANCEFIELD GROUP-C STREPTOCOCCUS-MILLERI, Oral microbiology and immunology, 8(3), 1993, pp. 161-166
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.