Chemical and Immunological Characterization of a Novel Amphipathic Antigen from Biotype B Streptococcus sanguis

A new type of amphipathic antigen was extracted from whole cells of Streptococcus sanguis ATCC 10557 (biotype B, serotype 11) by the phenol/water method. The extract was treated with nuclease P I, and was applied to a column of Sepharose 6B. Each fraction was checked by passive haemagglutination (PHA) and immunodiffusion tests against anti- 10557 serum which was obtained by immunizing rabbits with whole cells of strain ATCC 10557. Strong PHA activity was demonstrated in the first hexose-containing peak (peak 1) eluted near the void volume, while the second hexose-containing peak (peak 2) produced a heavy band against anti-10557 serum in an immunodiffusion test. The third peak (peak 3) which partially overlapped with peak 2 reacted with concanavalin A, but not with the antiserum, in agar gel. Peaks 2 and 3 had no PHA activity. Peak 1 contained only 1 % phosphorus, indicating that cells of strain ATCC 10557 possess an amphipathic antigen which differs from the lipoteichoic acids that are common in many Gram-positive bacteria. Peak 1 was a fatty acid-substituted heteropolysac-charide composed of glucose, galactose, mannose, glycerol and fatty acids in a molar ratio of approximately 1.0: 1-3: 2.7: 0-3: 1.0. PHA activity was inhibited in the presence of polymerized mannose. Peak 2 was composed of glucose, galactose, rhamnose and N-acetylgalactosamine in a molar ratio of approximately 1.0: 1-4: 0.8: 0.8, which was essentially identical to the serotype I1 carbohydrate antigen reported previously