No abstract

The serotype-specific antigen of Streptococcus sanguis ST3 (serotype I, biotype A) was extracted, chromatographically purified, and characterized by immunological and chemical methods. The antigen was extracted from purified cell walls with hot trichloroacetic acid, followed by ion-exchange chromatography on a DEAE-Sephadex A-25 column and gel filtration through a Sephadex G-100 column. A peak fraction was obtained that gave a single precipitin band when reacted with anti-type I serum. The type I antigen was a polysaccharide composed of glucose, rhamnose, and N-acetylglucosamine in a molar ratio of 1.4:2.5:1.0. Quantitative precipitin inhibition tests with various haptenic sugars indicated that an alpha-glucosidic linkage is the immunodeterminant of the type I antigen.

Summary. Certain strains of Streptococcus sanguis and group-H streptococci have been shown to have similar physiological properties and serological specificities. Serological studies revealed that serotype-I11 S. sanguis shared a common antigen with the so-called "British" group-H streptococci, but not with the "American" group-H streptococci. Serotype-I11 antigen was extracted in cold 5% trichloroacetic acid from isolated cell walls of S. sanguis ATCC 10558, and purified chromatographically. The purified serotype-I11 antigen consisted of neutral and amino sugars and some phosphorus, and was negatively charged. Hapten inhibition of the quantitative precipitin reaction between serotype-I11 antigen and antiserum indicated the strong possibility of a-glucosidic linkages being an immunodeterminant of the antigen.