[Physicochemical and immunochemical characteristics of the polysaccharides of Streptococcus pneumoniae serotype 3]

Capsular polysaccharides were isolated from Str. pneumoniae (serotype 3), grown on solid culture media, by the method of acetone sedimentation and subsequent deproteinization with phenol. The preparations thus obtained possessed serological type specificity, contained more than 40% of carbohydrates and insignificant amounts of protein and nucleic substances. The isolated polysaccharides contained a high-molecular fraction with the coefficient of distribution not exceeding 0.1, thus corresponding to the requirements for highly immunogenic preparations.