[Protective activity of antigenic preparations isolated by different methods from Streptococcus pneumoniae serotype...

The specific protective activity of antigenic preparations isolated from Str. pneumoniae culture by sedimentation with 96% ethanol or acetone was demonstrated in experiments with the active immunization of mice and their subsequent challenge with a virulent culture. The protective activity of antigenic preparations, expressed in micrograms, was shown to be directly related to the protein content of these preparations and inversely related to their carbohydrate content. The deproteinization of antigenic complexes isolated from Str. pneumoniae grown both in solid and in liquid culture media was accompanied by an increase in their immunogenicity.