Abstract: | Complex antigenic preparations obtained from noncapsular pneumococcal strains were used for the immunization of rabbits and guinea pigs. The injection of the preparations in complete Freund's adjuvant for 5 weeks led to the appearance of antibodies in their sera. The antibodies were detected by the double immunodiffusion test. The preparations obtained from different strains by extraction (with Triton X-100 or sodium deoxycholate) or by disintegration contain common pneumococcal antigens. |