Studies on vaccine control and immunogenicity of polysaccharides of Streptococcus pneumoniae.

An immunoelectrophoretic method was devised for quantitation of 14 polysaccharide components in the pneumococcal vaccine, and for determination of their stability in the final container. By this method the individual polysaccharide types, 1, 2, 3, 4, 6A, 8, 9N, 12F, 18C, 19F, 23F, and 25 (Danish nomenclature), were found to be present at 80%-123% of the manufacturer's listed concentrations. Pneumococcal polysaccharide types 3, 6A, 9N, and 19F, used as representative types, were heated at 37C for 24 hr and stored at 4 C. The concentrations of these polysaccharides remained constant over a 12-month period, and the molecular sizes of types 3 and 9N were stable during storage. In contrast, the molecular sizes of types 6A and 19F declined gradually during the 12-month storage period. Pneumococcal type 19F polysaccharide was conjugated to various proteins, i.e., bovine serum albumin, human immunoglobulin, and pneumococcal R61 cell wall protein, by the method of reductive amination. Immunization of mice with 19F polysaccharide-protein conjugates resulted in formation of more antibody than was found in the control group. Young mice exposed to pneumococcal type 19F polysaccharide-protein conjugate during gestation and suckling exhibited a greater antibody response than did mice that received no type 19F polysaccharide-protein conjugate while suckling or received the conjugate only when they were only two weeks of old.