title: Rabbit antibodies to the cell wall polysaccharide of Streptococcus pneumoniae fail to protect mice from lethal challenge with encapsulated pneumococci.
abstract: A conjugate, composed of the cell wall polysaccharide (C polysaccharide) of Streptococcus pneumoniae and bovine serum albumin (BSA), was prepared with the bifunctional agent N-succinimidyl-3-(2-pyridyldithio)-propionate. Analysis with monoclonal antibodies provided evidence that the phosphocholine (PC) moiety of the C polysaccharide was retained during the conjugation procedure. The C polysaccharide-BSA conjugate elicited antibodies to C polysaccharide in rabbits; no PC-specific antibodies were detected in globulins prepared from these hyperimmune sera obtained early and late after a second immunization. Rabbit hyperimmune sera were taken after multiple intravenous injections of the pneumococcus strain SRC-2, which has a capsulelike structure composed of the C polysaccharide. Globulin prepared from these antisera had both C polysaccharide- and PC-specific antibodies. Antibodies to C polysaccharide elicited by the C polysaccharide-BSA conjugate failed to protect mice against intraperitoneal challenge with a strain of type 3 or type 6A pneumococci. The anti-SRC-2 globulin conferred protection against both of these pneumococcal strains. Absorption of the SRC-2 globulin with C polysaccharide, however, failed to change its protective activity. These data provide evidence that antibodies to the C polysaccharide do not confer immunity against infection of mice with encapsulated pneumococci inoculated by the intraperitoneal route.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000008:administration & dosage* / Q000276:immunology; D002473:Cell Wall / Q000276:immunology; D007110:Immunity, Active; D005779:Immunodiffusion; D051379:Mice; D011008:Pneumococcal Infections / Q000276:immunology* / Q000517:prevention & control; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000302:isolation & purification; D011817:Rabbits / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D011135:Polysaccharides, Bacterial