title: Opsonic specificity of human antibody to the type III polysaccharide of group B Streptococcus.
abstract: The functional significance of vaccine-induced or naturally acquired antibody to the capsular polysaccharide of type III group B Streptococcus was determined in human sera by means of an opsonophagocytic assay. Sera containing a sufficient concentration of type-specific antibody and endogenous serum complement caused a significant reduction (greater than 1 log10) in colony-forming units for each of 22 type III clinical isolates after incubation for 40 min. In contrast, serum with a very low concentration of antibody (0.4 micrograms/ml) killed only one isolate. Absorption of serum containing vaccine-induced antibody with purified native type III polysaccharide decreased opsonophagocytosis by a mean of 1.2 log10 for 11 selected type III strains. These results indicate a lack of major antigenic differences among a wide spectrum of type III strains, since bactericidal activity of human serum is uniformly observed in the presence of complement and sufficient concentrations of antibody to the type III polysaccharide.
mesh_terms: D000042:Absorption; D000918:Antibody Specificity; D001428:Bacterial Vaccines / Q000276:immunology; D001770:Blood Bactericidal Activity; D006801:Humans; D009504:Neutrophils / Q000378:metabolism; D009895:Opsonin Proteins / Q000276:immunology*; D010101:Oxygen Consumption; D010587:Phagocytosis; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013292:Streptococcus agalactiae / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines; D009895:Opsonin Proteins; D011135:Polysaccharides, Bacterial