title: An enzyme-linked immunosorbent assay (ELISA) for human IgG antibody to the type Ia polysaccharide of group B streptococcus.
abstract: An ELISA was developed to measure human IgG antibody to the native polysaccharide antigen of GBS serotype Ia. Because the polysaccharide binds poorly to polyvinyl chloride, its adherence was enhanced by activation with cyanogen bromide and coupling to HSA in a molar ratio of polysaccharide to albumin of 1:4.5. There was minimal loss of sialic acid during coupling, and the coupled antigen showed identity with uncoupled native antigen by Ouchterlony analysis. OD values obtained by ELISA showed a log-linear relation to concentration of specific antibody in whole and affinity-chromatographed human sera measured by quantitative precipitation over a range of 0.25 to 3.5 microgram/ml. In replicate ELISA experiments using serially diluted human serum, dilutions with antibody content as low as 0.016 microgram/ml could be reliably differentiated from PBS or agammaglobulinemic serum. The concentration of antibody in 98 selected human sera measured by ELISA correlated well (r = 0.89, p less than 0.001) with results obtained by indirect IF assay. This quantitative ELISA for GBS antibody is rapid, convenient, economical, and suitable for routine use.
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D000949:Histocompatibility Antigens Class II / Q000032:analysis / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000592:standards; D007074:Immunoglobulin G / Q000032:analysis*; D011135:Polysaccharides, Bacterial / Q000032:analysis / Q000276:immunology*; D013292:Streptococcus agalactiae / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial