title: The Ibc protein fraction of group B streptococci: characterization of protein antigens extracted by HCL.
abstract: The Ibc protein fraction of group B streptococci was prepared by HCL extraction of the type Ic strains A909 and 335. The fraction from strain A909 contained two protein antigens (alpha A 909 and beta A909) that could be separated by ion-exchange chromatography and isoelectric focusing. The 335 extract contained the alpha (alpha 335)-but not the beta antigen. The alpha 335 antigen was purified by similar procedures. The beta A909 antigen had a molecular weight of several hundred thousands, was immunogenic in rabbits and dissociated into several polypeptides on SDS-PAGE. Polypeptides with sub-unit molecular weights corresponding to 70,000 daltons showed antigenic activity. The alpha 335 antigen had a molecular weight of approximately 75,000 daltons as judged from gel filtration and SDS-PAGE. The antigen was immunogenic in rabbits. In contrast, the alpha A909 antigen showed neither protein lines on SDS-PAGE, nor immunogenicity in rabbits. However, the two alpha antigens showed serological crossreactivity in tests with the anti-alpha 335 serum.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D000942:Antigens, Bacterial / Q000276:immunology / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000276:immunology*; D003429:Cross Reactions; D006851:Hydrochloric Acid; D008970:Molecular Weight; D011817:Rabbits; D013292:Streptococcus agalactiae / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D006851:Hydrochloric Acid