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THE Ibc PROTEIN FRACTION OF GROUP B STREPTOCOCCI: CHARACTERIZATION OF PROTEIN ANTIGENS EXTRACTED BY HC1

1981; Wiley; Volume: 89B; Issue: 1-6 Linguagem: Inglês

10.1111/j.1699-0463.1981.tb00177_89b.x

0304-131X

Lars Bevanger, Ole‐Jan Iversen,

Amoebic Infections and Treatments

The Ibc protein fraction of group B streptococci was prepared by HC1 extraction of the type Ic strains A909 and 335. The fraction from strain A909 contained two protein antigens (αA909 and βA909) that could be separated by ion‐exchange chromatography and isoelectric focusing. The 335 extract contained the α (α335) — but not the β antigen. The α335 antigen was purified by similar procedures. The βA909 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, 45,000, and 23,000 daltons showed antigenic activity. The α335 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 αA909 antigen showed neither protein lines on SDS‐PAGE, nor immunogenicity in rabbits. However, the two α antigens showed serological crossreactivity in tests with the anti‐α335 serum.