Characterization of two distinct opsonic and protective epitopes within the alpha C protein of the group B Streptococcus

David E. Kling, Claudia Gravekamp, Lawrence C. Madoff, James L. Michel

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Group B Streptococcus (GBS) is a major cause of neonatal sepsis, meningitis in early infancy, postpartum endometritis, and serious invasive infections in adults in the United States. We previously cloned, sequenced, and characterized the alpha antigen gene, bca, and showed that the alpha C protein of GBS is a trypsin-resistant, surface-associated polypeptide that contains a signal sequence, a unique N terminus, nine identical tandem repeats, and a C-terminal membrane anchor structure. Polyclonal antiserum raised to the recombinant alpha C protein and an opsonic monoclonal antibody, 4G8, raised to the native protein from GBS have been shown to be protective in a mouse model. The binding site of 4G8 has now been localized to the tandem repeat region of the alpha C protein. To determine whether the N terminus of the alpha C protein contains additional opsonic and/or protective epitopes, the sequence corresponding to the alpha C protein N terminus was subcloned into a pET vector, the expressed peptide from Escherichia coli was purified by Ni2+ affinity chromatography, and rabbit polyclonal antibodies were raised to the purified recombinant peptide. Antibodies to the alpha C protein N terminus were shown to be opsonic by an in vitro opsonophagocytosis assay. In addition, 69% of newborn mouse pups from mothers passively immunized with the antiserum to the recombinant N-terminal polypeptide of the alpha C protein were protected against lethal challenge with GBS A909. These data indicate that at least two distinct regions of the alpha C protein, the N terminus and the tandem repeat region, contain opsonic and protective epitopes.

Original languageEnglish (US)
Pages (from-to)1462-1467
Number of pages6
JournalInfection and Immunity
Volume65
Issue number4
StatePublished - 1997
Externally publishedYes

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Protein C
Epitopes
Tandem Repeat Sequences
Streptococcus agalactiae
Peptides
Immune Sera
Endometritis
Antibodies
Protein Sorting Signals
Affinity Chromatography
Meningitis
Trypsin
Postpartum Period
group B streptococci alpha C protein
Binding Sites
Monoclonal Antibodies
Escherichia coli
Rabbits
Antigens
Membranes

ASJC Scopus subject areas

  • Immunology

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Characterization of two distinct opsonic and protective epitopes within the alpha C protein of the group B Streptococcus. / Kling, David E.; Gravekamp, Claudia; Madoff, Lawrence C.; Michel, James L.

In: Infection and Immunity, Vol. 65, No. 4, 1997, p. 1462-1467.

Research output: Contribution to journalArticle

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