The alpha C protein mediates internalization of group B Streptococcus within human cervical epithelial cells

G. R. Bolduc, M. J. Baron, C. Gravekamp, C. S. Lachenauer, L. C. Madoff

Research output: Contribution to journalReview article

53 Scopus citations


Group B Streptococcus (GBS) is the leading cause of bacterial chorioamnionitis and neonatal pneumonia, sepsis, and meningitis. Deletion of the alpha C protein gene (bca) attenuates the virulence of GBS in an animal model; significant survival differences in the first 24 h of infection suggest a pathogenic role for the alpha C protein early in the infection process. We examined the role of alpha C protein in the association between GBS and mucosal surfaces using a human cervical epithelial cell line, ME180. Fluorescent and confocal microscopy and flow cytometry demonstrated that 9-repeat alpha C protein binds to the surface of ME180 cells. Isolated N-terminal region of this protein also binds to these cells and competitively inhibits binding of the full protein. Wild-type GBS strain A909 and the bca-null isogenic mutant JL2053 bound similarly to the surface of ME180 cells. However, A909 entered these cells threefold more. Internalization of A909 was inhibited with 2- and 9-repeat alpha C and with N-terminal region alone but not by repeat region-specific peptide. Translocation across polarized ME180 membranes was fivefold greater for A909 than for JL2053. These findings suggest a role for the alpha C protein in interaction with epithelial surfaces and initiation of infection.

Original languageEnglish (US)
Pages (from-to)751-758
Number of pages8
JournalCellular Microbiology
Issue number11
StatePublished - Nov 1 2002


ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology

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