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Title
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The alpha C protein mediates internalization of group B Streptococcus within human cervical epithelial cells.
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Authors
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G.R.Bolduc,
M.J.Baron,
C.Gravekamp,
C.S.Lachenauer,
L.C.Madoff.
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Ref.
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Cell Microbiol, 2002,
4,
751-758.
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PubMed id
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Abstract
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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.
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