Open AccessCharacterization of group B streptococcal invasion in HEp‐2 epithelial cells
Author(s) -
ValentinWeigand Peter,
Jungnitz Heidrun,
Zock Angela,
Rohde Manfred,
Chhatwal Gursharan S
Publication year - 1997
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1997.tb10222.x
Subject(s) - microbiology and biotechnology , group a , group (periodic table) , group b , characterization (materials science) , chemistry , biology , medicine , nanotechnology , materials science , organic chemistry
The invasion of group B streptococci (GBS) in HEp‐2 epithelial cells was analyzed by electron microscopy and a quantitative antibiotic survival assay. Invasion of GBS involved intimate attachment of streptococcal chains, engulfment of the adherent bacteria by cellular protrusions, entry of the bacteria in a `polar' fashion and formation of membrane‐bound vacuoles in which most of the intracellular streptococci resided. At later stages of infection bacteria were also found free in the cytoplasm. Efficient uptake of streptococci by HEp‐2 cells occurred within 20 min and live intracellular bacteria were detectable up to 48 h post‐infection. Invasion of GBS required activation of the eukaryotic actin microfilament system involving, at least partially, protein kinase signal transduction pathways. Invasion was inhibited in a dose‐dependent manner by decreasing extracellular Ca 2+ levels as well as by substances known to interfere with eukaryotic calcium regulatory systems. These results suggest that GBS invade HEp‐2 cells by triggering calcium‐dependent phagocytosis‐like internalization mechanisms and persist intracellularly both in vacuoles and free in the cytoplasm.