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Updated: Aug 20, 2026

Invasion of Human Cells by a Bacterial Pathogen
Published on: March 21, 2011
Streptococcus pneumoniae anchor to activated human cells by the receptor for platelet-activating factor
D R Cundell1, N P Gerard, C Gerard
1Laboratory of Molecular Infectious Diseases, Rockefeller University, New York, New York 10021-6399, USA.
Abstract:
The Gram-positive bacterium Streptococcus pneumoniae is a major cause of pneumonia, sepsis and meningitis. Although the invasive disease is severe, some 40% of individuals harbour the pneumococcus in the nasopharynx asymptomatically. Here we investigate the molecular elements of the encounter between host and pathogen that distinguish these different outcomes. We show that inflammatory activation of human cells shifts the targeting of the pneumococcus to a new receptor, that for the G-protein-coupled platelet-activating factor (PAF). Only virulent pneumococci engage the PAF receptor. Attachment of the bacterial phosphorylcholine to the PAF receptor enhanced adherence, which was coupled to invasion of endothelial, epithelial and PAF-receptor-transfected cells. This progression could be arrested in vitro and in vivo by PAF-receptor-specific antagonists, suggesting a possible approach to therapy.
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