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Updated: Jul 19, 2026

Tractable Mammalian Cell Infections with Protozoan-primed Bacteria
Published on: April 2, 2013
Biological Trojan horse: Antigen 43 provides specific bacterial uptake and survival in human neutrophils
Sara Fexby1, Thomas Bjarnsholt, Peter Østrup Jensen
1Center for Biomedical Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Denmark.
Abstract:
Escherichia coli is a versatile pathogen causing millions of infections in humans every year. This bacterium can form multicellular aggregates when it expresses a self-associating protein, antigen 43 (Ag43), on its surface. We have discovered that Ag43-expressing E. coli cells are efficiently taken up by human defense cells, polymorphonuclear neutrophils (PMNs), in an opsonin-independent manner. Surprisingly, the phagocytosed bacteria were not immediately killed but resided as tight aggregates within the PMNs. Our observations indicate that Ag43-mediated uptake and survival in PMNs constitute a mechanism to subvert one of the primary defense mechanisms of the human body.
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