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The frequency and duration of Salmonella-macrophage adhesion events determines infection efficiency.

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Achouri, Sarra 
Wright, John A 
Evans, Lewis 
Macleod, Charlotte 


Salmonella enterica causes a range of important diseases in humans and a in a variety of animal species. The ability of bacteria to adhere to, invade and survive within host cells plays an important role in the pathogenesis of Salmonella infections. In systemic salmonellosis, macrophages constitute a niche for the proliferation of bacteria within the host organism. Salmonella enterica serovar Typhimurium is flagellated and the frequency with which this bacterium collides with a cell is important for infection efficiency. We investigated how bacterial motility affects infection efficiency, using a combination of population-level macrophage infection experiments and direct imaging of single-cell infection events, comparing wild-type and motility mutants. Non-motile and aflagellate bacterial strains, in contrast to wild-type bacteria, collide less frequently with macrophages, are in contact with the cell for less time and infect less frequently. Run-biased Salmonella also collide less frequently with macrophages but maintain contact with macrophages for a longer period of time than wild-type strains and infect the cells more readily. Our results suggest that uptake of S. Typhimurium by macrophages is dependent upon the duration of contact time of the bacterium with the cell, in addition to the frequency with which the bacteria collide with the cell.



flagella, macrophage, motility, phagocytosis, salmonella, Animals, Bacterial Adhesion, Cell Adhesion, Cell Line, Macrophages, Mice, Movement, Mutation, Salmonella typhimurium

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Philos Trans R Soc Lond B Biol Sci

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The Royal Society
Biotechnology and Biological Sciences Research Council (BB/H021930/1)
Biotechnology and Biological Sciences Research Council (BB/K006436/1)
SA was supported by an Oliver Gatty studentship, and this work was funded from EU-ITN Transpol (PC), BBSRC Research Development Fellowship BB/H021930/1 (JAW and CEB).