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Infect. Immun., Dec 1996, 5075-5084, Vol 64, No. 12
JJ Daniels, IB Autenrieth, A Ludwig and W Goebel
Recent studies have shown that Salmonella typhimurium invades the M cells
of Peyer's patches (PP) of the murine ileum. The slyA gene of S.
typhimurium has also recently been reported to affect virulence of this
pathogen in mice and survival in macrophages. We therefore compared the
effect on PP tissue of four strains of S. typhimurium: a wild-type strain,
two slyA insertion mutants, and a recombinant S. typhimurium derivative
carrying multiple copies of slyA. Invasion assays performed 2 and 7 days
after orogastric infection revealed significantly lower numbers of bacteria
of the slyA mutants and of the SlyA-overproducing strain in PP than of the
wild type. However, similar numbers of bacteria of all strains were still
present in the lumen of the small intestine after these times. Invasion
assays of PP tissue after 90-min ileal loop infection yielded comparable
numbers of bacteria of all strains in PP. Transmission and scanning
electron microscopy of PP tissue after ileal loop infection demonstrated
that the two slyA mutants and the SlyA-overproducing strain were able to
attach to, induce membrane ruffling of, and invade M cells in a way
morphologically and quantitatively similar to that of the wild type. In
contrast to the wild type, both slyA mutants and, to a lesser extent, the
SlyA-overproducing strain were significantly impaired in their ability to
destroy M cells and adjacent enterocytes. Taken together, these data
suggest that slyA is involved in intracellular survival and M-cell
cytotoxicity but not in the invasion process and that the amount of SlyA
needs to be precisely balanced for virulence.
Copyright © 1996, American Society for Microbiology
The gene slyA of Salmonella typhimurium is required for destruction of M cells and intracellular survival but not for invasion or colonization of the murine small intestine
Lehrstuhl fur Mikrobiologie, Biozentrum, Universitat Wurzburg, Germany.
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