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Infect. Immun., May 1997, 1786-1792, Vol 65, No. 5
SJ Libby, LG Adams, TA Ficht, C Allen, HA Whitford, NA Buchmeier, S Bossie and DG Guiney
The pathogenic role of the spv (Salmonella plasmid virulence) genes of
Salmonella dublin was determined in the natural, bovine host. Since the
lack of overt signs of enteritis or enterocolitis due to Salmonella
infections in mice has limited the development of a convenient experimental
system to study enteric disease, we used calves to study the contribution
of the spv genes to S. dublin-induced salmonellosis. Since the SpvR
transcriptional regulator is required for expression of the spvABCD operon,
we constructed an spvR knockout mutation in a calf- virulent strain of S.
dublin. Calves were infected with the wild-type strain, an spvR mutant, and
an spvR mutant containing a complementing plasmid. Calves that were
infected with the wild type or the complemented spvR mutant rapidly
developed severe diarrhea and became moribund. Calves that were infected
with the spvR mutant showed little or no clinical signs of systemic
salmonellosis and developed only mild diarrhea. The survival and growth of
the wild-type strain and the spvR mutant were determined by using
blood-derived bovine monocytes. Wild- type S. dublin survived and grew
inside cells, while the spvR mutant did not proliferate. These results
suggest that the spv genes of S. dublin promote enhanced intracellular
proliferation in intestinal tissues and at extraintestinal sites in the
natural host.
Copyright © 1997, American Society for Microbiology
The spv genes on the Salmonella dublin virulence plasmid are required for severe enteritis and systemic infection in the natural host
Department of Medicine, University of California, San Diego, La Jolla 92093-0640, USA. slibby@popmail.ucsd.edu
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