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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #73470
Title: CONTROL OF SALMONELLA VIRULENCE IN THE NATURAL HOST

Author
item LIBBY, S - UNIV OF CA, SAN DIEGO
item Cray, Paula

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 3/13/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The sly and rpoS are chromosomally encoded genes that are involved in the pathogenesis of Salmonella. The sly gene is a cytolysin that has been shown to be required for virulence in mice. Preliminary studies indicate that it may also be required for virulence in swine. Swine that have been infected with a sly mutant of Salmonella typhimurium do not develop disease. The hypothesis for the function of this gene is that sly is one of the genes that is key for the survival of Salmonella in macrophages. We also propose that mutants of Salmonella that cannot survive in professional phagocytic cells should not persist in the g.i. tract and contribute to stress-induced reactivation. Mutants that are unable to cause disease may be good live vaccine candidates. The rpoS gene is the alternative, starvation-stationary sigma factor that is responsible for the global switch of gene expression as cells enter stationary phase growth or are starved for nutrients. We feel that both of these conditions exist in the host as rpoS mutants of Salmonella typhimurium are avirulent in mice. Evaluating the virulence of this mutant in Salmonella choleraesuis-infected swine will aid in the understanding of the conditions Salmonella must endure in the host. These studies are all designed to determine the genetic basis of host adaptation of Salmonella. Only by using specific mutations in isogenic pairs can a role be assigned to the function of the gene products. Vaccine development is the ultimate goal of the research, using defined mutations to create strains that are avirulent, highly immunogenic, protective, and do not linger or persist in the environment.