Contribution of Salmonella typhimurium virulence factors to diarrheal disease in calves - PubMed (original) (raw)

Contribution of Salmonella typhimurium virulence factors to diarrheal disease in calves

R M Tsolis et al. Infect Immun. 1999 Sep.

Abstract

Limited knowledge is available about the virulence mechanisms responsible for diarrheal disease caused by Salmonella typhimurium. To assess the contribution to diarrheal disease of virulence determinants identified in models of infection, we tested a collection of S. typhimurium mutants for their ability to cause enteritis in calves. S. typhimurium strains carrying mutations in the virulence plasmid (spvR), Salmonella pathogenicity island 2 (SPI-2) (spiB), or SPI-5 (sopB) caused mortality and acute diarrhea in calves. An S. typhimurium rfaJ mutant, which is defective for lipopolysaccharide outer core biosynthesis, was of intermediate virulence. Mutations in SPI-1 (hilA and prgH) or aroA markedly reduced virulence and the severity of diarrhea. Furthermore, histopathological examination of calves infected with SPI-1 or aroA mutants revealed a marked reduction or absence of intestinal lesions. These data suggest that virulence factors, such as SPI-1, which are required during intestinal colonization are more important for pathogenicity in calves than are genes required during the systemic phase of S. typhimurium infection, including SPI-2 or the spv operon. This is in contrast to the degree of attenuation caused by these mutations in the mouse.

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Figures

FIG. 1

FIG. 1

Representative examples of the gross pathology of Peyer’s patch and mucosa of the terminal ileum of calves inoculated orally with 1010 CFU of different S. typhimurium strains. (A) Severe acute fibrinopurulent necrotizing enteritis with segmental or continuous pseudomembrane formation of calves inoculated with wild type (IR715), strain STN272 (spvR), or strain SVM255 (sigD). (B) Moderate to marked subacute fibrinopurulent enteritis often confined to Peyer’s patches of calves inoculated with STN119 (spiB) or STN166 (rfaJ). (C) Normal Peyer’s patch and ileal mucosa of calves inoculated with STN61 (hilA), STN162 (prgH), or CL1509 (aroA) or of uninoculated controls. Bar = 1 cm.

FIG. 2

FIG. 2

Histopathology of Peyer’s patches and ileum from perinatal calves inoculated per os with 1010 CFU of the indicated strains of S. typhimurium per animal, photographed at a 40× magnification. Shown are hematoxylin-and-eosin-stained sections of Peyer’s patch (left column) and terminal ileum (right column). Short arrows indicate areas of marked lymphoid depletion; long arrows indicate zones of variable degrees of fibrinopurulent necrotizing ileitis at the mucosal surface.

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