Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 13, 2011
Publication Date: April 13, 2011
Citation: Bearson, S.M., Bearson, B.L., Lee, I. 2011. A mutation in the pnp gene encoding polynucleotide phosphorylase attenuates virulence of Salmonella enterica serovar typhimurium in swine [abstract]. 111th General Meeting American Society for Microbiology. p.1487. Technical Abstract: Background: The pnp gene encodes polynucleotide phosphorylase, an exoribonuclease involved in RNA degradation. A mutation in the pnp gene was previously identified by our group in a signature-tagged mutagenesis screen designed to search for Salmonella enterica serovar Typhimurium genes required for survival in an ex vivo swine stomach content assay. The current study evaluated the attenuation and colonization potential of the S. Typhimurium pnp mutant in the porcine host. Methods: Eight-week old pigs were intranasally inoculated with 109 cfu of either the 4232 S. Typhimurium parent strain or the pnp mutant (n=5/group). Over a 7-day study, rectal temperatures (fever) evaluated clinical signs of infection, while quantitative and qualitative bacteriological evaluation of fecal and tissue samples measured the level of Salmonella shedding and tissue colonization in the inoculated pigs. Results: An increase in the average rectal temperature (fever) was observed for the pigs inoculated with wild-type S. Typhimurium, whereas inoculation with the pnp mutant did not result in a significant increase in the average body temperature. Fecal shedding of the pnp mutant was significantly reduced during the 7-day study compared to the wild-type strain. Tissue colonization was also dramatically reduced in the pigs inoculated with the pnp mutant compared to the parental strain, including the tonsils, ileocecal lymph nodes, Peyer’s Patch region of the ileum, cecum and contents of the cecum. Conclusions: The pnp gene encoding polynucleotide phosphorylase is required for S. Typhimurium virulence and gastrointestinal colonization of the natural swine host.