Submitted to: Annual Merck Merial Veterinary Scholars Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 6/27/2005
Publication Date: 7/28/2005
Citation: Schatz, A.J., Morrison, E., Bearson, S.M. 2005. Monitoring the shedding of Salmonella enterica serovar Typhimurium from experimentally infected swine [abstract]. Annual Merck Merial Veterinary Scholars Symposium. p.48 Interpretive Summary:
Technical Abstract: The ability of Salmonella to establish a carrier state in swine and the development of porcine resistance to Salmonella shedding is not well understood. Differential expression of host-specific, immune-related genes may be responsible for variations in the susceptibility of individual swine to Salmonella colonization and infection. Thus, swine that are resistant to Salmonella may possess different genetic traits that reduce colonization. The identification and exploitation of these traits could enhance the resistance of swine herds to Salmonella via selective breeding as well as be used to develop diagnostic tools to identify Salmonella-carrier pigs. The goal of phase I of this project was to experimentally inoculate 40 pigs at 7 weeks of age with 1 X 10**9 CFU of Salmonella enterica serovar Typhimurium and monitor their fecal shedding of the bacteria over a three-week period to identify shedders and non-shedders for future porcine transcriptional profiling. Qualitative and quantitative bacteriology was performed on 1-gram fecal samples at 2 days (d), 7 d, 14 d, and 21 d p.i. Non-shedders were identified as pigs that tested Salmonella positive on day 2, but were subsequently negative 2 out of the 3 test days at 7 d, 14 d, and 21 d p.i., including testing Salmonella negative on day 21. Shedders were defined as pigs that tested Salmonella positive on day 2, and were also positive 2 out of the 3 test days at 7 d, 14 d, 21 d p.i., including testing Salmonella positive on day 21. Of the 40 pigs infected, 36 were classified as shedders (qualitative bacteriology) with 6 defined as strong-shedders based on quantitative bacteriology. The remaining 4 pigs met the criteria to be classified as non-shedders. Four animals from each of the strong-shedder and non-shedder groups have been chosen for RNA isolation from selected tissues and Affymetrix DNA microarray analysis to characterize the differential host gene expression profiles that are responsible for the susceptible and resistant shedding phenotypes of the Salmonella-infected pigs.