Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/7/2007
Publication Date: 5/12/2007
Citation: Bearson, S.M., Uthe, J.J., Wang, Y., Qu, L., Dekkers, J., Nettleton, D., Tuggle, C. 2007. Associations of the porcine immune response and genetic polymorphisms with the shedding of Salmonella enterica serovar Typhimurium. In: Proceedings of the 7th International Symposium on the epidemiology and control of foodborne pathogens in pork, May 9-11, 2007, Vernona, Italy. p. 413-417. Interpretive Summary:
Technical Abstract: A major focus of our collaborative research is to investigate the porcine response to infection with Salmonella to 1) identify porcine genes differentially regulated during infection and 2) identify and associate genetic polymorphisms within these genes with infection status across swine populations. In the current study, 40 crossbred pigs were intranasally inoculated with Salmonella enterica serovar Typhimurium and monitored for Salmonella fecal shedding and blood immune parameters at 2, 7, 14 and 20 days post-inoculation (dpi). Using a multivariate permutation test, a positive correlation was observed between Salmonella shedding and interferon-gamma (IFNG) levels at 2 and 7 dpi (p<0.05), with a greater number of Salmonella shedding in the animals with higher IFNG levels in the blood. In addition, a positive correlation was observed of the IFNG levels with the number of circulating neutrophils at 7 and 14 dpi, mature banded neutrophils at 2 dpi, monocytes at 7 dpi and white blood cells (WBCs) at 7, 14 and 20 dpi. We have further performed association studies of immune response parameters or shedding status of the Salmonella-infected pigs with single nucleotide polymorphisms (SNPs) in the following 5 genes: VCP, CCT7, LCP1, CD47 and TYROBP. Expression of these genes was identified by our group as differentially-regulated during Salmonella infection, and assays for these SNPs have been developed in our laboratories. Specifically, preliminary analysis suggests a positive association (p<0.05) of SNP genotype AG at nucleotide 1153 of the CCT7 gene with circulating neutrophils and WBCs and with Salmonella shedding at 7 dpi compared to the GG genotype. CCT7 encodes a molecular chaperone involved in tubulin folding and protection. Thus, our analyses are linking the porcine immune response to Salmonella infection with specific genes and genetic polymorphisms, thereby providing potential markers for carrier pigs as well as targets for disease diagnosis, intervention and prevention.