Pigs respond to Salmonella infection with reduced production efficiency, but fairly mild disease symptoms. The greater concern for Salmonella infection in swine production is for reasons of food safety and human health. Results obtained from a previous project suggest that it is possible to identify pigs that will mount a successful defense against Salmonella to clear the infection within a few days, compared to other pigs that persistently shed Salmonella by measuring the expression of genes in the blood. The proposed project will focus on the validation of identified biomarkers for reduced carriage of Salmonella following infection and to gain insights into the relationship between gene expression profiles and functional immune characteristics. As well as validating these genes as predictors of Salmonella shedding, they will explore whether the expression of these genes can be modified by environmental exposures, with particular focus on how variations in the intestinal microbiota affect the regulation of these genes prior to infection. This research will allow for the eventual implementation of blood biomarkers for breeding selection, providing a new means to improve animal resistance and improve food safety. Furthermore, the identification of microbial populations that associate with reduced shedding will allow for targeted efforts to shift microbial populations through dietary or management strategies.