1a.Objectives (from AD-416):
The current specific aims are: (1) profile the in vivo whole blood RNA and cytokine response to Salmonella Typhimurium (ST) infection in animals with high and low fecal shedding phenotypes; (2) using the same animals in Aim 1, profile the in vitro whole blood RNA and cytokine response to exposure to the general inflammatory endotoxin, lipopolysaccaride; (3) annotate response profiles for common expression patterns and functional themes and develop regulatory network information on response to inflammatory stimuli; and (4) test existing and develop improved predictive models for identifying pigs with decreased fecal shedding at multiple stages of post-infection pro and in naïve pigs.
1b.Approach (from AD-416):
Tests will be performed at BARC to quantitate RNA and protein levels for important markers of inflammatory and infectious processes critical to disease resistance. Simultaneously, the team plans to develop layers of information, based on transcriptional profiling data, on the mechanisms controlling inflammatory and infectious processes critical to disease resistance, and to integrate transcriptional and cromatin binding data available in the pig with similar data in other species to develop higher-level understanding of regulatory mechanisms.
Pigs with different Salmonella shedding outcomes develop distinct immune responses as early as 2 days after infection. Foodborne salmonellosis costs the U.S. $2.7 billion each year, including $100 million in annual losses to pork producers. Pigs colonized with Salmonella are usually asymptomatic with varied severity and duration of fecal shedding. ARS researchers at Beltsville, Maryland, partnered with Iowa State University (ISU) and ARS researchers at Ames, Iowa to identify how persistent Salmonella shedding (PS) pigs differed from low Salmonella shedders (LS). The desirable LS pigs had limited clinical symptoms, low fecal Salmonella bacterial counts, and higher serum immune protein interleukin-8 (IL-8). On the other hand, PS pigs had longer fever after Salmonella infection and their sera had different immune proteins (IL-1beta and interferon-gamma) elevated. These different immune mechanisms offer clear alternatives and indicate approaches that could be targeted to help PS pig reduce their fecal Salmonella shedding and this decrease foodborne salmonellosis.