| dc.description.abstract | Nontyphoidal Salmonella enterica infections are a concern for the agricultural and public health sectors. The aims of my research were to develop novel Salmonella inhibition strategies and explore the avian immune system. Study 1: We hypothesized that adding sodium bisulfate (SBS) to drinking water would decrease Salmonella Heidelberg (SH) biofilm on polyvinyl chloride (PVC) and decrease the horizontal transfer of SH in broilers. The PVC coupons were placed in SH inoculated broth and incubated for 6 days. A seeder: contact model was used for horizontal transfer. Treatments consisted of tap water or SBS in water at a pH of 3.5. Biofilm was significantly reduced by SBS when treated for 8 and 24 h. Crop colonization was significantly decreased in trials 1 and 2 in the SBS treatment. Crop pH was significantly decreased in trial 2. Cecal colonization was significantly decreased in trial 1. Study 2: We hypothesized that competitive exclusion between Salmonella serovars in neonatal broilers would reduce consequent colonization and affect the host immune response. Treatments consisted of a (1) negative control, (2) Salmonella Kentucky (SK) only on day 1 (D1), (3) Salmonella Typhimurium (ST) or Salmonella Enteritidis (SE) only on D1, (4) SK on D1 then ST or SE on day 2 (D2), (5) ST or SE on D1 then SK on D2, and (6) SK and ST or SE concurrently. When a serovar was administered first, colonization by the second serovar was significantly reduced. Significant changes were found in ceca and liver cytokine mRNA expression of IL-1β, IL-6, IL-10, IL-18, and IFN-γ across treatments. Study 3: We hypothesized that SK-derived secretome (SKS) grown under Salmonella pathogenicity islands-2 inducing, acidic conditions would induce an immune response in chicken macrophages (HD11). The SKS was purified, desalted, and concentrated before administering to HD11 macrophages. Nitric oxide was significantly increased by SKS in HD11 cells compared to the unstimulated cells. Gene expression of
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cytokines IL-1β, IL-6, and IFN-γ were significantly increased by SKS compared to unstimulated cells. The overall objectives of these projects were to reduce Salmonella and characterize the avian immune response. | en |
