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United States Department of Agriculture

Agricultural Research Service

Title: SALMONELLA IMMUNITY: DEVELOPMENT OF A NEUTROPHIL PHAGOCYTOSIS ASSAY AND STRESS MODEL IN SWINE

Authors
item Stabel, Thomas
item Cray, Paula
item Gray, J - USDA, ARS, NADC

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: March 13, 1996
Publication Date: N/A

Technical Abstract: Our laboratory is interested in the immunomodulation of porcine defense mechanisms against Salmonella spp. Route and dose of inoculum can play an important role in host immunity. Both oral and intranasal routes of inoculation with S. choleraesuis stimulate peripheral blood B-cells while the intranasal route is more effective at stimulating peripheral blood T-cells. At high doses S. choleraesuis causes signs of lymphocyte suppression, which may affect the ability of the immune system to eliminate the bacteria. Flow cytometry was used to measure the rate of ingestion of S. choleraesuis by neutrophils from swine inoculated with homologous organism. The rate of ingestion does not increase until 2 days postinoculation (PI) and remains elevated at least 4 days PI. The decreased rate of uptake, or early lag period, after S. choleraesuis exposure may provide an opportunity for the pathogen to colonize and/or replicate to levels that facilitate establishment of a carrier-state or clinical infection. A porcine stress model has been developed to study the effect of marketing stress on porcine immunity and bacterial shedding at time of slaughter. This model utilizes 2-deoxy-D-glucose (2DG) to induce many of the hallmark responses associated with physiological stress. 2DG remains in the blood stream for greater than or equal to 2 hours which should allow for proper induction of a stress response. Intravenous and subcutaneous routes of injection look most promising based on release of endogenous blood glucose and cortisol, respectively. An understanding of the interaction between stress and immunity will provide important direction for future research into ways to reduce or eliminate Salmonella and other diseases from pigs.

Last Modified: 10/31/2014