Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/1997
Publication Date: N/A
Technical Abstract: The identification of Salmonella choleraesuis and porcine reproductive and respiratory syndrome (PRRS) virus as two important causes of swine respiratory disease has occurred only recently. Field data suggests that infection with PRRS virus exacerbates infection with other pathogens. Experimental data indicates a detrimental synergism between PRRS virus, S. choleraesuis, and dexamethasone (Dex). Production of interferon-gamma (IFN) can be a good indication of T-cell stimulation. We evaluated the effects of PRRS, S. choleraesuis, and Dex administration on serum levels of IFN. Results indicate that Dex, Salmonella, and PRRS treatments are each capable of lowering IFN levels in the blood and injection of Dex following either a Salmonella or PRRS infection has a synergistic effect. Interestingly, the combination of Salmonella and PRRS together does not induce any synergistic effect on IFN levels nor does the triple combination of Salmonella, PRRS, and Dex cause any further synergism than already observed between Dex and either Salmonella or PRRS. Low levels of IFN secretion after exposure to Salmonella and subsequent injection with Dex may provide a more favorable environment for opportunistic PRRS virus. Salmonella infected pigs once stressed may be sufficiently immunosuppressed and thus more susceptible to PRRS virus infection.