|Falkenberg, Shollie - Mississippi State University|
|Carroll, Jeffery - Jeff Carroll|
|Best, Tim - Mississippi State University|
|Sartin, James - Mississippi State University|
|Buntyn, Joe - Mississippi State University|
|Schmidt, Ty - Mississippi State University|
Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2013
Publication Date: 12/21/2013
Citation: Falkenberg, S.M., Carroll, J.A., Elsasser, T.H., Best, T., Sartin, J., Buntyn, J.O., Schmidt, T.B. 2013. Evaluation of endocrine and immune disruption of steers challenged with infectious bovine rhinotracheitis virus. In: American Journal of Veterinary Research,74:1522-1529, 2013.
Interpretive Summary: One of the most economically devastating diseases the beef industry faces is bovine respiratory disease (BRD) caused by a primary pathogenic virus designated as infectious bovine respiratory virus (IBRV). It has been reported that the economic impact of BRD from mortality and morbidity ranges from $480 million to $624 million annually. We assessed the impact of IBRV infection on immune response and hormonal changes in young growing-age calves. Infection resulted in significant increases in the major viral immune response mediator, interferon gamma. In association with this, growth hormone levels were significantly depressed from the onset of the infection response to IBRV to the end of the study. The data suggest that the immune response to IBRV infection is mediated through the immune axis via release of interferon gamma and that metabolic rearrangements can occur to offset the inflammatory segment of the infection response through changes in the plasma concentrations of growth hormone.
Technical Abstract: Objective: To evaluate the endocrine response of steers administered an immune challenge utilizing infectious bovine rhinotracheitis virus (IBRV). Animals: Twelve crossbred steers (228.82 ± 22.15 kg BW) Procedures: Steers fitted with indwelling rectal probes and randomly assigned to a Control (CON) or IBRV treatment. Challenged steers received an intra-nasal dose of IBRV (8.0 TCID50/0.3 mL solution; 4 ml total volume; 2ml/nostril) and CON received intra-nasal dose of saline (2 ml/nostril). On day 0, steers challenged and placed into isolated paddocks. At 72 h post-infection steers were fitted with indwelling jugular catheters and placed into individual stanchions. Blood samples were intensively collected on d 4 - 8 post-infection. Serum was analyzed for Cort, IL-6, IFN-gamma, TNF-a, GH, and IGF-I. Results: On d 2, IBRV steers had increased RT compared to CON steers (P < 0.05); greatest temperature on d 4; returned to baseline on d 6. The response patterns for cortisol, IFN-gamma and GH for IBRV steers increased on approximately d 2, greatest increase on d 4, and subsiding on d 6. There was a difference (P < 0.05) in GH between treatment groups but no difference in IGF-I. Conclusion and Clinical Relevance: Collectively the data revealed the alterations in the somatotrophic axis were not associated with large increases in circulating pro-inflammatory cytokines. Results suggest that the dose of the virus used in the present study, while sufficient to elicit a febrile response, was not enough to elicit a robust immune response.