Dexamethasone treatment differentially alters viral shedding and the antibody and acute phase protein response after multivalent respiratory vaccination in beef steers

Authors: RICHESON, JOHN - Texas A&M University; Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; MAY, NATHAN - Texas A&M University; HUGHES, HEATHER - Texas A&M University; ROBERTS, SHELBY - Texas A&M University; Broadway, Paul; SHARON, KATE - Texas Tech University; BALLOU, MICHAEL - Texas Tech University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2016
Publication Date: 5/31/2016
Citation: Richeson, J.T., Carroll, J.A., Sanchez, N.C., May, N.D., Hughes, H.D., Roberts, S.L., Broadway, P.R., Sharon, K.P., Ballou, M.A. 2016. Dexamethasone treatment differentially alters viral shedding and the antibody and acute phase protein response after multivalent respiratory vaccination in beef steers. Journal of Animal Science. doi:10.2527/jas.2016-0572.

Interpretive Summary: This study was a collaborative effort between scientists from West Texas A&M University, the Livestock Issues Research Unit, and Texas Tech University to study the effects of short and long-term chronic stress on the antibody and acute phase protein response to vaccine administration. Prevention of disease by vaccination is a cornerstone of animal health management. Nearly all cattle are vaccinated with bovine viral diarrhea virus (BVDV; 95.1%) and infectious bovine rhinotracheitis virus (IBRV; 93.2%) antigens upon arrival in U.S. feedlots. However, stress experienced by cattle upon maternal separation and relocation to a stocker or feedlot facility can result in immunosuppression, and vaccination at this time may impact the immune response of calves to vaccine agents. The current study objectives were to establish a live animal model of acute and chronic immunosuppression using dexamethasone and to evaluate immunological and acute phase protein responses to a multivalent respiratory vaccine. Results from this study demonstrate that acute and chronic immunosuppression, due to treatment with dexamethasone, blunted the acute phase protein response following vaccination. However, there appeared to be a greater antibody response to the live-attenuated IBRV and BVDV vaccine agents, potentially due to an increase in viral replication as a result of immunosuppression. Further research is needed to determine if natural stress conditions imposed on beef calves during marketing and relocation to a stocker or feedlot facility result in immunosuppressive conditions that similarly alter the ability of vaccine agents to elicit an antibody response as observed in the current study. These data will be of interest to researchers in the field of immunology and stress physiology, as well as cattle producers.

Technical Abstract: Our objective was to examine immunosuppression induced by dexamethasone (DEX) administration in cattle upon immunological responses to a multivalent respiratory vaccine containing replicating and non-replicating agents. Steers ( n = 32; 209 +/- 8 kg) seronegative to infectious bovine rhinotracheitis virus (IBRV), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV) and parainfluenza-3 virus (PI3V) were stratified by BW and assigned randomly to 1 of 3 treatments: 1) Acute immunosuppression (ACU), 0.5 mg/kg BW DEX intravenously at 10am on d 0 only; 2) Chronic immunosuppression (CHR), 0.5 mg/kg BW DEX intravenously at 10am on d -3 to d 0; or 3) Control (CON), no DEX. On d -4, steers were fitted with intravenous catheters in the jugular vein and placed into individual stanchions. At 12pm on d 0, steers were administered a respiratory vaccine containing modified-live virus (MLV) isolates of IBRV, BVDV, BRSV and PI3V and a Manheimia haemolytica (MH) toxoid. On d 4, cattle were transported (177 km) and housed in an isolated outdoor pen. Serum was harvested on d 0, 7, 14, 21, 28, 35, 42, and 56 to determine IBRV-, BVDV-, BRSV-, and PI3V-specific antibody titer and MH whole cell and leukotoxin antibody concentrations. Sera from d -2, 0, 1, 3, 7, and 14 were used to quantify haptoglobin (Hp) concentration and ceruloplasmin (Cp) activity. Nasal swab specimens were collected on d 0, 3, and 14 to determine presence of IBRV, BVDV, BRSV and PI3V via PCR analysis. There was a treatment × d interaction (P < 0.01) such that CHR steers had a greater (P = 0.07) BVDV antibody titer on d 14, 21 and 28. Moreover, IBRV-specific antibody increased beginning on d 14 for CHR and d 28 for ACU, and remained greater through d 56 compared to CON (P = 0.03). Conversely, serum MH whole cell antibody concentration was least (P = 0.06) for CHR from d 7 to 28 and greatest for CON (P = 0.04) on d 56. Treatment altered Hp such that CON exhibited a greater (P < 0.01) Hp concentration than CHR but was not different from ACU (P = 0.16). On d 3, Cp was greatest for CON, intermediate for ACU, and least for CHR (trt × d; P = 0.01). Prevalence of IBRV and BVDV in nasal swabs on d 14 was 67 and 56% for CHR, 10 and 10% for CON and 9 and 0% for ACU (P = 0.006), respectively. Results suggest that CHR allowed increased replication of MLV vaccine agents. Conversely, DEX-induced immunosuppression blunted the acute phase protein and antibody response against the non-replicating MH toxoid.