Location: Livestock Issues ResearchTitle: Differential responses to a bovine respiratory disease challenge based on Bovine Herpes Virus 1 antibody titer status
Submitted to: Frontiers in Immunology
Publication Type: Abstract Only
Publication Acceptance Date: 2/7/2018
Publication Date: 8/31/2018
Citation: Broadway, P.R., Carroll, J.A., Sanchez, N.C. 2018. Differential responses to a bovine respiratory disease challenge based on Bovine Herpes Virus 1 antibody titer status. Joint XII Congress of the Latin American Association of Immunology and XXIII Congress of the Mexican Society of Immunology meeting, May 14-18, 2018, Cancun, Mexico. Frontiers ISBN: 978-2-88945-511-9; doi: 10.3389/978-2-88945-511-9; Pp. 1005-1006.
Technical Abstract: Bovine respiratory disease (BRD) is the most common and costly diseases in the beef cattle industry. However, advancements in vaccination, treatment, and management practices have yielded little to no improvement over the past five decades. Therefore, scientists seek to better understand what factors influence the progression of this disease, and are pursuing alternative ways to reduce and mitigate the negative impacts associated with BRD. The objective of this study was to determine if Bovine Herpes Virus 1 (BHV-1) antibody titer status would be predictive of the physiological and immune responses of beef heifers to a combined viral and bacterial BRD challenge. To accomplish this objective, 64 intact female (heifer) beef calves (~260 kg) were selected and balanced based on body weight, phenotype, and temperament ~30 d after arrival to a commercial feedlot in the panhandle west Texas. All heifers were vaccinated twice with a five-way modified-live respiratory vaccine >30 d before selection. At selection, 32 heifers presented with protective antibody titers to BHV-1 (=16: Protected: P), and the other 32 presented with no antibody titers to BHV-1 (0; not protected: NP). Heifers were relocated to the USDA-ARS, Livestock Issues Research Unit’s Research Complex in Lubbock, TX. Calves were administered 1.0 x 108 PFU of BHV-1 in each nostril via a nasal atomization device (d-3) and were held in covered dirt pens with access to feed ration and water. Additionally, calves were fitted with indwelling vaginal temperature (VT) recording devices set to record vaginal temperature at 5-min intervals for the duration of the study. On d 0, calves were fitted with indwelling jugular catheters and were administered ~2.0 x 107 CFU of log phase Mannheimia Haemolytica (MH) culture intratracheally in 100 ml of Tryptic Soy Broth to ensure adequate passage and lung coating. Following the MH challenge, calves were relocated to bleeding stalls in an environmentally controlled enclosed facility where serum and whole blood were collected every h for 8 h, every 12 h for 72 h, and again on d 7 to evaluate serum biomarkers and hematology, respectively. At 72 h post-MH challenge, jugular catheters were removed and heifers were treated with florfenicol. Nasal lesion scores were observed and recorded on d -3, 0, 3, and 7 relative to the MH challenge. Vaginal temperature patterns varied (P < 0.05) in that P heifers exhibited a spike in VT immediately following the MH challenge (1 h to 12 h) but retuned to baseline within 24 h. Conversely, NP heifers’ VT did not spike, but rather declined immediately following the MH challenge, and exhibited a delayed increase where VT was elevated above baseline from 30 h to 72 h. Interestingly, nasal lesion severity was more severe (P < 0.05) in P heifers when compared to NP. There were no differences (P > 0.05) in red blood cells, hematocrit, hemoglobin, lymphocytes, monocytes, or eosinophils between the treatments. Additionally, there was no difference (P > 0.05) in circulating concentrations of cortisol between NP and P heifers. Cortisol remained near basal concentrations following the MH challenge, and cortisol was only influenced by moving heifers through the working facility. Finally, P heifers had increased circulating neutrophils following the MH challenge when compared to NP heifers from 0 to 12 h (P < 0.05). In summary, variations exhibited between P and NP heifers in response to a controlled BRD challenge suggest minimal predictive value on the negative impacts of BRD based solely on selection for BHV-1 antibody titers.