|Briggs, Robert - Bob|
Submitted to: Canadian Journal of Veterinary Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/8/2000
Publication Date: 7/1/2000
Citation: Fulton, R.W., Purdy, C.W., Confer, A.W., Saliki, J.T., Loan, R.W., Briggs, R.E., Burge, L.J. 2000. Bovine viral diarrhea viral infections in feeder calves with respiratory disease: interactions with pasteurella spp. parainfluenza-3 virus and bovine respiratory syncytial virus. Canadian Journal of Veterinary Research. 64(3):151-159. Interpretive Summary: Acute bovine respiratory disease complex (BRDC) cost the feeder calf industry in excess of $750,000,000 dollars per year. The bovine viral diarrhea virus (BVDV) is frequently associated in the initial viral infections of market-stressed feeder calves. However, the dynamics of the BVDV infection and its part that it plays in BRDC in market-stressed feeder rcalves is not well understood. In this study 120 calves were purchased from 3 auction barns in TN, and transported a short distance to a TN order buyer barn (OBB) where it was determined that they were highly susceptible to viral infections (BVDV types 1 and 2, bovine herpes virus type 1 [BHV-1], Parainfluenza-3 virus (PI-3), and bovine respiratory syncytial virus [BRSV]). These calves were transported to Bushland, TX, where they entered a research feedyard for 34 days. During the study 16 calves died of BRDC. Viruses were isolated from the lungs of 9 dead calves: 7 PI-3, 1 BVDV 1, 1 with BVDV 1 & 2. The predominate bacteria isolated was Pasteurella haemolytica. From day 0 to day 34 there was serologic evidence from the 104 survivors for virus infections (serum conversions): 40/104 (38.5%) BVDV type 1, 29/104 (27.9%) to BVDV type 2, 71/104 (68.3%) to PI-3 virus, and 81/104 (77.9%) to BRSV. BVDV and other viruses played a significant role in the BRDC of this study.
Technical Abstract: The prevalence of bovine viral diarrhea virus (BVDV) infections was determined in a group of stocker calves undergoing acute respiratory disease. The calves were purchased from local auctions in East Tennessee and transported to an experimental feedlot facility in the panhandle region of Texas. Serums from the weekly bleedings were tested for viruses by cell lculture inoculation. Lung samples from the 16 calves dying during the study were examined by histopathology and for viruses by cell culture inoculation. Detection of viral infection by serology was based on 4-fold or greater rise in antibody titer to the respective virus. There was serologic evidence of infection with types 1 and 2 BVDV in the 104 surviving calves: 38.5% (40/104) to BVDV type 1; and 27.9% (29/104) to BVDV type 2. In most cases, the titers to type 1 BVDV were higher than to type 2 BVDV. However, there were 7 calves with higher type 2 BVDV titers indicating type 2 infection rather than crossreacting type 1 BVDV antibody titers. There were no BVDV persistently infected (PI) calves detected in these 120 calves upon entry (all negative at day 0). There were four calves with BVDV isolated from the serum at various collections. Viruses were isolated from lungs of 9 calves dying during the study: 7 PI-3V isolates, 1 calf positive for BVD alone, and 1 calf positive for both infectious bovine rhinotracheitis virus (IBRV) and BVDV. The BVDV isolates are being genotyped by a nested PCR assay. The initial objective of the study was to determine prevalence of BVDV PI calves entering the marketing channel from sale barn origins. Active BVDV infections were detected suggesting that the calves were either exposed at the sale barn and/or farm or origin to PI calves or animals shedding virus during active infections.