Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Proceedings
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Citation: Interpretive Summary:
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 of origin to PI calves or animals shedding virus during active infections.