Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/22/2009
Publication Date: 3/20/2010
Citation: Ridpath, J.F., Fulton, R.W., Kirkland, P.D., Neill, J.D. 2010. Prevalence and Antigenic Differences Observed between Bovine Viral Diarrhea Virus Subgenotypes Isolated from Cattle in Australia and Feedlots in the Southwestern United States. Journal of Veterinary Diagnostic Investigation. 22(2):184-191. Interpretive Summary: Bovine viral diarrhea viruses (BVDV) are economically important pathogens of cattle worldwide. While BVDV are found worldwide, there is a variation in the subgenotypes of BVDV isolated from different geographic regions. In this study BVDV isolated from the United States and Australia were compared. It was found that different subtypes of BVDV were found in the two countries and that differences in proteins made by these different virus subgenotypes could be detected using antibodies. This study suggests that vaccine protection may be improved by basing vaccines on the BVDV subgenotypes prevalent in the region in which the vaccine is to be used.
Technical Abstract: Bovine viral diarrhea viruses (BVDV) are divided into two different species within the pestivirus genus, BVDV type 1 (BVDV1) and BVDV type 2 (BVDV2). Further phylogenetic analysis has revealed subgenotype groupings within the BVDV1 and BVDV2 species. Thus far twelve BVDV1 subgenotypes (BVDV1a through BVDV1l) and two BVDV2 subgenotypes (BVDV2a and BVDV2b) have been identified. The purpose of this study was to determine the prevalence of BVDV subgenotypes in the US and Australia and to determine if there are detectable antigenic differences between the prevalent subgenotypes. To determine prevalence, phylogenetic analysis was performed on two blinded panels of isolates consisting of 351 viral isolates provided by the Elizabeth Macarthur Laboratory, New South Wales (NSW) and 514 viral isolates provided by Oklahoma State University. Differences were observed in the prevalence of BVDV subgenotypes between the U.S. (BVDV1b most prevalent subgenotype) and Australia (BVDV1c most prevalent subgenotype). To examine antigenic differences between the subgenotypes identified in samples from the U.S. and Australia, polyclonal antisera was produced in goats by exposing them at 3 week intervals to 2 noncytopathic and 1 cytopathic strains of either BVDV1a, BVDV1b, BVDV1c, BVDV2a or Border disease virus (BDV). Serum neutralization (VN) assays were then performed against 3 viruses from each of the five subgenotypes. Comparison of VN results suggest that there are antigenic differences between BVDV strains belonging to different subgenotypes. This study establishes a foundation for further studies that examine if vaccine protection can be improved by basing vaccines on the BVDV subgenotypes prevalent in the region in which the vaccine is to be used.