ARS | Publication request: PHYLOGENETIC ANALYSIS OF U.S. BORDER DISEASE VIRUS STRAINS: IMPLICATIONS FOR DIFFERENTIAL RT-PCR TEST DESIGN

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2004
Publication Date: July 10, 2004
Citation: Ridpath, J.F., Neill, J.D. 2004. Phylogenetic analysis of U.S. border disease virus strains: implications for differential RT-PCR test design. 23rd Annual Meeting of the American Society for Virology. Paper No. P26-6.

Technical Abstract: The pestivirus genus is comprised of four species: bovine viral diarrhea virus genotype 1 (BVDV1), BVDV2, classical swine fever virus (CSFV) and border disease virus (BDV). Phylogenetic analysis reveals that these four species can be segregated into two major branches. One branch consists of BVDV1 and BVDV2 while the other branch consists of CSFV and BDV. Historically BDV has been described as a pathogen of sheep that causes reproductive disease. A retrospective phylogenetic analysis was performed on 35 pestiviruses isolated from sheep and goats. These isolates were gathered from laboratories in the United States in response to a request for BDV isolates. Of the 35 isolates characterized, only 18 were determined to be "true" BDV strains. The other 17 isolates were either BVDV1 strains (7 isolates) or BVDV2 strains (10 isolates). Previous characterization of BDV isolated from sheep in Europe and New Zealand had demonstrated that BDV strains from these geographic areas could be divided into two subgenotypes, BDV-A and BDV-B. The U.S. BDV strains examined in this study were less heterogeneous, as all could be segregated into one subgenotype (BDV-B). While BDV isolations are relatively rare in the United States, they are not inconsequential. Border disease virus strains are not restricted to ruminant hosts and will replicate in porcine hosts where they may be mistaken for classical swine fever virus (CSFV) strains. Comparison of CSFV and BDV sequences reveals similarities that would lead to the failure of published RT-PCR tests to differentiate between BDV strains, which are considered endemic in the United States, and CSFV strains, which have been eradicated from the U.S. Analysis of the sequences derived from BDV strains used in this study revealed sequence motifs that could be incorporated into primers and probes for improved differentiation between CSFV and BDV strains.