|Frey, M - USDA-APHIS-NVSL, AMES, IA|
|Landgraf, J - USDA-APHIS-NVSL, AMES, IA|
Submitted to: European Society for Veterinary Virology
Publication Type: Abstract Only
Publication Acceptance Date: March 16, 1999
Publication Date: N/A
Technical Abstract: Bovine viral diarrhea virus (BVDV) continues to have a significant impact upon U.S. cattle producers despite the availability vaccines. Detection and control is hampered by viral heterogeneity that results in differences in neutralizing epitopes, cytopathology and virulence. Recently, it was found that there are two different genotypes, BVDV1 and BVDV2, among BVDV. Serologically, BVDV2 viruses can be distinguished from BVDV1 and border disease viruses. BVDV2 are relatively common in North America. Of 312 BVDV samples submitted to diagnostic laboratories in the U.S. and Canada, 49% were BVDV2. Symptoms resulting from BVDV2 infections may range from clinically inapparent to clinically severe. Like BVDV1 infections, BVDV2 infections are systemic and affect the immune, respiratory, reproductive and enteric systems. Recently, outbreaks of clinically severe disease, termed hemorrhagic syndrome (HS), have associated with viruses from the BVDV2 genotype. However, not all BVDV2 isolates cause clinically severe disease. Avirulent BVDV2 isolates do exist and may predominate over virulent BVDV2 in nature. Virulent and avirulent viruses differed in their replication rate in vivo and in binding to lymphoid cell in vitro. BVDV2 viruses may exist as one of two biotypes, cytopathic or noncytopathic, based on their activity in cultured cells. Cytopathogenic effects on cultured cells does not correlate with virulence in vivo. Unlike BVDV1, genomic recombination has been observed in both cytopathic and noncytopathic BVDV2. Virulent and avirulent noncytopathic BVDV2 may establish persistent infections.