Submitted to: Biologicals
Publication Type: Book / Chapter
Publication Acceptance Date: January 15, 2003
Publication Date: June 1, 2003
Citation: Ridpath, J.F. BVDV genotypes and biotypes: practical implications for diagnosis and control(1). Biologicals. 2003. v. 31. p. 127-131. Technical Abstract: BVDV is an umbrella term for a diverse group of viruses from the pestivirus genus. There are two genotypes of BVDV, BVDV1, and BVDV2. Recently, these two genotypes have been declared separate and distinct species. Frequently differentiation between BVDV1 and BVDV2 is made based on comparison of sequences from the 5' untranslated region (5' UTR). This region is highly conserved compared to the rest of the genome, so differences in the 5' UTR tend to be significant rather than just random variation. However, differences between BVDV1 and BVDV2 exist throughout the genome. The existence of two genotypes is significant because there are antigenic differences. Some of the earliest isolations of BVDV2 strains were as vaccine escapes. Differences in acute pathogenesis may exist between the genotypes. Severe acute (SA) disease has only be reported with BVDV2 strains. However, it should be noted that BVDV2 strains causing SA are in the minority and most BVDV2 strains are no more virulent that BVDV1 strains. BVDV's may also exist as one of two biotypes, cytopathic and noncytopathic. It is thought that cytopathic viruses arise from noncytopathic viruses. This switch is frequently associated with the insertion of host or viral sequences into the viral genome. Biotype is not correlated with antigenic variation or pathology in acute infections. Biotype is important in persistent infections. Persistent infections have only been reported with noncytopathic viruses. Persistently infected animals superinfected with a cytopathic BVDV may succumb to mucosal disease.