The genomic sequence of a virulent bovine viral diarrhea virus (BVDV) from the type 2 genotype: detection of a large genomic insertion in a noncytopathic BVDV.

A second genotype of bovine viral diarrhea virus, BVDV genotype 2 or BVDV 2, has been identified based on phylogenic analysis of sequences from the 5' untranslated region of the viral RNA. In this study, we derived the complete nucleic acid sequence of a virulent BVDV 2 virus, BVDV2-890, isolated from an animal that died of an acute uncomplicated BVDV infection. BVDV2-890 is noncytopathic in cell culture and does not produce a p80 viral polypeptide. The ORF of BVDV2-890 is 11,922 nucleotide bases long and codes for 3973 amino acids. In comparison, the ORFs of other noncytopathic pestiviruses are shorter by about 250 nucleotides. The sequence identity at the amino acid level, between BVDV2-890 and published sequences for other pestiviruses, is 74% or less. The most conserved nucleotide and amino acid sequences between BVDV2-890 and other pestiviruses are located in the region coding for the nonstructural protein p80. The least conserved are in the regions coding for the structural polypeptide gp53 and nonstructural polypeptides p54 and p58. The larger size of the BVDV2-890 ORF is due to a 228-nucleotide insertion in the portion of the genome coding for the viral polypeptide p54. The location of this insertion was upstream from those reported in cytopathic pestiviruses. This insertion was not characteristic of all of the BVDV 2 viruses or all of the virulent BVDV 2 viruses.