Genetic analysis of indian bovine viral diarrhea virus 1 isolates in N(pro) and entire gene region coding structural proteins.

Three Indian Bovine viral diarrhea virus 1 (BVDV-1) isolates were analyzed at genetic level in N(pro) (viral autoprotease) and entire gene region coding structural proteins, namely capsid (C) protein, E(rns), and envelope proteins E1 and E2. All these isolates were found to be of b subtype based on the entire 504 nt region of N(pro) and 1119 nt region of E2. However, in comparison with other isolates of this subtype, they were allocated inside the BVDV-1 subtype b cluster to a separate clade with a longer distance. Of six cysteine residues in N(pro) only three were totally conserved in all three isolates. The isolates showed 94.9-99.3% and 92.2-99.0% identities for the entire C-E2 gene region at nucleotide and amino acid levels, respectively. The lowest identity values (88.5-91.7%) were observed for E2 amino acid sequences. The identity of the isolates with Osloss, a reference BVDV-1 subtype b strain, was in the range of 82.1-89.9% for nucleotide and 78.6-89.2% for amino acid sequences in the C-E2 region. The N(pro)/C and E(rns)/E1 cleavage sites were highly conserved. The C/E(rns) and E1/E2 cleavage sites were more conserved from the N-end of E(rns) and the C-end of El, respectively. These findings suggest that some unique mutations have occurred in the described Indian BVDV-1 isolates, though they all belong to the BVDV-1 subtype b.