ABSTRACT
Bovine viral diarrhea virus (BVDV) is a pestivirus which infects cattle worldwide causing substantial economic losses in cattle farming. BVDV is divided into two recognized species, BVDV-1 and BVDV-2 and one tentative species, BVDV-3. Since, complete genome sequence analysis can provide better insights into molecular epidemiology of BVD, we report here the first complete genome sequence analyses of an Indian BVDV-2 strain isolated from cattle. The full-genome of strain Ind 141353 contains 12285 nucleotides (nt) with a single large open reading frame which codes for 3898 amino acids. Phylogenetic analysis indicated that this strain belongs to the BVDV-2a subtype and has highest (93%) level of genetic identity with the Chinese cattle strain JZ05-1. It was inferred that although introduction from China is possible, introduction of BVDV-2 into Indian and Chinese cattle from a common trade source cannot be ruled out completely. The results in this study extend the spectrum of pestivirus molecular data and provide important insights into BVDV molecular epidemiology.
ABSTRACT
Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle and sheep belonging to the genus Pestivirus of the family Flaviviridae. Although the BVDV non-structural N-terminal protease (Npro) acts as an interferon antagonist and subverts the host innate immunity, little is known about its immunogenicity. Hence, we expressed a recombinant BVDV Npro–His fusion protein (28 kDa) in E. coli and determined the humoral immune response generated by it in rabbits. The antigenicity of the Npro protein was confi rmed by western blot using anti- BVDV hyperimmune cattle, sheep and goat serum, and anti-Npro rabbit serum. When rabbits were immunized with the Npro protein, a humoral immune response was evident by 4 weeks and persisted till 10 weeks post immunization as detected by ELISA and western blot. Despite Npro-specifi c antibodies remaining undetectable in 80 serum samples from BVDV-infected sheep and goats, BVDV hyperimmune sera along with some of the fi eld cattle, sheep and goat sera with high BVDV neutralizing antibody titres were found positive for Npro antibodies. Our results provide evidence that despite the low immunogenicity of the BVDV Npro protein, a humoral immune response is induced in cattle, sheep and goats only with repeated BVDV exposure.