Sequence analysis of VP2 gene hyper variable region of a cell-culture adapted Indian classical infectious bursal disease virus of chicken

An Indian classical infectious bursal disease virus (IBDV), adapted to grow in primary chicken embryo fibroblast culture, was characterized by RT-PCR/RFLP and sequence,. analysis of VP2 gene hyper variable region. The Indian classical virus displayed restriction profile similar to that already reported for attenuated IBDV strains. Sixteen nucleotide changes in Indian classical virus were,revealed as compared to majority consensus with four unique changes, 797A-T, 887C-A, 953A-C and 1017A-G. Deduced amino acid sequence analysis showed two unique changes 270A-K and 296I-V. Presence of amino acid changes 253Q-H, 279D-N and 284A-T, as well as 330S-R indicated this virus to have undergone attenuation after serial passaging in cell-culture. Phylogenetic analysis further confirmed this virus to be most closely related to attenuated strain, PBG-98. Antigenic index analysis and hydrophilicity plots clearly show differences in. the peaks of cell culture adapted, classical and very virulent viruses. The present study confirmed that Indian very virulent viruses having not originated from Indian classical virus.