author(s)
Preeti, Suresh Kumar, Naresh Jindal and Ramkaran

abstract
The present study was conducted to characterize the infectious bursal disease (IBD) virus by phylogenetic analysis from IBD-affected broiler flocks in Haryana, India. Phylogenetic analysis revealed very virulent, virulent strains and classical strains of IBDVs of this study. All the IBDV strains of this study had 96.7-99.9% homology among themselves. The similarity with other already reported Indian strains was between 92.3-97.4% while it was 89.5-93.2% with IBDV strains from abroad. The deduced amino acids sequence analysis of VP2 gene revealed that 18 of the 20 IBDVs were of very virulent nature due to amino acid substitution at positions 242I, 253Q, 256I, 272I, 279D, 284A, 294I, 299S and 330S, specific to very virulent IBDV strains. The remaining two field strains showed substitutions at positions 272T, 279N, 284A, 294I, 299S and 330S which are characteristics of intermediate plus variant strain of IBD viruses. The substitution of amino acid at position 300 (glutamic acid to alanine) in a field strain HR/2960/15, at 359 (threionine to lysine) in a field strain HR/3123/16 and at 384 (isoleucine to valine) in field strains HR/0955/15, HR/2960/15 and HR/2940/15 was observed. Hence, it was concluded that there is a circulation of very virulent, virulent, classical and intermediate plus variant strains of IBDVs in broiler chickens in Haryana, India.