Monoclonal antibody development and antigenic epitope identification of infectious bursal disease virus VP5

Infectious bursal disease (IBD) is an important immunosuppressive disease affecting chickens and is caused by infectious bursal disease virus (IBDV) infection. VP5 is a non-essential protein for IBDV replication but plays a critical role in IBDV pathogenesis. A deeper understanding of the biological functions of VP5 is lacking. This study utilized a prokaryotic system to express and purify soluble VP5 from the dominant epidemic strain of IBDV and developed a hybridoma cell line capable of secreting IBDV VP5 monoclonal antibody (MAb). The VP5 MAb demonstrated strong specificity for IBDV VP5 and could effectively discriminate between IBDV and its VP5-deleted strain. Furthermore, the antigen epitope of 137RRDLPKPE145 from IBDV VP5 was identified, which is the first detailed report of an IBDV VP5 antigen epitope. This antigen epitope, which is located at the C-terminus of VP5, is conserved across various IBDV serotype 1 strains. The findings of this study offer valuable insights for further exploration of gene function and differential detection of VP5.