B cell epitope determination of chicken IBDV VP3 protein by overlap peptide scanning technique

To investigate B cell epitopes on the VP3 of infectious bursal disease virus (IBDV), the VP3 gene of IBDV were subcloned into the pET28a vector to construct expression vector of pETVP3. The recombinant VP3 (rVP3) was expressed in E. coli BL21(DE3) by inducing with IPTG. The expressed VP3 protein was recognized specifically by anti-IBDV antisera in western blot assays. According to antigenic structure of IBDV VP3, overlapping peptides which cover the full sequence of VP3 were synthesized and Conjugated to carrier Protein BSA to prepare conjugated antigens. Their reactivities with anti-IBDV monoclonal antibodies (MAb) or polyclonal antibody were detected by peptide-ELISA and Dot-ELISA The results showed that there were 2 linear epitopes recognized by neutralizing Mabs on the VP3, 728PRDWDRLPYLNL739 and 982PKPKPKPNAPTQ993, which can also react with IBDV antiserum. Dot-ELISA confirmed that there were still 4 linear epitopes recognized by polyclonal antibody on the VP3, 818LANAPQAGSKSQRA831, 851QREKDTRISKK METMGIYFATP872, 876ALNGHRGPSPGQLKYWQN TREI897 and 961QMKDLLLTAMEMK973. It is helpful for the developmentof IBD epitope vaccine.