Identification of novel linear antigenic epitope of IBDV VP3 recognized by monoclonal antibodies

This study aims to prepare specific monoclonal antibodies (mAbs) of IBDV VP3. We purified the recombinant VP3 protein to immunize the BALB/c mice for subsequently cell fusion. Following three rounds of sub-cloning, we successfully obtained three hybridoma cell lines (3B, 5 G, 6A) capable of stably secreting anti-VP3 mAbs with highly specificity and sensitivity. Preliminary identification using truncated Western blotting indicated that the mAbs primarily recognized the antigenic epitope in the C-terminus of VP3. Then, we employed alanine-scanning mutagenesis to precisely identify the key amino acid residues of this linear epitope as G243, R244, G246, W248 and I249. This discovery offers a new insight on the immunological characteristics of IBDV VP3 and might lay a solid basis for the advance of novel diagnostic tools based on C-terminal epitopes.