Detection of Infectious bursal disease virus by ELISA using an antipeptide antibody raised against VP3 region

Antigenic determinant analysis was carried out on VP3, one of major immunogenic proteins of Infectious bursal disease virus (IBDV) using computer algorithms. Altogether 17 peptides were synthesized for predicted putative regions and were tested for their reactivity with IBDV-positive polyclonal sera as well as with antisera to other common avian viruses to confirm specificity and to rule out cross reactivity. Of 17 peptides tested, three were selected and synthesized in multiple antigenic peptide (MAP) format. The immunization of rabbits with the three MAPs resulted in high humoral immune response. The purified antipeptide antibodies were screened against native IBDV antigen and the respective titers were determined. Out of the three antisera to MAPs that raised against the MAP3, spanning the amino acids (aa) 974-995 region on the VP3 protein had a very high titer (2048) and reacted specifically with IBDV. Thus, the antiserum to MAP3 detected native virus in enzyme-linked immunosorbent assay (ELISA), revealing the presence of a potential antigenic determinant on the C-terminus of the protein. This study proved that an antipeptide antibody could be used as a safe and specific tool for the diagnosis of IBD in chickens.