MAPPING OF NEUTRALIZATION EPITOPES ON INFECTIOUS PANCREATIC NECROSIS VIRUSES

We have characterized and mapped variable and conserved neutralization epitopes of serogroup A strains of aquatic birnaviruses. Epitope mapp ing using monoclonal antibodies (MAbs) and Escherichia coli-expressed deletion fragments of VP2 of the N1 strain of infectious pancreatic ne crosis virus (IPNV) demonstrated that two variable epitopes, H8 and B9 , depend on the variable region between amino acid 204-330. A conserve d neutralization epitope, F2, was shown to depend on the same region a s epitopes H8 and B9 but was additionally dependent on amino acids bet ween 153-203. The neutralization epitopes H8, B9 and F2 were also show n to overlap by a competitive binding assay. One conserved neutralizat ion epitope, AS-1, was not exposed on any of the recombinant VP2 delet ion fragments and was therefore not possible to map. However, the MAbs AS-1 and F2 were partly competitive indicating that these epitopes ar e overlapping. All neutralization epitopes were independent of a conse rved non-neutralization epitope, E4, Our results demonstrate that the central third of VP2 contains several partly overlapping neutralizatio n epitopes, both variable and conserved among serogroup A strains of I PNV.