Analysis of the antibody response in Atlantic salmon against recombinant VP2 of infectious pancreatic necrosis virus (IPNV)

An IPNV-specific humoral immune response was demonstrated in Atlantic salmon (Salmo salar) pre-smolts and in rabbits immunised with purifiedE. coli-expressed recombinant VP2. In ELISA all anti-rVP2 sera generally showed a stronger reaction with rVP2 than with IPNV, except for one rabbit anti-rVP2 serum that reacted more strongly with IPNV than with rVP2. In Western blotting, both anti-rVP2 and anti-IPNV sera reacted well with viral VP2 and rVP2, but all anti-IPNV sera also reacted with VP3. IPNV-neutralising antibodies were detected in all tested anti-IPNV sera but not in anti-rVP2 sera. However, the anti-rVP2 and anti-IPNV sera had comparable IPNV titre-reduction capacity when immunocomplexes were subtracted from a mix of IPNV and antisera, indicating an antiviral effectin vivo.