ANTIGENIC ANALYSIS OF REFERENCE STRAINS AND NORWEGIAN FIELD STRAINS OF AQUATIC BIRNAVIRUSES BY THE USE OF 6 MONOCLONAL-ANTIBODIES PRODUCED AGAINST THE INFECTIOUS PANCREATIC NECROSIS VIRUS N1 STRAIN

Six monoclonal antibodies (MAbs) produced against the infectious pancr eatic necrosis virus (IPNV) N1 strain were used in a dot-blot assay to examine reference strains of the nine proposed serotypes and a repres entative selection of 81 Norwegian aquatic birnavirus isolates. These isolates had earlier been serotyped by use of a panel of 11 MAbs produ ced against other strains of IPNV. Correlations between the reaction p atterns of the two panels of MAbs were found. All reference strains an d field isolates shared two epitopes, one on VP2 and one on VP3. Seven ty-seven of the field isolates reacted identically with the N1 strain (positive with all six MAbs). The Sp type strain was positive with fiv e of the MAbs and was different from all the field strains. The other reference strains (WB, VR299, Ab, Ja, Te, He, C1, C2 and C3) were posi tive with two to four of the MAbs. Together with previously published data, these findings indicate that most Norwegian isolates are closely related to, or identical with, the Nl strain and belong to the Sp ser otype. No correlation between the health status of Atlantic salmon and antigenicity of the isolates was found. Testing of the reference stra ins in ELISA revealed some discrepancies with the dot-blot results.