DETECTION AND CHARACTERIZATION OF RAINBOW-TROUT ANTIBODY AGAINST INFECTIOUS HEMATOPOIETIC NECROSIS VIRUS

Sera from 143 rainbow trout Oncorhynchus mykiss surviving 1 and 5 exposures to infectious hematopoietic necrosis virus (IHNV) were analyzed for specific antibody against the virus with an enzyme linked immunoassay (ELISA), plaque neutralization test (PNT) and western blot. By the ELISA, 92 % of all survivors demonstrated antibodies against IHNV, while 82 % of them showed neutralizing antibodies against the virus by PNT. A correlation analysis (Kendall's Tau-b) performed on the ELISA values and PNT values indicated the results of the 2 assays correlated (p < 0.05). Sera from fish which had survived 1 exposure (1 X) to IHN had similar ELISA and PNT values compared to fish which had survived 5 exposures, but were rested in pathogen-free water for 80 d before bleeding (5 X R). Fish which had survived 5 exposures (5 X) and bled 20 d after placement in pathogen-free water had a significantly different distribution of titer values compared to the other 2 groups. Sera from survivors were reacted in a western blot with the 5 IHNV proteins and probed with a monoclonal antibody recognizing trout immunoglobulin. The majority (74/143) of the trout sera gave no reaction in the western blot. In the groups of survivors which gave positive reactions, the proteins most frequently recognized were the viral membrane protein [M1] by 1 X survivors (9/28) and the glycoprotein [G] by 5 X survivors (38/82). The group of 5 X R survivors also recognized G (10/33) most frequently.