Isolation in cell culture of nodavirus from farmed Atlantic halibut Hippoglossus hippoglossus in Norway

Isolation in cell culture of nodavirus from Atlantic halibut Hippoglossus h ippoglossus suffering from viral encephalopathy and retinopathy (VER) is de scribed. The cell line SSN-1 was inoculated with tissue material from affec ted juveniles (60 d after first feeding). Extensive cytopathic effects (CPE ) developed approximately 5 d after inoculation, and were also observed aft er several passages in the same cell line. Cells from infected cultures sho wed reactivity with an antiserum against sea bass Dicentrarchus labrax noda virus in an indirect immunofluorescence test. Analysis of infected cells wi th reverse transcriptase-polymerase chain reaction (RT-PCR) resulted in a p roduct of the predicted size using primers specific for striped jack Pseudo caranx dentex nodavirus. Electron micrographs of infected SSN-1 cells demon strated virus particles that were approximately less than 30 nm. Challenge of Atlantic halibut larvae (4 d post-hatching) with supernatants from infec ted SSN-1 cells resulted in development of VER as verified by immunohistoch emistry performed on larvae sampled from Day 9 after challenge. The present results show that a nodavirus from Atlantic halibut has been isolated usin g the SSN-1 cell line and that virus propagated in cell culture retained vi rulence.