It recognizes a 68 kDa protein corresponding to ISAV nucleoprotein. ISAV is an enveloped virus that belongs to the family Orthomyxoviridae and genus Isavirus. Its genoma comprises eight negative-sense, single-stranded RNA segments and encodes four major structural proteins including the matrix, the nucleoprotein, and two membrane glycoproteins (hemagglutinin-esterase and gp50). ISAV infects mainly endothelial cells and leukocytes and causes a multisystemic disease characterized by high mortality with exophthalmia, pale gills, ascites, hemorrhagic liver necrosis, and renal interstitial hemorrhage. Infectious salmon anemia or anaemia (ISA) is a viral disease of Atlantic Salmon (Salmo salar) that affects fish farms in Canada, Norway, Scotland and Chile, causing severe losses to infected farms. The disease is listed as a non-exotic disease of the EU and is therefore watched closely by the European Community Reference Laboratory for Fish Diseases. The aetiological agent of ISA is the infectious salmon anemia virus (ISAV). ISAV, a RNA virus, is the only species in the genus "Isavirus" which is in the family Orthomyxoviridae.