Identification and characterization of segments 3 and 4 of the ISAV genome

Infectious Salmon Anaemia is a serious disease of farmed Atlantic Salmon on three continents. The disease causes severe anaemia and haemorrphagic live r necrosis, and carries major economic consequences for affected areas. Nev ertheless, the causative agent, a novel orthomyxo-like Virus (Infectious Sa lmon Anaemia Virus - ISAV), is only partially characterized at the molecula r level. We report the isolation and characterization of two novel ISAV seg ments at the genomic and proteomic levels. These segments are the third and fourth largest of the (ISAV) genome and may code for a nucleocapsid protei n (NP) and a polymerase (PA). Western blot analysis using an ISAV polyclona l antibody identified one of these novel proteins as being the major tissue antigen. We discuss the implications of our findings for vaccine developme nt and surveillance of Infectious Salmon Anaemia.