ABSTRACT
Nervous necrosis virus (NNV) belongs to the Nodaviridae family, which typically causes viral encephalopathy and retinopathy (VER). VER was rst reported to be present in barramundi (Lates calcarifer) farmed in Australia (Glazebrook et al. 1990). There are over 30 species of culture marine sh that could be infected by NNV worldwide (Munday et al. 2002). An acute infected sh typically shows loss of appetite, darker skin color, and abnormal spiral swimming behavior. In histology, this acute infection usually shows serious VER symptoms, such as vacuolating necrosis in the brain, retina, and spinal cord. This acute infection could nally cause such high mortality of up to 100% in larval and juvenile sh (Tanaka et al. 2004).
