Infectious hematopoietic necrosis virus

Infectious hematopoietic necrosis virus (IHNV), is a negative-sense single-stranded RNA virus that is a member of the Rhabdoviridae family, and from the genus Novirhabdovirus. It causes the disease known as infectious hematopoietic necrosis in salmonid fish like trout and salmon. IHNV is commonly found in the Pacific Coast of Canada and the USA, and has also been found in Europe and Japan. IHNV is transmitted following shedding of the virus in the feces, urine, sexual fluids, and external mucus and by direct contact or close contact with surrounding water. The virus gains entry into fish at the base of the fins.

Clinical signs of infection with IHNV include abdominal distension, bulging of the eyes, skin darkening, anemia and fading of the gills. Infected fish commonly hemorrhage in several areas; the mouth and behind the head, the pectoral fins, muscles near the anus, and (in fry) the yolk sac. Diseased fish weaken eventually floating “belly-up” on the surface of the water. Necrosis is common in the kidney and spleen, and sometimes in the liver.

The complete RNA genome of IHNV has been sequenced. This virus encodes a leader sequence of 60 amino acids and 6 proteins; nucleocapsid (N), polymerase-associated phosphoprotein (P or M1), matrix protein (M or M2), surface glycoprotein (G), non-virion protein (NV) and virus polymerase (L).