Abstract
Infectious pancreatic necrosis (IPN) was first reported in freshwater trout in 1940’s in Canada and in 1950’s in the USA, and subsequently spread around the world. The causative agent, infectious pancreatic necrosis virus (IPNV), which was the first fish-virus isolated in a cell culture, is a double-stranded RNA virus in the family Birnaviridae. In 1960’s, Japanese rainbow trout aquaculture suffered a lot of fish losses at the fry stage, and the cause was confirmed to be IPNV by the virological study. In 1980’s, IPN in Japan has gradually calmed down due to being worked synergistically with hatchery biosecurity practice, increase of host resistance and decrease of virus virulence. However, it is still one of the obstacles in the Atlantic salmon industry in the world.
