Complex sentence: Infectious pancreatic necrosis is a severe viral disease of salmonid fish caused by a virus, infectious pancreatic necrosis virus (IPNV), which is a member of the birnaviridae family.
Split into simpler sentences: Infectious pancreatic necrosis is a severe viral disease of salmonid fish. It is caused by a virus called infectious pancreatic necrosis virus (IPNV), which is a member of the birnaviridae family.