Infectious pancreatic necrosis: Selection of virus-free stock from a population of carrier trout

Infectious pancreatic necrosis (IPN) is a virulent disease of young trouts and is easily transmitted from infected animals through water and with eggs. At present, the most effective control measure consists of propagation of specific pathogen-free stock. Methods are described for using fish cell cultures to detect IPN virus in peritoneal washes, feces, and gonadal fluids and thereby to identifiy carrier and non-carrier fish. The procedures were used to derive virus-free progeny from a hatchery trout population containing about one-third carrier fish. The progeny were reared to maturity, spawned for 3 successive years, and at each spawning they proved free of virus. Recommendations and precautions are given for those who may wish to apply the procedures.