Transmission of Infectious Pancreatic Necrosis Virus in Oncorhynchus mykiss
Presented by: Lara Colton
Mentor: Paul Reno
Hatfield Marine Science Center, Oregon State University

Abstract
Infectious pancreatic necrosis virus (IPNV) is a double-stranded RNA virus which causes high mortality in most sainionid fish species, creating high losses to the aquaculture industry. IPNV has also been detecte(i in i-nany marine species. The destruction of infected fish is the only effective prevention method available. The definitive methods by which IPNV is transferred among feral, hatchery, freshwater and saltwater fish are undetermined. To address the mechanism of transmission, eight isolates of IPNV were obtained froni Steelhead trout (Oticoi-hytichils mykiss) reared in facilities along the Columbia River in Washington and ftom other sites in Idaho. Isolates from the Snake River in southei-n Idaho liave been characterized as the Buhl-Al serotype. However, isolates from the Clai-k Fork River near Lake Pend Oreille in northern Idaho have been characterized as West Buxtoii, Buhl and Jasper serotypes. Through an immunodot assay, the Washington isolates were all determined to be of the Buhl-A I serotype, which has not been detected previously in ttie state of Washington. Infori-nation was then obtained from hatchery records in Washington to determine tile possible origin of the fish from whicii these particular viruses were isolated. The information obtained indicates the most likely mechanism of transfer is that of vertical transmission (parent to progeny). The origin of the virus in the Washington fish was probably from infected Idaho Steelhead. Currently, sequencing of the viral genome is being undertaken. The sequences of the eight isolates from Washington will be compared with similar serotypes already sequenced from Idaho. This may establish clearer evidence concerning the method and extent of the BLihi serotype transmission. Insights into the transmission of IPNV may lead to a better understanding of more effective prevention methods and reduce fish losses to the aquaculture industry.