DEVELOPMENT OF AN IHN RESISTANT STRAIN OF RAINBOW TROUT

Infectious hematopoeitic necrosis (IHN) is a highly contagious rhabdoviral disease of important species of trout and salmon. There are presently no proven or accepted methods for prevention or treatment of IHN. Under the intensive conditions of aquaculture, IHN virus (IHNV) causes significant losses at nearly all stages of production. The results of Phase I studies indicated that intraspecific variation for IHNV resistance exists in rainbow trout and steelhead. The results of molecular genetic studies indicated that sufficient genetic variation exists both within and between the two strains of Oncorhynchus mykiss to allow for identification of genetic markers associated with IHN resistance which would significantly reduce the time required to develop IHN resistant strains. The Phase II research will determine the linkage of molecular markers to quantitative trait loci (QTL) associated with resistance to IHN. Disease resistance has a high environmental component of variability in expression, making it difficult to not only study but also to breed for the trait. Finding a molecular marker that is linked to a QTL will permit more rapid gains in selection for improvement in IHN resistance by marker assisted selection. This approach has found widespread use in plant breeding for viral disease resistance.