Infectious hematopoietic necrosis (IHN) is a highly infectious rhabdoviral disease of important species of trout and salmon. both cultured commercially and as part of Federal and State sport fisheries and enhancement programs. There are presently no proven or accepted methods for prevention or treatment of IHN. Under the intensive culture conditions of aquaculture, IHN virus (IHNV) can cause significant losses at nearly all stages of production. The results from preliminary studies suggest that intraspecific variation for IHNV resistance exists in rainbow trout, steelhead, and reciprocal crosses and this may be useful in breeding used to enhance for this trait. In addition to evaluating select crosses for IHNV resistance, molecular approaches will be used to identify genes associated with resistance. We anticipate demonstrating the feasibility of using PCR based RAPD analysis to identify unique genetic differences between trout groups differing in the IHNV susceptibility phenotype and to develop an initial set of markers for detailed genetic analyses during the second phase of these studies.Applications:The level of resistance to IHNV infection in rainbow trout, steelhead, and reciprocal crosses will be assessed and genetic variability levels estimated. Growth of pure species and reciprocal crosses will be assessed under production conditions. Additionally, genetic differences between and within species will be examined. Identification of genetic markers associated with IHN resistance would significantly reduce the time required to develop IHN resistant strains. This could save millions of dollars of lost salmonid production and reduce the costs of fish health monitoring.
