Evaluation of a Subunit Vaccine to Infectious Hematopoietic Necrosis Virus, July 31, 1988 to September 20, 1989 Annual Report.

A recombinant DNA vaccine to IHNV was prepared and tested in field trials at Clear Springs Trout Company's Box Canyon Hatchery in Buhl, Idaho this year in Phase III of the project. The vaccine under consideration in these field trials consisted of lysed bacteria that contained a plasmid which expressed an antigenic portion of the IHNV glycoprotein. In addition, laboratory trials with a bacterial expressed viral nucleoprotein indicated that this served as an immune adjuvant. Therefore, a decision was made to conduct these field trials on a vaccine containing both IHNV glycoprotein and IHNV nucleoprotein. Original plans to conduct the field trial at Dworshak National Fish Hatchery were canceled because a management decision was made by Dworshak Fish and Wildlife personnel to rear steelhead salmon eggs from IHNV positive parents at Kooskia National Fish Hatchery. This decision, which was made without prior notification to us, resulted in some discussion at the IHNV committee meeting convened by the Fish and Wildlife Service in Moscow, Idaho on April 27, 1989. At that time, the authors dismay at this decision was voiced and the prediction that an outbreak of IHNV would occur at Kooskia was made. In less than a week, a massive IHNV outbreak did occur at Kooskia and plans to run a field trial at this facility had to be discarded. An alternative site was found at the Box Canyon Hatchery site of Clear Springs Trout Company. Dr. Robert Busch, Director of Research and Development for Clear Springs Trout Company, offered the use of the site. In preparation for the site change they consulted Mary Buckman, Oregon Department of Fish and Wildlife statistician, and they obtained a sample of the IHN virus present at Box Canyon. The Box Canyon virus isolate was typed by reactivity with monoclonal antibodies by Dr. Sandra Ristow at Washington State University. There was insufficient time to examine the vaccine efficacy with the Box Canyon virus isolate in laboratory trials and they had to prepare for field trials without this supporting data. In addition, they had to make numerous changes in the vaccination schedule and in the design of the challenge to accommodate the new site. Most importantly, an application for a change in site had to be approved by the Idaho State Veterinarian and the Veterinary Biologics Group at the USDA National Office in Hyattsville, Maryland. A new work plan was formulated, approvals were obtained, the demands for statistical analyses were satisfied in the new work plan, and 20,000 rainbow trout fry were vaccinated on July 19, 1989. The following is a summary of the results of the work that was initiated at Box Canyon Hatchery