Abstract
The pathological characteristics of salmonid herpesviruses (strain H-83, and OO-7812 strain of Oncorhynchus masou virus (OMV)) to three species of salmonid fish and the antibody production of the fish to the viruses were investigated. The strain H-83 was pathogenic to masu salmon (O. masou) and rainbow trout (Salmo gairdneri) fry. OMV was also pathogenic in masu salmon and coho salmon (Oncorhynchus kisutch) fry. Coho salmon developed tumors in the eyes and in and around the oral cavity. From the results of virus re-isolation, the liver seemed to be the target organ of OMV infection. In vitro passages of both herpesviruses resulted in the decrease of pathogenicity to masu salmon. Yearling masu salmon and rainbow trout appeared not to be sensitive to the infection with the strain H-83. The fish produced virus-neutralizing antibody but the antibody titers were relatively low. The expression of seconday immune response was observed.
