Abstract
The characteristics of virus (strain H-83) isolated from apparently healthy masu salmon (Oncorhynchus masou) were investigated. The isolate replicated in line cells derived from salmonid fish but not in those from non-salmonid fish. Cell monolayers infected with the virus showed cytopathic effect characterized by syncytia with intranuclear inclusion bodies and many metachromatic granules in the cytoplasm. Enveloped virions were estimated to be approximately 250nm in diameter and possessed hexagonal nucleocapsides of 103 to 118nm. The physicochemical and morphological features indicated that the strain H-83 is a herpesvirus. Viral antigens were detected in the cytoplasm and membrane of virus-infected cells by immunofluorescent antibody test. Cross neutralization test among strain H-83 and two other herpesviruses, Herpesvirus salmonis and Oncorhynchus masou virus (OMV), indicated that these three viruses were serologically different from each other. Further, the restriction endonuclease cleavage analysis of viral DNA showed that the cleavage pattern of the strain H-83 DNA was similar to that of OMV, while apparently distinct from H. salmonis.
