CHARACTERIZATION AND PATHOGENICITY OF A H ERPESVIRUS ISOLATED FROM CUTANEOUS LESION IN JAPANESE EEL, ANGUILLA-JAPONICA

A disease showing erosive and ulcerative cutaneous lesions occurred in Japanese eels Anguilla japinica, reared in warm-water ponds in the sp ring of 1992. In this study, virological investigation, histological a nd electron microscopic observations were performed in both naturally and experimentally infected eels. A herpesvirus was isolated from the skin lesions and EK-1 cells inoculated with the isolated virus formed polynulcear giant cells at 25 degrees C within 2 days after inoculatio n. The isolate was neutralized with an anti-Herpesvirus anguillae seru m. Electron microscopy revealed enveloped virions with a diameter of 2 00nm in the cytoplasmic vesicle and nucleocapsids with a diameter rang ing 114-115nm in nuclei of infected EK-1 cells. the isolate did not ha ve lethal effect on eels during rearing period of 14 days at 25 degree s C. were produced at the inoculated sites. Histologically, the cutane ous lesions of naturally as well as experimentally infected fish, show ed similar signs: fibrocytes in the dermis were infected and necrotize d, accompanied with necrotic changes of melanocytes and subsequent inf iltration of inflammatory cells. The fibrocytic necrosis and the infil tration of inflammatory cells extended into the subcutaneous adipose t issue and lateral musculature.