Characterization of a herpes-like virus isolated from cultured Japanese eels in Taiwan

The present paper describes a herpes-like virus, tentatively designated as EHVF (Eel Herpesvirus in Formosa), isolated from diseased Japanese eels (Anguilla japonica Temminck & Schlegel) in Taiwan. This virus had DNA as its nucleic acid, sensitive to ether and chloroform, and resistant to freezing and thawing treatments. Enveloped mature viral particle measured 200 nm in diameter with nucleocapsid of 120 nm. The virus successfully replicated in CCF, CCT, TO-2, BGK, DK-1 and EO-2 cell lines at temperatures from 15°C to 33°C (optimal temperature 24°C). When these cells were infected with EHVF, syncytium formations were observed in CCF, CCT, TO-2, BGK, EK-1 and EO-2 cell lines. However, HeLa, Vero, L, AF, AK, BF-2, CCG, CCO, CF, CHH-1, CHSE-214, EPC, FHM, FS, JF, LF, MH and RTG-2 cell lines were refractory to the multiplication of this virus. No mortalities were observed among eels injected with EHVF, but the virus was reisolated from the kidneys and livers of infected eels 60 days after injection. On the other hand, carp injected with EHVF showed 37% mortality during 60 days and the virus was reisolated from all the dead fish and 84% of the survivors.