Herpesvirus cyprini: biological and oncogenic properties.

In the present paper, we described the general biological properties and the oncogenicity of Herpesvirus cyprini or cyprinid herpesvirus 1 (CHV) (SANO, et al., 1984) which were isolated from nine papilloma tissues developed on the skin or the caudal fin of Japanese carp. The virus size were as follows; envelope diameter 190.4p27.2 nm, projection length 20.5p4.4 nm, capsid diameter 113.4p8.6 nm. This herpesvirus showed good significant growth on FHM and MCT. The virus titer on FHM cells reached more than 105.5 TCID50/ml at 20°C incubation temperature for 14 days. Syncytium formation was not found in these cell lines. Both FHM and EPC cells infected with this virus possessed intranuclear inclusion, Cowdry type A. It occupied a relatively large area revealing rather irregular shape. The virus titer reduction of over 103 TCID50/ml occurred before and after treatment with ether, pH 3, 50°C heating and IUdR.A cluster of the virus particles was found inside and outside inclusion body in FHM cells infected with the virus. Virus particles were more numerous in the karyoplasm undergoing karyorrhexis. Budding immature virus particle from the nuclear membrane, as well as released virions in intracellular space, were observed.Oncogenicity trial which we performed using common carp revealed grossly tumors on three fish out of ten. These tumor formations occurred more than five months after inoculation at 15.2°C of rearing temperature. The tumor cells induced in Asagi carp inoculated with the virus showed many virus particles in the karyoplasm and the cytoplasm. The experimentally induced tumors on common carp and spontaneously-developed tumors on colored carp possessed the property to be desquamated at the natural condition.