Lymphocystis Disease in Kurosoi Sebastes schlegeli and Hirame Paralichthys olivaceus in Hokkaido, Japan

Abstract

Lymphocystis disease of Kurosoi Sebastes schlegeli and cultured and wild Hirame Paralichthys olivaceus in Hokkaido, Japan was studied by light and electron microscopy.
Seasonal variation in the incidence of lymphocystis was recognized and the incidence of lymphocystis was greatest in July (37%) in the cultured Hirame.
Lymphocystis cells were observed mainly on the fins of Kurosoi and were observed in various places on the body surface of Hirame.
Lymphocystis cells showed characteristics figures, including cellular hypertrophy, cell enclosure by a distinctive hyaline capsule, enlarged nucleus and granular-appearing cytoplasm with prominent inclusions.
The virus particles were polyhedral, represented as hexagonal or pentagonal profiles in sections. They are about 273nm in mean diameter in Kurosoi and about 259nm in mean diameter in both cultured and wild Hirame. They may often be seen in crystalline array and they are always located in the cytoplasm. Virogenic particles were observed around the inclusion body see on light microscopy.