Grunt fin (GF) cells. For the preparation of a vaccin the supernatant of RSIV-infected GF cells, the culture
medium of RSIV-infected GF cells was cen-tnfuged at 2500 X g for 10 min at 4°C. Formalin (0.1V/V) was then added to the supernatant, which con tained 107.5T CIDSOm l-' of the virus, and the virus was inactivated for 12 d at 4°C; then inactivation of the virus was confirmed. The other group, which served as controls, were non-treated. After vaccination, the vac
cinated fish were kept in tanks for 1 wk then moved to a seawater net pen (2.5 X 2.5 X 2.5 m).