TABLE 1.

Isolation of the virus responsible for mortality in carp^a

Subjects for expt	Result of indicated expt (no. of dead fish/no. of inoculated fish [%] or no. of plaques/culture [for expts with KFC])
	Inoculation with infected cell extracts	Inoculation with medium from uninfected KFC	Inoculation with medium from infected KFC
Fish	15/20 (75)	0/15 (0)	14/17 (82)
KFC cocultivated with 104 fish cells	1.8 × 102	0	1.5 × 102
Fish	Not done	0/10 (0)	4/10 (40)

^aMedium and cells extracts harvested from the fifth passage of the virus in cell culture were used for intraperitoneal injection of juvenile naive carp (top row). Kidney cells taken from an inoculated fish from each group were cocultivated with KFC (middle row). The medium harvested from KFC that were cocultivated with carp cells (middle row, last column) was transferred three times in KFC and then used to reinfect juvenile carp (bottom row).