Enhanced Production of Virus-Inhibiting Factor (Interferon) in Human Diploid Cells by Ultraviolet Irradiation and Temperature Shift-Down after Stimulation with Newcastle Disease Virus

Abstract

The production of the virus-inhibiting factor or interferon (IF) was highest in cells incubated at 37 C after inoculation with Newcastle disease (ND) virus and decreased as the incubation temperature was lowered. Shift-down of incubation temperature to 32 C or 34 C after incubation at 37 C for 4-7 hr enhanced IF production in cell cultures stimulated with ND virus, as compared with cultures incubated continuously at 37 C. Shift-down to 32 C after incubation at 37 C for 6 hr was optimal for this enhancement of IF yield. Enhanced IF production was also observed in cell cultures irradiated by ultraviolet light 4-7 hr after stimulation with ND virus.