Abstract
When chick embryo cells were infected with fowl plague virus, the rate of protein synthesis fell to 30 to 40% of controls by 8 hr after infection. This effect was prevented by ultraviolet irradiation of the virus, but more slowly than the capacity to produce infectious virus. The inhibition of protein synthesis was not delayed by incubation of the cells with 1 µg./ml. of puromycin for 5 hr, but addition of 50 µg./ml. of puromycin or cycloheximide delayed development of the inhibitory effect. No inhibition developed in cells which had been incubated with partially purified interferon before infection. Addition of p-fluorophenylalanine did not affect the development of the inhibition, which was also unaffected by addition of actinomycin or by ultraviolet irradiation of the cells. The effect was thought to depend upon the synthesis of a virus-directed protein using the RNA of the infecting virus.