The study of the rous virus synthesis in mammalian embryonic tissues growing in vitro.

The genome of Rous sarcoma virus was found in mouse and hamster embryo cells growing in vitro shortly after the infection and long before cell transformation occurred. The virus genome was not detected in embryo cells when they were treated with actinomycin D or when the temperature of incubation was lowered to +20 degrees C. This suggested that the synthesis of Rous virus genome could have taken place de novo in the cells investigated.