Alteration of DNA metabolism in fowlpox-infected chick embryo monolayers

Secondary chick embryo monolayers infected with fowlpox virus incorporate more thymidine into acid-insoluble material than do control cells for the first 48–72 hr after infection. After this time incorporation in the infected cells falls below control levels. Separation of infected cells into nuclear and cytoplasmic fractions reveals that the major portion of the incorporation occurs in the nuclear fraction. Hybridization of DNA from infected cultures shows that little viral DNA is made before 12 hr post infection, while cellular DNA synthesis proceeds at an essentially normal rate during this time. Viral DNA is synthesized at a rapid rate from 12 to 48 hr while cellular DNA synthesis declines. Although little cellular DNA synthesis can be detected after 60 hr, fowlpox infection does not cause a rapid cessation of cellular DNA synthesis as has been shown for other poxviruses.