Key words: FV 3/arginine/DNA replication~nuclear ocalization Fate of Frog Virus 3 DNA Replicated in the Nucleus of Arginine-deprived

In a productive infection, frog virus 3 (FV 3) DNA was synthesized in both the cell nucleus and cytoplasm. The infection was aborted in arginine-starved Chinese hamster ovary cells and viral DN A replication was then restricted to he nuclear compartment. It has been demonstrated that the newly synthesized FV 3 DNA present in the nucleus is of genomic size. After the addition of arginine, this DNA is transferred into the cytoplasm and can be encapsidated. The formation of infectious particles occurred even if an inhibitor of DNA synthesis was added simultaneously with arginine. Although the synthesis of early FV 3 polypeptides and their intracellular distribution were comparable in the presence or in the absence of arginine, the production of late species was greatly reduced by arginine deprivation; one of these late proteins must be involved in the passage from the nuclear to the cytoplasmic phase of FV 3 DNA replication. This system made it possible to carry out an independent analysis of the nuclear events that comprise the first stage of FV 3 multiplication