Effect of simian virus 40 on the temporal and spatial organization of DNA replication in Muntjac cells.

We examined the effects of simian virus 40 infection on the temporal and spatial organization of initiation sites for DNA replication in Muntjac cells by means of light microscopic DNA fiber autoradiography. Initiation at multiple sites along the DNA fiber in virus-infected confluent Muntjac cells was more nearly synchronous than in serum-deprived controls, although temporal control in the infected cells did not reach the level observed in cells incubated in serum-enriched medium. Initiation sites in virus-infected cells appeared to be spatially closer together than in either uninfected serum-deprived or uninfected serum-enriched cells. This change did not appear to be the result of the induction or repression by simian virus 40 of clusters of replication units with new and different organizations.