Polyoma "tumor antigen": an activator of chromosome replication?

We have studied the temporal relationship between the appearance of polyoma-specific "tumor antigen" and polyoma-induced activation of the cellular DNA-synthesizing apparatus in "contact-inhibited" mouse-kidney tissue-culture cells. The experimental results are compatible with the hypothesis that virus-induced replication of the mouse cell chromosomes, which accompanies the actual production of progeny virus, is triggered by the tumor antigen. On the basis of the experimental evidence at present available we propose a tentative scheme of the lytic cycle of polyoma virus, that is of the events which lead to and accompany the production of polyoma progeny virus.