INDUCTION OF CELLULAR DNA SYNTHESIS BY POLYOMA VIRUS

The transformation of normal cells into tumor cells by polyoma virus is caused by the interaction of susceptible cells with the DNA of the virus. Thus, purified polyoma virus DNA has been shown to transform cells cultured in vitro,1 whereas the empty protein shells of the virus do not produce this effect.2 Consequently, a knowledge of the functions of the viral genes is basic to an understanding of the mechanisms of cell transformation. With the hope of identifying these functions, we have initiated a study of the biochemical events which occur after the cytocidal infection of mouse kidney cells by polyoma virus. This article describes the effects of virus infection upon DNA synthesis and upon the activity of enzymes involved in DNA synthesis. One of the most interesting findings was that the virus induces the synthesis of cellular DNA in addition to viral DNA.