Effect of 5-bromo-2'-deoxyuridine on the in vitro DNA synthesizing activity of polyoma virus-infected cells.

The in vitro synthesizing activity of uninfected and polyoma virus-infected mouse embryo (ME) cells was investigated by measuring the incorporation of 3H-thymidine (dTR) into acidinsoluble material in cell-free extracts. The character of the enzyme reaction was described in uninfected cells and an activating effect of 0.01 M dithiothreitol (DTT) was observed. A variation of the enzyme activity in the course of cultivation of ME cells in primary culture was demonstrated. The induction of the DNA synthesizing activity due to polyoma virus infection was markedly increased in the presence of 5-bromo-2-deoxyuridine (BUDR), what emphasizes the importance of the de novo synthesized viral and/or cellular DNA in the regulation of induction enzymes participating in DNA synthesis.