Rapid Transformation of Cells by Rous Sarcoma Virus

The conditions for synchronous transformation of chick embryo cells by infection with Rous sarcoma virus are studied. Two factors, the treatment of cells with DEAE-dextran and the use of cells which grow rapidly following virus infection, are found to be most important. Under the conditions described, the Schmidt-Ruppin strain of Rous sarcoma virus at a multiplicity of higher than 5 induces morphological alteration in about 90 per cent of the cell population within 24 hours after infection. The alteration in the morphology is accompanied by acquisition of the ability of cells to grow in agar medium and by the increased rate of incorporation of thymidine and uridine into nucleic acids.