Oncogenicity by DNA tumor viruses: enhancement after ultraviolet and cobalt-60 radiations.

Simian virus-40, polyoma, and LLE46 virus preparations were treated with ultraviolet or gamma radiations (cobalt-60) in a frozen state. Infectivity and induction of complement-fixing antigen and DNA synthesis declined as a logarithmic function of dose, the latter two properties being more resistant than infectivity to radiation by a factor of 2 to 5. Oncogenicity of all three viruses did not decrease with progressive amounts of both types of irradiation, but actually increased in absolute and relative terms (per infectious unit), even at the maximum dose of irradiation used (24,000 ergs per square millimeter per minute and 2.7 x 10(6) rads).