RELATIVE ULTRAVIOLET RADIATION TARGET SIZE OF CERTAIN FUNCTIONS OF POLYOMA VIRUS

It has been shown earlier for polyoma virus that the radiation target size for ability to transform is five times smaller than for ability to form plaques. In the present experiments ultraviolet irradiation has been applied in a similar manner in order to study two further characteristics of polyoma virus: ability to induce nuclear T antigen and ability to induce homograft rejection antigen. The results show that about half the viral genome is required for the former but only a sixth for the latter. It is concluded that the more sensitive attribute of the virus (determining nuclear T antigen) is present in cells transformed by the more resistant part of the viral genome. This is explained by the fact that after irradiation, a larger number of virions can cause abortive infection of cells that can cause transformation, thus leading to a relative increase in the power to transform. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company