Susceptibility of cells in different stages of the mitotic cycle to transformation by polyoma virus.

The susceptibility to malignant transformation by polyoma virus of cells infected in different phases of the mitotic cycle has been studied using the hamster fibroblast line BHK21 (clone 13). It appears that cell competence is not restricted to a portion of the mitotic cycle. However, susceptibility to transformation increases with the progress of the cell through interphase. The variations observed cannot be entirely ascribed to different degrees of virus adsorption. Moreover, the possibility that the cells engaged in DNA synthesis are the most susceptible has been excluded. The results are consistent with the hypothesis that the probability of transformation of a cell is directly related to its DNA content at the time of infection.