抄録
Small DNA-containing tumor viruses (simian virus 40, mouse polyoma-virus, and adenoviruses) malignantly transform fibroblasts of the susceptible rodents. Fibroblasts can exist, in vitro and in vivo, in either of the two states: the proliferating state or the quiescent state. In the present study, we examined whether the state of fibroblasts at the time of exposure to these DNA viruses affects the frequency of transformation. Dense-focus formation in monolayer culture of rat 3Y1 fibroblasts was used to quantitate transformation. Results show that the frequency of transformation by simian virus 40 and mouse polyomavirus was reduced when cells were in the proliferating state at the time of virus inoculation as compared to cells in the quiescent state, whereas that by adenovirus type 12 was similar in the two cellular states. The reduction of the frequency of transformation in proliferating cells infected with simian virus 40 was also observed in BALB/c 3T3 mouse cells. Mechanisms underlying the difference between the two cellular states and the difference between the papovavirus and adenovirus in this aspect of transformation remain to be investigated.
