Identification of a UV-induced trans-acting protein that stimulates polyomavirus DNA replication.

Previous studies provided indirect evidence that the ability of a variety of DNA-damaging agents to induce asynchronous polyomavirus DNA replication in the H3 rat fibroblast cell line is mediated by a trans-acting factor. Using an erythrocyte insertion technique to introduce protein fractions from UV-irradiated cells into unirradiated H3 cells, we have now obtained evidence that this factor is a 60-kilodalton protein. These findings provide evidence that DNA damage in mammalian cells induces a factor that can alter the replication of a viral DNA.