Photodynamic induction of an oncogenic virus in vitro.

Infectious simian virus 40 (SV40) was induced from SV40-transformed hamster kidney cells by treatment with proflavine and visible fluorescent light. The optimum levels of SV40 induced were about three orders of magnitude above spontaneous background levels observed with untreated cells. No virus induction above background levels was found by treatment of cells with either proflavine or light alone.