Enhancement of biochemical transformation of mammalian cells by herpes simplex virus following nitrosomethylurea treatment.

A quantitative assay for the biochemical transformation of thymidine kinaseless mouse cells (N cIA cI10 cells) to an enzyme-positive phenotype by herpes simplex virus has been used to examine the effect of the carcinogen nitrosomethylurea on cell transformation. Exposure of cells to the chemical carcinogen, followed by virus infection, resulted in enhancement of transformation when compared to that seen with virus or chemical alone. Enhancement occurred after doses of nitrosomethylurea that were nontoxic to treated cells. A strong time dependence after treatment was demonstrated for enhancement which was correlated with the presence and excision-repair of alkylated DNA in treated cells.