Characterization of Epstein-Barr virus-related thymidine kinase induced in nonproducer cells by superinfection or chemical treatment.

Chemical treatment with a combination of 12-O-tetradecanoylphorbol-13-acetate and n-butyrate or superinfection with P3HR-1 virus effectively induced a novel thymidine kinase (TK) in Raji and NC37 TK-negative mutant cells. Sera from patients with nasopharyngeal carcinoma containing a high antibody titer against Epstein-Barr virus early antigen could inactivate this induced enzyme while sera from normal donors, even those containing a high titer of antibodies to virus capsid antigen, had no effect on the enzyme. Also, the induced enzyme was relatively insensitive to thymidine triphosphate inhibition.