Abstract
TUMOUR promoters of the diterpene type efficiently induce Epstein-Barr virus (EBV) and additional persisting herpes viruses in genome-harbouring lymphatic cells1,2. The tumour-promoting activity of these substances to some extent parallels their efficiency in virus induction2: the most active tumour promoters induce EBV even at concentrations of 10−10–10−9 M, whereas 100–500-fold higher concentrations are required for induction by weak promoters. Treatment of cells with tumour promoters results in a fast and reproducible increase in the activity of ornithine decarboxylase (ODC)3,4 up to 250-fold levels of normal activity. Recent reports5,6 described the inhibition of ODC induction by pretreating the cells with retinoic acid. Moreover, retinoic acid has been reported to act as an inhibitor in experimental 2-stage carcinogenesis models7. We have therefore investigated the possible interaction of retinoic acid with virus induction by tumour promoters. The effect of retinoic acid was also studied on the induction of early antigens (EA) of EBV by the pyrimidine analogue, iododeoxyuridine (lUdR)8,9, by treatment of IgM- producing cells with anti-IgM antibodies10 and by superinfection with EBV from P3HR-1 cells11,12. The data indicate that retinoic acid specifically interferes with induction by non-viral reagents without affecting EBV antigen synthesis after superinfection.
Published Version
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