Retinoic acid and steroids inhibit Epstein-Barr virus-induced nuclear antigen, DNA synthesis and lymphocyte transformation.

Retinoic acid, dexamethasone and prednisolone were evaluated for their effects on Epstein-Barr virus (EBV)-induced nuclear antigen (EBNA), DNA synthesis and transformation of human thymus-independent, B lymphocytes. It was found that continuous treatment of target cells with these agents completely inhibited EBV-induced transformation events. However, discontinuous treatment of the virus-infected cultures with these agents resulted in the recovery of DNA synthesis, and the appearance of EBNA and transformation. When the cells were treated with these agents 8 days after the virus infection, the inhibitors had no effect. These results show that only continuous treatment with these agents inhibited EBV-mediated transformation; these inhibitors had no effect once the EBNA and EBV-induced DNA synthesis were initiated in target lymphocytes.