Sequence of spontaneous Epstein-Barr virus activation and selective DNA synthesis in activated cells in the presence of hydroxyurea.

The sequence of spontaneous Epstein-Barr virus activation was studied in P3HR-1 carrier cells and in P3HR-1(BrdU) cells made resistant to 5-bromodeoxyuridine. Virus activation was initiated during the normal cell cycle, and recruitment of additional virus-activated cells was prevented by the DNA inhibitors, 1-beta-D-arabinofuranosylcytosine and hydroxyurea. Virus activation was followed by synthesis of the early antigen complex in the absence of additional detectable DNA synthesis. Early antigen synthesis was followed by hydroxyurea-resistant synthesis of new DNA, which in the case of P3HR-1(BrdU) cells was characterized by the appearance of thymidine kinase. The newly synthesized DNA banded in neutral cesium chloride at peaks corresponding to normal human DNA and Epstein-Barr viral DNA. Synthesis of viral antigen was seen only in cells that had undergone hydroxyurea-resistant DNA synthesis.