On the Mechanism of Selective Inhibition of Herpesvirus Replication by (E)-5-(2-bromovinyl)-2′-deoxyuridine

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 78; no. 5; pp. 2698 - 2702
• Main Authors: Allaudeen, H. S., Kozarich, J. W., Bertino, J. R., De Clercq, E.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.05.1981; National Acad Sciences
• Subjects: Antiviral Agents - pharmacology; Antivirals; Biochemistry; Bromodeoxyuridine - analogs & derivatives; Bromodeoxyuridine - pharmacology; Carcinoma; Cell Line; DNA; DNA Polymerase II - metabolism; DNA-Directed DNA Polymerase - metabolism; Enzymes; Herpesviridae; Human herpesvirus 1; Humans; KB cells; Kinetics; Mouth Neoplasms; Nucleosides; Simplexvirus; Simplexvirus - drug effects; Simplexvirus - enzymology; Virus Replication - drug effects; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.78.5.2698

Bromovinyldeoxyuridine (BVdUrd) is a potent antiherpesvirus compound with low cytotoxicity. To gain an insight into its selectivity and mechanism of inhibition, we chemically synthesized the 5′-triphosphate of BVdUrd, BVdUTP, and tested its effect on the activities of DNA polymerases [DNA nucleotidyl-transferase (DNA directed), EC 2.7.7.7] of two herpesviruses--i.e., herpes simplex virus type 1 (HSV-1) and Epstein-Barr virus (EBV)--as well as cellular DNA polymerases α , β , and γ . The effects on the DNA polymerases were determined under assay conditions optimal for the individual polymerases. We found that the BVdUTP was considerably more inhibitory to the utilization of dTTP by the HSV-1 DNA polymerase than by the cellular DNA polymerases. For instance, as little as 1 μ M BVdUTP inhibited the utilization of dTTP by HSV-1 DNA polymerase 50%, whereas the same concentration inhibited the DNA polymerase α and the DNA polymerase β activities only 9% and 3%, respectively. The BVdUTP inhibited DNA synthesis by competing with the natural substrate, dTTP. The Kmfor dTTP and the Kifor the BVdUTP of the HSV-1 DNA polymerase were 0.66 and 0.25 μ M, respectively. Kinetic analyses with the DNA polymerases α and β and the EBV DNA polymerase also reflected a similar difference in sensitivity between the HSV-1 enzyme and other enzymes. Increasing the concentration of either the DNA template or the enzyme in the reaction mixture did not bring about a significant change in the extent of inhibition. Preincubation of the inhibitor with the enzyme was not necessary for inhibition. Studies on time course of inhibition revealed that the compound is inhibitory even after the initiation of DNA synthesis. These studies indicate that the ability of BVdUTP to preferentially inhibit the HSV-1 DNA polymerase may contribute towards its selective inhibition of the viral DNA replication in infected cells.