A proposed mechanism for the selective inhibition of human cytomegalovirus replication by 1-(2'-deoxy-2'-fluoro-beta-D- arabinofuranosyl)-5-fluorouracil

S Suzuki, HK Misra, LI Wiebe, EE Knaus and DL Tyrrell

The biological activities of 1-(2'-deoxy-2'-fluoro-beta-D- arabinofuranosyl)-5-fluorouracil (2'F-ara-FU), 1-(3'-deoxy-3'-fluoro- beta-D-arabinofuranosyl)-5-fluorouracil (3'F-ara-FU) and 1-beta-D- arabinofuranosylthymine (ara-T) were compared in human cytomegalovirus (HCMV)-infected and noninfected human fibroblasts. 2'F-ara-FU inhibited HCMV plaque formation (ED50, 16 microM for AD 169 strain) at lower concentrations than 3'F-ara-FU (ED50, 100 microM for AD 169). These nucleoside analogues are expected to be phosphorylated to their 5'- phosphate forms by cellular thymidine kinase in HCMV-infected cells. The thymidine kinase activities in the virus-infected and noninfected cells were compared. Cellular thymidine kinase was increased in the virus-infected cells and showed better phosphorylation of 2'F-ara-FU than did 3'F-ara-FU. HCMV DNA polymerase was purified using affinity column chromatography, and the inhibitory effect of the 5'-triphosphate derivatives of 2'F-ara-FU (2'F-ara-FUTP) and 3'F-ara-FU (3'F-ara-FUTP) against viral and host DNA polymerase alpha was examined. No significant difference in the effectiveness of inhibition was observed between viral DNA polymerase and host polymerase alpha. However, viral polymerase incorporated 2'F-ara-FUTP into newly synthesized DNA, whereas polymerase alpha did not utilize 2'F-ara-FUTP as a substrate. Thus, viral polymerase differs from host polymerase alpha in its recognition and utilization of 2'F-ara-FUTP. This difference may be important to the design of selective antiviral agents for HCMV.

Volume 31, Issue 3, pp. 301-306, 03/01/1987
Copyright © 1987 by American Society for Pharmacology and Experimental Therapeutics