Ia R= H b R= CH, OH herpes selectivity from phosphorylation by the virus-encoded deoxythymidine (dThd) kinase.'The resulting acyclovir monophosphate is phosphorylated further by host cell enzyme (s), eg, GMP kinasea8 Acyclovir triphosphate inhibits viral DNA synthesis by preferential binding to the virus-encoded polymeraseg and by incorporation at the growing 3'-end and tight complexing of this terminated DNA fragment with the viral ...