This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Pharmacology
[{'content': 'Mechanism of action of Acyclov ir is \nSelect and explain. \nA. Inhibitor of viral DNA polymerase, B. Inhibitor of viral thymidine kinase, C. Inhibitor of viral reverse transcriptase, D. Inhibitor of HSV polymerase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (D) Inhibitor of HSV polymerase # Mechanism of action:> Acyclovir differs from previous nucleoside analogues in containing only a partial nucleoside structure: the sugar ring is replaced with an open-chain structure. It is selectively converted into acyclo-guanosine monophosphate (acyclo-GMP) by viral thymidine kinase, which is far more effective (3000 times) in phosphorylation than cellular thymidine kinase.ANTIVIRAL AGENTS ACTIVE AGAINST HERPESVIRUSESAgentDescription* AcyclovirInhibits HSV polymerase* FamciclovirProdrug of penciclovir (a guanosine analogue)* ValacyclovirProdrug of acyclovir; better absorption* GanciclovirMore potent polymerase inhibitor; more toxic than acyclovir* ValganciclovirProdrug of ganciclovir; better absorption* CidofovirNucleotide analogue of cytosine* FoscarnetPhosphonoformic acid; inhibits viral DNA polymerase', 'role': 'assistant'}]