Which viral enzyme is targeted by acyclovir to treat infections?

Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly herpes simplex virus (HSV) and varicella-zoster virus (VZV). The mechanism of action for acyclovir involves its targeting of viral DNA polymerase.

When acyclovir is phosphorylated inside infected cells, it becomes acyclovir triphosphate, which mimics the natural nucleoside guanosine. This triphosphate form then competes with the natural nucleotides for incorporation into the viral DNA during replication. This competitive inhibition is primarily effective because acyclovir triphosphate is preferentially taken up by viral DNA polymerase over the host's DNA polymerases. Once incorporated, acyclovir effectively terminates the growing DNA chain, preventing further viral replication.

This specificity for viral DNA polymerase makes acyclovir particularly effective in treating infections caused by the herpes virus family, as these viruses rely heavily on their own DNA polymerase for replication. Other enzymes listed, such as reverse transcriptase (which is involved in retroviral replication), integrase (which merges viral DNA into the host genome), and helicase (which unwinds DNA strands during replication), do not play a direct role in the