How does Acyclovir exert its antiviral effect?

Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly herpes viruses. It exerts its antiviral effect by specifically targeting viral DNA polymerase, an enzyme crucial for the replication of viral DNA. When Acyclovir enters an infected cell, it is first phosphorylated by viral thymidine kinase, converting it into its active form, acyclovir triphosphate. This active form is then incorporated into the viral DNA during replication.

Due to its structural similarity to the natural nucleoside deoxyguanosine, acyclovir triphosphate acts as a substrate for viral DNA polymerase. However, once incorporated into the growing viral DNA strand, it prevents further elongation because it lacks the necessary components to allow for the addition of further nucleotides. This halts the replication of viral DNA and, subsequently, inhibits the proliferation of the virus itself. This mechanism is specifically effective against viruses that utilize the viral thymidine kinase for activation, which is a key distinction that enhances the selectivity and effectiveness of acyclovir in treating infections like herpes simplex and varicella-zoster virus.

Other options describe mechanisms that do not accurately represent how Acyclovir functions. For instance, inhibiting viral