How does acyclovir inhibit herpes virus replication?
Acyclovir and ganciclovir are variants of acycloguanosine and are used to treat herpes simplex virus and cytomegalovirus infections, respectively. Both agents are viricidal and act by interfering with viral polymerase activity. In the case of herpes simplex virus infection, the virally- coded thymidine kinase monophosphorylates the acyclovir. Cellular kinases then add two more phosphates, creating a nucleotide that is accepted by the virally-coded DNA polymerase. The structural analog is incorporated into the growing DNA chain and elongation is terminated. Ribavirin, used to treat paramyxovirus (respiratory syncytial virus) infection, works by interferring with viral messenger RNA (mRNA) capping. Amantadine, used to treat influenza A infections, blocks viral un coating. It is most effective when given before viral infection occurs. Reverse transcriptase inhibitors (e.g., azidothymidine, didioxycytocine, didioxyinosine) directly interfere with normal enzyme activity. These agents are virostatic, and virus growth occurs when the agents are removed. Interferons are induced as a result of viral infection of a cell. Products of viral nucleic acid replication activate genes that code for interferons, which directly prevent virus growth by inducing an antiviral protein within virus- infected cells.
They block capping of viral mRNA
They inhibit reverse transcriptase activity
They inhibit viral polymerase activity
They block viral uncoating