Antiviral agents active against the herpes group of viruses
Start with the big picture
Acyclovir, valacyclovir, and famciclovir are guanosine analogs activated by viral thymidine kinase; their active forms inhibit viral DNA polymerase and terminate DNA-chain growth. Penciclovir shares this pathway and is used topically for recurrent herpes labialis. For CMV, ganciclovir and valganciclovir depend on the viral UL97 kinase, while cidofovir bypasses the need for viral kinase activation. Foscarnet directly inhibits viral polymerases and can be used for resistant herpesvirus infections. Other agents have more specific roles, including topical options for HSV and letermovir for CMV prophylaxis after HSCT. The lesson also connects drug toxicities with practical precautions and explains how viral kinase or polymerase changes may contribute to resistance.
What you'll learn
- Explain how acyclovir-group drugs are activated and inhibit viral DNA synthesis.
- Distinguish the activation pathways and uses of ganciclovir, cidofovir, and foscarnet.
- Identify key herpesvirus drug toxicities and associated precautions.
- Describe resistance mechanisms involving viral thymidine kinase, UL97, and DNA polymerase.
- Match selected topical and CMV-directed agents with their clinical roles.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
