Antiviral drugs and interferons

• Antiviral agents selectively inhibit viral function or interrupt with growth of virus
• Properties of antiviral agents

  • Target viral enzymes
  • Minimal similarity with host protein to reduce side effects
  • Minimal effect on biochemical pathways of host cells
  • Little or no effect on immune system
  • Reduce severity of disease but are not cures
  • Broad effectiveness should be considered
• Mainly act against

  • Herpes viruses
  • Influenza viruses
  • Hepatitis B & C viruses
  • Retroviruses
• List of currently used drugs 1 (Herpes)

  • Brivudin
  • Famciclovir
  • Foscarnet
• Brivudin is a 5'-halogenated thymidine nucleoside analogue
• Famciclovir is a diacetyl 6-deoxy analogue of penciclovir
• Foscarnet is a non-nucleoside pyrophosphate analogue
• List of currently used drugs 2 (Herpes)

  • Penciclovir
  • Valganciclovir
• Penciclovir is an acyclic guanine analogue
• Valganciclovir is an L-valyl ester prodrug of gancyclovir
• List of currently used drugs (Influenza)

  • Rimantadine
  • Zanamivir
• Rimantadine is a symmetric tricyclic amine
• Zanamivir is a neuraminidase inhibitor
• Nucleos(t)ide analogues for HBV

  • Emtricitabine
  • Lamivudine
• Emtricitabine is an analogue of cytidine
• Lamivudine is an N(s)A of cytosine
• Lamivudine


  N(S)A of cytosine
• Tenofovir

  Acyclic N(s)A-phosphodiester
• Protease Inhibitors for HCV

  5/23/2022
• Telaprevir

  • Inhibitor for non-structural 3/4 A serine protease
• Entry Inhibitors

  5/23/2022
• Mature HIV-1 virion

  • Attachment & fusion
  • Co-receptor: CCR5 or CXCR4
• Reverse transcriptase Inhibitors

  • Viral RNA
• Integrase Inhibitors

  • Viral DNA
  • Integration into nuclear genome
• Maturation Inhibitors

  • Viral polyproteins
  • Viral mRNA
• Protease Inhibitors

  • Protease
  • Budding
• GP120


  • Viral genomic RNA
• Antiviral agents: risks

  5/23/2022
• Risks of antiviral agents

  • Emergence of drug resistant strains
  • Loss of antiviral effect
  • Side effects
• Side effects

  Usually mild clinical symptoms<|>May result in change of drugs
• Drug resistance: emergence

  5/23/2022
• Factors contributing to drug resistance

  • High rate of replication of viruses
  • Error in viral polymerases
  • Many variants exist
  • Quasi-species
  • Fittest virus represents majority population
• Drug resistance-concept

  5/23/2022
• Suboptimal use of drugs

  • Emergence of drug resistant strains
  • Fittest in the presence of the drug
• Viral Dynamics and Drug Resistance: Incomplete Suppression of Replication

  5/23/2022