Immunology / Microbiology: Anti-Viral Agents Overview

Antiviral Agents

Virustatic

• Antiviral drugs are effective only against actively replicating viruses.
• They cannot eliminate latent viruses in the body.

Virus Life Cycle

• Stages include:
  • Adhesion
  • Entry
  • Uncoating
  • Synthesis and Assembly
  • Virion release

Antiviral Agents & Mechanisms

Disruption of Viral Envelope or Surface Proteins

• Mechanism:
  • Lipids, detergents, acids, and anti-viral molecules disrupt virus surfaces.
  • Example: Citric acids can disrupt rhinovirus surface proteins.

Prevention of Attachment

• Mechanism:
  • Antibodies neutralize viral attachment proteins.
  • Peptide analogues block host attachment proteins, e.g., HIV co-receptor blockers.
  • Peptides bind sites like heparan sulfate to block HIV and Herpes Simplex Viruses.

Prevention of Penetration & Uncoating

• Mechanisms:
  • Inhibition of viral fusion proteins, e.g., Enfuvirtide for HIV.
  • Inhibition of envelope fusion, e.g., Docosanol for HSV.
  • pH Neutralization to inhibit uncoating, e.g., Amantadine for Influenza A.
  • Prevention of penetration, e.g., Tromantadine for HSV.
  • Receptor blocking to prevent uncoating, e.g., Arilidone for picornaviruses.

Inhibition of RNA or DNA Synthesis / Blocking Viral Replication

• Nucleoside Analogs:
  • Acyclovir, Valacyclovir for Herpesviruses, VZV.
  • Penciclovir, Famciclovir for HSV, VZV, EBV, CMV.
  • AZT, Dideoxyinosine, Stavudine, Lamivudine for HIV.
• Nucleotide Analogs:
  • Cidofovir for CMV, AIDS-related viruses.
  • Adefovir for Hepatitis B.
• Non-nucleoside Polymerase Inhibitors:
  • Foscarnet for Herpes, HIV, CMV retinitis.
  • Nevirapine, Delvaridine, Efavirenze for Herpes, HIV.

Blocking Assembly and Release

• Protease Inhibitors:
  • Saquinavir, ritonavir, indinavir for HIV.
• Neuraminidase Inhibitors:
  • Zanamivir, oseltamivir for Influenza A and B.

References

• Discussed studies and articles on antiviral treatments and mechanisms.
• Notable references include journals and studies on Sofosbuvir, HIV interactions, and antiviral peptides.