Mechanism of Action of Antiviral Agents

Mechanism of Action

of antiviral agents

Viral therapeutics can be divided into three main classes

Immuno-modulators

Virucides

Antivirals

- Physical or chemical agents that deactivate or destroy viruses and are used outside the human body

- Drugs that inhibit further development of the target viruses inside host cells.

- Drugs that stimulate the immune system of the host

For this topic, we will only be focusing on the mechanism of the antivirals

Antivirals can be classified into groups based on their targeted processes

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Reverse Transcriptase Inhibitors

DNA Polymerase Inhibitors

Protease Inhibitors

Integrase Inhibitors

Fusion Inhibitors

Signalling Inhibitors

• Rimatadine
• Zidovudine
• Didanosine
• Zalcitabine
• Nevirapine
• Lamivudine
• Delavirdine
• Efavirenz
• Adefovir
• Abacavir
• Tenofovir
• Emcitricitabine
• Entecavir
• Etravirine
• Telbivudine

• Idoxuridine
• Vidarabine
• Trifluridine
• Acyclovir
• Foscarnet
• Ganciclovir
• Penciclovir
• Cidofovir
• Famciclovir
• Valaciclovir
• Valganciclovir

• Saquinavir
• Indinavir
• Amprenavir
• Nelfinavir
• Ritonavir
• Tipranavir
• Atazanavir
• Darunavir
• Zanamivir
• Oseltamivir

• Resveratrol
• Ribavirin

• Raltegravir

• Cyclosporine
• Maraviroc
• Enfuviritide
• Docosanol

These different classes of antivirals function by targetting different stages in the viral growth cycle

The viral growth cycle

Selective inhibitors

• Antiviral antibodies eg. gamma globulins

Attachment and penetration

• Amantadine, rimantadine
• Interferons

Uncoating

The viral growth cycle

Selective inhibitors

• Fomivirsen

Early translation (early mRNA and protein synthesis)

• Inhibitors of DNA Polymerase
• Acyclovir
• Gancyclovir
• Famcyclovir
• Cidofovir

• Vidarabine
• Idoxuridine
• Trifluridine
• Foscarnet

Transcription (viral genome replication)

• In­hibitors of Reverse Transcriptase
• Zidovudine
• Didanosine
• Stavudine

• Zalcitabine
• Lamivudine
• Foscarnet

The viral growth cycle

Selective inhibitors

Late translation (late mRNA and protein synthesis)

• Ribavirin
• Interferons

• Protease inhibitors
• Saquinavir
• Indinavir
• Ritonavir

Posttranslational modifications(proteolytic cleavage)

The viral growth cycle

Selective inhibitors

Assembly (packaging of viral nucleic acids)

• Interferons
• Rifampin

• Antiviral antibodies
• Cytotoxic T lymphocytes

Release(virion is released from cell)

The major sites of antiviral drug action

The diagram shows the sites that the antivirals target during the viral growth cycle. In parentheses are the viruses that the drugs are used to target against.

• HIV : Human Immunodefficiecy Virus
• HSV : Herpes Simplex Virus
• RSV : Respiratory syncytial virus
• HBV : Hepatitis B Virus
• HCV : Hepatitis C Virus
• CMV : Cytomegalovirus

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