Antiviral

Question 1

There are various steps in the virus replication cycle (entry, replication etc.). Give examples of anti-viral drugs targeting each step of virus replication. Also include the name of the virus each drug is effective against.

Answer 1

• Viral Insertion
• Penetration
• Uncoating: Amantadine Rimantidine (Inlfuenza A)
• Early Protein Synthesis: Fomivirsen (CMV)
• Nucleic Acid Synthesis: Purine and Pyrimidine Analogs, reverse transciptase inhibitors (HIV)
• Late Protein Synthesis/Processing: Methizone (variola), Protease Inhibitors (HIV)
• Packaging and Assembly: Rifampin (vaccinia)
• Release: Neuraminidase Inhibitors (Influenza)

Question 2

Name three agents licensed to treat Herpes Simplex Virus (HSV) and Varicella Zoster (VZV). Describe their mechanism of action.

Answer 2

• Acyclovir IV and PO and Topical: converts into ACV-TP. It inhibits viral DNA polymerase.
• Valacyclovir PO: converted to acyclovir, then ACV-TP. It inhibits viral DNA polymerase.
• Famciclovir PO: converts into penciclovir. It inhibits viral DNA polymerase.

Question 3

List 4 main drugs used for influenza. Describe their mechanism of action.

Answer 3

1. Oseltamivir: a neuraminidase inhibitor, preventing new viruses from emerging from infected cells.
2. Zanamivir: a neuraminidase inhibitor, prophylaxis
   of both Influenza A and Influenza B.
3. Amantadine: Resistance related to point mutations in the binding region of M.
4. Rimantadine: Resistance related to point mutation in the transmembrane domain of M.
   - Both: antagonizes the viral protein M2, which is
   needed for the viral particle to become “uncoated. Thus, no coating = no viral replication.

Question 4

Describe the 5 main types/classes of anti-retrovirals for HIV. Include the site of action of each therapeutic class.

Answer 4

1. Entry and Fusion Inhibitors
2. The nucleoside reverse transcriptase inhibitors (NRTI)
3. Nucleotide Inhibitors
4. The non-nucleoside reverse transcriptase inhibitors (NNRTI)
5. Protease Inhibitors

Question 5

Describe HAART.

Answer 5

is a medication regimen used to manage and treat human immunodeficiency virus type 1 (HIV-1), by suppressing plasma viral load.

• Combination treatment is essential: 2 NRTIs + 1 NNRTI (Z+L+Efavirenz) or 2 NRTIs + 1 or 2 Protease inhibitors (Z+L+lopinavir).

Question 6

Name two anti-viral drugs available for the treatment for CMV. Describe their mechanism of action.

Answer 6

1. Cidofor: inhibits DNA polymerase.
2. Fomivirsen: inhibits protein synthesis –
   therefore; inhibits viral replication.

Question 7

Name two anti-viral drugs available for the treatment for Hepatitis B. Describe their mechanism of action.

Answer 7

1. Lamivudine: suppresses HBV DNA replication.
2. Adefor: a nucleotide analog that competitively inhibits Hepatitis B DNA polymerase and causes chain termination.

Question 8

Name two anti-viral drugs available for the treatment for Hepatitis C. Describe their mechanism of action.

Answer 8

1. Sofosbuvi: NS5B RNA polymerase inhibitor, NI (nucleoside inhibitor).
2. Ledipasvir: NS5A replication complex inhibito