Final answer:
Antiviral drugs work by inhibiting viral DNA/RNA synthesis, blocking reverse transcription, acting as protease inhibitors to stop viral maturation, or functioning as entry and fusion inhibitors to prevent viruses from entering host cells.
Step-by-step explanation:
The modes of action for antiviral drugs include the following:
- Inhibition of viral DNA/RNA synthesis: Some antiviral drugs, like acyclovir, target the viral DNA polymerase enzyme, preventing the virus from replicating its genetic material.
- Blocking reverse transcription: Drugs such as zidovudine (AZT) prevent the reverse transcription of viral RNA into DNA, particularly in retroviruses like HIV.
- Protease inhibitors: These prevent the processing of viral proteins, inhibiting the maturation of virus particles. For example, simeprevir is used for treating hepatitis C.
- Entry and fusion inhibitors: Drugs like enfuviritide prevent the merging of the viral envelope with the host cell membrane, thereby blocking the virus's entry into the cell.
It's crucial for these drugs to target proteins encoded by the virus without affecting the host's healthy cells to minimize host damage.