How do antiviral drugs work?

• A. Interfering with nucleic acid synthesis
• B. Inhibiting protein synthesis
• C. Blocking cell wall synthesis
• D. Enhancing host immune cell replication

Answer: (A)

Antiviral drugs work by stopping viruses from copying their genetic material, which is essential for making new virus particles. Many antivirals are nucleoside or nucleotide analogs that resemble the building blocks of DNA or RNA. When a viral polymerase copies the viral genome, these analogs get incorporated and either terminate the growing genome or introduce errors, halting replication. Some drugs are activated specifically in infected cells by viral enzymes, which helps them target the virus more selectively. For example, a drug can be activated by a viral kinase and then inhibit the viral DNA polymerase, preventing genome synthesis. Others block the activity of enzymes the virus needs to copy its RNA or DNA, such as reverse transcriptase in HIV or RNA polymerases in other viruses. Since the unifying goal is to prevent genome replication, interfering with nucleic acid synthesis is the central mechanism.

Blocking protein synthesis isn’t the main antiviral strategy because viruses rely on the host’s ribosomes for translating their proteins, so inhibiting protein synthesis would affect the host as well and isn’t how these drugs achieve selective antiviral action. Blocking cell wall synthesis is a bacterial-targeted mechanism, not applicable to viruses. Enhancing host immune cell replication isn’t how antivirals work; immunotherapies and vaccines modulate the immune response, whereas antivirals directly disrupt viral genome replication.