What is the mechanism of action of these antiviral drugs?

Okay, no problem.

Hello! I'll try to explain how antiviral drugs work in an easy-to-understand way.

You can imagine a virus as a "super simplified" robber. It has nothing of its own; no "factory" to replicate itself. So, its sole goal is to break into our body's cells (these cells are the "factories"), and then use the factory's equipment and raw materials to frantically replicate thousands of new robbers just like itself.

Antiviral drugs are like the "special agents" or "sabotage experts" we send into these factories. Their purpose is to disrupt the virus's replication plan at various stages.

The virus's entire "criminal process" generally involves several steps, and our "special agents" (drugs) counter them at each of these steps:

Stage One: Preventing the Virus from "Breaking In"

Some drugs act like security guards at the factory gate. Some can block the "keys" (proteins on the virus's surface) that the virus uses to unlock, while others can pre-block the "locks" (receptors on our cell surfaces). In any case, they prevent the virus from entering.

Stage Two: Disrupting the "Production Workshop" (The Most Crucial Step)

This is the most common tactic. After successfully entering a cell, the virus takes out its "blueprint" (which is the virus's genetic material, DNA or RNA) and forces the cell's production line to manufacture new viral components according to this blueprint.

This is where our drug agents truly shine. Taking herpes virus, which you mentioned, as an example, the famous antiviral drug "Acyclovir" works like this:

• Providing "Fake Raw Material": When a cell replicates the virus's DNA, it needs a raw material called "nucleotide". Acyclovir disguises itself as a "fake" nucleotide raw material.
• Breaking the Production Line: The virus's "construction crew" (something called "polymerase") isn't very discerning; it mistakenly picks up and uses this "fake raw material". But once this fake raw material is incorporated into the growing viral DNA chain, the entire chain can no longer be extended, like a road that ends abruptly halfway through construction.
• Production Halted: As a result, the new viral DNA cannot be fully replicated, and the entire production plan is ruined.

Many antiviral drugs use this "deception" approach to interrupt the viral replication process.

Stages Three & Four: Interfering with "Assembly" and "Release"

• Interfering with Assembly: After the various viral components are produced, they need to be precisely "cut" and "assembled" into a complete new virus. Some drugs (like certain protease inhibitors for HIV treatment) are specifically designed to disrupt this assembly process, ensuring that only defective, non-infectious viruses are put together.
• Preventing Release: In the final step, thousands of new viruses need to leave the cell to infect others. Another class of drugs (like Oseltamivir/Tamiflu for influenza) acts as gatekeepers; they block the cell's "exit", preventing mature viruses from leaving. They are trapped inside the cell and thus cannot continue to spread.

To Summarize

So, unlike antibiotics that directly "kill" bacteria, antiviral drugs are more like precise "disruptors". They specifically target and interfere with a particular stage in the virus's replication process, effectively preventing the virus from "reproducing".

It's precisely because of this targeted approach that drugs for herpes are ineffective against influenza, and drugs for influenza are useless against hepatitis B. Different viruses have different "production processes" and "equipment", so our "special agents" must also be specialized for their specific tasks.

I hope this explanation makes it easier for you to understand!