why do antiviral drugs not work in the same broad capacity as antibiotic drugs?

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Antibiotic drugs treat a large degree of bacterial infections, but viral infections seem to be trickier to develop medicinal treatment for. Why?

In: Biology

Many drugs that treat viral infections like immunoglobulin don’t actually act on the virus itself; they supercharge the body’s immune system so that it can deal with the virus (and the damaged cells). Some anti-virals are indeed broad, like pleconaril, they work on a number of common-cold viruses because the infection pathways are similar so the drug can act on it. Some, while they do act on the same process that many viruses employ to infect cells, simply work better on some than another; one of the anti-HIV drugs, that prevents RNA transcription also works on Hep-B; it’s just that there are other treatments for Hep-B that might be more effective.
Viruses are generally more tricky to develop treatments for for a variety of reasons – unlike bacteria; you have to test on living cells that are infected by the virus; unlike in bacteria where you can grow a culture and test on the bacteria first. Viruses when they’re not infecting a living cells don’t have metabolism; they don’t breathe, process nutrients, etc etc etc, so unlike bacteria, you can’t poison them before they attack. Etc etc….

Viruses and bacteria have very different mechanisms to survive and perform replication. Viruses replicate by inserting themselves into the host cell and use their replication mechanisms. They join with the host cells DNA, make themselves fancy new protein/phosopholipid sheaths, and then lyse the cell to go back into the environment.

A virus can be wiped out by the immune system, and then cells lyse and release more virus. Antivirals have to deal with this while antibiotics do not.

Viruses as a whole also mutate much faster than bacteria on average.

Sorry, currently not home and I’m on my phone so this might be a little choppy.

Simply put — Viruses, unlike bacteria, stick to your DNA and reproduce — they never go away once you have them.

In fact, viruses cannot be fully “removed” from your body (unlike bacteria), because they are literally stuck in your DNA. You body just learns to destroy any new copies when the virus re-activates.

Bacteria are vulnerable in three different ways and each of the three groups of antibiotics targets one of those vulnerable spots penicillins, macrolides and fluoroquinolones https://youtu.be/04brjRdc02w since viruses are not actually cells they don’t have these key weak spots to target so the antiviral drugs have to be more targeted at the specific virus in order to somehow disable it.

Thank you for all the wonderful responses, this helps 😃

The other posters already explained how viruses work and how bacteria work. I need to add that scientists think of a true broad spectrum antiviral as of a possible discovery; there still could be a mechanism common to different types of viruses that can be messed with to stop viruses from breeding and/or kill infected cells. If such a broad spectrum antiviral is discovered, it will become the antiviral equivalent of an antibiotic, which will be of immense benefit to mankind. It would be the proverbial cure to the common cold; other viruses currently considered very dangerous, such as the rabies virus, could also be treated by this drug. Current broad(ish) spectrum antivirals only target groups of similar viruses, while other antivirals are designed to fight a specific virus.