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Comment by mcculley | Hacker News Reader

I always wonder this and maybe people in the comments here know the answer: If humans had the technology to eliminate all viruses on Earth, what would be the outcome? Do viruses keep other bad things in check? Would there be bad consequences if we eliminated all viruses?

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The world of viruses is wide and beyond our current understanding. 50 years ago one might have dreamily wondered whether "eliminating all bacteria" would improve the world. Now we know we'd all die quickly without bacteria (e.g. gut biome). I think we're about at that level of understanding today regarding viruses.

There's a hypothesis that a viral gene made mammalian placenta possible: [pubmed](https://pubmed.ncbi.nlm.nih.gov/10693809/).

And there's not even the only one (there are other syncitins).

Disclaimer: I'm not a medical professional

For one thing, viruses keep bacteria in check. Bacteria populations live in an equilibrium standoff with bacteriophages (viruses). The human gut contains more bacteriophage virions than bacterial cells. So eliminating all viruses could lead to bacteria overgrowth

Most viruses are bacteriophages, so I imagine bacteria would run wild!

Aren't bacteria generally much larger than viruses?

Phages don't devour bacteria, they get inside and hijack them, like viruses tend to do with cells.

Sometimes when phages get enough copies inside bacteria. The host will explode and release all phages inside it.

Seems strange to call them that, then; but such is English I suppose.

Eliminate all viruses: Population issues in other organisms down to bacteria is my guess. We break a link in a significant food chain, basically.

Eliminate human-tropic viruses: We have to monitor for outbreaks when new viruses mutate and jump species to successfully infect humans. If there's zero mass immunity across the population at every outbreak, we're still in a high-risk situation.

Loss of genetic diversity overtime will happen as well as a different path of evolution. Much of what you see on earth today is the result of virus-host interactions shaping evolutionary outcomes. Viruses are capable of providing horizontal inheritance of genetic material.

Viruses have had a lot to do with the evolution of life and specifically us, where perhaps our distant ancestors were bestowed with a system of transcribing short term memory into long term memory via the hijacked machinery from a virus. This is only one example that I could remember off the top of my head, there are surely many more. Would that matter going forward? I feel like we'd better be sure that we aren't causing more problems than we are solving.

Viruses kill a lot of bacteria. We might trade viral infection for increased bacterial infections

We aren't the target of most viruses.

It could be chaotic, I think.

https://m.youtube.com/watch?v=SbvAaDN1bpE

Are we also eliminating transposons? We would not survive that.

https://en.m.wikipedia.org/wiki/Transposable_element

Viruses are part of other biological processes as well as keeping things in check. For example, there is a bunch of viral activity involved in human pregnancy. A quick web search found this:

https://pmc.ncbi.nlm.nih.gov/articles/PMC6177113/

I would be worried about:

* An increase in autoimmune diseases (related to the hygiene hypothesis).

* Decreased resistance to future viral pandemics, since the body wouldn't have practice since childhood in fighting viral disease.

On the other hand viral infections themselves can instigate autoimmunity. After all, your body now has to fight your own cells (in contrast to other foreign infection)

Yep, hard to know for sure which way it would go.

Population control.

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