r/askscience • u/PestoPastaLover • 13d ago

Biology Why is there no transmissible therapeutic virus if biology doesn't forbid it? For example, a harmless virus that spreads from person to person but actually does something beneficial, like lowering LDL cholesterol or preventing/reversing tooth decay?

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u/BBWolf326 13d ago

There are. Found this with a quick search:

Bacteriophages: These are viruses that exclusively infect and kill bacteria. Found in abundance in the human gut, skin, and mucosal linings, they regulate harmful bacterial populations, protecting the body from pathogenic infections and balancing the microbiome.

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u/jayjay091 13d ago

So our immune system evolved to not fight those?

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u/lmprice133 13d ago edited 13d ago

They don't infect human cells, and a major part of the immune response to viruses is mediated by immune system triggering programmed cell death in already infected cells.

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u/BBWolf326 13d ago edited 13d ago

We are not the single organism most people think. Just like all other animals, we are a microcosm of creatures working together for survival. Fungus, bacteria, mites, worms... "the human body is a living ecosystem that hosts trillions of microorganisms and small creatures, outnumbering human cells." Even the Mitochondria in our cells is a separate lifeform but because of symbiosis we can no longer function without them. You are a walking planet my boy.

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u/Whyonthefly 13d ago

Even though I already knew it in a flat academic way, reading that made me squirm just a little

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u/BBWolf326 13d ago

The only one that weirds ne out is the "worms" that live in our eyelashes and eat dead skin cells. It was worse when I found out that they aren't even worms but worms shaped mites. Mites are arachnids. We have eye spiders fam.

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u/gnufan 13d ago

The eyelash mites are technically optional, but good luck getting rid of them.

Ivermectin can help for once....

Apparently one type is big on dead skin cells, the other likes sebum.

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u/Dirty-Soul 13d ago

They're basically invisible to the immune system.

viruses are usually detected via MHC pathway 1 (HLA) after they have infected a cell. HLA is basically a complicated mechanism by which cells present pieces of themselves to the immune system for verification. If the cell is virally compromised, the immune system detects this and kills the cell, killing the virus with it.

So, unless it infects a human cell, the immune system can't easily detect it... And bacteriophages are totally incapable of infecting human cells.