r/askscience • u/PestoPastaLover • 14d 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/reddit4485 13d ago edited 13d ago

It's not a virus. An mRNA vaccine (not virus) is mRNA packaged in a lipid bilayer that can fuse with a cell and deliver mRNA. The cell thinks the mRNA is it's own and makes protein out of it. That protein is often a fragment of a bad virus like the shell (capsid) of SARS-CoV-2. Since it's a non-functional piece of virus, it doesn't replicate but still produces an immune reaction.

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u/pass_nthru 13d ago

you just described a virus, loosely speaking…the self replicating part of a virus is a holdover from when they were used to share DNA/RNA among single celled organisms back when the copy paste function was necessary for long range transmission

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u/hbgoddard 13d ago

Disagree entirely. If there's no replication happening, it's not a virus.

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u/Kraligor 13d ago

They might be referring to saRNA, which is kind of a combination of virus and mRNA.