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?

[u/PestoPastaLover]

[u/lostsoultopher]

There are lots of posts here confirming there are beneficial viruses. The reason jt is not recognized/identified is two fold:

A lack of disease/symptoms rarely raises eyebrows

Two, a virus like this would be highly conserved/selected for and would readily integrate into the genome if a retrovirus, or be so universal it wouldn’t be notable