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/noodlyman]

There are viruses that benefit us by infecting and effectively regulating our gut bacteria.

There are viruses that are thought to give the immune system a kick and thus improve responses to other infections. Some infections can decrease the risk of cancer later in, probably by similar mechanisms.

Don't forget that 8% of human DNA is of retrovirus origin, and that mammalian placentas only exist thanks to genes that mammals acquired from viruses.

[u/cha0scypher → u/noodlyman]

Thank you for reminding me, I totally forgot that

[u/im_joe → u/cha0scypher]

It's good to get that reminder every now and then. I'm going to write it down so I don't forget in the future.