[nikartix]

How old are these proteins? If the do spread and remain dormant in soil they would have been a threat for entire existence of life on this planet. Exponential growth would only cause every place, especially a bio-reach locations to be full of it as food chain making more and more of the protein and animals remains are not handled in any way in the wild.

[dnautics]

They're old. Yeast have genes that transmit information generationally via the same mechanism. Probably the same "exponential" mechanism is involved in diabetes, alzheimer's, melanin storage (not a disease, the actual normal process).

Proteins, eventually degrade, even prions. We probably have an enzyme that accelerates degradation of them (my bet is it's insulin-degrading enzyme).

[AnimalMuppet]

I don't think proteins will live forever in the wild. Between bacteria, fungi, and just oxidation, I'm pretty sure a protein just sitting out there on its own is going to have a finite half-life.

[chasil]

It appears that the first mention of scrapie in scientific literature is 1755, and the disease increased with inbreeding (and lessened when this practice was stopped):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114482/

The wiki also indicates that a sheep vaccine distributed in 1935 caused an epidemic, as it contained contaminated neural tissue:

https://en.wikipedia.org/wiki/Scrapie

It also seems to me that the recent mRNA vaccines could be repurposed to target a section of a prion, so the immune system could clean them from the blood. An interesting question would test mRNA vaccine effectiveness in the cerebrospinal fluid, where microglia would be required to perform this function, as macrophages (and friends) are not present there.

[eximius]

This is a very interesting idea! But, is it known that macrophages are able to break down prions? My understanding of the problem is that part of it is that they're just quite hardy.

[chasil]

Even if they can't, it's probably better for them to build up in macrophages, dendritic cells, etc. rather than in neurons.

[dnautics]

Disagree. Every single antibody alzheimer's drug that has targeted the amyloid plaques and none of them have succeeded.

You're just as likely to elicit an immune response to the prion plaques, stabilize them, and recruit inflammation to the point of deposit, making matters worse.