What gets me is why these prions seem to be primarily brain related. Just coincidence or is it something in the nature of mammalian brain biology that leads to prions?
There are already a bunch of prions generated in the body and hanging around neurons; the body can’t sort the invasive prions from the native ones that cause proteins to fold wrong.
Neurons are long lived. Most cells in your body are thrown away often.
Prions are attracted to or at least congregate in and around nerve cells. That's why as they spread around, they always eventually end up in the brain.
Do we know if prions are especially attracted to nerve cells, or if nerve cells are just a typical cause of death by prion disease?