I don't know what you're asking here, but I'll try to answer.

A prion is a sort of biological computer virus. Assuming evolution, it's perfectly plausible that the same mechanism created prions, since they're extremely hardy and so the first one or two of each type would multiply and spread wildly in the poor creature in which they appeared. (Assuming a creator… well, we have plague, smallpox and HIV, so 🤷.)

A prion is a protein that doesn't do its job properly. Normally that wouldn't be so bad (if your body produces the faulty proteins, you have something like Cystic Fibrosis and die a slow, painful death, but it doesn't infect anyone else), but something about the shape of prions causes other, functional proteins to misfold up into the more stable, non-functional prion shape. Like enzymes, the great biological catalysts, only evil. (To anthropomorphise.)

Does this help?