Do plants have even have diseases that would have a way of making the jump to humans? Blight, dutch elm disease, something along those lines?
No idea, I'm afraid. I'm out on a limb in speculative mode here. Technically, people shouldn't catch sheep diseases either. If CJD is a scrapie variant, we are looking at human agricultural methods creating a disease in sheep, transferring it to cattle, then on to humans, all without benefit of direct tampering with the genome of any of the three animals, in a timespan of a few centuries.
Now that we actually
are deliberately transferring DNA between different plant species and possibly between animals / fungi and plants, we may have some kewl surprises in store.
In any case, it's not the
disease that is necessarily transferred. My point is that alien protein might cause a new disease if it gets into a very distantly related species. If the supply of "prionisable" protein is limited , as is more likely in an unrelated creature, the effects might be minor.
Athon- while prions seem to be halfway between memes and "real" life forms- ie their "reproductive" method is not directly DNA moderated- the fact remains that the prion must move from one host to another like any other parasite.
I agree it may be more likely to thrive where there is a big supply of sufficiently similar protein "feedstock",but it is also more likely to destroy that feedstock- ie its host.
What I'm getting at is that a " normal" protein in a wholly unrelated beastie might have the potential to "turn prion" if transferred. Until we know the details of how the specific shape of each protein is generated, I don't see how we can be sure that related protein is more apt to
cause prion type diseases than alien protein, though the effects of a related prion will be very severe because of the availability of that large, related feedstock (a brain, a heart, whatever) waiting to be prionised.
I have a suspicion (and it's a wildass, wholly unsubstantiated one), that we will eventually find that
many minor diseases involve prion transfer from alien sources, as well as the few we are aware of now- Kuru, scrapie, CJD- (are there more?), which involve "related" mammal proteins.
These all have similar, massive effects on the nervous system, but even so, it took a long time to isolate the causative agents.
What if there are
millions of
potential prions in the environment, most of which have far less overt symptoms?
