RE: The Laughing Death - Why Cannibalism is Bad for You
Great question! It's a normal protein that is produced in the central nervous system so it doesn't need to replicate.
The abnormal form (PrPsc) replicates because it can change the shape of the regular version (PrPc)- but like I said we don't fully understand the process.
It is possible that there is some bidirectionality in the process in that the abnormal PrPsc can get converted back into the normal PrPc but the current research would suggest that the effect is minimal.
Once introduced the net effect is the accumulation of the abnormal PrPsc. One thing I forgot to say is that the damage may be a secondary result of the abnormal prion protein accumulating.
It may be that the normal PrPc carries out some kind of very vital role in protecting/preserving brain tissue - when it changes to the abnormally shaped version it can no longer do this and so damage accumulates just by normal brain processes.
Synthesis by ribosomes then, like other proteins? I just wondered, because if they reproduced, and what with its helical structure (I looked that up 8-), it almost sounds like a very primitive, pre-DNA form of life, but its being synthesised puts a stop to that idea. Bummer.
So, PrPC is synthesised, and prions multiply by imposing their shape on PrPC, so they don't "procreate" either.
Have they found a reason why prions occur in dead tissue? I mean, what mechanism makes them fold after death to become PrPSc?
Note to self: I should be googling this. Sorry.
Yes exactly.
It is an interesting thing to explore. The problem is they are not really alive by any definition - there is no real metabolic process as such. They are more like viruses in that sense, except even simpler.
Not sure if the process actively happens in dead tissue or not. I suppose it would depend on the physical conditions.
If there are no peri- or postmortem processes changing the shape of PrPC, then there is a patient zero, and this patient zero would have had to be infected in another way, or have a genetic defect that caused the ribosomes to synthesise PrPSc directly, or is the PrPC able to spontaneously transform? Or am I missing an option?
Sorry about the incessant questions, I'm in sponge mode 8-).
The initial patient likely had a mutation to the gene that produces PrPc similar to the sporadic form of CJD - it occurs at a rate of about 1 in every million people if I remember correctly.
Technically such a person would be producing the abnormal protein.
So it is likely that at some point a number of people consumed a relative/friend who had the sporadic mutation and whose body contained the abnormally shaped version.
After doing this, these people then became carriers and subsequently when they died their bodies were consumed and those people became carriers and if their bodies were consumed that spread it onto others...
This way even a very rare disease event i.e. the sporadic mutation can get amplified because of the way that these prion diseases spread.
Further due to the potentially very long incubation period in certain genotypes many cases would be unknown as the people would potentially have died of other causes before they developed Kuru.
No problem I find it fascinating to talk about. It is hard to say with too much certainty about these things as there is still a lot that is not known.