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The most terrifying thing about prions is that they are infectious but not alive: they can't be "killed" in the normal sense by sterilization. The proteins must
by jcromartie 10y ago
The most terrifying thing about prions is that they are infectious but not alive: they can't be "killed" in the normal sense by sterilization. The proteins must literally be dissolved to neutralize them.
- deleted 10y ago[deleted]
- hodwik 10y agoI slept through biology class, could you explain how that's not also true for virii, given that they are also not "alive"?
- danieltillett 10y agoViruses have nucleic acids which are shredded by the high temperatures used to sterilise items (121C). Dry heat will inactivate prions, but you need 200C for 4 hours or more which is more than most plastics can handle.
- hodwik 10y agoThanks. I would mention memes too, but I think 121C would shred their host as well. Edit: Actually, Carl Sagan wrote his memes in metal (and shot them into the universe) so I take that back.
- danieltillett 10y agoYes being autoclaved (this is what the process of sterilising with steam at 121C is called) is not the most pleasant way to die.
- logfromblammo 10y agoViruses have two main components. The first is the delivery package. This is the element that is capable of delivering a payload into the interior of a cell. The second is the genetic code that hijacks a cell's normal functioning to produce more viruses. Viruses have a genetic component, either RNA or DNA, which contain instructions for building their viral envelopes. The genetic material is as vulnerable to damage as cellular DNA. Prions are a single component. They are proteins with the same amino acid sequence as a protein normally produced by an organism. Except they have been misfolded. The geometry of the misfolded protein is such that it becomes a catalyst to reproduce the same misfolding error. There are no "brains" in them. They can arise entirely accidentally. They're a bit like the ice-nine from Vonnegut's _Cat's Cradle_, in which a crystal of a novel form of solid water that melts at a higher temperature can recruit liquid water to grow the crystal without limit. Each individual prion can misfold any number of same-sequenced amino acid chains. And like the ice-nine, which melted at a temperature above human body temperature, the prion may be able to survive through more extreme conditions than other forms of the protein. In the best case scenario, the prion does little more than cause a deficiency of the normally-folded protein forms in the body. In the worst-case scenario, it poisons some other process within the body in its misfolded form.
- hodwik 10y agoGot it. It's like honey crystals. They force other crystals to be of the same size and shape. (That's why creamed honey producers put a "starter" crystal in, which is tiny, that forces the honey to produce other tiny crystals.)
- josu 10y agoMy understanding is that the fact that viruses are not alive is more of a convention, similar to Pluto not being a planet. This is more of a question than a statement, I would love it if somebody with some knowledge on the matter could chime in.
- ctdonath 10y agoBacteria can do things on their own (say, swim in water). Viruses can't do anything without a host's reproduction engine (like a program which can't do anything without a computer to run on). Prions are misshapen proteins which tend to damage other proteins such that the result is the same misshapen, and thus duplicating, form.
- PascalsMugger 10y agoI think what was meant is that on the grand scale of "aliveness" viruses are more alive than prions. Viruses have DNA, they actively seek out host cells to hijack so they can reproduce, etc. Prions are much simpler and aren't alive at all. They're just accidentally self-reproducing patterns, basically. They don't have DNA, they don't make any specific effort to reproduce, they just "happen" from weirdly broken matter bumping together.
- hodwik 10y agoViruses don't make any specific effort to reproduce, they too are just accidentally self-reproducing patterns.
- Ericson2314 10y agolife, species, organism.... all are leaky abstractions. [There's a "species" that spread around the Andes and eventually reached itself on the other side---and could no longer breeed with "itself". Genes could still in theory travel all the way around and back to the discontinuous point, however.] edit: http://i.stack.imgur.com/4VsFW.png http://i.stack.imgur.com/4VsFW.png will make this less confusing, and quite unintentionally :).
- 10y ago
- henrikschroder 10y ago> virii Pet peeve of mine, but it looks like you slept through English class as well. The plural of "virus" in English is "viruses". "virus" in latin is a mass word and has no plural, like "sugar" and "air".
- pluma 10y agoActually isn't virus in Latin u-declension, i.e. the plural form would be virus (long u)?
- goldbrick 10y agoTo add to that, even if virus was to be pluralized in Latin, it would be "viri" not "virii".
- hodwik 10y agoVira, actually. However, virii is the hacker subculture form. This being hackernews... I'm comfortable with my decision.
- hodwik 10y agoYour perscriptivism here seems misguided then, because if virus is a mass word we shouldn't be saying viruses either: just "virus". And anyway, if we absolutely had to express a plurality of virus, it would be "vira". Anyway, this is hackernews. For those of us who grew up in internet hacking communities of the early 90's "virii" was the plural form in the lingua franca. As a descriptivist of great habit, I will continue to use that form.
- henrikschroder 10y agoI am actually a descriptivist myself, but the prescriptive approach usually works best when trying to convince people how to write. Apparently not so in this case. How about this argument then: "virii" is f*ckin ugly? No? Darn. :-)
- henrikschroder 10y ago
- Grazester 10y agoWhen I was a teen I was so freaked out by this fact during the mad cow episode in England that I never ate beef since. I would not for a few years even eat anything prepared in close proximity to where beef was being prepared. I lived in the Caribbean at the time...
- danieltillett 10y agoThe risk with beef was always pretty low. Actually not eating beef and eating an alternative meat is probably riskier given the prevelance of salmonella and other nasty bacteria in chicken.
- pc86 10y agoIf you are specifically (and erroneously) terrified of catching a prion disease, chicken is still better. You're much more likely to get sick but much less likely to catch a prion disease.
- Razengan 10y agoWhat about fish and other seafood?
- pm90 10y agoMercury poisoning. https://en.wikipedia.org/wiki/Mercury_in_fish https://en.wikipedia.org/wiki/Mercury_in_fish
- yourapostasy 10y agoWhich has to be the leading contender for our civilization's equivalent to "those Roman Empire folks were so dumb for using lead, ha ha". Though it is highly doubtful that lead poisoning caused the downfall of the Roman Empire, one to two order of magnitude elevated levels of exposures compared to normal background levels were no picnic the bodies of for those exposed. Another example of distributed costs, concentrated benefits really screwing us over in the long-run.
- ekianjo 10y agoViruses are not alive either, actually. Viruses can only thrive and replicate once they are in a host system. On their own they can do nothing.
- creshal 10y agoAnd it makes them incredibly hard to fight. We basically have two ways of dealing with them: • Use vaccination to train the host's immune system deal with it, should it ever encounter the full version. • Use special drugs to slow down their replication to let the host's immune system deal with the rest. Prions have no special, prion-only replication strategy we can target, and I'm not sure whether the immune system can be trained to attack only prions and not their regular protein equivalents.
- Lawtonfogle 10y ago>and I'm not sure whether the immune system can be trained to attack only prions and not their regular protein equivalents. A prion tends to be vastly different than the original protein. I thought the bigger problem was that prions are the metaphorical tanks of the protein world. Just look at what it takes to denature a prion compared to other proteins.
- patall 10y agoI think you underestimate the immune system. We automatically remoce thousands of misfolded proteins every second in our cells. Its just those few the cellular defence has not yet adapted to too much that we notice. Some kinds of vaccination might work (like expressing part of the misfolded protein to make it an antigen) etc. The reason why we do not have any medication against prions is because they have never been a big thread to us. Pretty much like asteroids, if they fell on us regulary, we would build a planetary defense. But for now, that not up on the agenda
- pohl 10y agoHow about this re-phrasing: The most terrifying thing about prions is that they are infectious but not life: they can't be "killed" in the normal sense While viruses are generally not considered to be alive, they are considered to be instances of life, aren't they?
- esm 10y agoSpores formed by bacteria like C. botulinum or B. anthracis are also very difficult to neutralize. The key is knowing if there is an exposure risk and taking added precautions. The good news is that some people are "immune" to developing an infectious prion disease. Turns out that certain mutations prevent normal proteins from interacting with a complementary prion in a way that would cause them to become misfolded.
- djsumdog 10y agoSo for people with Alzheimer's disease, is that plaque always associated with prions/protein mis-folding? (and if so, is it worthless to do things like "Learn a second language," "Learn to play more instruments," etc because our brain usage doesn't really play into the development of Alzheimer's? It's mostly a genetic thing?
- rbanffy 10y agoI guess it's more complicated than that. Brain usage affects its chemistry - how much of what is available where - which, in turn, may have an effect on how misfolded proteins interact with normal ones. Keep in mind I'm no expert, but this seems to be a reasonable assumption.
- esm 10y agoIt's an unsatisfying answer, but Alzheimer's (and most disease for that matter) is a combination of genetic risk and what you do with your life. It is hard to know exactly how much genes or the environment contribute. There are subsets of neurodegenerative diseases that are almost entirely genetic (Huntington's, some forms of Parkinson's, etc.) and some that are almost 100% environmental (there's an interesting story about a group of IV drug users in San Francisco who developed Parkinson's after taking something laced with MPTP). Most cases are somewhere in the middle though. Learning other languages or instruments is probably useful from a brain health standpoint regardless of your genetics (even if you already have early-stage AD you can slow progression), but they are just proxies for activity. I would guess that learning something that interests you is more important than what that thing actually is.
- restalis 10y agoYes, it can not be "killed" but, as other dangerous/infectious particles (like viruses), it can be destroyed. The immune system is able to naturally develop defenses against both live and inert foreign bodies, but only if the given body is over a certain size. The small objects (relative to cell size) do not trigger antibody creation and that is why this abnormally folded protein is so dangerous. There are, however, methods in which the organism is trained to recognize and develop natural defenses against bodies as small as a molecule, say, to prevent relapse in drug addicts: http://www.doctortipster.com/11968-new-vaccine-against-methamphetamine-drug-addiction-shows-promising-results.html http://www.doctortipster.com/11968-new-vaccine-against-metha... http://www.livescience.com/21132-cocaine-vaccine-cure-addiction.html http://www.livescience.com/21132-cocaine-vaccine-cure-addict... http://www.voanews.com/content/scientists-develop-experimental-vaccine-against-heroine/1658448.html http://www.voanews.com/content/scientists-develop-experiment... This method may be a little bit costly (relative to promised returns of solving a problem that does not directly affect humans) and with limited effect, but still, it may be a way worth investigating.