Are Viri (viruses?) Alive?

I'll come down on the opposite side: like prions, I think they're just short of being alive.My reason is that they require other living things to perform "basic" life functions, and in the absence of those other organisms are unable to use resources, reproduce, or evolve.I don't think they're exactly non-living, either - maybe, proto-life? Sub-life?

In fact, it looks like it needs everything that it uses in the cells. And it doesn't appear to be the entire virus that is replicating, just the RNA payload. No protein coat, nothing but the RNA.I can stick my DNA in a test tube and run a PCR to duplicate it a thousand-fold, but I've hardly "self-replicated."At best, we're on two sides of a very thin line, I think. You say tomato, etc.

I guess I thought I covered that. It's not really replicating, because it's not reproducing the entire thing. Just the RNA.I mean, how is what this RNA is doing different than crystal growth?

It seems to me that something must have a sufficient number of "systems" on-board to be really alive. Viri just don't do enough by themselves.Do viri do the same things as bacteria? Sure. But only in the presence of cells. Prior to that they're inert, lifeless. Bacteria may take on a similar spore form, but that's a specific reaction to a stimulus, not their basic state.I realize that my line may be arbitrary, but the thing is, I think yours is, too. If viri are alive, are prions? And if prions are alive, are crystals? All these things reproduce soley in a specfic chemical environment. Prions are more like crystals than they are like bacteria. And viri are more like prions then they are like bacteria. Therefore I come to the conclusion that viri, like crystals and prions, are not living things. They're the closest you can get to life without actually being alive, maybe.Heh, I think we're all hampered by the fact that nature feels no particular need to divide itself into easily recognized boundaries, but rather, there's an entire continuum of life, and every time you try to draw a line, there's something with a foot on both sides. [This message has been edited by crashfrog, 02-03-2004]

Nonetheless I see the distinction as arbitrary. A virus can only replicate in a specific chemical environment - the cell. A prion can only replicate in a specific chemical environment - one that includes the nominal protien. A bacterium can replicate in any envrionment in which it can maintain life chemistry."Modifers?" Prions modify protiens into exact copies of themselves. Living things "modify" materials into copies of themselves. Seems like the terms aren't much of a distinction to me.Viruses have no metabolism. Prions have no metabolism. Bacteria have metabolism.Viruses don't respond to changes in their environment. Prions don't respond to changes in their environment. Bacteria respond to changes in their environment.To me, it's like the difference between a combustion engine and a lever. At idle, the engine is still doing something. The lever does nothing until you use it for a task. Even if a bacteria isn't responding to something in the environment, it's still doing something - life processes continue. The virus is inert until specific chemical interactions occur.Viruses seem much more like prions than like bacteria to me. But then, I'm no biologist. Maybe my criteria are irrelevant, but they seem noteworthy to me.I'm comfortable with putting viruses and prions in a "proto-life" category, as I feel that they're more alive than crystals. But they're less alive than bacteria, it seems to me.If I might ask - how would you tell the difference between a "living" virus and a dead one?[This message has been edited by crashfrog, 02-03-2004]

And animated by foul necromancy!I'll accept this classification. Damned, dirty zombie viruses.

Well, the T-Virus can reanimate dead tissue. It's true! I saw it in a movie.Yeah, the undead suffer from universally negative portrayals in movies. That's why I've started the Zombie Anti-Defamation League. I'm lobbying Hollywood to opt for more appropriate movie villians, like Nazis or those darn Ay-rabs.

That's a really great point, and it leads me to consider - where is the most useful division between life and non-life going to be?Which "rules" are going to be most useful when applying them to viruses - life rules or crystal rules?Upon reflection, I'd have to say life rules. So I guess I'm changing my position. It's most useful to consider viruses as alive but prions as not.

I don't think they're the first ones to make up the "zombism caused by virus" idea, by any means.

That was a bitchin' movie, but I didn't really think it was a "zombie" movie... zombies are usually supposed to be the walking dead. Those folks were still alive.It'd chalk it up as an "outbreak" movie, not a zombie movie. But I'm a stickler for genres, I guess.