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Author Topic: Are Viruses Alive?  (Read 9735 times)

Offline John Chapman

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Are Viruses Alive?
« on: 01/02/2009 11:46:05 »
When I was at school my biology teacher told me that if I held a hamster our relative proportions would be about the same as a human cell and a bacteria. He then said if I held a kitten and I was the size of the bacteria the kitten would be proportional to a virus. ie viruses are very small! He said that viruses were virtually nothing but a vessel of DNA which could lay dormant indefinitely and only become triggered into effectiveness once inside a host cell.

My question is this:

Are viruses alive?

What exactly is a virus? My school biology definition of life included such considerations as reproduction, adaptation and response to stimuli (all of which I assume viruses do) but also included 'can it move?, 'does it metabolise?', 'is it homeostatic?' and 'does it grow?' (which I'm not so sure about).

Can anybody enlighten me?


 

Offline syhprum

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Are Viruses Alive?
« Reply #1 on: 01/02/2009 15:53:26 »
I am often surprised that the term 'killed virus' is bandid about for certain vaccines, how does one kill a virus when in normal meaning of the word it is not alive.
 

Offline John Chapman

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Are Viruses Alive?
« Reply #2 on: 01/02/2009 16:08:43 »
Good point syhprum

OK. New question. Can anyone also tell me what they do to a virus to make it safe to innoculate someone with?
 

blakestyger

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Are Viruses Alive?
« Reply #3 on: 01/02/2009 18:36:54 »
I did a paper on this once, it's here:

http://blakestyger.livejournal.com/

I'd be interested to know if you can access it without having to open an account yourself. If you can't open it I'll try and get it available some other way as it will answer your question. The format was an interview but when I posted it the introduction got lost. The article addressed the question 'Are viruses alive?'
 

Offline John Chapman

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Are Viruses Alive?
« Reply #4 on: 02/02/2009 23:41:09 »
Thanks Blakestyger

No problems accessing that at all.

That is absolutely fascinating. It answers my original question perfectly and so much more. What a clever chappy you are! :D
 

blakestyger

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Are Viruses Alive?
« Reply #5 on: 04/02/2009 17:49:27 »
You're welcome - glad that it's been of us to someone.
 

Offline TonyCap

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Are Viruses Alive?
« Reply #6 on: 16/02/2009 09:23:44 »
I would say yes.  It replicates, grows... has most if not all of the basic characteristics of other living things.  Viruses are alive, now Prions, I would say are not.
 

Offline John Chapman

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Are Viruses Alive?
« Reply #7 on: 16/02/2009 10:45:03 »
That's interesting. I don't really know what prions are. I sort of assumed, in my ignorance, that prions were the products of existing disease, all be it a fairly early step along a pathway of destruction. Are prions not a denatured protein which then go on to do other damage - to neurones, I think. Is prion creation not a symptom of whatever caused the disease in the first place? If not, where do they come from?

Prions are what is implicated in BSE & CJD, aren't they?

Can you tell me any more, TonyCap?
 

Offline sittingoverhere

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Are Viruses Alive?
« Reply #8 on: 25/08/2010 06:50:10 »
I would argue, strongly, that viruses are not alive. They do not satisfy the requirements of MRS GREN ( newbielink:http://www.sambal.co.uk/mrsgren.html [nonactive]) which work as the basis for life as far as I am aware.
Prions are miss-folded proteins that a) can sometimes take on a new role or stop performing the role they would normally perform if folded properly and b) act as an enzyme that catalyses the transition from the correctly folded form of the protein to the aberrantly folded version.
 

Offline Variola

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Are Viruses Alive?
« Reply #9 on: 25/08/2010 08:46:47 »
See now I always thought that too, but if you consider some vaccines are made with irradiated viruses, their definition is that the virus is killed, dead, with no chance of living, it is dead, the opposite of alive.( different from attenuated of course)
So a virus outside it's host is not dead as in the definition above, it is very much capable of life and of replication in the right host. By those terms it can be considered alive.
If I took a bacterium and put it in a media that inhibits it's growth, it could be argued that is the same as not being inside the right environment for replication, like the virus. And what about bacteria that sporulate? Sometimes those spores lay dormant for years until the right environment happens.
In technical terms the virus is not alive, being incapable of independent living, however from my view it is a tenuous label. 
« Last Edit: 25/08/2010 08:50:58 by Variola »
 

Offline sittingoverhere

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Are Viruses Alive?
« Reply #10 on: 27/08/2010 03:27:06 »
some vaccines are made with irradiated viruses, their definition is that the virus is killed 
I had always been taught they were 'inactivated' as opposed to 'killed' but I see you point.
As for the bacteria in the wrong media environment I would argue that it is irrelevant because in the right media the bacterium is capable of independent growth, something viruses are never be capable of.
 

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Are Viruses Alive?
« Reply #10 on: 27/08/2010 03:27:06 »

 

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