Lifespan of a virus

[rov1200]

On the TV yesterday viruses were seem swimming in a small pool of water trapped in a block of ice. They had been there for more than 1 million years. Do they live indefinately?

[dizmouk2009]

Depends on the virus I suppose - although nothing lives indefinately.

[jake-the-peg]

Viruses merge the boundary of what is and what is not alive

Outside of a host cell they are simply chemicals. They cannot move, metabolise reproduce or do anything.

If they latch onto a suitable organism they can get into the cell and there they hijack the cell's systems to reproduce.

You might as well ask the same question as whether a water molecule lives indefinately.

Incidently the question does arise as to how long something that reproduces asexually like an amoeba lives.

When it divides who is to say which is the "parent"

In a sense death is the price we pay for sex

[dizmouk2009]

That answer was so much better than mine - clearly I'm showing signs of being tired.

[jason.p]

Viruses are just a nucleus of either RNA or DNA protected by a protein coat. It probably depends on the size and nature of this coat as to how long they can survive outside the host. The pox virus is a relatively large DNA virus and I believe can survive quite well.

[heathfield]

They weren't viruses, they were microbes - something simpler and completely different.

http://www.microbewor...icle&id=156&Itemid=87

[theprof]

jake is right. Viruses are considered non-living as they do not follow most of the requirements for life ie they cannot move around independently, they don't produce nor excrete waste, they do not metabolise nutrients and they do not consist of cells. They also cannot be "killed" - antiviral agents merely prevent a virus from carrying out its destructive function.

There are also other reasons while they don't meet the criteria for living organisms but these are more complex.

It is true that viruses are a coiled string of nucleic acid surrounded by a protein coat. It is best not to refer to a "nucleus" of RNA or DNA to avoid confusion with the cell nucleus.

Finally, yes they can survive indefinitely as there is nothing to die in the true biological sense

[vascop]

As heathfield says, they were NOT viruses, they were microbes, so all this discussion of viruses is not relevant. Interesting, but totally irrelevant.

[Lborobrewer]

The fact that viruses cannot be killed makes a nonsense of the claims by certain cleaning products that they can kill the H1N1 (swine) flu virus.
If the outer protein case is denatured and the inner DNA exposed then the virus will be 'dead'.

[theprof]

Vascop, I'd like to take the opportunity to thank you for your most useful comment.

I'm sure you'll correct me if I'm wrong, but I think that until heathfield enlightened us that microbes rather than viruses were involved, it's fair to say that everyone, with the exception of myself, provided answers in good faith about viruses. The reason? Well, it's because rov1200 was convinced that the TV program was discussing viruses.

My reply was made to clarify two points. The first was regarding the term "nucleus" and the second was regarding virus indefinite survival, which was asked but not answered by others.

A question on viruses was asked and answers about viruses were provided. In that context, it is incorrect to state that the discussion on viruses is irrelevant.

[theprof]

Lborobrewer, in the strict sense it is true that cleaning product manufacturers are being economical with the truth when they advertise their products as virus killers. I've been opposed to such claims for years as have many of my colleagues in the scientific community.

However, the reason that manufacturers are allowed to continue making this assertion is based upon a fundamentally incorrect assumption: people still consider that every organism must be either alive or dead and this has been been extended to all pathogens in a very broad sense. It is difficult to envisage viruses as harmful but not alive as historically, they've been classified alongside motile bacteria. Therefore a deactivated virus is regarded as a "dead" virus. It follows that if a virus is dead, it must have been "alive". Taking this one step further, if an "alive" virus can be turned into a "dead" virus by the action of a cleaning product, it can be "killed".

This sort of pseudo-scientific claptrap originally arose due to misunderstandings over technical details between marketing and R&D departments in the major household product manufacturers. Nowadays, it's commonplace for manufacturers to make these claims under the guise of a simplistic explanation more suited to the understanding of Joe Public.

[rov1200]

Sorry to partly mislead you but the TV was not occupying 100% of my time. Heathfield had the right answer and his link supports the theory of not just 1 million years old but 250million, even before the dinosaurs. In fact those squiggly bits moving inside the block of ice were microbes and bacteria was also mentioned.

A bacterium can be a host to nucleophages like Ix 174 which attach themselves to a bacteria insert their DNA and produce multiple copies.

[Lborobrewer]

The latest issue of the BBC Focus magazine includes a short piece answering the question "How long can viruses exist outside the Human Body"; the answer given suggests that it depends on the type of surface the virus is spread to; with hard surfaces the time given is a few hours, whilst for bank notes it could be several days.

[rov1200]

Thanks lborobrewer while we are also on the subject of viruses they don't seem to exist for very long. When we talk about viruses I am reminded about the foot and mouth virus which somehow seemed to cover most of the country. The theory then was that it blew in the wind to the adjacent farms.

[rov1200]

Some interesting pictures of viruses

http://images.google....num=1&ved=0CBUQsAQwAA