And so proceed ad infinitum

>> Friday, August 08, 2008

So, naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite 'em,
And so proceed ad infinitum

-Jonathan Swift, "On Poetry: a Rhapsody"


Now here's something interesting: French virologists have found a virus that infects other viruses. It seems that in 2003 scientists discovered that a microorganism that had previously been thought to be a bacterium was actually a virus--it just happened to be a really fucking big virus. Now the aforementioned French team has found another "monster virus," and with it a teeny-tiny 21-gene virus that inserts itself into the monster's DNA and uses the larger virus' genetic mechanisms to replicate itself when the larger virus inserts itself into a cell.

I.e. "sputnik," as the little virus is called, infects a "mamavirus," and then when mamavirus infects a cell--specifically, an amoeba--sputnik uses mamavirus' use of the amoeba to replicate itself.

And, interestingly, it replicates itself at the expense of the mamavirus. It parasitizes another virus.

I don't know if this leads to one excited French scientist's conclusion that "There’s no doubt this is a living organism..."; then again, I've never quite latched onto the idea that viruses aren't alive. I've tended to think that the debate over whether viruses count as living organisms said more about the limits of our understanding than about the underlying subject. (An overview of the subject can be found here, at Wikipedia; you'll note that attempts to define "life" inevitably run into trouble because something that is "obviously" alive isn't, or something that is "questionably" alive is, and don't we all end up looking pretty stupid in the process?)

I suppose that my tendency to think of viruses as "alive" or "alive, sorta" is the reason that I think this discovery is remarkable. Not because it provides any kind of confirmation of my bias or belief, but because I see it as another example of the marvelous adaptability of genes. Here's a clot of DNA that has "figured out" (in the evolutionary sense, not the literal sense) how to exploit a reproductive niche. I guess you could take the sort-of-opposite angle--that "life" is a semi-meaningless description of a venue for chemical processes--and end up in the same awestruck place: here is an example of how the automatic chemistry of DNA will self-replicate and self-organize anywhere and at any time, forming increasingly more-complicated assemblages at various scales. Either way, it's something special.

2 comments:

Random Michelle K Friday, August 8, 2008 at 3:21:00 PM EDT  

I prefer to see viruses as NOT alive, because then colds and the flu feel less personal.

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