May 13, 2004

iruses share a common ancestor that existed over 3 billion years ago and may even have even preceded cellular forms of life. Researchers at Montana State University have come to this conclusion after comparing the protein coating of an exotic virus strain, recently isolated from a hot spring at Yellowstone National Park, with a range of vastly different virus types. Unlike most viruses, this new virus doesn't reproduce by infecting living cells but through a chemical reaction and yet it has been found to share a common protein structure with the other viruses. Furthermore, these proteins have shown no significant similarities with the proteins of living cells and this suggests that viruses must have split of from other forms off life very early on. There are even wilder possibilities: that viruses may have preceded cellular life on Earth or even arrived here from outer space.
posted by John Hardy 20 years ago
  • That of course was supposed to say "viruses share a common ancestor" etc etc
  • Wow! [banana]
  • Awesome.
  • Woah. Brings to mind the rats' song from Gaiman's Coraline: "We are small, we are many We are many, we are small We were here before you rose, We will be here when you fall." Good one, John Hardy.
  • How do they suggest viruses lived without other organisms' cells to support them? I had always thought viruses were dependant on the cells of other organisms to replicate themselves.
  • The virii may not have been dependent on other cells in the past. I believe mitochondria used to be independent organisms as well, way back when. Perhaps the virii went the same way, hitching a ride on other organisms to reproduce faster?
  • And I'm remembering mitochondria with personality from Wind in the Door, though probably I shouldn't rely on children's fantasy for my main source of knowledge on human biology.
  • Freeman Dyson reckons that replicating RNA/DNA and metabolising cells developed quite separately, and only got together at a later stage. If I understand him correctly.
  • These hot spring viruses are not parasitic on cells. I had never heard of this before but apparently they reproduce in the complex chemistry of the spring (think: "primordial soup de jour"). To quote from that second link:
    "TBI virologist, Dr. Mark Young, along with several collaborators, are the first scientists to systematically look for viruses in Yellowstone high temperature environments greater than 80° C (176° F) with pH of 3 or lower, essentially the equivalent of looking for viruses replicating in boiling acid!
    That article goes on to say that these viruses are completely novel and not related to viruses found at normal temperatures. They seem now to have changed their minds and think that given the probabilities involved that all these viruses share similar proteins then they must be related.
  • OT In case you were wondering, JH has the rockingest blog ever. /OT
  • Also OT: There is no such word as "virii." The plural of virus is viruses. (The word had no plural in Latin, in case you were wondering.) /OT Great post!
  • There is no such word as "virii." The plural of virus is viruses. now there's a meme! *honks horn, does a little dance*
  • Most interesting, John Hardy!
  • JH - very cool article, and go montana state! (used to live near there, my aunt's an alumna, my sister was born at the university hospital in bozeman...) but a couple of points are bothering me here: 1) no need for another cell to replicate? where'd that info come from? i can't find that statement anywhere, in any of the linked articles. these appear to be viruses that infect archaea, which are one-celled organisms. archaea are often called "extremophiles" because they exist in conditions that would kill the average bacterial or eukaryotic cell, like hot springs, acidic pools, etc. archaea have only fairly recently been accepted as important enough to belong to their own group, separate from bacteria. these viruses infect archaea, and survive in the same conditions that archaea are subject to, but they do seem to need a cell in which to reproduce, unless there's another article you aren't linking to. the PNAS article spends a bit of time talking about surface proteins used for host recognition and about specific strains of sulphur-loving archaea that the virus infects, but no mention of any host-less replication. the important thing is that the archaeal viruses share characteristics with bacterial or eukaryotic viruses - which means that all viruses seem to share a common ancestor, dating back to before the three major domains of life (bacteria, archaea, and eukarya) diverged. (for the record - bacteria and archaea arose first, and eukarya appears to be archaeans that incorporated symbiotic bacteria that eventually became mitochondria and chloroplasts, both of which resemble bacteria in many ways. there were multiple rounds of gene-swapping between groups early on though, so the picture is a little muddy.) 2) i can't find the primary PNAS article linked to in the "Scientist" website. in fact there is no May 3 edition of PNAS - there's a May 4, though. the "Scientist" site doesn't make it very clear that this is a pre-press release, and not an officially published article - if you want to read it, go here for the direct link to the article (if you have access to full-text). 3) just a snark: that "Scientist" site has some incedibly obtuse web design. there are 1300 lines of javascript code (yes, i counted) before you even get to the body of the article. i checked the source when i noticed that the damn thing did an auto-reload every minute or so. there are programs that have less lines of code than that one web page - and that 1300 lines doesn't even include the linked CSS file (another 320 lines) or the linked javascript file (yet another 530 lines). i have absolutely no idea why a web designer would add that much overhead to a website. there's absolutely no need for it, and the person in charge of coding that site should know better. or they should hire someone else. either way.
  • There is no such word as "virii." The plural of virus is viruses. No! Say it ain't so, 'hat! *weeps* Dang. And it sounded so good too.
  • alnedra - it's true. hey, bet ya didn't know that the the singular form of "paramecium" is just "mecium". really don't know why they travel in pairs. but they do. that's a joke. really. there's no such thing as a mecium.
  • 1) no need for another cell to replicate? where'd that info come from? Good question, on reflection I think I made it up. Looking back over the articles of course the virus needs a cellular host and the host is as you say an archaea organism. Nevertheless I keep running over the "may have predated cellular life" line which I now take to mean that virus-like particles may have existed before cell-based life emerged. This is a pretty hard claim to prove or disprove, I imagine, seeing how little is known about the origin of life. Thanks for clearing up a misunderstanding on my part.
  • There is no such word as "virii" - Although Alnedra had to trii.
  • What we need *now* is a really effective way to kill them.
  • - Alnedra, Alnedra, in Plural we Need ya! - I know I'm not dumb there's but one Alnedrum
  • ool link, JH I like viruren myself
  • But I like the way "ii" looks! They're so cute together!
  • I like "Equus", for the same reason.
  • languagehat, you do not lie-i there ain't no such word as virii but you make us wanna cri-i 'cos it seems so apt that i-i Just wanna say it til I die-i Is it wrong, or is it righ'-i? /the worst of the verse
  • ok, so if we can't have virii, can we at least have virus/viroose?
  • I think it should be vire, rhymes with shire, which I still think should have been scourged at the end of that movie!
  • I hates vireeses to pieces!
  • virus plural = h0s3d
  • virii: an 8, with an r wedged in its middle.