Songbird Fossil Virus May Help Predict Pandemics

An anonymous reader writes "Researchers announced they found a fossil virus hiding in the most unexpected place: the chromosomes of several songbird species. This ancient virus resembles human hepatitis B virus. Finding this ancient virus will catalyze new lines of inquiry that may help scientists predict and prevent future human viral pandemics that originate in birds."

Comments

Birds themselves could be creating new viruses

[BadAnalogyGuy]

If this is true, then birds themselves may not only be carriers of diseases like influenzae, but actually be actively developing the viruses in their own DNA. That would make sense as birds are typically the first species to be attacked by such viruses. The endoviruses embedded in their DNA may be involved in new virus creation.

That's pretty cool! And scary...

Re:Birds themselves could be creating new viruses

[BadAnalogyGuy]

http://en.wikipedia.org/wiki/Noncoding_DNA

Look into it.

Re:Birds themselves could be creating new viruses

[ColdWetDog]

No, you have it backwards. Yet another bad analogy... These viral sequences have been embedded in the bird DNA by mechanisms carried by the viruses. That's why they were first found in retroviruses (that do this sort of thing for a living). The bird DNA isn't 'making' the virus. In fact, the viruses are not coding for proteins due to numerous mutations that hit that part of the genome over time. Since the DNA is silent, the mutations don't affect anything and there is no selection for an active virus (or active anything).

While it's theoretically possible that more mutations could recreate functional proteins, the odds of that would be astoundingly low. You could also envision some sort of chromosomal rearrangement that would re create something biologically active, but again that is very, very unlikely. It is a bit more likely (although there is no current evidence of this) that small bits of viral DNA would code for some controlling RNA or small protein that would interact with bird DNA in some way. The state of the art isn't able to tease things apart at this level. But the bird genome isn't 'creating' a virus. This would be like asking a word processing program written for CP/M then transferred by paper tape to a TRS 80, then transferred by modem a computer running OS X to start decoding video streams. Not going to happen.

Re:Birds themselves could be creating new viruses

[Kilrah_il]

That would make sense as birds are typically the first species to be attacked by such viruses.

Where did you get that from? Yes, there's the Avian Influenza, but from there to go on and say that birds are typically the source of such viruses? Most human Influenza viruses are from a human-origin. From Wikipedia:

"All influenza A pandemics since [the Spanish flu pandemic], and indeed almost all cases of influenza A worldwide (excepting human infections from avian viruses such as H5N1 and H7N7), have been caused by descendants of the 1918 virus, including "drifted" H1N1 viruses and reassorted H2N2 and H3N2 viruses. The latter are composed of key genes from the 1918 virus, updated by subsequently incorporated avian influenza genes that code for novel surface proteins, making the 1918 virus indeed the "mother" of all pandemics"

Further searching did not reveal the the origin of the 1918 virus was birds.

And talking about "such viruses", the article was talking about the Hepatitis Virus B (HBV). I don't know of any evidence that the virus came from birds, So please clarify the meaning of your original statement.

Re:Birds themselves could be creating new viruses

[TheLink]

The bird DNA isn't 'making' the virus. In fact, the viruses are not coding for proteins due to numerous mutations that hit that part of the genome over time. Since the DNA is silent, the mutations don't affect anything and there is no selection for an active virus (or active anything).

Apparently some viruses can insert themselves into the germline/genome and reactivate later:

http://www.sciencedaily.com/releases/2010/03/100308151055.htm

The team presented clear evidence that the virus can insert its DNA specifically into telomeres -- structures at the ends of each chromosome that play key roles in both aging and cancer.

Finally, the team showed that the chromosomally integrated HHV-6 (CIHHV-6) genomes can be reactivated to an infectious form.

More details here:
http://schaechter.asmblog.org/schaechter/2010/08/when-the-end-is-the-story.html

Re:Birds themselves could be creating new viruses

[ColdWetDog]

Nice pickup, I said unlikely, but not impossible. The big difference here is that these viruses are inserting themselves in toto in the target genome remaining active to some degree or another. The 'ancient' viruses may well have started out like that but some millions of years ago they shut down, quit being selected for, but the sequences where never 'cleaned out'.

This has been speculated to be an important role for new gene products but likely happens rather rarely in complex multi cellular organisms. Like on the order of millions of years between successful occurrences. It certainly doesn't happen the way BadAnalogyGuy postulated to happen (and dissed Bruce Perens for no particularly good reason).

Just like cyclical development

[eqreed]

Quote: "But when deactivated fragments of these viral freeloaders reside in a host's genome for millions of years"

Don't you hate it when no one cleans up the unused code?

Re:Just like cyclical development

[FooAtWFU]

Nonononono! Don't delete that line! That could be a load-bearing comment!

;)

Re:Ugh, boring.

[Tangentc]

Way to not invent a hover-board again science.

I love that this comment implies that the /. user base would not only like scientific research to favor the production of trivial amusement devices rather than preventing massive death tolls from illnesses, but would prefer that those amusement devices be almost suicidal to use.

Reading comprehension 101

[Black Parrot]

TFArticle doesn't say that anyone was surprised to find the fossil in the chromosome. The surprise is that it's > 19 million years old.

(Creationist bashers can take delight in the fact the these viruses were previously thought to be only 6000 years old.)

Re:Embedded virus ?

[khallow]

If a virus embed itself in the chromosomes of its host I am afraid it is no longer considered as a "virus".

You should rethink your position. The trick can be used to hide from the immune system and generate viruses of the sort you're familiar with at a future time.

Re:Embedded virus ?

[telomerewhythere]

What's interesting to me is (1) This type of virus doesn't normally put its code into host dna. and (2)The Hep(b) fossil in the songbirds genome and the Hep(b) virus infecting humans now are almost identical... Things to ponder.

As to 'viruses' in host dna, it's called "fossil virus", kind of like an animal fossilized in limestone etc. Not an animal, but we can learn from them.

DNA under selection rarely does nothing

[SpeleoNut]

I found these two statements in the article to be somewhat at odds with each other.
1. "The viruses that we found are very old, are integrated in the bird genome, and do not have the potential to encode any functional protein product," said Dr Gilbert. "So they do not have any effect in songbirds."
2. "a strikingly slow, long-term mutation rate that is 1,000 times slower than the viral [mutation] rates that had previously been estimated based on comparisons of currently circulating viral sequences only."
If the sequences are being in someway preserved they may well be having an effect. Perhaps not coding a protein themselves but altering the levels, timing or tissue specificity of gene expression in their vicinity. Also the presence of these similar sequences throughout the songbird genome can drive novel DNA recombination events which can result in new phenotypes, driving songbird evolution.