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

[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).

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.)

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.