Earlier this year, scientists published a study describing how they revived another one of these giant viruses, which has been frozen in Siberian permafrost for 30,000 years! We’ll discuss why they did this in a bit, but let’s first talk about how they did this.
Over the years, lots of cool stuff has been found well-preserved in ice. Otzi, a 5,000 year old “ice man” was a historic find in 1991. He went on to become a spokesperson for the GEICO auto insurance company. |
While we
can feel the pain that they cause, especially during cold and flu season, we can’t see the
culprits. Viruses are really, really tiny - most are smaller than the molecular
complex cells use to make proteins.
Many viruses are under 100 nM (0.1 micron), but some (like Ebola) are almost 1.0 micron. Compared to viruses, even a bacterium is enormous. |
Amoebas
are single-celled organisms called protozoa that, like most cells, fall prey to
viruses. By putting permafrost into amoeba cultures, scientists were able to
screen samples for those that could kill the amoebas. And they found a “big”
surprise.
The virus
spotted in these infected amoeba cultures resembled a so-called “pandoravirus”
or “giant” virus. They are still microscopic of course, but considerably larger
than the viruses we know of today (about 1.5 microns in length and 0.5 microns
across). Not only are they larger in size, but they contain many more genes. By
way of comparison, HIV contains less than 15 genes, but this giant virus has
500 genes. They christened this new giant virus “Pithovirus sibericum”, and it is the
oldest virus ever to have been revived to date.
Thick membrane or no, Pithovirus invades amoebas. Who knows…with this discovery, maybe scientists can devise a new treatment that targets the deadly brain-eating amoeba, Naegleria. |
A “huge” find in the world of virology, Pithovirus is now growing in labs again after a 30,000 year slumber. Image taken from Legendre, et al. |
Of course
not. As climate change continues to melt more and more ice, it is possible that
these viruses are going to revive naturally. By resurrecting them in the lab in
controlled conditions, researchers can get ahead of this curve by studying the
virus. Study of the virus can help determine which one(s) pose a threat and, if
so, vaccine and drug development efforts can get underway thanks to our
knowledge of the virus. And don’t worry about Pithovirus – it was already found
to be incapable of infecting animal cells.
Another reason these viruses are worthy of study is that they can reveal new insights into how cells evolved, since viruses can transfer their DNA to their hosts. They may even shed light on the greatest biological mystery: the origin of DNA/RNA and how life came to be on Earth.
The same team of scientists isolated yet another ancient giant virus this year from the same permafrost and named it Mollivirus sibericum. You may also be wondering what Siberian virus hunters listen to while exploring those Hoth-like landscapes. I'll take a guess and hope that it is wrong...
Another reason these viruses are worthy of study is that they can reveal new insights into how cells evolved, since viruses can transfer their DNA to their hosts. They may even shed light on the greatest biological mystery: the origin of DNA/RNA and how life came to be on Earth.
The same team of scientists isolated yet another ancient giant virus this year from the same permafrost and named it Mollivirus sibericum. You may also be wondering what Siberian virus hunters listen to while exploring those Hoth-like landscapes. I'll take a guess and hope that it is wrong...
Contributed by: Bill Sullivan, Ph.D.
Follow Bill on Twitter.
Legendre, M., Lartigue, A., Bertaux, L., Jeudy, S., Bartoli, J., Lescot, M., Alempic, J., Ramus, C., Bruley, C., Labadie, K., Shmakova, L., Rivkina, E., Couté, Y., Abergel, C., & Claverie, J. (2015). In-depth study of , a new 30,000-y-old giant virus infecting Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1510795112
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