World’s biggest viruses lurk in Chilean rivers and Australian lakes
by Charles Choi, LiveScience [July 18, 2013]
IMAGE: Electron microscopy image of a Pandoravirus particle (edited using Adobe Photoshop artistic filters). CREDIT: Chantal Abergel / Jean-Michel Claverie
Giant viruses, more than twice as big as the last largest known viruses, have now been unearthed from sludge across the world, researchers say. Even more titanic viruses might await discovery, the scientists said, and they may have features that could blur the lines between life and viruses, which are not considered to be living things.
Ten years ago, researchers accidentally discovered mimivirus, what until now was the biggest, most complex virus known. Mimivirus — a name derived from “mimicking microbes,” chosen because the viruses were nearly the size of some bacteria — and its relatives the megaviruses can reach sizes of more than 700 nanometers (a nanometer is one billionth of a meter), and possess more than 1,000 genes, features typical of parasitic bacteria.
Typical viruses are maybe 20 to 300 nanometers large, and many viruses, such as influenza or HIV, get along very well with 10 or fewer genes.
Now the research team that discovered those giant viruses have unearthed two more that are even bigger. The shape of these new viruses, which resemble ancient Greek jars, reminded the scientists of the myth of Pandora’s box, giving the germs their name — pandoraviruses.
"The opening of the box will definitively break the foundations of what we thought viruses were," researcher Chantal Abergel, research director at the French National Center for Scientific Research in Marseille, told LiveScience.
The new record-breaking viruses are visible with a traditional light microscope, being a full micrometer or millionth of a meter in size, or approximately a hundredth the width of a human hair. They also each possess a whopping roughly 2,500 genes.