Scientists Discover Missing Link Between Viruses and Cells: Pandoravirus

Giant viruses are some of the most complex viruses on Earth. Containing over a thousand genes and with a size that's far larger than typical viruses, they may just be the missing link between viruses and cells. Now, scientists have discovered two new giant viruses, which could lead to more information about the evolutionary history of cells.

The two new viruses are called Pandoravirus salinus and Pandoravirus dulcis. While the first one was found on the coast of Chile, the other was discovered in a freshwater pond in Australia. Detailed analysis of both reveals that they have virtually nothing in common with previously discovered giant viruses. Not only that, but the scientists have found that only a very small percentage of proteins encoded by Pandoravirus salinus are similar to those already identified in other viruses or cellular organisms.

In fact, Pandoravirus salinus is more complex than some eukaryotic cells. It also has no gene allowing them to build a protein like the capsid protein, which is the basic building block of traditional viruses. That said, these two new viruses still bear the hallmarks of regular viruses; they contain no ribosome, produce no energy and do not divide.

What's most interesting about these Pandoraviruses is that they use the same universal genetic code shared by all living organisms on the planet. This, in particular, reveals that they may bridge the gap between viruses and cells. This particular gap was proclaimed as dogma at the very outset of modern virology back in the 1950s.

The findings are important for understanding exactly how evolution might have occurred in the past. In addition, they reveal just how much more there is to learn when it comes to microscopic biodiversity. The simultaneous discovery of two specimens of this new virus family in sediments located thousands of miles apart indicates that Pandoraviruses, which were unknown until now, are very likely not as rare as we might think. In addition, the discovery shows that cell life could have emerged with a far greater variety of pre-cellular forms than those conventionally considered.

The findings are published in the journal Science.