A pair of French scientists have discovered record-breaking viruses that are larger than many bacteria and even some eukaryotic cells. But more impressive than their size is their composition. Just seven percent of their genetic make up matches those cataloged in existing genetic databases. “This is a major discovery that substantially expands the complexity of the giant viruses and confirms that viral diversity is still largely underexplored,” says Christelle Desnues, a virologist at the French National Centre for Scientific Research in Marseilles, who was not involved in the study.
What’s the Big Idea?
The researchers dubbed their find the Pandoravirus because it may unlock secrets about the evolution of life at the cellular level. It has long been suspected that giant viruses evolved from cells. If that is true, the ancestors of Pandoraviruses must have been very different from the bacteria, archaea and eukaryotes we have today. “We think that at some point, the dynasty on Earth was much bigger than those three domains,” said Chantal Abergel, one of the researchers involved in the study. It seems some cells gave rise to modern life, and others survived by parasitizing them and evolving into viruses.