Ocean water off the coast of Chile has yielded the biggest virus ever discovered. Megavirus chilensis is up to 20 times wider than the average virus and is bigger than many bacteria. Megavirus, like all other viruses, infects the cells of living organisms to replicate itself—but humans don't need to worry. Researchers believe it only infects single-celled organisms floating in the sea. They suspect the amoebas may be attracted by the virus' similarity to bacteria.
The origins of giant viruses—which are big enough to get their own viruses—are still unclear, but scientists plan to keep trawling the sea for specimens, some of which may be even bigger than Megavirus. "This is a new way of doing virology," the lead researcher tells the BBC. "Previously, we only discovered viruses because they caused disease in humans, or animals, and plants. But now we are initiating what might be called environmental virology, and we are looking for viruses everywhere."