Melting ice in the Arctic circle has been thawing out some gigantic ancient viruses.

Last month, researchers announced they were studying a 30,000-year-old giant virus calledMollivirus sibericum that theyfound in melted Siberian permafrost. The virus was functional and able to infect amoeba.

This isn’t the first time researchers have found big virusesthat have challenged what we thought we knew about the tiny invaders. Mimivirus, discovered in 2003, has 1,200 genes and is twice the width of traditional viruses.

But it was this most recently discovered virus which prompted several outlets to suggest that once it thawed out, it could escape and make lots of people sick.

We recently chatted with New York Times columnist and “A Planet of Viruses” author Carl Zimmer to see what he thought about the discovery. In terms of its potential risk to people, he said we don’t need to be concerned.

But he said the finding is fascinating for several other reasons, including what it tells us about viruses in general.

“These particular viruses infect amoeba. So if you’re an amoeba, yeah you should be really scared,” Zimmer told Business Insider. “There are no human pathogens that have burst out of the Siberian permafrost. That’s not to say that viruses won’t emerge, but there are so many viruses circulating in living animals, I think we should put these frozen viruses very low on our list of concerns.”

Instead, Zimmer said they were more fascinating than scary.

These viruses are about 30 times bigger than your average virus, rivaling the size of a bacterium. Here’s a shot of Mollivirus sibericum under the microscope:


In addition to its unusual size, Mollivirus sibericum has other components which separate it from the vast majority of viruses. It has more than 500 genes, for example, which give the virus instructions for making proteins. By contrast, HIV has just nine genes.

“They’re in and of themselves fascinating and they really challenge us to think about what viruses are,” said Zimmer.

Viruses are technically not considered alive, but these giant viruses do seem to have some of the qualities of being alive, like a functioning metabolism. If we’re ever going to rethink the characteristics of viruses, these giant thawed-out viruses will be the ones to make us do it.

This article is published in collaboration with Business Insider. Publication does not imply endorsement of views by the World Economic Forum.

To keep up with the Agenda subscribe to our weekly newsletter.

Author: Lydia Ramsey is an Editorial Intern for Business Insider Science. Erin Brodwin is Business Insider’s Science Editor.

Image: A nurse poses for a photo in a trauma center of the University of Mississippi Medical Center in Jackson. REUTERS/Jonathan Bachman