The one from Siberia is a new kind of giant virus, joining a group that was first discovered 10 years ago.
The researchers said their finding suggests that dangerous germs might emerge in the future as permafrost thaws because of global warming or mineral exploration. They said sampling permafrost to look for ancient viruses that infect amoebas is an inexpensive and safe way to assess that potential threat.
The new work was reported Monday in the Proceedings of the National Academy of Sciences.
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