By this point, we’re all pretty familiar with viruses. We’re sick from them. And we’re sick of them! What if I told you that viruses dating back 15,000 years have been found in an unlikely place – glacial ice originating in the Tibetan Plateau (35o17’N, 81o29’E)? Analysis of an ice core from the summit of Guliya (22,000 feet above sea level, a mere baby by Himalayan standards), has revealed genetic code for 33 viruses, with four of them previously identified by science. That means most of these viruses are novel – and about half of them seemed to have survived at the time they were frozen. So, they survived not in spite of the ice, but because of it.
“These viruses have signatures of genes that help them infect cells in cold environments — just surreal genetic signatures for how a virus is able to survive in extreme conditions. These are not easy signatures to pull out, and the method developed to decontaminate the cores and to study microbes and viruses in ice could help us search for these genetic sequences in other extreme icy environments — Mars, for example, the moon, or closer to home in Earth’s Atacama Desert” says Matthew Sullivan, professor of microbiology at Ohio State University.
Viruses don’t share a common gene so to compare these unidentified viruses with known ones, the scientists compared gene sets which are catalogued in databases. Analysis showed that the four (known) viruses originated with soil or plants, not with animals or humans, based on both the environment and database. As for the rest, that’s still unknown. In good news, the viruses aren’t ‘active’ as they are ‘killed’ by the chemistry of nucleic acid extraction. And given the viruses found in the ice core were adapted to survive in extremely cold temperatures, this limits their ability to spread, in nature, as the ice melts.
However, climate change is thawing out permafrost – ground that’s supposed to remain permanently frozen – which does have potential to release active viruses that haven’t circulated on Earth for thousands of years. Thus, it’s important to remain vigilant and to apply the lessons learned from the current pandemic.