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Ancient 15,000-Year-Old Viruses Appear In Melting Glacier Ice

Century-old moss that has been frozen away in the depths of a Tibetan Glacier has melted to reveal ancient viruses, giving scientists a real glimpse into the organisms that lived tens of thousands of years ago on Earth, as well as the history of their ecosystems.

“The melting has also created some concerns about ancient viruses coming back to haunt us. Melting will not only lead to the loss of those ancient, archived microbes and viruses, but also release them to the environment in the future,” microbiologist Zhi-Ping Zhong wrote in a new study.

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Scientists luckily have access to technology that can keep the ice samples completely sterilized, which makes it easier to work with when it comes to analyzing what exactly is in the ice. Recently, scientists identified dozens of 15,000-year-old viruses from the Guliya ice cap of the Tibetan Plateau.

“These glaciers were formed gradually, and along with dust and gases, many, many viruses were also deposited in that ice. These microbes potentially represent those in the atmosphere at the time of their deposit.”

“These are viruses that would have thrived in extreme environments, with 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,” said microbiologist Matthew Sullivan, who also worked on the study.

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When the scientists compared the genetic sequence of the recent discovery they found that a majority of the viruses present in the ice core samples were bacteria that infect Methylobacterium; this classifies the group of bacteria responsible for the methane cycle of ice in a glacier.

These types of bacteria are typically found in plant or soil habitats, which indicates to the researchers that the viruses likely were deposited in the ice through dust particles that lifted from soil tens of thousands of years ago.

“These frozen viruses likely originate from soil or plants and facilitate nutrient acquisition for their hosts.”

“We know very little about viruses and microbes in these extreme environments, and what is actually there,” says Earth scientist Lonnie Thompson.

“How do bacteria and viruses respond to climate change? What happens when we go from an ice age to a warm period like we’re in now?”

Melting Glacier

Climate Change May Release Ancient Viruses Trapped in Melting Glaciers

It’s common knowledge at this point that global warming is melting the world’s glaciers, leading to a rise in sea level and the destruction of habitats for life around the North and South Pole. However, scientists now have an additional concern relating to the melting of glaciers, which is that this melting may lead to the release of never-before-seen frozen viruses which have been trapped within glaciers for fifteen thousand years. As scientists have never before had an opportunity to study these mysterious viruses, they are of significant scientific interest, as not only do they offer a window into the history of the evolution of viruses, but learning about these viruses may give doctors a better chance of treating people who could potentially be affected by them. While it’s unlikely that humans will contract diseases caused by the release of these ancient viruses, the fact that so little is currently known about them leads researchers to be on high alert, as no one can say for certain what effect they might have on human beings.

Accordingly, a study, which was posted on the bioRxiv database but has not yet been peer reviewed, explores a novel method of studying these ancient viruses that minimizes the chances of contamination by modern-day bacteria. In order to prevent contamination, the researchers brought two ice core samples collected from the Guliya ice cap on the Tibetan Plateau to a cold room, where the thermometer was set to 23 degrees Farhrenheit, and cut into the ice sample with a sterilized band saw. Then, they washed the ice cores with ethanol and sterile water to expose an uncontaminated layer of ice. 

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By examining this layer of ice, the researchers found 33 groups of virus genuses, 28 of which were previously unknown to science. Between the two ice core samples, the microbes differed significantly, representing the fact that the two ice cores existed in very different climates at the time that the viruses became embedded in the ice. Researchers expect that glaciers around the world contain substantially more ancient, frozen viruses that are currently unknown to science.

One of the dangers posed by climate change is not only that these mysterious viruses could be released into the world, but that the melting of glaciers could destroy these preserved viruses, preventing scientists from learning more about the history of the evolution of viruses. Currently, glacial viruses are severely understudied, and climate change may have the effect of making study of these viruses impossible.