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Scientists have found viruses nearly 15,000 years old hidden inside glacier ice from the Tibetan Plateau in China. Many of these ones had never been seen before. The discovery came from ice cores taken from the Guliya ice cap in western China, a glacier located high in the mountains at around 6,700 meters above sea level. The study, published in Microbiome in 2021, shows how glaciers can preserve traces of viruses and other microorganisms from long-lost environments.
When glaciers form, they slowly build up layer after layer of ice. Along the way, they trap particles from the surrounding atmosphere, including dust, gases, microbes, and viruses. These frozen layers act like a timeline, allowing scientists to study what was present thousands of years ago.
To examine the samples, researchers created a new ultra-clean method designed to study microbes and viruses in ice without introducing modern contamination. As Zhi-Ping Zhong, lead author of the study from the Ohio State University Byrd Polar and Climate Research Center, explained, glaciers contain records of past environments, and viruses are part of that history.
Ancient Viruses Found Hidden In Ice
The scientists analyzed ice cores collected in 2015 from the Guliya ice cap. After studying the samples with different dating techniques, they determined that the ice was almost 15,000 years old.
Inside the frozen samples, the team found genetic traces from 33 viruses. Four of them were already known to scientists, but at least 28 had never been identified before.
Researchers compared the genetic material with existing virus databases to understand where these viruses fit among known viral groups. The results showed that some of the pathogens carried genetic features linked to survival in extremely cold environments.
“These are viruses that would have thrived in extreme environments,” saidMatthew Sullivan, professor of microbiology at Ohio State University and co-author of the study. He explained that: “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.”
Frozen Viruses Traced Back To Plants And Soil
The researchers also looked at where these viral agents may have originated. Their analysis, published in Microbiome, pointed toward soil and plant environments rather than animals or humans. Among the ancient viral particles identified, four belonged to families that usually infect bacteria. Scientists also found that the number present in the glacier samples was much lower than what is normally found in places such as oceans or soil.
The study adds new information to a young area of research focused on viruses trapped in glaciers. Only a few previous studies have identified ancient viral relics in glacier ice. Scientists still know relatively little about the microbes and viruses that exist in extreme environments.
“We know very little about viruses and microbes in these extreme environments, and what is actually there,” he said. “The documentation and understanding of that is extremely important: 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?” Lonnie Thompson, senior author of the study and senior research scientist at the Byrd Polar Research Center, explained.
He added that studying these frozen organisms can help researchers understand how microbial communities existed during different periods of Earth’s climate history.
A New Way To Study Life In Extreme Places
The cleaning and analysis methods developed by the team could help scientists investigate other environments where studying microorganisms is difficult. The researchers designed their approach to recover genetic information from ancient samples while avoiding contamination.
Sullivan noted that the technique could also be used to search for viral genetic sequences in other extreme environments.
“These are not easy signatures to pull out, and the method thatZhi-Ping 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.”
