Glacier scientists have found viruses nearly 15,000 years old in two ice samples taken from the Tibetan plateau in China.
As the authors of the study, published in the journal Microbiome, note, the viruses survived because they were frozen. In addition, they turned out to be unlike any viruses known to science today.
Glacial ice stores information, including microbiological information, that helps uncover the history of the paleoclimate and predict future climate change. Although glacial bacteria are studied using culture or amplicon techniques, more sophisticated metagenomic approaches that provide access to functional, genomic information and viruses are underutilized, in part due to low biomass and potential contamination.
The researchers analyzed ice cores taken in 2015 from an ice cap from the Tibetan plateau in western China. Cores are collected at high altitudes, so, in particular, the summit, where this ice was formed, is located at an altitude of almost 7 km above sea level. Ice cores contain layers of ice that accumulate year after year. They capture everything that was in the atmosphere around them during the freezing of each layer. These layers create a kind of timeline that scientists have used to learn more about climate change, bacteria, viruses, and gases throughout history.
Using a combination of traditional and new dating methods, the researchers determined the ice to be nearly 15,000 years old. After analyzing the ice, they found the genetic codes of 33 viruses. Four of them are already known to science. The remaining 28 are new. It turned out that about 14 managed to survive, as they were frozen into the ice.
As the authors of the study note, the detected viruses could thrive quite successfully in extreme conditions thanks to the special signatures of the genes.