15,000-year-old viruses discovered in Tibetan Glacier ice: All you need to know
Of late, researchers who were studying Tibetan Glaciers have discovered unknown mysterious viruses that are 15,000 years old in two ice samples. Most of these viruses survived as they appear to have loved the extreme cold in which they lived.
The findings of the study have been published in the journal Microbiome. These will help scientists to dig deeper into how viruses have evolved over centuries. For the purpose of this study, scientists also created a new ultra-clean method of analysing microbes and viruses in ice without contaminating it.
1- The team analysed glacier samples taken in 2015 from the summit of the Guliya ice cap in western China, 22,000 feet above sea level.
2- Each sample is made up of layers, telling stories of past climates and environments.
3- Genetic codes for 33 viruses have been discovered by scientists. Of these, only 4 were previously known and others were novel.
4- The viruses likely originated with soil or plants, not with animals or humans, as per the researchers based on both the environment and the databases of known viruses.
5- These viruses have signatures of genes that help them infect cells in cold environments.
"These glaciers were formed gradually, and along with dust and gases, many, many viruses were also deposited in that ice," said lead author Zhi-Ping Zhong, a researcher at The Ohio State University`s Byrd Polar and Climate Research Centre who also focuses on microbiology.
He further added, "The glaciers in western China are not well-studied, and our goal is to use this information to reflect past environments. And viruses are a part of those environments."
"We know very little about viruses and microbes in these extreme environments, and what is actually there," said Lonnie Thompson, professor of earth sciences at Ohio State University in the U.S., who also co-authored the study.
No Common Universal Gene
Viruses do not share a common, universal gene. Therefore, naming a new virus and attempting to figure out where it fits into the landscape of known viruses involves multiple steps. To compare unidentified viruses with known viruses, scientists compare gene sets. Gene sets from known viruses are catalogued in scientific databases.
The four viruses that seem familiar actually belong to virus families that typically infect bacteria. The researchers found the viruses in concentrations far lower than their normal levels when detected in soil or ocean.
Viruses Emerging Out of Melted Glaciers
Experts have pointed out that climate change is melting the permafrost soils that have been frozen for thousands of years, and as they melt, ancient viruses and bacteria are released that lay dormant and spring back to life.
A notable example from the past: In 2016, a 12-year-old boy in Siberia died and at least twenty people were hospitalized after being infected by anthrax. The scientists at that time theorized that a reindeer infected with anthrax more than 75 years ago may have died and its frozen carcass trapped under frozen soil may have become permafrost. Due to severe heatwaves, the ice could have thawed causing the dormant virus to emerge.
The study of viruses in glaciers is relatively new as only two previous studies have identified viruses in ancient glacier ice but it is becoming more important as the climate changes. The questions such as 'How do bacteria and viruses respond to climate change? What happens when we go from an ice age to a warm period like we are in now?' are yet to be answered.