Ancient viruses 15,000 years old found in melting Tibetan glaciers

(ORDO NEWS) — Ancient creatures emerge from the cold vaults of melting permafrost, almost like something out of a horror movie.

From incredibly preserved extinct megafauna like the woolly rhinoceros to 40,000-year-old remains of a giant wolf and over 750,000-year-old bacteria. Not all of them are dead.

Centuries-old moss was able to come back to life in the warmth of the laboratory. So are the tiny 42,000-year-old roundworms.

These fascinating insights into organisms from Earth’s distant past reveal the history of ancient ecosystems, including details of the environment in which they lived.

However, the melt has also raised some concerns that ancient viruses could return to haunt us.

“Thawing will not only result in the loss of these ancient, archived microbes and viruses, but will also release them into the environment in the future,” researchers explained in a study last year led by first author and Ohio State University microbiologist Zhi-Ping Zhong.

Thanks to metagenomics and new ways to sterilize ice core samples, researchers have been able to better understand what lurks in the cold.

Through the study, the team was able to identify an archive of dozens of unique 15,000-year-old viruses from the Gulia ice cap in the Tibetan Plateau and gain insight into their functions.

“These glaciers formed gradually, and along with dust and gases, many, many viruses entered the ice,” says Zhong.

These microbes are potentially those that were in the atmosphere at the time they were deposited, the team explains in their paper.

Past research has shown that microbial communities are correlated with changes in atmospheric dust and ion concentrations, and may also be indicative of climate and environmental conditions at the time.

In these frozen records from ancient times at 6.7 km (22,000 feet) above sea level in China, researchers found that 28 of the 33 viruses they identified had never been seen before.

“These are viruses that could thrive in extreme conditions,” Ohio State University microbiologist Matthew Sullivan said.

“The genes that help them infect cells in cold conditions are just surreal genetic indications of how a virus can survive in extreme conditions.”.

By comparing their genetic sequences to a database of known viruses, the team found that the most common viruses in both ice core samples were bacteriophages that infect Methylobacterium, bacteria important to the methane cycle in ice.

They were most closely related to the viruses found in strains of Methylobacterium in plant and soil habitats – in line with a previous report that the main source of dust deposited on the Gulia ice cap probably comes from soils.

“These frozen viruses likely originate from soil or plants and provide nutrients to their hosts,” the team concluded.

While the specter of ancient viruses seems particularly troubling in the wake of the COVID-19 pandemic, the greatest danger lies in what else the melting ice is unleashing – vast reserves of sequestered methane and carbon.

But it is clear that the ice may also contain information about past environmental changes and the evolution of viruses.

“We know very little about viruses and microbes in these extreme environments and what’s really going on there,” said geoscientist Lonnie Thompson, noting that many important questions remain unanswered.

“How do bacteria and viruses respond to climate change? What happens when we move from an ice age to a warm one, as we are now?”

Much remains to be explored.

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