Researchers have identified 33 viruses in ancient ice cores that are 15,000 years old, at least 28 of which are in the world of modern science.
According to News i and quoted by New AtlasScientists have collected viruses from nearly 15,000-year-old ice samples from Tibetan glaciers and found that dozens of species are unknown to the world of science, and their discovery could provide a fascinating look at the history of viral evolution.
Glaciers are great for preserving the depth of history because they trap dust particles, traces of gas, microbes and plant material from different time periods. Because these layers accumulate over time, scientists can dig and study the cores of these ice cubes to learn more about the ancient climate and what was in the atmosphere, and the types of life in different parts of history.
In this new study, led by researchers at Ohio State University, ice cores were drilled from an ice cap called the Guliya on the Tibetan Plateau, which dates back 14,400 years.
The team then analyzed the samples and found that they contained several types of viruses. Eventually, the genetic codes of 33 types of viruses were identified, and four of them belonged to known bacteriophage strains (viruses that hunt bacteria). But at least 28 of them do not correspond to any known type and are completely new.
Researchers suspect that these viruses may have originated in plants and soil, but have not necessarily been neutralized by the cold. In fact, half of them seemed to have good living conditions on ice.
“These are viruses that grow in harsh environments,” says study co-author Matthew Sullivan. These viruses have genes that help infect cells in cold environments and have a genetic signature on how the virus survives in extreme conditions.
Contamination with modern microbes is a serious problem for this type of study, so researchers have developed a new method for sterilizing ice kernels. They scraped the outer half-centimeter layer of the samples by various techniques, then washed with ethanol and finally sterilized with water. Then the inner part of the sample could be examined without the possibility of contamination.
The research team first tested the sterilization process on artificial ice cores containing bacteria and viruses, and found that after the three-step sterilization process, no trace of these contaminants was observed.
Researchers say the ability to better study ancient microbes could help scientists better understand their evolutionary history, as well as how they reacted to climate change in the past, as well as their chances of success in the future.
This method of sterilization can also be useful for finding traces of viral genetic sequences in samples taken on the moon or Mars.
The study is published in the journal Microbiome.