The coronavirus epidemic dates back 20,000 years.
A study published in Current Biology shows that the peoples of East Asia had to deal with a coronavirus epidemic that left in their DNA the genetic traces of a long coexistence.
The study shows that human coronaviruses capable of causing serious disease are not just a threat of the last 20 years.
In the past two decades we have gone through three epidemics caused by Betacoronavirus, human coronaviruses capable of causing serious diseases, like SARS-CoV, which started in China in 2002 and killed more than 800 people; MERS-CoV, the coronavirus virus of the respiratory syndrome in the Middle East, which caused 850 deaths and most recently SARS-CoV-2, which has caused over 3.8 million deaths so far.
A study on the evolution of the human genome, conducted by the University of Arizona, the University of California San Francisco and the University of Adelaide (Australia), sheds light on another much older coronavirus epidemic in East Asia, the area now occupied by China, Japan, Mongolia, North Korea, South Korea and Taiwan.
“All genomes constantly accumulate mutations, most of which are harmless and do not lead to changes in gene function. “We can imagine the frequency of mutations as a continuous genetic clock,” Kirill Alexandrov, one of the study’s authors, told Focus.it.
“When there is selective pressure, the clocks of some genes start to vibrate faster as they accumulate beneficial mutations. Our study showed that, over 20,000 years ago, many of the human genes that SARS-CoV-2 uses to manipulate body cells began to vibrate more rapidly simultaneously, as if to indicate that there was a viral pandemic caused by a similar virus ”.
The scientists used data from the 1000 Genomes Project, the largest and most detailed catalog of human genetic variability, to observe how human genes that encode proteins capable of interacting with SARS CoV-2 have changed over time. . Separately, they also synthesized human proteins and proteins typical of coronaviruses, such as spikes, and showed that these interact in a direct way and that the way to attack the virus cells of this family has been preserved over time.
Studying how the human genome evolved in regions that encode proteins that interact with these pathogens, the team concluded that, more than 20,000 years ago, the ancestors of today’s East Asian populations faced an epidemic caused by a coronavirus which caused a disease similar to Covid, or from a virus that attacked cells by the same mechanism.
During the epidemic, natural selection acted on the human genome by favoring, as in some form of adaptation, genetic variants capable of leading to a less severe disease.
“The modern human genome contains evolutionary information that allows us to go back tens of thousands of years ago, as if we were studying the rings of a tree to get information on the conditions that went through the growth phase,” Alexandrov explains.
In principle, proceeding with this type of analysis can compile a list of viruses, or at least families of viruses, that have caused large-scale outbreaks in the past, and that can repeat this throughout history.