A new study by researchers at the University of Arizona found that a coronavirus pandemic broke out in the East Asia region more than 20,000 years ago, with traces of the outbreak evident in the genetic makeup of people in that area.
In an article published in the journal Current Biology, the researchers analyzed the genomes of more than 2,500 modern humans from 26 populations around the world, to better understand how humans have adapted to historic coronavirus outbreaks. The team, co-led by researchers from the University of Arizona and the University of Adelaide, used computational methods to discover genetic traces of adaptation to coronaviruses, the virus family responsible for three major outbreaks in the past 20 years, including the current COVID-19.
In the past 20 years, there have been three severe epidemic coronavirus outbreaks: SARS-CoV that caused severe acute respiratory syndrome, which originated in China in 2002 and killed more than 800 people; MERS-CoV leading to Middle East respiratory syndrome, which killed more than 850 people; and SARS-CoV-2 that has caused COVID-19, which has killed 3.8 million people.
But This study of the evolution of the human genome has revealed another major coronavirus pandemic that broke out thousands of years earlier. “It’s like finding fossilized dinosaur tracks rather than finding fossilized bones directly,” explained Dr. David Enard, a professor in the Arizona Department of Ecology and Evolutionary Biology and one of the study’s lead authors. “We do not find the ancient virus directly, but rather find signatures of natural selection that imposed on human genomes at the time of an ancient pandemic”.
The scientists synthesized human and SARS-CoV-2 proteins, without using living cells, and showed that these interacted directly and specifically, pointing to the conserved nature of the mechanism that coronaviruses use to invade cells. Modern human genomes contain evolutionary information dating back hundreds of thousands of years, including physiological and immunological adaptations that have enabled humans to survive new threats, including viruses.
According to experts, the ancestors of East Asian people experienced a pandemic of a coronavirus-induced disease similar to COVID-19 in East Asia, an area now made up of China, Japan, Mongolia, North Korea, South Korea, and Taiwan.
To invade cells, a virus must bind and interact with specific proteins produced by the host cell known as viral interaction proteins (VIPs). The researchers found signs of adaptation in 42 different human genes that encode VIP, suggesting that the ancestors of modern East Asians were first exposed to coronaviruses more than 20,000 years ago.
“We found that the 42 VIPs are mainly active in the lungs, the tissue most affected by coronaviruses, and we confirm that they interact directly with the virus underlying the current pandemic,” said the first author of the article, Yassine Souilmi, from the Faculty of Biology from the University of Adelaide. Sciences. In addition to VIPs, which are found on the surface of a host cell and are used by coronaviruses to enter the cell, viruses interact with many other cellular proteins once inside.
“We discovered that human genes that encode proteins that prevent or help the virus multiply have undergone much more natural selection about 25,000 years ago than would normally be expected, Enard said. The work shows that throughout the pandemic, selection favored certain human gene variants involved in virus-cell interactions that could have led to less severe disease.
Studying the “footprints” left by ancient viruses can help researchers better understand how the genomes of different human populations adapted to viruses that have emerged as important drivers of human evolution.
Other independent studies have shown that mutations in VIP genes can mediate susceptibility to coronavirus and also the severity of COVID-19 symptoms. And several VIPs are currently being used in drug treatments for COVID-19 or are part of clinical trials for further drug development.
“Our past interactions with viruses have left telling genetic signals that we can harness to identify genes that influence infection and disease in modern populations., and can inform drug reuse efforts and the development of new treatments, “said study co-author Ray Tobler of the University of Adelaide College of Biological Sciences.
“By discovering the genes previously affected by historical viral outbreaks, our study points to the promise of evolutionary genetic analysis as a new tool to combat the outbreaks of the future,” Souilmi said. The study authors say their research could help identify viruses that have caused pandemics in the distant past and may do so in the future. Studies like yours help researchers compile a list of potentially dangerous viruses and then develop diagnostics, vaccines, and drugs in case they return.