University studies in the United States and Australia suggest the ancient epidemic had a protective effect, so the death toll in Asia this time was low.
Author: ANDRÉS ALBURQUERQUE F. / Photo: Archives and Institutions
This question is on the minds and lips of many scientists, doctors and researchers: If Covid 19 emerged in Asia and spread like oil spills in China, why did they occur in that country and continent? so few deaths?
modern human genome Contains evolutionary information from hundreds of thousands of years agoincluding physiological and immune adaptations that allow us to defend against new threats, including viruses, a large family of viruses that typically cause mild or moderate upper respiratory tract illness, such as the common cold.
However, over the past twenty years Some novel coronaviruses have emerged from animal hosts and caused severe, widespread illness and death around the world. (Like SARS in 2002, which killed 800 people, and MERS-CoV, which killed 850 four years later).
But there is no doubt that the deadliest variant is the last one, Emerged in China in December 2019 and was declared a global pandemic by the World Health Organization on March 11, 2020. Although it has not yet been completely controlled, it is known to have killed approximately 3.9 million people worldwide. However, the total death toll in Vietnam, China and Japan is only 19,375, according to official figures.
Driven by confusion, a team of researchers from universities in the United States and Australia began studying the DNA of 2,500 people from 26 populations around the world to find answers. Traces of mutations created to protect against ancient diseases.
Scientists use the 100,000 Genomes Project British initiative The project to sequence and study the role our genes play in health and disease was ready and made public in December 2018.
According to DNA research (main photo)Ancient virus epidemic Can be identified by adaptive mechanisms in the host genome. As a result, studies by paleovirologists using genetic methods and DNA testing have shown that coronaviruses date back more than 20,000 years ago and came from East Asia.
Research has found that a This deadly variant of the new coronavirus emerged more than 25,000 years ago, wiping out much of the East Asian population, especially in a country with such a low mortality rate. People closely observed unusual elements in the genetic code and soon discovered unique sequences in genes that stood out from the crowd. China, Vietnam and Japan.
“It’s like looking for fossilized dinosaur footprints instead of directly looking for fossilized bones. We have not yet directly identified the ancient virus causing the epidemicbut rather a ‘signature’ of natural selection that it imposed on the human genome at that time,” said David Enard, Professor of Ecology and Evolutionary Biology at the University of Arizona (USA).
Soon scientists discovered that changes had already begun about 900 generations ago, so the most severe moment of the epidemic must have been around 25,000 years ago. on the contrary, After 500 generations, mutations begin to decreaseuntil genes stabilized about five thousand years ago, the date when epidemics ended when viruses were overcome by new defense systems.
This genomic improvement is key Making the people of Northeast Asia more resistant to a disease that has repeatedly hit the region in successive epidemicsproduced by new mutations in the virus.
Having established the characteristics and scope of this ancient epidemic, the second phase of the research was to examine whether the detected defense responses could be functional today. Professor Kirill Alexandrov and his team at the University of Queensland, Brisbane, AustraliaThey were responsible for verifying that some mutations could still act as a barrier against the virus and would be included in next-generation vaccines.
Studies such as this can help researchers compile a List potentially dangerous viruses and develop diagnostics, vaccines and drugs should they re-emerge. However, according to many evolutionary geneticists, such predictions are not easy and cannot be easily accepted, as is the case with COVID-19.
