The ancestors of the novel coronovirus have probably been roaming in bats for decades. According to a new study, those coronaviruses also had the ability to infect humans.
To understand where the novel coronovirus, known as SARS-CoV-2, originated and how it spread to humans, scientists need to trace its evolutionary history through the genes of the virus, Which are encoded in ribonucleic acid or NNA. But the evolutionary history of SARS-CoV-2 is complex, because Coronavirus Often known for exchange genetic material With other coronations.
Gene-swabbing, called genetic recombination, is also difficult for scientists to see how coronovirus first spreads in humans; Some researchers propose a direct bat-to-human transmission, while others hypothesize that there was a middle species, such as pangolins, Is included.
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In the new study, researchers first identified those parts of RNA in the SARS-CoV-2 genome that “co-exist as a whole piece”, as far as they could study, without genetic recombination. Head Maxies said, “Bonnie is an Associate Professor of Biology of Infectious Disease Dynamics of the Penn State Center.
They then compared these genetic regions to similar coronaviruses found in bats and pangolins. Adding evidence to support previous findings, they discovered that SARS-CoV-2 was most closely related to another bat coronavirus, known as RaTG13.
In previous studies, scientists specifically looked at the genes responsible for the so-called receptor-binding domain (RBD) of the coronovirus. “Spike” Protein – The fragment that allows the ACE2 receptor in human cells to dock viruses and infect them. That research found that the RBD portion of the spike protein is genetically more similar to the coronavirus found in pangolin (called pangolin-2019) than RaTG13. There are two possible explanations for this finding: first, that the SARS-CoV-2 virus had developed its ability to spread to humans in pangolins (unlikely, given that SARS-CoV-2 was not a known pangolin virus. Se is more closely related to RaTGEN Black)), or another, that SARS-CoV-2 acquired this RBD through recombination with pangolin virus, Bonnie said.
But in the new analysis, researchers found no evidence of recombination in the genes of the SARS-CoV-2 spike protein. Instead, new genetic sequencing data reveal what had happened: the gene for the spike protein, and thus the coronovirus’s ability to infect human cells, had passed below a common ancestor, which eventually led to a trio of coronaviruses Gave birth to: SARS-CoV-2, RaTG13 and Pangolin-2019.
The authors note that it is still possible that the pangolin “or another hysteroid undiscovered species” could act as an intermediate host that helped the virus to spread to humans. But “it’s unlikely,” Bonnie said. Rather, new findings suggest that the ability of both humans and pangolins to replicate in the upper respiratory tract has actually evolved in bats. From bats, SARS-CoV-2 could spread directly to humans.
Wandering for decades
But when the lineage first gave SARS-CoV-2, who deviated from the other two virus lineages? To find this out, researchers identified mutations or differences in specific nucleotides – molecules that make up the RNA of the coronavirus – between different viruses. They then counted the number of mutations present in regions of the SARS-CoV-2 genome that did not undergo recombination. And after finding out the approximate rate at which the coronovirus mutates each year, they calculated how long it had been since the three.
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They found that a century ago, there was a single lineage that would eventually give rise to SARS-CoV-2, RaTG13 and Pangolin-2019 viruses. Still, “This dynasty was probably necessary amino acids Bonnie stated that its receptor-binding site, to infect human cells, has building blocks of amino acids. Protein Such as spike proteins).
At that time, the pangolin-2019 virus isolated from the SARS-CoV-2 and RaTG13 viruses. Then, in the 1960s or 1970s, this lineage split into two, creating the RaTG13 lineage and the SARS-CoV-2 lineage. Sometime between 1980 and 2013, the RaTG13 lineage lost its human receptor-binding capacity, but SARS-CoV-2 did not.
Bori stated, “The SARS-CoV-2 lineage has been operational in bats for 50 or 60 years before jumping to man.” Near the end of 2019, “someone became very unlucky” and came in contact with SARS-CoV-2 and set a Universal epidemic.
Bonnie said there are likely to be descendants of other viruses from the same century-old ancestor, which have been developing for decades, “that we have not yet characterized.” “The question is, ‘Are there half a dozen, 20 or hundred of these descendants?” – No one else knows. “He said that there is a possibility that there might be someone else hiding in the bats that would be able to spread to humans.
Dr., an infectious disease specialist at the Johns Hopkins Center for Health Security in Baltimore. Amesh Adalja said “This paper provides more clues to understand how this and other coronavir may emerge”, which was not part of the study. “We really know the tip of the iceberg when bats have viruses.” Given that relatives of the coronovirus have been around for so many years, it shows that there are many more. “When it comes to epidemic preparedness, having a very robust surveillance system is really the only way we are going to protect against these threats in the future,” Adalja said.
Bonnie said a lot of virus samples are taken in domestic and wild birds to prevent a potential bird flu pandemic in East Asia, Southeast Asia and other parts of the world. “If someone gets infected by avian Influenza Virus, the time to understand that something like 48 hours will happen and we will know immediately that this person has to be isolated immediately and follow other measures. “But for Bat Coronavirus, there are no such preventive measures, he added.
Bonnie said that after more than a month SARS-COV-2 was first spread to the genome of a novel coronovirus spread in humans – enough time for the virus to spread to a thousand people. “It was too late at that time.”
The findings were published in the journal on 28 July Nature microbiology.
Originally published on Live Science.