Image courtesy: Wikimedia Commons
The pandemic coronavirus SARS-CoV-2 originated in bats and jumped to humans; Scientists know this. However, a lingering mystery of the pandemic is the precise origin of this virus and how this closest ancestor made this leap from animal to human. One of the deep concepts is that an intermediate animal is involved in the jump of the coronavirus from animal to human, that the coronavirus jumped first on the intermediate animal, then on humans and led to the pandemic.
Now, in a twist, an organization of virologists believes that finding the direct ancestor of the SARS-CoV-2 virus would be highly unlikely. They also say the COVID virus likely shared an ancestor with coronaviruses discovered in bats more recently than previously thought. The organization of virologists presented their locations at the 7th One Health World Congress held in Singapore on November 8. They will also publish them in a peer-reviewed journal.
Since the beginning of the pandemic, scientists have sought to detect the origin of the coronavirus. The origin of coronaviruses in bats is well known. But not all of those coronaviruses jump to humans. To find the exact origin of SARS-CoV-2, scientists compared the genetic structure of the virus with many others. But they failed to locate the exact origin. It is also the basis of the rumor that SARS-CoV-2 did not have an herbal source since its origin evolved in a laboratory at the Wuhan Institute of Virology. The laboratory in question housed several bat viruses for research.
Even former US President Donald Trump was one of the driving forces behind this claim about the Chinese laboratory, which led to the SARS-CoV-2 virus being declared the “Chinese virus”. However, with time and many warnings, it is now widely believed that SARS-CoV-2 had a plant origin. Now, an organization of virologists has explained why scientists might never notice the exact origin of the pandemic virus.
SARS-CoV-2 and several other very similar bat coronaviruses are known to have a common ancestor a few decades ago. But those viruses exchanged parts of their RNAs with each other, which is called recombination. RNA is the genetic tissue of those viruses, and recombination, they exchange parts of their genetic curtains with each other. At its presentation in Singapore, the virologists’ organization said they had fragments of coronavirus genetic curtains by comparison. Their research suggests that some of the bats coronaviruses and SARS-CoV-2 represented a common ancestor until 2016, just 3 years before the pandemic began. According to the researchers, they tried to reduce the time between the ancestor of local SARS-CoV-2 in bats and that of the virus jumping to humans.
The researchers infer that it would be near impossible to pinpoint the exact ancestor of the SARS-CoV-2 in bats due to extensive recombination among it and several other bat coronaviruses.
Joel Wertheim, a molecular epidemiologist at the University of California and a contributor to the present work, in a statement, commented about the implications of their finding, saying, “SARS-CoV-2’s direct ancestor probably formed from several viruses and has been recombining and mutating in bats ever since. Sampling bats for coronaviruses could possibly identify viral fragments that are more closely related than those found in known coronaviruses so far, but probably won’t reveal one direct ancestor.”
Since the beginning of the pandemic, scientists, especially from Southeast Asia, have actively sequenced coronaviruses in bats and other mammals. But they were unable to locate an ancestor of SARS-CoV-2. The new findings shed light on why scientists were unable to pinpoint the precise origin.
With the whole genome sequencing approach, scientists deciphered the entire series of genetic curtains of various viruses (DNA or RNA). But, this approach neglects the role of recombination, the researchers say. and pangolin viruses very similar to SARS-CoV-2 by splicing them into 27 fragments.
Remember that the pangolin was considered the intermediate animal by which the coronavirus jumped to humans from animals.
“Each segment, with a few hundred or thousands of nucleotide sequences, has another evolutionary history,” said Spyros Lytras, who presented the effects at the Singapore conference. Lytras is an evolutionary virologist at the University of Glasgow, UK. His paintings published on a website.
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