According to news reports, researchers discovered coronaviruses in Laotian bats. These viruses are the closest relatives of SARS-CoV-2 (the virus that causes COVID-19), which was reported by reporters.
Researchers from France's Pasteur Institute and the University of Laos collected 645 bats from limestone caves of northern Laos. They then tested them for SARS-CoV-2 viruses. Three viruses were identified, BANAL-222, BANAL103, and BANAL-236. They infected horseshoe bats with the virus and shared more that 95% of their genome with SARS.
Nature News reported that BANAL-552 was 96.8% similar to SARS-CoV-2. BANAL-52 is genetically more similar to SARS CoV-2 than any other virus. Nature News reported that RaTG13 was the closest known SARS-CoV-2 relative. It was discovered in horseshoe bats and shared 96.1% with SARS-CoV-2.
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The three newly discovered viruses also share a key component of their genome, the receptor binding domain (RBD), that is more similar than any other known viruses. The virus' receptor binding domain (RBD) is what allows it to attach to host cells. The RBD binds with SARS-CoV-2 to ACE2 receptors on human cells. This receptor is used by the virus as a gateway to cells.
The new study has shown that BANAL-236, BANAL-236, and BANAL103 can bind to ACE2 to allow it to enter human cells. This is critical. Researchers stated that other candidates for the ancestors to SARS-CoV-2, such as RaTG13, have not been able do this so far. They said that the three viruses could bind with ACE2 as well as the early SARS-CoV-2 strains found in Wuhan.
These findings, posted to Research Square's preprint server Research Square, Sept. 17, provide further evidence that SARS-CoV-2 was not a result of escaping from a laboratory.
Researchers wrote that the results showed "sequences very similar to those of early strains of SARS/CoV-2... exist in nature", in their paper. This paper has not yet been peer-reviewed.
"The receptor binding domain of SARSCoV-2 was unusual at first because there were so many viruses to compare it with," Edward Holmes, an evolutionary biologist from the University of Sydney, said to Bloomberg. Holmes stated that "now that we're sampling more from the natural world, we are beginning to find these closely related bits" of gene sequence.
According to the authors, their findings support the theory that SARS-CoV-2 was caused by a recombination between viral sequences found in horseshoe bats.
Nature News reports that although the viruses discovered are very similar to SARS-CoV-2 they lack the sequence known as the furin cleavage location. This sequence is found in SARS-CoV-2. It aids virus entry into cells. To better understand SARS-CoV-2's origins, further research is required to determine when and how the furin site was created.
Bloomberg reported that the findings are being reviewed for publication in Nature journals.
Original publication on Live Science
