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Researchers have discovered hidden coronaviruses in Laotian bats that appear to be the closest known relatives of SARS-CoV-2, the virus that causes COVID-19, found to date, according to news reports.
In a new study, researchers from the Institut Pasteur in France and the University of Laos captured 645 bats in limestone caves in northern Laos and screened them for viruses linked to SARS-CoV-2. They found three viruses – which they dubbed BANAL-52, BANAL-103, and BANAL-236 – that infected horseshoe bats and shared over 95% of their overall genome with SARS-CoV -2.
One of the viruses, BANAL-52, was 96.8% identical to SARS-CoV-2, according to Nature New. This makes BANAL-52 more genetically similar to SARS-CoV-2 than any other known virus.
Previously, the closest known relative of SARS-CoV-2 was RaTG13, which was found in horseshoe bats in 2013 and shares 96.1% of its genome with SARS-CoV-2, Nature News reported.
Related: 7 Facts About The Origin Of The New Coronavirus
Additionally, the three newly discovered viruses are more similar to SARS-CoV-2 in a key part of their genome – called the receptor binding domain (RBD) – than other known viruses.
RBD is the part of the virus that allows it to bind to host cells. With SARS-CoV-2, RBD binds to a receptor called ACE2 on human cells, and the virus uses this receptor as a gateway to the cells.
Critically, the new study found that BANAL-52, BANAL-103, and BANAL-236 can bind to ACE2 and use it to enter human cells. So far, other candidates proposed as the ancestors of SARS-CoV-2 found in bats, including RaTG13, have not been able to do so, the researchers said.
The three viruses could bind to ACE2 as well as the first strains of SARS-CoV-2 found in Wuhan, they said.
The results, which were posted on the Research Square preprint server on September 17, add to the evidence that SARS-CoV-2 had a natural origin, rather than escaping from a lab.
The results show “that sequences very similar to those of the first strains of SARS-CoV-2 … exist in nature,” the researchers wrote in their paper, which has not yet been peer-reviewed.
“The SARS-CoV-2 receptor binding domain looked unusual when it was first discovered because there were so few viruses to compare it to,” Edward Holmes, an evolutionary biologist at the University of Sydney, which was not involved in the research. Bloomberg said.
“Now that we are taking more samples from nature, we are starting to find these closely related pieces of genetic sequence,” Holmes said.
The authors claim that their results support the hypothesis that SARS-CoV-2 was the result of recombination of viral sequences existing in horseshoe bats.
Yet even though the newly discovered viruses are closely related to SARS-CoV-2, all three viruses lack a sequence for what is called the “furin cleavage site”, which is seen in SARS. -CoV-2 and facilitates the entry of the virus into cells, according to Nature News. This means that to better understand the origins of SARS-CoV-2, more research is needed to show how and when the furin site was introduced.
The results are currently under review for publication in a Nature newspaper, Bloomberg reported.
Associated content:
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This article was originally published by Live Science. Read the original article here.
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