Fecal samples from three bats in the northern region of Laos, a country in Southeast Asia, contained coronaviruses that were very similar to that of SARS-CoV-2, the virus responsible for COVID-19 infections, according to findings published in the preprint server Research Square.
In summer 2020, researchers collected the samples from bats in the forests of northern Laos and studied them in high security biosafety labs, The New York Times reports. Their findings are awaiting peer review and were published Sept. 17 in the preprint server.
They found two dozen kinds of coronaviruses, three of which contained a molecular hook on their surface that allowed them to bind to human cells.The molecular hook was strikingly similar to the hook on the COVID-19 virus, researchers told the Times.
"It is even better than early strains of SARS-CoV-2," Marc Eloit, a virologist at the Pasteur Institute in Paris who led the study, told the news outlet, referring to how well the receptor-binding domain in the Laos coronaviruses binds to human cells.
Some scientists suspect these types of SARS-CoV-2-like viruses may already be infecting people, causing mild and limited outbreaks. Given how well the viruses latch on to human cells, the findings suggest it is in fact possible that the SARS-CoV-2 virus naturally spilled over from an animal to a human.
"This really puts to bed any notion that this virus had to have been concocted, or somehow manipulated in a lab, to be so good at infecting humans," Michael Worobey, PhD, a virologist at the University of Arizona in Tucson who was not involved in the research, told the Times.
The coronaviruses detected in the three bats from Laos make them the closest known relative to the COVID-19 virus. Previously, a bat coronavirus first discovered in 2016 from a mine in southern China's Yunnan Province, known as RaTG13, was thought to be the closest relative.