Newly Discovered Bat Viruses Give Hints to Covid’s Origins

In the summer of 2020, half a year into the coronavirus pandemic, scientists traveled into the forests of northern Laos to catch bats that might harbor close cousins of the pathogen.

In the dead of night, they used mist nets and canvas traps to snag the animals as they emerged from nearby caves, gathered samples of saliva, urine and feces, then released them back into the darkness.

The fecal samples turned out to contain coronaviruses, which the scientists studied in high security biosafety labs, known as BSL-3, using specialized protective gear and air filters.

Three of the Laos coronaviruses were unusual: They carried a molecular hook on their surface that was very similar to the hook on the virus that causes Covid-19, called SARS-CoV-2. Like SARS-CoV-2, their hook allowed them to latch onto human cells.

“It is even better than early strains of SARS-CoV-2,” said Marc Eloit, a virologist at the Pasteur Institute in Paris who led the study, referring to how well the hook on the Laos coronaviruses binds to human cells. The study was posted online last month and has not yet been published in a scientific journal.

Virus experts are buzzing about the discovery. Some suspect that these SARS-CoV-2-like viruses may already be infecting people from time to time, causing only mild and limited outbreaks. But under the right circumstances, the pathogens could give rise to a Covid-19-like pandemic, they say.