The coronavirus pandemic circling the globe is caused by a natural virus, not one made in a lab, a new study says.
The virus’s genetic makeup reveals that SARS-CoV-2 isn’t a mishmash of known viruses, as might be expected if it were human-made. And it has unusual features that have only recently been identified in scaly anteaters called pangolins, evidence that the virus came from nature, Kristian Andersen and his colleagues report March 17 in Nature Medicine.
When Andersen, an infectious disease researcher at the Scripps Research Institute in La Jolla, Calif., first heard about the coronavirus causing an outbreak in China, he wondered where the virus came from. Initially, researchers thought the virus was being spread by repeated infections jumping from animals in a seafood market in Wuhan, China, into humans and then being passed person to person. Analysis from other researchers has since suggested that the virus probably jumped only once from an animal into a person and has been spread human to human since about mid-November (SN: 3/4/20).
But shortly after the virus’s genetic makeup was revealed in early January, rumors began bubbling up that maybe the virus was engineered in a lab and either intentionally or accidentally released.
An unfortunate coincidence fueled conspiracy theorists, says Robert Garry, a virologist at Tulane University in New Orleans. The Wuhan Institute of Virology is “in very close proximity to” the seafood market, and has conducted research on viruses, including coronaviruses, found in bats that have potential to cause disease in people. “That led people to think that, oh, it escaped and went down the sewers, or somebody walked out of their lab and went over to the market or something,” Garry says.
Accidental releases of viruses, including SARS, have happened from other labs in the past. So “this is not something you can just dismiss out of hand,” Andersen says. “That would be foolish.”
Looking for clues
Andersen assembled a team of evolutionary biologists and virologists, including Garry, from several countries to analyze the virus for clues that it could have been human-made, or grown in and accidentally released from a lab.
“We said, ‘Let’s take this theory — of which there are multiple different versions — that the virus has a non-natural origin … as a serious potential hypothesis,’ ” Andersen says.
Meeting via Slack and other virtual portals, the researchers analyzed the virus’s genetic makeup, or RNA sequence, for clues about its origin.
It was clear “almost overnight” that the virus wasn’t human-made, Andersen says. Anyone hoping to create a virus would need to work with already known viruses and engineer them to have desired properties.
But the SARS-CoV-2 virus has components that differ from those of previously known viruses, so they had to come from an unknown virus or viruses in nature. “Genetic data irrefutably show that SARS-CoV-2 is not derived from any previously used virus backbone,” Andersen and colleagues write in the study.
“This is not a virus somebody would have conceived of and cobbled together. It has too many distinct features, some of which are counterintuitive,” Garry says. “You wouldn’t do this if you were trying to make a more deadly virus.”
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