BEIJING (AP) — Genetic material collected at a Chinese market near where the first human cases of COVID-19 were identified shows raccoon dog DNA mixed with the virus, suggesting the pandemic may have originated from animals, not animals. a laboratory, say international experts.
Other experts have not yet verified their analysis, which has yet to appear in a peer-reviewed journal. How the coronavirus started making people sick remains uncertain. The sequences will need to be matched to the genetic record of how the virus evolved to see which came first.
“These data do not provide a definitive answer to how the pandemic started, but each data is important in moving us closer to that answer,” World Health Organization director-general Tedros Adhanom Ghebreyesus said on Friday.
He criticized China for not sharing genetic information earlier, saying in a press conference that “this data could and should have been shared three years ago.”
Samples were collected from the surfaces of Huanan Seafood Market in early 2020 in Wuhan, where the first human cases of COVID-19 were found in late 2019.
Tedros said the genetic sequences were recently uploaded to the world’s largest public virus database by scientists at the China Center for Disease Control and Prevention.
They were then removed, but not before a French biologist spotted the information by chance and shared it with a group of scientists based out of China who are investigating the origins of the coronavirus.
The data show that some of the COVID-positive samples collected from a stall known to be involved in the wildlife trade also contained genes from raccoon dogs, indicating that the animals may have been infected with the virus, according to the scientists. Their analysis was first reported in The Atlantic.
“There’s a good chance that the animals that deposited that DNA also deposited the virus,” said Stephen Goldstein, a virologist at the University of Utah who was involved in analyzing the data. of a zoonotic spillover event… this is basically exactly what you would expect to find.
The canines, named for their raccoon-like faces, are often raised for their fur and sold for meat in animal markets throughout China.
Ray Yip, an epidemiologist and founding member of the US Centers for Disease Control’s China office, said the findings were significant, even if they weren’t definitive.
“The environmental market sampling data released by the China CDC is by far the strongest evidence supporting animal origins,” Yip told the AP in an email. He wasn’t connected to the new analysis.
WHO COVID-19 technical lead Maria Van Kerkhove warned that the analysis did not find the virus inside any animals, nor did it find any concrete evidence that the animals had infected humans.
“What this provides are clues to help us understand what might have happened,” he said. The international team also told WHO it found DNA from other animals and raccoon dogs in samples from the fish market, he added.
“There is molecular evidence that the animals were sold at the Huanan market and this is new information,” Van Kerkhove said.
The genetic code of the coronavirus is strikingly similar to that of bat coronaviruses, and many scientists suspect that COVID-19 entered humans directly from a bat or via an intermediate animal such as pangolins, ferrets or raccoon dogs.
Efforts to determine the origins of the COVID-19 pandemic have been complicated by factors including the massive surge in human infections in the first two years of the pandemic and an increasingly bitter political dispute.
It has taken virus experts more than a dozen years to pinpoint the animal origin of SARS, a related virus.
Goldstein and his colleagues say their analysis is the first solid indication that there may have been wildlife infected with the coronavirus at the market. But it’s also possible that humans brought the virus to market and infected raccoon dogs, or that infected humans simply left traces of the virus near the animals.
After scientists in the group contacted China’s CDC, they say, the sequences were removed from the global virus database. Researchers are puzzled as to why data on samples collected more than three years ago hasn’t been made public sooner. Tedros pleaded with China to share more of its COVID-19 research data.
Gao Fu, the former head of China’s CDC and lead author of the Chinese paper, did not immediately respond to an Associated Press email request for comment. But he told Science magazine that the sequences are “nothing new. It was known that there was an illegal trade in animals and that is why the market was immediately closed.”
Goldstein said his group presented its findings this week to an advisory panel that WHO has charged with investigating the origins of COVID-19.
Mark Woolhouse, an infectious disease expert at the University of Edinburgh, said it will be crucial to see how the genetic sequences of raccoon dogs match what is known about the historical evolution of the COVID-19 virus. If dogs are shown to have COVID and those viruses are shown to have earlier origins than those that have infected people, “that’s probably the strongest evidence we can expect to get that it was a market spillover event.” “.
After a week-long visit to China to investigate the origins of the pandemic, WHO released a report in 2021 concluding that COVID-19 most likely entered humans from animals, dismissing the possibility of a laboratory origin as “extremely unlikely”.
But the United Nations health agency backed down the following year, saying it was still “key pieces of data” missing. And Tedros said all hypotheses remain on the table.
Scientists from China’s CDC who previously analyzed samples from the Huanan market published a preprint article in February suggesting that humans brought the virus to market, not animals, implying that the virus originated elsewhere. . Their paper did not mention that animal genes were found in the samples that tested positive.
Wuhan, the Chinese city where COVID-19 was first detected, is home to several labs involved in collecting and studying coronaviruses, fueling theories that the virus may have leaked from one of them.
In February, The Wall Street Journal reported that the US Department of Energy had assessed “with low confidence” that the virus had leaked from a laboratory. But others in the US intelligence community disagree, believing it is more likely to come from animals initially. Experts say the true origin of the pandemic may not be known for many years, if ever.
Cheng reported from London.