Where did COVID-19 come from? DNA suggests animal ties

BEIJING –

Genetic material was collected in the Chinese market where the first human cases were discovered COVID 19: International experts say the findings show that the raccoon dog’s DNA is mixed with the virus, suggesting the outbreak may have originated in animals rather than a laboratory.

Other experts have not yet peer-reviewed their analysis, which has yet to appear in a peer-reviewed journal. How the coronavirus began to make people sick remains unclear. The sequences have 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 epidemic started, but every piece of data is important in bringing us closer to that answer,” World Health Organization Director-General Tedros Adhanom Ghebreyesus said Friday.

He criticized China for not sharing genetic information earlier, telling a press briefing that “this data could and should have been shared three years ago.”

The samples were collected in early 2020 from the surfaces of the Huanan seafood market in Wuhan, where the first human cases of COVID-19 were identified in late 2019.

Tedros said the genetic sequences were recently uploaded to the world’s largest public virus database by scientists at China’s Centers for Disease Control and Prevention.

They were then removed, but not before a French biologist stumbled upon the information and shared it with a group of scientists outside China studying the origins of the coronavirus.

The data showed that some of the COVID-positive samples collected from the wildlife trade stall also contained genes from raccoon dogs, indicating that the animals may have been infected with the virus, the scientists said. Their analysis was first reported in The Atlantic.

“There’s a good chance that the animals that accumulated that DNA also accumulated the virus,” said Steven Goldstein, a virologist at the University of Utah who was involved in the data analysis. “If you were to go and do environmental sampling of a zoonotic outbreak, this is basically what you would expect to find.”

The dogs, named for their raccoon-like faces, are often bred for their fur and sold for meat in pet markets in China.

Ray Yip, an epidemiologist and founding member of the US Centers for Disease Control and Prevention’s China Office, said the findings are significant, although they are not conclusive.

“Market data from environmental sampling published by the China CDC is the strongest evidence to support an animal origin,” Yip told the AP in an email. He had nothing to do with the new analysis.

The WHO’s technical lead for COVID-19, Maria Van Kerkhove, cautioned that the analysis did not detect the virus in any animals, and found no hard evidence that any animals had infected humans.

“What it provides are clues to help us understand what might be going on,” he said. The international group also told the WHO that they found DNA from other animals as well as raccoon dogs in samples from the seafood market, it added.

“There is molecular evidence that animals were sold in the Huanan market, and that is new information,” Van Kerchow said.

Efforts to determine the origins of the COVID-19 pandemic have been complicated by factors including a massive surge in human infections in the first two years of the pandemic and an increasingly violent political dispute.

It took virus experts more than a dozen years to identify the animal origin of SARS, a related virus.

Goldstein and his colleagues say their analysis is the first solid indication that wild animals infected with the coronavirus may have been on the market. But it is also possible that people brought the virus to the market and infected the raccoon dogs, or that infected people simply accidentally left traces of the virus in the animals.

After the team’s scientists contacted China’s CDC, they say the sequences were removed from the global virus database. Researchers are puzzled as to why data from samples collected more than three years ago were not released sooner. Tedros has asked China to share more of its COVID-19 research data.

Gao Fu, the former head of China’s CDC and the lead author of a Chinese newspaper, did not immediately respond to an email from The Associated Press seeking comment. But he told Science magazine that sequences are “not a new thing. It was known that there was illegal trade in animals and so the market was immediately closed down.”

Goldstein said his group presented its findings this week to an advisory panel commissioned by the WHO to investigate the origins of COVID-19.

Mark Woolhouse, an infectious disease expert at the University of Edinburgh, said it would be important to see how the genetic sequences of raccoon dogs match up with what is known about the historical evolution of the COVID-19 virus. If dogs are found to have COVID-19, and those viruses predate those that have infected humans, “that’s probably as good evidence as we can expect that this was a spillover event in the marketplace.” “.

After a week-long visit to China to investigate the outbreak’s origins, the WHO issued a report in 2021 concluding that COVID-19 most likely jumped from animals to humans, dismissing the possibility of a laboratory origin as “highly unlikely”.

But the UN health agency backtracked the following year, saying “key data” was still missing. And Tedros said that all versions remain on the table.

China’s CDC scientists, who previously analyzed samples from the Huanan market, published a paper in February as a preprint suggesting that humans brought the virus to the market, not animals, suggesting the virus originated elsewhere. Their paper does not mention that animal genes were found in the positive samples.

Wuhan, the Chinese city where COVID-19 was first discovered, is home to several laboratories involved in collecting and studying the coronavirus, fueling theories that the virus may have leaked from one.

In February, the Wall Street Journal reported that the US Department of Energy assessed with “low confidence” that the virus had leaked from a laboratory. But other members of the US intelligence community disagree, saying it’s more likely that it first came from animals. Experts say the true origins of the epidemic may not be known for many years, if ever.

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Cheng reported from London.