Genetic material collected at a Chinese market near where the first human cases of Covid-19 were identified show raccoon dog DNA comingled with the virus, adding evidence to the theory that the virus originated from animals, not from a lab, international experts say.“These data do not provide a definitive answer to how the pandemic began, but every piece of data is important to moving us closer to that answer,” World Health Organisation Director-General Tedros Adhanom Ghebreyesus said Friday.How the coronavirus emerged remains unclear. Many scientists believe it most likely jumped from animals to people, as many other viruses have in the past, at a wildlife market in Wuhan, China.But Wuhan is home to several labs involved in collecting and studying coronaviruses, fuelling theories scientists say are plausible that the virus may have leaked from one.The new findings do not settle the question, and they have not been formally reviewed by other experts or published in a peer-reviewed journal.Tedros criticised China for not sharing the genetic information earlier, telling a press briefing that “this data could have and should have been shared three years ago.” The samples were collected from surfaces at the 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 biggest public virus database by scientists at the Chinese 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 outside China that’s looking into 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 raccoon dog genes, indicating the animals may have been infected by 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. “If you were to go and do environmental sampling in the aftermath 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 bred for their fur and sold for meat in animal markets across China.Ray Yip, an epidemiologist and founding member of the US Centers for Disease Control office in China, said the findings are significant, even though they aren’t definitive.“The market environmental sampling data published by China CDC is by far the strongest evidence to support animal origins,” Yip told the AP in an email. He was not connected to the new analysis.WHO’s Covid-19 technical lead, Maria Van Kerkhove, cautioned that the analysis did not find the virus within any animal, nor did it find any hard evidence that any animals infected humans.“What this does provide is clues to help us understand what may have happened,” she said. The international group also told WHO they found DNA from other animals as well as raccoon dogs in the samples from the seafood market, she added.The coronavirus’ genetic code is strikingly similar to that of bat coronaviruses, and many scientists suspect Covid-19 jumped into humans either directly from a bat or via an intermediary animal like pangolins, ferrets or racoon dogs.Efforts to determine the origins of the Covid-19 pandemic have been complicated by factors including the massive surge of human infections in the pandemic’s first two years and an increasingly bitter political dispute.It took 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 is also possible that humans brought the virus to the market and infected the raccoon dogs, or that infected humans simply happened to leave traces of the virus near the animals.After scientists in the group contacted the China CDC, they say, the sequences were removed from the global virus database. Researchers are puzzled as to why data on the samples collected over three years ago wasn’t made public sooner. Tedros has pleaded with China to share more of its Covid-19 research data.Gao Fu, the former head of the Chinese CDC and lead author of the Chinese paper, didn’t immediately respond to an Associated Press email requesting comment.But he told Science magazine the sequences are “nothing new. It had been known there was illegal animal dealing and this is why the market was immediately shut down.” Goldstein said his group presented its findings this week to a WHO advisory panel investigating Covid-19’s origins.Michael Imperiale of the University of Michigan, a microbiology and immunology expert who was not involved in the data analysis, said finding a sample with sequences from the virus and a raccoon dog “places the virus and the dog in very close proximity. But it doesn’t necessarily say that the dog was infected with the virus; it just says that they were in the same very small area.” He said the bulk of the scientific evidence at this point supports a natural exposure at the market, and pointed to research published last summer showing the market was likely the early epicenter of the scourge and concluding that the virus spilled from animals into people two separate times. “What’s the chance that there were two different lab leaks?” he asked.Mark Woolhouse, an infectious diseases expert at the University of Edinburgh, said it will be crucial to see how the raccoon dogs’ genetic sequences match up to what’s known about the historic evolution of the Covid-19 virus. If the dogs are shown to have Covid and those viruses prove to have earlier origins than the ones that infected people, “that’s probably as good evidence as we can expect to get that this was a spillover event in the market.” After a weeks-long visit to China to study the pandemic’s origins, WHO released a report in 2021 concluding that Covid-19 most probably jumped into humans from animals, dismissing the possibility of a lab origin as “extremely unlikely.” But the UN health agency backtracked the following year, saying “key pieces of data” were still missing.And Tedros has said all hypotheses remain on the table.The China CDC scientists who previously analyzed the Huanan market samples published a paper as a preprint in February suggesting that humans brought the virus to the market, not animals, implying that the virus originated elsewhere. Their paper didn’t mention that animal genes were found in the samples that tested positive.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 lab.But others in the US intelligence community disagree, believing it more likely it first came from animals. Experts say the true origin of the pandemic may not be known for many years — if ever.
Written by Benjamin MuellerThe World Health Organisation rebuked Chinese officials Friday for withholding research that may link Covid-19’s origin to wild animals, asking why the data had not been made available three years ago and why it is now missing.Before the Chinese data disappeared, an international team of virus experts downloaded and began analysing the research, which appeared online in January. They say it supports the idea that the pandemic could have begun when illegally traded raccoon dogs infected humans at a Wuhan seafood market.But the gene sequences were removed from a scientific database once the experts offered to collaborate on the analysis with their Chinese counterparts.“These data could have — and should have — been shared three years ago,” WHO Director-General Tedros Adhanom Ghebreyesus said. The missing evidence now “needs to be shared with the international community immediately,” he said.According to the experts who are reviewing it, the research offers evidence that raccoon dogs — foxlike animals known to spread coronaviruses — had left behind DNA in the same place in the Wuhan market that genetic signatures of the new coronavirus also were discovered.To some experts, that finding suggests that the animals may have been infected and may have transmitted the virus to humans.With huge amounts of genetic information drawn from swabs of animal cages, carts and other surfaces at the Wuhan market in early 2020, the genetic data had been the focus of restless anticipation among virus experts since they learned of it a year ago in a paper by Chinese scientists.A French biologist discovered the genetic sequences in the database last week, and she and a team of colleagues began mining them for clues about the origins of the pandemic.That team has not yet released a paper outlining the findings. But the researchers delivered an analysis of the material to a WHO advisory group studying Covid’s origins this week in a meeting that also included a presentation by Chinese researchers regarding the same data.The analysis seemed to clash with earlier contentions by Chinese scientists that samples taken in the market that were positive for the coronavirus had been ferried in by sick people alone, said Sarah Cobey, an epidemiologist and evolutionary biologist at the University of Chicago who was not involved in recent research.“It’s just very unlikely to be seeing this much animal DNA, especially raccoon dog DNA, mixed in with viral samples, if it’s simply mostly human contamination,” Cobey said.Questions remain about how the samples were collected, what precisely they contained and why the evidence had disappeared. In light of the ambiguities, many scientists reacted cautiously, saying that it was difficult to assess the research without seeing a complete report.The idea that a lab accident could have accidentally set off the pandemic has become the focus of renewed interest in recent weeks, thanks in part to a fresh intelligence assessment from the Department of Energy and hearings held by the new Republican House leadership.But a number of virus experts not involved with the latest analysis said that what was known about the swabs gathered in the market buttressed the case that animals sold there had sparked the pandemic.“It’s exactly what you’d expect if the virus was emerging from an intermediate or multiple intermediate hosts in the market,” Cobey said. “I think ecologically, this is close to a closed case.”Cobey was one of 18 scientists who signed an influential letter in the journal Science in May 2021 urging serious consideration of a scenario in which the virus could have spilled out of a laboratory in Wuhan.On Friday, she said lab leaks continued to pose enormous risks and that more oversight of research into dangerous pathogens was needed. But Cobey added that an accumulation of evidence — relating to the clustering of human cases around the Wuhan market, the genetic diversity of viruses there and now the raccoon dog data — strengthened the case for a market origin.The new genetic data does not appear to prove that a raccoon dog was infected with the coronavirus. Even if it had been, the possibility would remain that another animal could have passed that virus to people, or even that someone infected with the virus could have transmitted it to a raccoon dog.Some scientists stressed those points Friday, saying that the new genetic data did not appreciably shift the discussion about the pandemic’s origins.“We know it’s a promiscuous virus that infects a bunch of species,” said David Fisman, an epidemiologist at the University of Toronto, who also signed the May 2021 letter in Science.Chinese scientists had released a study in February 2022 looking at the market samples. Some scientists speculated that the Chinese researchers might have posted the data in January because they were required to make them available as part of a review of their study by a scientific journal.The Chinese study had suggested that samples that were positive for the virus had come from infected people, rather than from animals sold in the market. That fit with a narrative long promulgated by Chinese officials: that the virus sprang not only from outside the market but from outside the country altogether.But the Chinese report had left clues that viral material at the market had been jumbled together with genetic material from animals. And scientists said the new analysis by the international team illustrated an even stronger link with animals.“Scientifically, it doesn’t prove that raccoon dogs were the source, but it sure smells like infected raccoon dogs were at the market,” said Jeremy Kamil, a virologist at Louisiana State University Health Sciences Center Shreveport.He added: “It raises more questions about what the Chinese government really knows.”Scientists cautioned that it was not clear that the genetic material from the virus and from raccoon dogs had been deposited at the same time.Depending on the stability of genetic material from the virus and the animals, said Michael Imperiale, a virologist at the University of Michigan, “they could have been deposited there at potentially widely different times.”Still, Dr. Arturo Casadevall, an immunologist at the Johns Hopkins Bloomberg School of Public Health who co-authored a recent study with Imperiale examining the origin of the coronavirus, said that linking animal and viral material nevertheless added to the evidence of a natural spillover event.“I would say it strengthens the zoonotic idea,” he said, “that is, the idea that it came from an animal at the market.”In the absence of the actual animal that first spread the virus to people, Casadevall said, assessing the origins of an outbreak would always involve weighing probabilities. In this case, animals sold at the market were removed before researchers began taking samples in early 2020, making it impossible to find a culprit.Tim Stearns, dean of graduate and postgraduate studies at the Rockefeller University in New York, said the latest finding was “an interesting piece of the puzzle,” although he said it was “not in itself definitive and highlights the need for a more thorough investigation.”For all the missing elements, some scientists said the new findings highlighted just how much information scientists had managed to assemble about the beginnings of the pandemic, including home addresses for early patients and sequence data from the market.Theodora Hatziioannou, a virologist at the Rockefeller University, said it was critical that the raw data be released. But, she said, “I think the evidence is overwhelming at the moment toward a market origin.”And the latest data, she said, “makes it even more unlikely that this started somewhere else.”Felicia Goodrum, an immunobiologist at the University of Arizona, said that finding the virus in an actual animal would be the strongest evidence of a market origin. But finding virus and animal material in the same swab was close.“To me,” she said, “this is the next best thing.”
