Genetic material collected from a Chinese market near where the first human cases of COVID-19 were identified shows raccoon dog DNA mixed with the virus, adding evidence to the theory that the virus originated in animals and not from a laboratory, according to international experts.
“These data do not provide a definitive answer to how the pandemic started, but every piece of data is important in bringing us closer to that answer,” World Health Organization Director-General Tedros Adhanom said on Friday. Ghebreyesus.
Raccoon dogs (Nyctereutes procyonoides) are native to China and Japan, where they are known as tanuki. Canines, named for their raccoon-like faces, are not closely related to raccoons. They are often bred for their fur and sold for meat in animal markets across China. They are not domesticated like dogs but are part of the Canidae family, more closely related to foxes.
How the coronavirus emerged remains unclear. Many scientists believe it most likely jumped from animals to humans, like 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, fueling theories that scientists are plausible that the virus could have leaked from one.
The new findings do not settle the matter, and they have not been formally reviewed by other experts or published in a peer-reviewed journal.
Tedros criticized China for not sharing the genetic information sooner, telling a press briefing that “this data could and should have been shared three years ago.”
The mixture of DNA from the virus and raccoon dogs is a strong indication that mammals, which would have been sold alive on the food market and known to be susceptible to coronaviruses, have been infected, said Dominic Dwyer, a medical virologist and medical specialist. of infectious diseases who studied the genesis of the pandemic in China.
“It’s not ‘eureka’ time, but it’s a pretty big breakthrough,” said Dwyer, who was part of a joint mission to study the origins of COVID in early 2021. The material was collected in an area of the market where cases were known to have happened.
“It still doesn’t tell you how it got into a raccoon dog or how it got into a human, but it’s important circumstantial evidence,” said Dwyer, clinical professor of medicine at the University of Sydney in Australia. .
The samples were taken from surfaces at the Huanan Seafood Market in early 2020 in Wuhan, where the first human cases of COVID-19 were discovered in late 2019.
Tedros said the genetic sequences were recently uploaded to the world’s largest public virus database by scientists from the Chinese Center for Disease Control and Prevention.
They were later taken down, but not before a French biologist spotted the information by chance and shared it with a group of scientists based outside China who are studying the origins of the coronavirus.
The data shows that some of the COVID-positive samples taken from a stall known to be involved in the wildlife trade also contained raccoon dog genes, indicating the animals may have been infected with the virus, the scientists say. Their analysis was first reported in The Atlantic.
“There is a good chance that the animals that deposited this DNA also deposited the virus,” said Stephen Goldstein, a virologist at the University of Utah who helped analyze the data. “If you were to go do environmental sampling following a zoonotic spread event…this is basically exactly what you would expect to find.”
WHO COVID-19 technical officer Maria Van Kerkhove warned that the analysis did not find the virus in any animals, nor did it find hard evidence that animals have infected humans.
“What this provides are clues to help us understand what may have happened,” she said. The international group also told the WHO that they had found DNA from other animals as well as raccoon dogs in the seafood market samples, she added.
The genetic code of the coronavirus is strikingly similar to that of bat coronaviruses, and many scientists suspect that COVID-19 jumped to humans either directly from a bat or via an intermediate animal like pangolins, ferrets or raccoon dogs.
Goldstein and his colleagues say their analysis is the first solid indication that there may have been wild animals infected with the coronavirus on the market. But it’s also possible that humans brought the virus into the marketplace and infected raccoon dogs, or that infected humans simply left traces of the virus near the animals.
Michael Imperiale of the University of Michigan, a microbiology and immunology expert who was not involved in the data analysis, said the discovery of a sample with sequences of the virus and a raccoon dog ” places the virus and the dog very close”. But this does not necessarily mean that the dog has been infected with the virus; it just says they were in the same very small area.
He said the bulk of the scientific evidence at this stage supported natural exposure in the market, and pointed to research published last summer showing the market was likely the first epicenter of the plague and concluding that the virus has spread. spread from animals to people twice. . “What’s the chance there were two different lab leaks?” He asked.
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 up with what is known about the historical evolution of the COVID-19 virus. . If dogs are shown to have COVID and these viruses turn out to have older origins than those that have infected people, “that’s probably the best evidence we can expect to get that it’s was a spillover event in the market”.
After a week-long visit to China to study the origins of the pandemic, the WHO released a report in 2021 concluding that COVID-19 most likely spread to humans from animals, ruling out the possibility of a laboratory origin as “extremely unlikely”.
But the UN health agency backtracked the following year, saying “key pieces of data” were still missing. And Tedros said all assumptions remain on the table.
The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Science and Education Media Group. The AP is solely responsible for all content. Bloomberg News contributed.