Are raccoon dogs actually dogs? New COVID-19 testing spotlights animal sometimes sold at Wuhan market
Genetic material collected at a Chinese market near where the first human cases of COVID-19 were identified show raccoon dog DNA commingled 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 Organization Director-General Tedros Adhanom Ghebreyesus said Friday.
Raccoon dogs (Nyctereutes procyonoides) are native to China and Japan, where they are known as tanuki. The 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 members of the canid family, most closely related to foxes.
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, fueling 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 criticized 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 mingling of DNA from the virus and from raccoon dogs is a strong indication that the mammals, reportedly sold live in the food market and known to be susceptible to coronaviruses, were infected, said Dominic Dwyer, a medical virologist and infectious diseases physician who has studied the genesis of the pandemic in China.
“It’s not the ‘eureka’ moment, but it’s a pretty big advance,” said Dwyer, who was part of a joint mission to study COVID’s origins in early 2021. The material was collected in an area of the market where cases were known to have occurred.
“It still doesn’t tell you how did it get into a raccoon dog, or how did it get into a human, but it’s important circumstantial evidence,” said Dwyer, a clinical professor of medicine at the University of Sydney in Australia.
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.”
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 raccoon dogs.
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.
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 U.N. 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 Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content. Bloomberg News contributed.