Raccoon dog in Wuhan may be linked to the origin of Covid – 03/17/2023 – Health
An international team of virus experts said on Thursday it had found genetic data from a market in Wuhan, China, linking the coronavirus to raccoon dogs for sale there, adding to the case evidence that the worst pandemic in a century it may have been initiated by an infected animal traded in the illegal wildlife trade.
The genetic data was extracted from samples collected in and around the Huanan Seafood Wholesale Market starting in January 2020, shortly after Chinese authorities closed the market on suspicions that it was linked to the outbreak of a new virus. By this time, the animals had already been removed, but the researchers took samples from walls, floors, metal cages and carts often used to transport animal cages.
In samples that tested positive for the coronavirus, the international research team found genetic material belonging to animals, including large amounts that were compatible with the raccoon dog, said three scientists involved in the analysis.
Mixing genetic material from the virus and the animal does not prove that a raccoon dog itself has been infected. And even if a raccoon dog had been infected, it would not be clear whether the animal had spread the virus to people. Another animal could have passed the virus to people, or someone infected with the virus could have passed it to a raccoon dog.
But the analysis established that raccoon dogs — furry animals related to foxes and known to be capable of transmitting the coronavirus — deposited genetic signatures in the same spot where genetic material from the virus was left, the three scientists said. That evidence, they said, was consistent with a scenario in which the virus had spread to humans from a wild animal.
A report with the full details of the international research team’s findings has yet to be published. His analysis was first reported by The Atlantic magazine.
The new evidence is sure to shake up the debate over the origins of the pandemic, even if it doesn’t settle the question of how it started.
In recent weeks, the so-called lab leak theory, which posits that the coronavirus emerged from a research lab in Wuhan, has gained traction thanks to a new intelligence assessment by the US Department of Energy and hearings conducted by the new House Republican leadership. .
But market genetic data offers some of the most tangible evidence of how the virus could have spread from animals to people outside of a lab. They also suggest that Chinese scientists have given an incomplete account of evidence that could offer details on how the virus spread in the Huanan market.
Jeremy Kamil, a virus expert at the Shreveport Center for Health Sciences at Louisiana State University who was not involved in the study, said the findings showed that “market samples that contained early strains of Covid were contaminated with DNA readouts from wild animals”.
Kamil said there is no conclusive evidence that an infected animal triggered the pandemic. But “it really draws attention to the illegal animal trade in a narrow way.”
Chinese scientists released a study of the same market samples in February 2022. That study reported that the samples were positive for coronavirus, but suggested that the virus came from infected people shopping or working at the market, not from animals sold there.
At some point, these same researchers, including some affiliated with the China Center for Disease Control and Prevention, published the raw data from samples from across the market on Gisaid, an international repository of virus genetic sequences. Attempts to contact the Chinese scientists by telephone on Thursday (16) were unsuccessful.
On March 4, Florence Débarre, an evolutionary biologist at the National Center for Scientific Research in France, was searching this database for information related to the Huanan market when, as she said in an interview, she noticed more sequences than usual. Confused at first about whether they contained new data, Débarre set them aside, only to log back in last week to find they contained a treasure trove of raw data.
Virus experts have been waiting for the raw market sequence data since they first learned of its existence in the February 2022 Chinese report. Débarre said he had alerted other scientists, including the leaders of a team that published a set of studies last year pointing to the market as origin.
An international team—which included Michael Worobey, an evolutionary biologist at the University of Arizona; Kristian Andersen, a virus expert at the Scripps Research Institute in California; and Edward Holmes, a biologist at the University of Sydney in Australia—started exploring the new genetic data last week.
One sample in particular caught our eye. It was taken from a cart attached to a specific stall in the Huanan market that Holmes visited in 2014, scientists involved in the analysis said. This pen, Holmes discovered, contained caged raccoon dogs on top of another bird cage, exactly the kind of environment conducive to the transmission of new viruses.
The research team found that the sample taken from a cart in early 2020 contained genetic material from both the virus and a raccoon dog.
“We were able to find relatively quickly that at least one of these samples had a lot of raccoon dog nucleic acid, along with virus nucleic acid,” said Stephen Goldstein, a virus expert at the University of Utah who worked on the new analysis. Nucleic acids are the chemical building blocks that carry genetic information.
After the international team came across the new data, it reached out to the Chinese researchers who had uploaded the files with a proposal to collaborate, following the rules of the online repository, said scientists involved in the new analysis. After that, the sequences disappeared from Gisaid. It’s not clear who removed them or why.
Débarre said the research team was seeking more data, including some from undisclosed market samples. “The important thing is that there is still more data,” she said.