China releases data showing raccoon dog DNA in Wuhan market

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Chinese government scientists released a much-anticipated study of a market in the city of Wuhan on Wednesday, acknowledging that animals susceptible to the coronavirus were present at the time the virus appeared.

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But the scientists also said it was stationary without being clear how the pandemic started

Fritzi the raccoon plays with water at the home of veterinarian Mathilde Laininger in Berlin, Germany on January 27.  REUTERS/Hannibal Hanschke

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Fritzi the raccoon plays with water at the home of veterinarian Mathilde Laininger in Berlin, Germany on January 27. REUTERS/Hannibal Hanschke

The study, published in the journal Naturefocused on swabs taken from surfaces in early 2020 at the Huanan Seafood Wholesale Market, a large market where many of the earliest known COVID patients had worked or shopped.

Chinese scientists had published an early version of their genetic analysis of those samples in February 2022, but downplayed the possibility of animal infections on the market at the time.

The scientists, many of whom are affiliated with the Chinese Centers for Disease Control and Prevention, also wanted to publish their data in a peer-reviewed journal.

And as part of that process, the scientists uploaded more genetic sequence data to a large international database, database administrators said last month.

Just weeks after the data was made public, a team of international scientists studying the origins of the pandemic said they had stumbled upon the footage.

They found that the samples that tested positive for the coronavirus contained genetic material from animals, including large amounts that matched the raccoon dog, a fluffy mammal sold for its fur and meat that was known to spread the coronavirus.

That analysis, the subject of a report posted online in late March, didn’t prove that the raccoon dog itself was infected or that the animals transmitted the virus to people.

But he determined that the raccoon dogs deposited their genetic signatures in the same place where the genetic material of the virus was left.

Many virologists argued that this hypothesis was consistent with one in which the virus was transmitted to people from a wild animal traded illegally on the market.

Apparently, the international team’s analysis has accelerated the publication of the study by Chinese scientists on the same data:

The paper appeared on the Nature website Wednesday with a note saying it had been accepted for publication but was still a “first version” and it hadn’t been published yet.

Several China CDC-affiliated authors of the article, William J. Liu, George Gao, and Guizhen Wu, did not respond to requests for comment.

In their first version of the article, dated February 2022, the Chinese authors did not mention the discovery of raccoon dog genetic material in market swabs taken from walls, floors, metal cages and cars.

Other than that, they said the data didn’t point no infected animals.

But in Wednesday’s release, just over a year later, they wrote that the study “confirmed the existence of raccoon dogs” and other coronavirus-susceptible animals on the market.

Many scientists believe that the existing evidence suggests that these animals probably acted like intermediate hosts of the virus, which probably originated in bats.

But they also say the evidence doesn’t entirely rule out the possibility that people passed the virus to animals in the marketplace.

The Chinese authors have pointed this out uncertainty in the new study.

They also raised the idea that the virus could have reached the Wuhan market in packets frozens, also known as cold chain products.

Many scientists consider this hypothesis highly unlikely, but China has promoted it because it gives credence to the idea that the pandemic may have started outside the country and arrived through imported food.

“The possibility of a possible introduction of the virus into the market via infected humans or cold chain products cannot yet be ruled out,” the article states.

The study also included other unlikely findings, outside scientists said in interviews Wednesday.

For example, that the swabs contained genetic material from a number of animals that were almost certainly not on the market, such as pandas, chimpanzees and mole rats.

Alice Hughes, an associate professor at the University of Hong Kong specializing in conservation biology, said the inclusion of these animals suggested the authors had misclassified genetic material or that the samples had been contaminated during laboratory sequencing.

“The greatest value of this work is that it frees up a dataset for other scientists to examine more carefully and responsibly,” Hughes said.

“Given the obvious errors of this analysis, it was not done with sufficient care to be sure of any of the results.”

Doubts

When asked how Nature’s peer review process handled the species findings, a spokesperson for the journal said the authors included a caveat that the list of identified species on the market “it wasn’t final” and further analyzes were needed.

For international scientists who first reported finding evidence of raccoon dogs in COVID-positive swabs last month, the latest Nature study leaves unanswered a number of important questions about the methods used by the Chinese team to analyze the sequences.

However, the publication, as well as an earlier version posted online by Chinese scientists last week, yielded key new data, such as the number of swabs performed from every market stall, according to Alexander Crits-Christoph, a former postdoctoral researcher and computational biologist at Johns Hopkins University who helped lead the international team’s analysis.

With this information, Crits-Christoph said he and his collaborators were able to confirm an important finding:

Swabs taken in a corner of the market where wild animals were sold were more likely to test positive for the virus, a finding that couldn’t be explained simply because Chinese researchers had taken more samples in that corner, he said.

“It’s a really impressive dataset and its significance is pretty high,” Crits-Christoph said of the market champions.

“And so, I think it’s good that these data have been published in the scientific literature, even if I don’t agree with all the interpretations.”

c.2023 The New York Times Society

Source: Clarin

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