Covid: Chinese market in Wuhan had raccoon dog DNA – 04/12/2023 – Science

Chinese government scientists on the 5th published a long-awaited study on the fish market in the city of Wuhan, admitting that animals susceptible to the coronavirus were there at the time the virus emerged. But scientists also said it was still unclear how the pandemic started.

The study, published in the journal Nature, focused on samples taken from surfaces in early 2020 at the Huanan Fishery Wholesale Market, where many of the first known Covid patients worked or shopped. Chinese scientists published an early version of the genetic analysis of these samples in February 2022, but at the time they downplayed the possibility of infections in animals on the market.

The scientists, many of whom are affiliated with China’s Centers for Disease Control and Prevention, also wanted to publish their data in a peer-reviewed journal. And as part of that process, they’ve uploaded more genetic sequence data to a large international database, the repository’s administrators said last month.

A few weeks after the data were published, a team of international scientists studying the origins of the pandemic said they had found the sequences. They found that samples that tested positive for the coronavirus contained genetic material belonging to animals, including large amounts that were compatible with the raccoon dog, a mammal sold for skin and meat consumption that was already known for its ability to transmit the coronavirus.

That analysis, the subject of a report posted online in late March, did not prove that a raccoon dog was infected or that animals transmitted the virus to people. It only found that there were genetic marks of raccoon dogs in the same place where the genetic material of the virus was found.

Many virologists said the scenario was consistent with one in which the virus spread to people from an illegally traded wild animal.

It seems that the international team’s analysis accelerated the release of the Chinese scientists’ study on the same data: the article appeared on Wednesday on the Nature website with a note saying that it had been accepted for publication, but was an “early version” and had not yet been edited.

Several authors of the paper affiliated with the Chinese CDC, William J. Liu, George Gao and Guizhen Wu, did not respond to requests for comment.

In their first version of the article, in February 2022, the Chinese authors did not mention having found genetic material from raccoon dogs in the market samples, which were taken from walls, floors, metal cages and carts. Furthermore, they said the data did not indicate any infected animals.

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

Many scientists believe that existing evidence points to these animals possibly acting as intermediate hosts for the virus, which likely originated in bats. But they also say the evidence doesn’t completely rule out a scenario where people transmitted the virus to animals at the market.

Asked how Nature’s peer review process handled the species’ findings, a spokesperson for the journal noted that the authors included a disclaimer that the list of identified species on the market “was not definitive” and there was a need for more analyses.

For the international scientists who first reported finding raccoon dog signals in Covid-positive samples last month, the latest Nature study left a number of important questions unanswered about the methods used by the Chinese team to analyze the sequences. .

Still, the publication, like an earlier version of it released online by Chinese scientists last week, provided critical new data, including the number of samples taken from each market stall, said Alexander Crits-Christoph, a former researcher and biologist. Johns Hopkins University, which helped lead the international team’s analysis.

With that information, Crits-Christoph said he and his collaborators were able to confirm an important finding: samples taken from a corner of the market that sells wild animals were more likely to test positive for the virus, a result that could not be explained by Chinese researchers alone. they collected more samples in that corner, he said.

“It’s an impressive dataset, and its importance is quite high,” Crits-Christoph said of the market samples. “And so I think it’s good that they were published in the scientific record, even if I don’t agree with all the interpretations.”

^{Translated by Luiz Roberto M. Gonçalves}