New clue to the origins of COVID-19, as WHO says all options “remain on the table”.

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GENEVA – There is a tantalizing new clue in the search for the origins of the COVID-19 pandemic.

A new analysis of genetic material collected from January to March 2020 at Huanan Seafood Market in Wuhan, China, found animal DNA in samples already known to be positive for SARS-CoV-2, the coronavirus that causes COVID-19. A large amount of that DNA appears to be from animals known as raccoon dogs, which were known to be traded on the market, World Health Organization officials discussed the new evidence at a news conference on Friday.

The connection to raccoon dogs was revealed after Chinese researchers shared raw genetic sequences from samples collected from the market at the start of the pandemic. The sequences were uploaded to the GISAID data sharing site in late January 2023, but have recently been removed.

An international team of researchers noticed them and downloaded them for further analysis, WHO officials said on Friday.

The new findings, which have not yet been released publicly, do not shed light on how the pandemic began. They do not prove that raccoon dogs were infected with SARS-CoV-2, nor do they prove that raccoon dogs were the animals that first infected people.

But because viruses don’t survive long outside their hosts, finding much of the virus’ genetic material mixed with genetic material from raccoon dogs is highly suggestive that they could be carriers, according to the scientists who worked on it. the analysis

Kristian Andersen, an immunologist and microbiologist at Scripps Research, led the analysis; Edward Holmes, a virologist at the University of Sydney; Michael Worobey, an evolutionary biologist at the University of Arizona. These three scientists who are delving into the origins of the pandemic were interviewed by reporters from The Atlantic magazine. CNN has reached out to Andersen, Holmes and Worobey for comment.

Details of the international analysis were first reported by The Atlantic on Thursday.

New data is emerging as congressional Republicans open investigations into the origins of the pandemic. Previous studies had shown that the virus arose naturally in the market, but could not point to a specific origin. Some US agencies, including a recent assessment by the US Department of Energy, say the pandemic was caused by a lab leak in Wuhan.

What the samples show

In a news release on Friday, WHO Director-General Tedros Adhanom Ghebreyesus said the organization had been informed of the sequences on Sunday.

“As soon as we became aware of these data, we contacted the Chinese CDC and asked them to share them with the WHO and the international scientific community so that they could be analyzed,” Tedros said.

The WHO also convened the Scientific Advisory Group on the Origins of New Pathogens, known as SAGO, which has been investigating the roots of the pandemic, to discuss the data on Tuesday. The team heard from the Chinese scientists who originally analyzed the sequences, as well as taking a fresh look at the international team of scientists.

WHO experts said at a conference on Friday that the data are inconclusive. They still can’t say whether the virus escaped from a lab or spread naturally from animals to humans.

“These data do not give a definitive answer to the question of how the pandemic started, but all the data are important to get closer to that answer,” said Tedros.

What the sequences prove, WHO officials said, is that China has more data that could be related to the origins of the pandemic that it has not yet shared with the world.

“This data could have been shared three years ago, and should have been,” Tedros said. “We continue to urge China to be transparent about data sharing and to conduct the necessary investigations and share the results.

“Understanding how the pandemic started remains a moral and scientific imperative.”

CNN has reached out to the Chinese scientists who analyzed and shared the initial data, but has not heard back.

There is more data there

Chinese researchers, affiliated with that country’s Centers for Disease Control and Prevention, shared an analysis of the samples in 2022. In that preprint study published last year, they concluded that “there is no animal host for SARS-CoV-2.” will be concluded”.

The study analyzed 923 environmental samples taken from the seafood market and 457 samples taken from animals, and found 63 environmental samples that tested positive for the virus that causes COVID-19. Most were taken at the west end of the market. None of the animal samples taken from refrigerated and frozen products for sale were positive, the Chinese authors wrote in 2022.

When they analyzed the different DNA species represented in the environmental samples, the Chinese authors only saw a link to humans, but not to other animals.

When an international team of researchers recently took a new look at the genetic material in the samples – which were washed up in and around market stalls – using an advanced genetic technique called metagenomics, the scientists said they were surprised. DNA from raccoon dogs, a small animal related to foxes. Raccoon dogs can be infected with the virus that causes COVID-19 and have topped the list of suspected animal hosts for the virus.

“What they found is molecular evidence that animals were sold in that market. That was suspected, but they found molecular evidence of that. And also that some of the animals there were infected with SARS-CoV-2, and some of those animals include raccoon dogs. Maria Van Kerkhove, WHO’s technical lead for COVID-19, said at Friday’s briefing.

“This does not change our approach to studying the origins of COVID-19. It tells us that more data exists, and that data should be shared in full,” he said.

Van Kerkhove said that until the international scientific community is able to review more evidence, “all hypotheses remain on the table.”

More evidence of a natural origin?

Some experts have called the new evidence convincing, if not entirely convincing, of its origins in the market.

“The data further points to the origin of the market,” Andersen, an evolutionary biologist at Scripps Research who attended the WHO meeting and is one of the scientists analyzing the new data, told Science magazine.

His assertions about the new data quickly sparked debate in the scientific community.

Francois Balloux, director of the Institute of Genetics at University College London, said that the new analysis had not yet been published publicly for scientists to examine, but that it had been clear in the news, caution was needed.

“Articles like this don’t help because they only polarize the debate further,” Balloux posted. Twitter. “Those convinced of a zoonotic origin will read it as the final proof of their conviction, and those convinced it was a laboratory escape will interpret it as an attempt to cover up the weakness of the evidence.”

Other experts who were not involved in the analysis said the data could be key to showing that the virus had a natural origin.

Felicia Goodrum is an immunobiologist at the University of Arizona who recently published a review of all available data for various theories behind the origins of the pandemic.

Goodrum says the strongest evidence of a natural release would be the isolation of the virus that causes COVID-19 from an animal that was on the market in 2019.

“Obviously, that’s impossible because we can’t go back in time any further than through sequencing, and there were no animals when the sequences could be collected. To me, this is the next best thing,” Goodrum said. e-mail to CNN.

In the WHO briefing, Van Kerkhove said that Chinese CDC researchers uploaded the sequences to GISAID while updating the original study. He said they are resubmitting their first paper to be updated and published.

“GISAID has told us that they are updating and disseminating data from the Chinese CDC,” he said.

Van Kerkhove said on Friday that what the WHO would like to do is find the source of where the animals came from. Were they wild? Were they from the farm?

He said that during the investigation into the origin of the pandemic, the WHO had repeatedly asked China to carry out investigations to return the animals to their farms of origin. According to him, the WHO also asked the people who worked in the market to do blood tests, as well as the animals that may come from the farms to do the tests.

“Share the data,” Dr. Mike Ryan, executive director of the WHO’s health emergencies program, said on Friday to scientists around the world who may have important information. “Let science do the work, and we’ll get the answers.”

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