Scientists parse another clue to possible origins of Covid-19 as WHO says all possibilities ‘remain on the table’ | CNN


A new clue is being found in the search for the origins of the CoVID-19 pandemic.

A new analysis of collected genetic material From January to March 2020, DNA from animals at Huanan Seafood Market in Wuhan, China, has already been known to be positive for SARS-CoV-2, which causes Covid-19. According to World Health Organization officials, who addressed the new evidence at a news briefing on Friday, a significant amount of that DNA came from animals known as raccoon dogs, which were traded in the market. was going

The raccoon-dog connection came to light when Chinese researchers shared raw genetic sequences taken from swab samples collected at the market early in the pandemic. The sequence was uploaded to the data-sharing site GISAID in late January 2023, but has recently been removed.

An international team of researchers spotted them and downloaded them for further study, WHO officials said Friday.

The new findings — which have not yet been publicly posted — do not resolve the question of how the pandemic began. They do not prove that raccoons were infected with SARS-CoV-2, nor do they prove that raccoons were the animals that first infected people.

But because viruses don’t survive long in the environment outside of their hosts, finding a lot of genetic material from the virus mixed with genetic material from raccoons is a strong indication that they could have been carriers. , according to scientists who worked on it. Analysis. Analysis was conducted. By Christian Anderson, an immunologist and microbiologist at Scripps Research; Edward Holmes, a virologist at the University of Sydney; Michael Woroby, an evolutionary biologist at the University of Arizona. The three scientists, who are digging into the origins of the pandemic, were interviewed by reporters from The Atlantic magazine. CNN has reached out to Anderson, Holmes and Woroby for comment.

Details of The international analysis was first reported by Thursday Atlantic Ocean.

The new data comes as Republicans in Congress launch an investigation into the origins of the pandemic. Previous studies provided evidence that the virus likely emerged naturally in the market, but could not point to a specific origin. Some US agencies, including a recent one US Department of Energy assessmentsay the pandemic likely resulted from a lab leak in Wuhan.

At a news briefing on Friday, WHO Director-General Tedros Adhanom Ghebreyesus said the organization was first made aware of the outbreak on Sunday.

“As soon as we became aware of this data, we contacted the Chinese CDC and urged them to share it with the WHO and the international scientific community for analysis,” Tedros said.

The WHO also convened its Scientific Advisory Group on the Origins of Novel Pathogens, known as SAGO, which is investigating the origins of the pandemic, to discuss the data on Tuesday. The group heard from Chinese scientists who originally studied the sequence, as well as a group of international scientists taking a fresh look at it.

The figures are not conclusive, WHO experts said at a briefing on Friday. They still can’t say whether the virus leaked from a lab, or whether it spread naturally from animals to humans.

“These data do not definitively answer the question of how the pandemic started, but every piece of data is important in getting us closer to that answer,” Tedros said.

WHO officials said what the series shows is that China has more data that could be related to the origins of the pandemic that it has not yet shared with the rest of the world. What is it.

“This data could have been shared three years ago, and should have been,” Tedros said. “We continue to call on China to be transparent in data sharing and to conduct necessary investigations and share findings.

“Understanding how the pandemic started is an ethical and scientific imperative.”

CNN reached out to Chinese scientists who previously analyzed and shared the data, but did not receive a response.

Chinese researchers, affiliated with the country’s Centers for Disease Control and Prevention, shared their analysis of the samples in 2022. In a preprint study posted last year, they concluded that “no animal host of SARS-CoV2 can be predicted.”

research looked at 923 environmental samples taken from inside seafood markets and 457 samples taken from animals, and found 63 environmental samples that were positive for the virus that causes Covid-19. Most were taken from the western end of the market. Chinese authors wrote in 2022 that any of the animal samples, taken from refrigerated and frozen products for sale, were taken from live, stray animals roaming the market.

When they looked at the different types of DNA shown in environmental samples, the Chinese authors only saw connections to humans, but not to other animals.

When recently an international team of researchers Using a new genetic technique called metagenomics to take a fresh look at the genetic material in the samples – which were swept up in and around the market stalls – scientists said they were related to dogs. were surprised to find a significant amount of DNA. A small animal related to the fox. Raccoons can be infected with the virus that causes CoVID-19 and are high on the list of suspected animal hosts for the virus.

“What they found was molecular evidence that animals were being sold in that market. It was suspected, but they found molecular evidence. And also that some of the animals there were infected with SARS-CoV2, and Some of these animals include raccoons.

“It doesn’t change our approach to studying the origins of Covid-19. It just tells us that there is more data, and that data needs to be shared more fully,” he said.

Until the international scientific community is able to evaluate more evidence, “all hypotheses remain on the table,” von Kerkhof said.

Some experts found the new evidence persuasive, if not entirely convincing, of the market’s originality.

“The data point further to a market origin,” said Anderson, an evolutionary biologist at Scripps Research who attended the WHO. One of the scientists who analyzed the new data is meeting, told the magazine. science.

The claims made on the new data quickly sparked debate in the scientific community.

Francois Balloux, director of University College London’s Genetics Institute, said the fact that the new analysis had not yet been publicly posted for scientists to examine, but appeared in the news, called for caution.

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

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

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 epidemics.

Goodrum says the strongest evidence of natural spread would be to isolate the virus that causes Covid-19 from an animal on the market in 2019.

“Obviously, that’s impossible, because we can’t go too far back in time through the sequence, and there were no animals at the time the sequence was collected. To me, it’s the next best thing.” Goodrum said in an email to CNN.

At a WHO briefing, von Kerkhoff said the Chinese CDC researchers had uploaded the sequence to GISAID as they were updating their original research. He said his first paper is in the process of being updated and resubmitted for publication.

“We have been informed by GISAID that the China CDC data is being updated and expanded,” he said.

What the WHO would like to do is find the source of where the animals came from, von Kerkhof said on Friday. Were they wild? Did they farm?

It said during its investigation into the origins of the pandemic, WHO China has repeatedly been asked for studies to return the animals to their source farms. He said that the WHO had asked for the blood test of the people working in the market as well as the test of the animals coming from the farms.

“Share the data,” Dr. Mike Ryan, executive director of the WHO’s Health Emergencies Programme, said Friday, addressing scientists around the world who may have relevant information. “Let the science do the work, and we’ll find the answers.”

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