The search for the causes of the Covid-19 pandemic has a tantalizing new lead.
Previously known to be positive for SARS-CoV-2, the coronavirus that causes Covid-19, recent examination of genetic material taken from January to March 2020 at the Huanan Seafood Market in Wuhan, China, has shown animal DNA in samples. Officials with the World Health Organization addressed the new data in a news briefing on Friday, saying that a sizable portion of that DNA appears to belong to creatures known as raccoon dogs, which were known to be exchanged at the market.
Chinese researchers provided raw genetic sequences obtained from samples swabbed at the market early in the pandemic, which led to the discovery of the link to raccoon pups. The sequences were posted to the data-sharing website GISAID in late January 2023 but have since been taken down.
The WHO authorities announced Friday that an international team of researchers discovered them and downloaded them for more research.
The question of how the epidemic began is still open in light of the latest discoveries, which have not yet been made publicly available. They do not establish either that raccoon dogs carried the SARS-CoV-2 virus or that they were the first animals to infect humans.
Yet, because viruses can’t survive outside of their hosts for very long, researchers believe that the fact that so much of the virus’ genetic material coexisted with raccoon dogs’ genetic material strongly suggests that the latter might have been carriers.
The investigation was headed by Michael Worobey, an evolutionary biologist at the University of Arizona, Edward Holmes, a virologist at the University of Sydney, and Kristian Andersen, an immunologist and microbiologist at Scripps Research. Reporters for The Atlantic magazine spoke with these three scientists about their research into the pandemic’s roots. Andersen, Holmes, and Worobey have been contacted by CNN for comment.
The Atlantic broke the story of the international analysis’s specifics on Thursday.
Republicans in Congress have started looking into the causes of the pandemic, and fresh information is now becoming available. Earlier research could not pinpoint the virus’s exact origin but did present evidence that it most likely arose spontaneously in the market. The pandemic was most likely caused by a lab leak in Wuhan, according to certain American authorities, including a recent report from the US Department of Energy.
The results of the samples
WHO Director-General Tedros Adhanom Ghebreyesus stated at the news conference on Friday that the organization learned about the sequences for the first time on Sunday.
As soon as we learned of this information, we got in touch with the Chinese CDC and pushed them to send it to WHO and the international scientific community for analysis, according to Tedros.
The Scientific Advisory Group on the Origins of New Pathogens, or SAGO, which has been looking into the causes of the epidemic, met on Tuesday to discuss the information. The group heard from both the international team of experts reexamining the sequences as well as the Chinese scientists who had initially researched them.
The data are not definitive, according to WHO experts who spoke at the conference on Friday. They are still unable to determine whether the virus spread spontaneously from animals to humans or if it originated in a lab.
Every piece of information, according to Tedros, “is significant in bringing us closer to that solution” even though these data “do not provide a definitive answer to the question of how the epidemic began”.
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The sequences do show, according to WHO officials, that China possesses additional information it has not yet shared with the rest of the world that may be relevant to the pandemic’s origins.
Tedros stated, “This data could have and should have been released three years ago. “We keep urging China to exchange data transparently, carry out the required inquiries, and report the findings.
“It is still morally and scientifically necessary to understand how the pandemic started.”
The Chinese researchers who initially examined and provided the data have been contacted by CNN, but no response has been received.
more information is available
In 2022, the researchers from China, who are associated with the Centers for Disease Control and Prevention in that nation, released the results of their own study of the samples. They came to the conclusion that “no animal host of SARS-CoV2 can be deduced” in the preprint paper that was published last year.
The study examined 457 samples from animals and 923 samples from the environment, and discovered 63 environmental samples that tested positive for the virus that causes Covid-19. Most were taken from the market’s western end. The Chinese authors reported in 2022 that none of the animal samples, which were taken from live, stray animals roaming the market as well as from frozen and refrigerated food for sale, were positive.
The Chinese authors only discovered a connection to humans and not to other animals when they examined the many species of DNA found in the ambient samples.
Using a cutting-edge genetic technique called metagenomics, an international team of researchers recently took a fresh look at the genetic material in the samples, which were swabbed in and around the market’s stalls. The researchers said they were surprised to find a sizable amount of DNA belonging to raccoon dogs, a small animal related to foxes. The virus that causes Covid-19 can infect raccoon dogs, who are frequently mentioned as potential hosts for the virus.
They discovered molecular proof that animals were bought and traded at the market. Although it was suspected, scientists discovered molecular proof of it. Maria Van Kerkhove, WHO’s technical lead for Covid-19, stated in the briefing on Friday that some of the animals that were there were susceptible to SARS-CoV2 infection, some of which were raccoon dogs.
This does not alter how we plan to investigate the Covid-19’s genesis. It only indicates that there is more data available, and that data must be given completely, according to her.
According to Van Kerkhove, “all possibilities remain on the table” until the global scientific community can examine further evidence. Further proof of a natural origin?
Some scholars considered the new evidence of a market origin to be at least somewhat convincing. The evidence does support a market genesis, according to Andersen, an evolutionary biologist from Scripps Research who attended the WHO meeting and is one of the researchers examining the new evidence. Andersen’s analysis was published in the journal Science.
The claims made in relation to the new data immediately generated discussion among scientists.
The new data has not yet been made available for researchers to review for themselves, according to Francois Balloux, director of the Genetics Institute at University College London, therefore he advised caution.
Balloux wrote in a thread on Twitter, “Such publications actually don’t help since they merely polarize the debate further. “Those who are sure that it has a zoonotic origin would take it as conclusive evidence for their opinion, and those who are certain that it was a lab leak will interpret the inadequacy of the evidence as attempts at a cover-up,” said the author.
The information may be crucial in demonstrating the virus’s natural origin, according to other specialists who were not engaged in the analysis.
University of Arizona immunobiologist Felicia Goodrum recently presented an assessment of the information pertinent to the many hypotheses regarding the origin of the pandemic.
According to Goodrum, the best evidence for a natural spillover would be to find the virus that causes Covid-19 in an animal that was sold in 2019.
“Obviously, that is not feasible because neither sequencing nor time travel allow us to travel back in time, and the time sequences were obtained while no animals were present. This is the next best thing in my opinion, Goodrum wrote in an email to CNN.
The Chinese CDC researchers had submitted the sequences to GISAID as they were revising their initial research, according to Van Kerkhove, who spoke at the WHO conference. She stated that a revised version of their initial manuscript has been submitted for publication. The data from China’s CDC is being updated and expanded, according to GISAID, she said.
Van Kerkhove stated on Friday that finding the origin of the animals is something WHO would like to be able to undertake. Were they savages? Are these farm animals?
She claimed that as part of its inquiry into the pandemic’s beginnings, WHO had repeatedly requested studies from China to identify the farms where the animals originally came from. She claimed that in addition to testing animals that might have originated from farms, WHO had also requested blood work from market employees.
Dr. Mike Ryan, the executive director of the WHO’s health emergency program, urged experts worldwide who might have pertinent data to “share the data” on Friday. We will learn the answers if we let science do the work.