There is a new lead in the search for the origins of the Covid-19 pandemic.
A new analysis of genetic material collected from January to March 2020 at the Huanan Seafood Market in Wuhan, China, has found animal DNA in samples already known to be positive for SARS-CoV-2, the coronavirus that causes COVID-19. -19.
A significant amount of that DNA appears to belong to animals known as raccoon dogs, which were known to be traded in the market, according to experts from the World Health Organization (WHO), who addressed the new evidence in a press conference on Friday. fair (17).
The raccoon dog connection surfaced after Chinese researchers shared raw genetic sequences taken from specimens collected from the market at the start of the pandemic. The sequences were shared at the end of January this year, on the international Gisaid database, but were recently removed.
An international team of researchers observed and downloaded the information for further study, WHO experts said.
The new findings – which have yet to be publicly released – do not resolve the question of how the pandemic started. They do not prove that raccoon dogs were infected with SARS-CoV-2, nor do they prove that raccoon dogs were the first animals to infect people.
But because viruses don’t survive in the environment outside their hosts for very long, finding so much of the virus’s genetic material mixed with genetic material from raccoon dogs is highly suggestive that they could be hosts, according to scientists who worked on the analysis.
The research was conducted by Kristian Andersen, an immunologist and microbiologist at Scripps Research; Edward Holmes, a virologist at the University of Sydney and Michael Worobey, an evolutionary biologist at the University of Arizona.
These three scientists, who are investigating the origins of the pandemic, were interviewed by reporters from “The Atlantic” magazine. A CNN reached out to Andersen, Holmes and Worobey for comment.
The details of the international analysis were first reported on Thursday (16) by “The Atlantic”.
The new data is emerging as Republicans in the United States Congress have opened investigations into the origin of the pandemic.
Previous studies have provided evidence that the virus likely arose naturally in the marketplace, but have failed to pinpoint a specific origin.
Some US agencies, including a recent Department of Energy assessment, say the pandemic likely resulted from a lab leak in Wuhan.
What the samples say
At the press conference on Friday, WHO Director-General Tedros Adhanom stated that the organization became aware of the sequences on Sunday (12).
“As soon as we became aware of this data, we contacted the CDC [Centro de Controle e Prevenção de Doenças] Chinese and we urge them to share them with the WHO and the international scientific community so that they can be analyzed”, explained Adhanom.
The WHO also convened its Scientific Advisory Group on the Origins of New Pathogens, known as SAGO, which investigates the roots of the pandemic, to discuss the data on Tuesday. The group listened to the Chinese scientists who originally studied the sequences, as well as the group of international scientists who examined them with a new perspective.
WHO experts exposed, however, that the data are not conclusive. They still can’t say whether the virus leaked from a lab or spread naturally from animals to humans.
These data do not provide a definitive answer to the question of how the pandemic started, but each piece of data is important in bringing us closer to that answer.
Tedros Adhanom, Director-General of the WHO
What the sequences prove, the WHO scientists said, is that China has more data that could relate to the origins of the pandemic that has yet to be shared with the rest of the world.
“These data could and should have been shared three years ago,” said the WHO director-general. “We continue to urge China to be transparent in sharing data and conduct necessary investigations and share results.”
“Understanding how the pandemic began remains a moral and scientific imperative,” he concluded.
A CNN contacted the Chinese scientists who first analyzed and shared the data, but there was no response.
More data is available
The Chinese researchers, affiliated with the Centers for Disease Control and Prevention, shared their own analysis of the samples last year. In that preprint study, without peer review, they concluded that “no animal host of SARS-CoV-2 can be deduced”.
The research analyzed 923 environmental samples taken from the seafood market and 457 samples taken from animals, and found 63 environmental samples positive for the virus that causes Covid-19. Most were taken from the West end of the market.
None of the animal samples, which were taken from refrigerated and frozen products for sale and from live animals roaming the market, were positive, the Chinese authors wrote.
When they looked at the different DNA species represented in the environmental samples, the Chinese authors only saw a link with humans, not other animals.
When an international team of researchers recently examined the genetic material in the samples — which were collected in and around market stalls — using an advanced genetic technique called metagenomics, the scientists said they were surprised to find a significant amount of DNA belonging to dogs. -raccoons, a small animal related to foxes.
Raccoon dogs can be infected with the virus that causes Covid-19 and are high on the list of animals suspected of harboring the virus.
“What they found is molecular evidence that animals were sold in that market. That was suspicious, but they found molecular evidence of it. And also that some of the animals that were there were susceptible to SARS-CoV-2 infection, and some of those animals include raccoon dogs,” said Maria Van Kerkhove, WHO technical lead for Covid-19.
“This does not 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 in its entirety.”
Van Kerkhove said that until the international scientific community is able to review more evidence, “all hypotheses remain on the table”.
More evidence for a natural origin?
Some experts found the new evidence persuasive, if not entirely convincing, of a Wuhan market origin.
“The data points even more towards a market origin”, explained Andersen to Science magazine, an evolutionary biologist from Scripps Research who participated in the WHO meeting and is one of the scientists analyzing the new data.
Claims made about the new data quickly sparked debate in the scientific community.
François Balloux, director of the Institute of Genetics at University College London, explained that the fact that the new analysis has not yet been posted publicly for scientists to examine, but has surfaced in news reports, warrants caution.
“These articles really do not help, as they only further polarize the debate,” Balloux posted on social media. “Those convinced of a zoonotic origin will read this as final evidence for their conviction, and those convinced it was a laboratory leak will interpret the weakness of the evidence as attempts at a cover-up.”
Other experts, who were not involved in the analysis, said the data could be the key to showing that the virus has a natural origin.
Felicia Goodrum is an immunobiologist at the University of Arizona, who recently published a review of all available data for the various theories behind the origin of the pandemic.
Felicia cites that the strongest proof of a natural ‘spillover’ would be to isolate the virus that causes Covid-19 from an animal that was present on the market in 2019.
“Clearly this is impossible as we cannot go back in time any further than through sequencing, and no animals were present at the time the sequences could be collected. For me, this is the closest thing,” Felicia said in an email to CNN .
In the WHO press briefing, Maria Van Kerkhove reported that Chinese researchers at the CDC had made the sequences available on the data sharing system while updating their original research. She said her first article is in the process of being updated and resubmitted for publication.
“We were informed by Gisaid that the China CDC data is being updated and expanded,” he said.
Maria Van Kerkhove also said that the WHO would like to discover the origin of the animals. Were they wild? Were they grown?
She pointed out that, in the course of its investigation into the origins of the pandemic, the WHO has repeatedly asked China for studies to trace the animals back to their farms of origin. She said the WHO had also asked for blood tests on people working in the market, as well as tests on animals that may have come from the farms.
“Share the data,” said Mike Ryan, executive director of the WHO’s health emergencies program, addressing scientists around the world who may have relevant information. “Let science do its job and we’ll get the answers.”
Source: CNN Brasil
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