New analysis of samples from Wuhan's animal market confirms that it was an epicenter of the early spread of the new coronavirus.

CNN
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After detailed analysis of genetic material from hundreds of swabs taken from walls, floors, machines and drains at the Huanan Seafood Wholesale Market in Wuhan, China – said to be the early epicenter of COVID-19's spread – scientists say they have pinpointed which animal species were in the same areas where investigators found the most positive samples for the virus that causes COVID-19.

Species found in areas with the highest number of SARS-CoV2 samples include raccoon dogs, white rats, dogs, European rabbits, hedgehogs, Malayan porcupines, muntjacs, Himalayan marmots and palm civets.

The new findings suggest that the SARS-CoV2 virus can jump from infected animals to humans, and that the market Central Site Early adoption.

The researchers identified the species of animals on the market using a technique called metagenomic sequencing, which reads and sifts through all the genetic material in a sample to understand its origins.

This analysis is Released Thursday The paper, published in the journal Cell, does not prove that animals were infected with the virus, but animal DNA was found in close proximity to the virus, sometimes on the same swabs, meaning the animals likely became infected at the market.

Among the animals in the market, rabbits, dogs and raccoon dogs are known to be susceptible to the new coronavirus. Raccoon Rats have also been shown to be vectors of infection, making it highly likely that they were the animals that first transmitted the virus to humans.

The international team of researchers who carried out the study also carried out an evolutionary analysis using genetic material from samples found at the market, a technique that can help estimate when the virus first emerged and what its closest genetic relatives are.

“This is basically carbon dating the virus,” said Dr. Christian Andersen, director of infectious disease genomics at the Scripps Translational Research Institute in La Jolla, California, and senior author of the study.

By understanding how quickly the virus that causes COVID-19 changes, or mutates — it undergoes genetic changes about twice a month — it's possible to work out its approximate age.

Researchers believe the virus that caused the pandemic emerged between mid-November and mid-December 2019.

Their analysis shows that the SARS-CoV2 virus present in the market emerged at the same time as the larger pandemic virus, suggesting that they are one and the same.

Andersen said that if the virus first came from somewhere else and was then transported to the marketplace where it spread (as the lab-leak theory of COVID-19's origins suggests), the virus found in the market would have emerged at a different time than the virus that caused the pandemic; the pandemic virus would have had to have emerged much earlier.

Other evidence points in the same direction.

Of the first 174 people infected with the coronavirus, almost a third had links to the market, and many others without direct links lived around the market in the city of 12 million people.

“I was astonished” when he first saw the crowding, Andersen said.

When Andersen began seeing results from hundreds of swab tests taken at the market in January 2020, “I was literally blown away to see what was actually going on inside the market and to see the positivity of the environment coming together. I couldn't believe what I was seeing here,” Andersen said.

Another key clue that this market may be where the pandemic began is that both strains of the virus that were circulating early on in the pandemic – the “A” and “B” strains – were present on swabs taken at the market.

Andersen said scientists have never had this much information at this level of detail about previous pandemics.

The results are broadly consistent with similar analyses conducted by Chinese scientists. Published in Nature magazine The data used for the analysis in 2023 was: The subject of international intrigue The information was quietly posted in March 2023 on GISAID, a site where scientists share genetic sequences of viruses for research purposes.

Professor Florence Debarre, a researcher at the French National Center for Scientific Research (CNRS), discovered the data in 2023 and quickly alerted other scientists. She is also the lead author of the new Andersen study.

“This adds to the weight of evidence,” DeVere said in an interview about the new study, “because as the data accumulates, all the results still point in the same direction, which is an origin related to wildlife trade in the South China market.”

This study Some important scientific papers Research results from the same research group have been published in a leading academic journal, suggesting that the COVID-19 pandemic may have had an animal origin.

Andersen knows many people will see his name on a new study about the origins of COVID-19 and be quick to dismiss the findings. He says he's not worried.

“They'll look at the author list of a paper and say, 'Oh, yeah, I can't trust any of this,' so they don't even need to read the paper,” Andersen said.

Andersen is Most prominent leaders An international group of scientists is reviewing scientific evidence collected in the early weeks of the pandemic, seeking to understand how the global public health crisis began.

Andersen has been the focus of government investigations and social media conspiracy theories because he changed his mind: He initially believed SARS-CoV2 came from a Wuhan lab that was engineering a similar virus, but then published a scientific paper explaining why the virus that caused the COVID-19 pandemic likely came from an infected animal and then infected humans, a phenomenon known as spillover.

Such animal-borne infections are how most pandemics begin.

The supporters Laboratory leak theory I suspect Andersen was pressured by top scientists at the National Institutes of Health to change his mind.

Andersen said none of that was true: He simply did what scientists do when presented with evidence that contradicts their original ideas: he changed his hypothesis.

DeVere said he also initially believed the virus came from a lab.

“A laboratory origin is a possibility. The origin of SARS-CoV2 needs to be seriously considered and is a legitimate possibility that we have considered,” Debarre said.

Andersen is best known as the original “lab leaker,” she said.

“So none of us have ruled out the possibility of a lab leak, but we are scientists and we go where the data takes us, and right now all the available data and all the different types of data are all pointing in the same direction, that it's an animal leak event that probably occurred at the Huanan market.”

Lessons from past pandemics

Understanding the origins of SARS-CoV2 is crucial not only for understanding what happened with Covid-19, but also for understanding how future pandemics may arise.

Andersen said that while much work has been done since the pandemic to improve laboratory safety and the possibility of accidental release of dangerous viruses, less attention has been given to the trade in wild and farmed animals, which still poses serious risks.

“There's more than $50 billion a year of unregulated wildlife trade in China, but I don't know how much of it is being discussed,” Andersen said.

Andersen noted that another emerging virus, the H9N2 influenza virus, was also found in samples taken from the Huanan market.

He said this was a frightening reminder that SARS-CoV2 was not necessarily special — it was simply a virus that was in the right place at the right time.

The same scenario that played out in Wuhan in 2019 could be playing out now with the H5N1 avian flu virus in U.S. chicken and dairy farms. As long as the virus is circulating, “it's a game of luck,” he said.

Andersen agreed that tighter regulation of virus labs was needed, but said more attention needed to be paid to animal markets.

“We have a much bigger problem ahead of us, which is the unregulated wildlife trade,” Andersen says, “and it's not even being discussed.”