Raccoon dog at food market in China Credit: AFP
Raccoon dogs blamed for Covid pandemic not responsible, new analysis suggests that samples on the market in Wuhan are virtually free of the virus.
Last month, a controversial study found that raccoon dog DNA found at the Huanan Seafood Wholesale Market in January 2020 was mixed with Covid-19, providing «strong evidence» that the coronavirus passed to humans from animals.
< p>The document was based on swabs taken by Chinese market researchers at the beginning of the pandemic, which were recently uploaded to an international database. The authors stated that this indicates a zoonotic origin of the pandemic, and not a leak from the laboratory.
But a new in-depth genetic analysis of the samples by esteemed computer virologist Dr. Jesse Bloom of the Fred Hutchinson Cancer Center in Seattle in the US showed that Covid-19 was virtually unmixed with raccoon dog DNA.
Of the 14 raccoon dog samples examined, 13 had no Covid-19 at all, and one had only one piece of DNA. virus per 200 million animal DNA fragments.
On the contrary, the virus was found in large quantities mixed with human DNA, as well as species such as largemouth bass, catfish, cow, carp and snakehead, none of which could not transmit the virus to humans.
The team concluded that there was in fact a «negative correlation» between Covid-19 and raccoon dog DNA.
2,804 raccoon dogs
Dr Bloom also warned that samples were taken weeks after how the first cases of Covid appeared in Wuhan, at a time when people have already spread Covid-19 widely in the market.
“What can we do about this? Does Covid-19 come from all of this? Probably a little,” he said.
“We have to analyze everything, but this data does not tell us how the pandemic started.
“Environmental samples taken more than a month after the virus began to spread do not reliably indicate the source of the outbreak.
«If we ever learn about the origin of Sars2, I suspect it will come from information about events that happened in November 2019 or earlier.»
The Huanan Seafood Wholesale Market has been linked to a cluster of early cases, leading some scientists to speculate that this is where Covid-19 jumped from animals to humans.
Raccoon dogs were considered a likely candidate because they are known to be susceptible to the virus, but DNA linking the animal to Covid-19 has never been found.
Huanan Seafood Wholesale Market in Wuhan has been linked to a group of early cases, leading some scientists to speculate that this is where Covid-19 jumped from animals to humans. Photo: AP
Earlier this year, a team of Chinese scientists uploaded genetic data from swabs taken on the market during the early days of the pandemic that appeared to show raccoon dog DNA mixed with Covid-19.
The upload was spotted by Dr. Florence Debarre, An evolutionary biologist at the French National Center for Scientific Research who, along with colleagues, published a peer-reviewed report claiming to have «strong evidence» for spread from animals.
Before publication, the story was also leaked to The Atlantic, which claimed it was «the strongest evidence that an animal started the pandemic.»
The Chinese scientists who collected the original samples published their own study in the journal. Nature says there is no way to know if raccoon dogs are infected and warns that the origin of Covid cannot be determined from their samples.
The researchers noted that humans were already infected by the time they first swabbed in January 2020, so even if the animals were infected, they could have contracted the virus from humans.
The Chinese team also detected Covid. -19 in sewers, suggesting that infected people or animals may have contributed to the spread of the virus. Previous studies have shown that the highest concentration of Covid-19 was found near market toilets.
The Huanan Seafood Wholesale Market was just a few miles from the Wuhan Institute of Virology, where experiments were assembled and carried out. about bat coronaviruses, Covid-19's closest relatives.
Last week, a U.S. Senate committee released a 300-page report concluding that the pandemic was most likely the result of a leak from a lab, which was the result of a «research incident» in Wuhan.
The report says that the theory that Covid-19 passed from animals to humans in the market «no longer deserves doubt or presumption of accuracy» .
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