Scientists present new version of the origin of coronavirus in China
New evidence links the origin of COVID-19 to raccoon dogs in the Wuhan market in China. Gene sequence analysis by an international team has revealed COVID-positive samples rich in raccoon dog DNA.
Recently released genetic data collected at a live food market in Wuhan, China linked COVID-19 to raccoon dogs, lending weight to the theory that infected animals sold at the site caused the coronavirus pandemic, say researchers involved in the work.
According to The Guardian, swabs taken from stalls at the Huanan Seafood Market in the two months after it closed on January 1, 2020 were previously found to contain both COVID and human DNA. When the results were published last year, Chinese researchers said the samples contained no animal DNA.
This conclusion has now been refuted by an international team of scientists, writes The Guardian. Their analysis of gene sequences posted by the Chinese team to the Gisaid scientific database showed that some of the COVID-positive samples were rich in raccoon dog DNA. Traces of DNA belonging to other mammals, including civets, were also present in COVID-positive samples.
The discovery does not prove that raccoon dogs or other animals infected with COVID caused the pandemic, but scientists who presented their work to a World Health Organization panel on Tuesday believe it makes it more likely.
“Data further point to a market origin,” Professor Christian Andersen, an evolutionary biologist at Scripps Research in La Jolla, Calif., told Science. Andersen attended the meeting of the WHO scientific advisory group on the origin of new pathogens and is working on the findings.
The newly uploaded gene sequences were discovered by an evolutionary biologist at the French National Center for Scientific Research. Florence Debarre. She alerted Prof. Andersen and Prof. Michael Sparrow, an evolutionary biologist at the University of Arizona, who both wrote papers supporting the market origin of the pandemic.
What started the worst pandemic in a century has been the subject of intense – and often vitriolic – debate. One theory suggests that the virus originated in wild animals and spread to humans through infection in the market. Another theory suspects the virus broke out of the nearby Wuhan Institute of Virology, where researchers are working on similar pathogens, The Guardian recalls.
The lab leak theory has made headlines in recent weeks after the U.S. Department of Energy assessed intelligence and US Republican hearings on the causes of the pandemic. Concrete evidence is lacking for any of the theories and may never be found.
The latest genetic evidence does not prove that raccoon dogs or other mammals were infected with COVID and spread it on the market. If the animals were infected, they may have contracted the coronavirus from infected humans. But the findings point to the possibility that the pandemic was caused by an infected animal and, ultimately, the illegal wildlife trade.
While scientists expect the debate to continue, questions are being raised as to why the Chinese team did not release the genetic data sooner. One of the team members, George Gao, a former head of China's Centers for Disease Control and Prevention, told Science the sequences were “nothing new.” Why the data was later pulled from the Gisaid site is also unclear.
Florence Debarre said she is working on a report of the results, which will be made public, and will only answer questions once it is done.
Dr Jonathan Stoye, virologist and senior team leader at the Francis Crick Institute in London, said: “The discovery of Sars-CoV-2 infected raccoon dogs strengthens the possibility that coronavirus-infected farm animals were an important link in the series of events leading up to the Covid-19 pandemic. . However, this does not disprove the lab leak theories: this would require a demonstration that such animals were infected prior to their arrival and display at the Huanan Seafood Market, which may never be possible.”
Also in Friday, the WHO said the COVID-19 pandemic could subside this year, posing a risk similar to that of the flu.
“I think we are getting to the point where we can look at COVID-19 the same way how we look at seasonal flu: a health threat, a virus that will continue to kill, but a virus that does not destroy our society,” said Michael Ryan, director of emergencies at WHO, adding: “I believe it will happen… this year.