The long-running debate over the origins of Covid-19 took another turn this week, after a French scientist discovered that genetic sequences put into a database by Chinese researchers suggest the coronavirus responsible could come from animals like raccoon dogs in Huanan. Seafood market in Wuhan.
Within a few days, the same researchers removed the footage, though a few other scientists managed to download it beforehand and are investigating further.
“It’s really critical that any and all data related to how this pandemic started is immediately available.” Maria Van Kerjove at the World Health Organization (WHO) said at a press conference on March 17.
“There are several hypotheses that need to be examined, including how the virus entered the human population, either from a bat, through an intermediate host, or through a breach in laboratory biosecurity. And we don’t have a definitive answer.”
Huanan market has long been seen as a likely origin of the SARS-CoV-2 coronavirus, as many of the first cases of covid-19, in December 2019, were in people with a connection and the stalls sold a range of live and dead animals, not just shellfish.
The original host of SARS-CoV-2 is believed to be bats, as they carry many coronaviruses, although they have not yet encountered SARS-CoV-2. The ancestor of this virus may have jumped from bats to an intermediate host sold in the market and then to people.
An alternative explanation is that the virus escaped from the Wuhan Institute of Virology, where researchers were known to be studying bat coronaviruses, but not SARS-CoV-2. While this is a less favored idea among scientists, in February the US Department of Energy said it was the most likely explanation, but published no supporting evidence.
Now, genetic sequences uploaded to a global virology database called GISAID by the Chinese Center for Disease Control and Prevention may have shed more light on the origin of SARS-CoV-2. These sequences were derived from swabs taken from various surfaces on the market in early 2020 after it closed.
They were noticed by florence debarre at the French National Center for Scientific Research, who shared his findings with the WHO on March 14. “I was concentrating on the market sequences when I logged in, but I didn’t expect to find the data that I did,” says Débarre.
Débarre declined to say more until his analysis is complete, but Van Kerkhove told the press conference: “Among the samples that tested positive for SARS-CoV-2, they saw evidence of DNA from animals. Some of these animals include raccoon dogs.”
Raccoon dogs (Nyctereutes procyonoides) have previously been found to be susceptible to and able to spread SARS-CoV-2. “We know they are good at carrying it,” he says alice hughes at the University of Hong Kong.
This does not prove that the raccoon dogs or any of the other animals on the market were infected with the virus in December 2019 and such evidence is now impossible to obtain, Hughes says.
jonathan stoye at the Francis Crick Institute in London says: “The data seems to provide compelling evidence that raccoon dogs and other animals were present on the market at a critical time. This is another link in the chain that one would expect to see if the pandemic started that way.”
Following the information Débarre shared, Van Kerkhove said the WHO has asked the Chinese Center for Disease Control and Prevention to re-publish the genetic data. “The big problem is that this data exists and that it is not easily available to the international community, not to mention that it should have been available years before.”
