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Bats in China’s southern and southwestern border regions harbor other coronaviruses that already have the ability to pass to humans, a leading Chinese scientist said.
Dr Shi Zhengli from the Wuhan Institute of Virology said these viruses, including close relatives of Sars-CoV-2, which causes Covid-19, are likely to be circulating in the wild beyond China.
“We should not only look for them in China, but also in South Asian countries,” said Shi, who is nicknamed “Bat Woman” because her research group studies bat coronaviruses.
His comments, which were made at a webinar organized by the French medical and veterinary academies, came as two international teams, one coordinated by the World Health Organization and another created by the Lancet medical journal, prepared to investigate the origins. of the pandemic. year after it officially began.
These efforts have become very politicized. The United States and China accuse each other of being at the origin of the pandemic as their trade war progresses. Other countries, including India, have also been named as possible sources. Shi’s lab was accused of being the source of an accidental viral leak earlier in the year. There is no evidence to support the accusation and Shi has vigorously denied it.
The virologist was not suggesting that China should be removed from the investigations, only that those inquiries should go beyond China, which they will.
The natural reservoir for Sars-CoV-2 is believed to be bats, and while Shi said the virus was most likely transmitted to another animal before reaching humans, that animal (the immediate host) has yet to be found. has identified.
It’s also unclear how long the virus might have been circulating in that animal or humans before it was detected late last year: Shi said it could have been in one or the other “for a long time.”
Professor Edward Holmes, a virologist at the University of Sydney, agreed that the virus could have been in an intermediate host for a long time, and perhaps even humans for a few months before it was reported.
“It is perfectly possible that the initial interspecies transmission event did not occur in or around Wuhan,” said Holmes, who did not attend the webinar.
“It may not have even happened in Hubei province, although there are obviously a large number of possible animals to test to solve this.”
Shi’s group has so far been unable to detect the virus in farm animals or wildlife they have sampled around Wuhan, the capital of Hubei province.
He said if the intermediate host was the pangolin, as some have proposed, then the virus reached China via infected pangolins smuggled into the country from Asian nations, including India.
However, Professor David Robertson, who studies viruses at the University of Glasgow, said research should remain focused on China.
“We are pretty sure that pangolins have contracted their virus, presumably from horseshoe bats, after being imported into China,” said Robertson, who also did not attend the webinar.
He said his group’s research indicated that Sars-CoV-2 acquired most of the mutations that made the virus transmissible to humans while it was still in bats.
Those who participated in the Lancet and WHO investigations know that they may never be able to clarify the exact path the virus took toward transmitting the virus to humans, so long after the event.
Your goal is to map the ecosystem that made that crossing possible to prevent it from happening again.
Shi’s group reported last year that there were hot spots in China, especially in the south and southwest, where Sars-like coronaviruses show high genetic diversity and therefore high mutational capacity.
Analysis the team published in October indicated that some were already capable of invading human cells, a finding Shi described in the webinar as “very surprising.”
Other coronaviruses, related to the one that caused the Middle East respiratory syndrome (Mers) outbreak in Saudi Arabia in 2012, are circulating in animals in Europe and Africa.
“We believe that these viruses have a high risk of interspecies transmission to humans,” Shi said.
Shi urged greater vigilance at two points in the chain by which a disease of non-human animal origin becomes human: between wild and domesticated or farm animals, and between farm animals and humans. Recently, monitoring of avian flu outbreaks in British poultry farms, for example, was intensified.
“On the human side, we clearly need to improve at tracking new disease outbreaks,” Robertson said.
