Scientists have uncovered another clue to the origins of the virus that causes Covid-19, with bats living in caves in Laos carrying a similar pathogen that experts say could potentially directly infect humans.
The virus has killed millions of people since it emerged in China in late 2019, and controversy continues to revolve around where it came from.
Some experts say it is an animal, but others have pointed to the possibility that the pathogen escaped from a lab.
Researchers from the Institut Pasteur de France and the National University of Laos said their findings showed viruses genetically similar to the SARS-CoV-2 virus “exist in nature” among bat species in limestone caves in northern Laos, neighboring China.
Of the viruses they identified among the hundreds of bats tested in Vientiane province, three were found to closely resemble the virus that causes Covid-19, particularly in the binding mechanism to human cells.
“The idea was to try to identify the origin of this pandemic,” Marc Eloit, who heads the pathogen discovery laboratory at the Institut Pasteur, told AFP.
Eloit, whose team analyzed the samples collected, said there were still key differences between the viruses found and SARS-CoV-2.
But he said the work was “a big step forward” in identifying the origin of the pandemic, confirming the theory that the coronavirus that has spread across the world could have started with bald people. live mice.
The authors of the study, which was submitted to Nature for peer review, warned that their findings suggest that the new viruses “appear to have the same potential to infect humans as the early strains of SARS-CoV-2. “.
“People working in caves, such as guano collectors, or certain ascetic religious communities who spend time in or very near caves, as well as tourists who visit caves, are particularly at risk of exposure,” said declared the authors.
– ‘Natural repercussions’ –
International experts sent to China by the World Health Organization (WHO) in January concluded that the SARS-CoV-2 virus was very likely to have passed from bats to humans via an animal intermediary.
A competing hypothesis that the virus has leaked from a lab like the Wuhan Specialized Virology Lab has been deemed “extremely unlikely,” although it has not yet been ruled out.
Martin Hibbert, professor of emerging infectious diseases at the London School of Hygiene and Tropical Medicine – who was not involved in research in Laos – said the most closely related virus has been shown to be able to infect human cells “As easily” as SARS -CoV-2 and therefore may be able to infect humans.
But he stressed that the virus is “not an ancestor of the pandemic strain”.
“This work confirms the expected diverse nature of bats infecting coronaviruses and increases the evidence that natural events of spillover from bats to humans can occur,” Hibbert said.
The authors of the Laos study, which was published on the Research Square website, said their results suggest that the pandemic coronavirus potentially evolved by mixing between different viruses and bat species.
James Wood, head of the department of veterinary medicine at the University of Cambridge – who was also not involved in the research – said this suggests that “recombination between different viruses was probably involved, rather than it” there is a simple evolution of a single line over a long period ”.
In a comment to the Science Media Center, he said that this not only highlights the likely role that bats and perhaps other animals play closely together, but also shows the “risks inherent in the animal trade. wild animals ”, where markets can help stimulate interspecies zoonosis. transmission.
© 2021 AFP