Scientists have revealed that coronaviruses related to Sars-CoV-2 may be circulating in bats across parts of Asia.
A virus, which is a close match to one the virus which causes Covid-19, was found in bats in an animal sanctuary in eastern Thailand.
However, it is thought to be unable to infect people, as it cannot bind to the ACE2 receptor on human cells - the gateway that allows Covid-19 to enter the body.
Clues for how Covid-19 emerged
The discovery has given scientists another set of clues surrounding how Covid-19 might have first emerged.
Scientists predict that similar coronaviruses may be present in bats across many parts of Asia’s nations and regions, as well as in Thailand.
Antibodies circulating in the blood of infected bats and pangolins - which were also found to be carriers of similar coronaviruses - are effective at neutralising the SARS-CoV-2 virus. The biological paradox indicated has led to scientists speculating that bat-based coronaviruses can not, as standard, infect humans.
Past studies since the beginning of the pandemic suggest that Covid-19 first emerged in an animal, most likely a bat, before it spread to humans.
Authors of the study, who are based at Duke-NUS Medical School in Singapore, are now considering that coronaviruses can only evolve the ability to infect human cells after first being passed into an intermediate host, such as a pangolin.
In the intermediate host, the virus mutates and changes shape slightly, giving it the ability to bind to ACE2 cells, the study’s authors theroise.
The current theories of where Sars-CoV-2 came from?
A team commissioned by the World Health Organisation (WHO) is currently investigating the precise origin of the virus.
On 10 February, the experts dismissed the theory that the virus originated from a laboratory in China, with the head of the WHO team, Peter Ben Embarek saying this was “extremely unlikely”. The laboratory theory was popular with former US President, Donald Trump.
The WHO team is focusing on south east Asia, and investigating when the virus originated in animals before spreading to humans.
Animals being considered are bats and pangolins. However, the viruses identified in these species were “insufficiently similar to be identified at the progenitor of Sars-CoV-2,” said Professor Liang Wannian, head of expert Covid-19 panel at China’s National Health Commision.
Other potential candidates being considered are feline species, including mink and cats.
Dr Embarek said their work had pointed to a “neutral reservoir” in bats. However, this was unlikely to have happened in Wuhan. He added that there was most likely a crossover point from an intermediary species.
There is also going to be further investigation into the possibility of “cold chain” transmission. This refers to whether the virus spread through the transport and trade of frozen food.