Scientists have discovered a new coronavirus in bats in Thailand shares over 90 per cent of its genes with the virus that caused the Covid-19 pandemic.
The new virus, named as RacCS203 by the researchers, was discovered in a species of horseshoe bat living in a Thai cave.
The finding was made by scientists from Chulalongkorn University in Bangkok, who also found that the new virus cannot bind to human ACE-2 receptors, meaning it is theoretically unable to directly infect humans.
In the report, published in Nature Communications, scientists say that viruses related to Sars-CoV-2 (the virus that causes Covid-19) are "widely present in bats across many nations and regions in Asia".
RacCS203 shares 91.5 per cent of its genome with Sars-CoV-2, while a related virus found in bats in China - named RmYN02 - has 93.6 per cent similarity.
One of the lead scientists says the results show what is needed to find the source of the Sars-Cov-2 virus that sparked the deadly Covid-19 pandemic.
"We need to do more surveillance in animals," Professor Lin-Fa Wang told the BBC. "In order to find the true origin, the surveillance work needs to go beyond the border of China."
The inability of the new virus to directly infect humans supports the theory that coronaviruses found in bats need to pass through an intermediate host, such as a pangolin, before they are able to bind to human ACE-2 receptors and infect us.
The new study examined antibodies found in bats and a trafficked pangolin in Thailand and discovered that these antibodies could neutralise Sars-CoV-2, evidence that related coronaviruses are circulating across Asia.
The findings of the new study back those from the World Health Organisation, which yesterday announced it was "extremely unlikely" that Sars-CoV-2 leaked from a laboratory.
Peter Ben Embarek said the World Health Organisation team's findings suggest "that the laboratory incident hypothesis is extremely unlikely to explain introduction of the virus into the human population".
The team said the virus was likely circulating for several weeks before it was detected in December 2019, as they delivered a summary of their findings on Covid-19 in Wuhan on Tuesday night.
Embarek, the WHO's food safety and animal disease specialist and chairman of the investigation team, said that according to their research, an intermediary host species is "the most likely pathway [for crossover into humans] and one that will require more studies and more specific targeted research".
The panel said it was likely other animals may serve as reservoirs, including those from the feline family, given the high susceptibility of minks and cats to the virus.
- Additional reporting, news.com.au