A new coronavirus discovered in China is only a small step from mutating and causing another global pandemic, experts have warned.
Scientists believe the variant, called HKU5-CoV-2, may infect a broader range of animals than Covid-19 – which caused millions of deaths – and may have more potential for jumping between species.
US researchers fear that HKU5-CoV-2, found in China, in February, could also infect humans, leading to a widespread outbreak.
The new study, published in Nature Communications, looked at a lesser-known group of coronaviruses called merbecoviruses, which includes HKU5 and MERS-CoV, which is responsible for the deadly Middle East Respiratory Syndrome.
The team from Washington State University looked at how the new pathogen interacts with human cells.
They found that a small change in the virus's spike protein could allow it to attach to human ACE2 cells in people's throats, mouths and noses.
HKU5-CoV-2 can infect and replicate inside human cells in both the airways and gut.
According to the World Health Organisation, about 35 per cent of people infected with Middle East Respiratory Syndrome die. Since 2012, some 27 countries have reported cases, leading to 858 known deaths due to the infection, which spread from camels.
But when HKU5 was discovered in February, scientists warned against exaggerating the risks because it does not enter human cells as readily as Sars-CoV-2, which caused Covid-19.
HKU5 was first detected in bats by scientists from the Chinese laboratory where some say Covid originated in 2019.
Prof Michael Letko, a virologist who co-led the study, said: “HKU5 viruses in particular really hadn't been looked at much, but our study shows how these viruses infect cells.
“What we also found is HKU5 viruses may be only a small step away from being able to spill over into humans.”
When Covid-19 emerged it was widely blamed on markets in China where different breeds of wild animal are kept caged and often slaughtered close to other animals. Meat is sold at the open-air stalls.
Critics said the markets were the perfect breeding ground for new zoonotic diseases – those that spread to humans – to emerge.
The scientists, whose experiments studied how the new pathogen interacts with human cells, believe the virus would have to carry certain mutations if it were to infect humans.
“These viruses are closely related to MERS, so we have to be concerned if they ever infect humans,” Prof Letko said.
“While there's no evidence they've crossed into people yet, the potential is there and that makes them worth watching.”
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