A study in the journal Nature Communications suggests experts might have underestimated the surprising variety of animals that could become hosts for future coronaviruses.
New coronaviruses arise through a process called homologous recombination, in which two such viruses infect the same cell, exchange genetic information and have offspring. This gene swap might grant daughter viruses the ability to infect humans or supply other harmful traits to those that already can.
So University of Liverpool scientists sought future hosts among the animals infected with the most coronaviruses.
"We found that there were hosts all across the mammals, and this was quite surprising. They weren't just focused in bats," said virologist and co-author Marcus Blagrove.
Potential hosts include several animals that live near humans, such as common hedgehogs, European rabbits, domestic cats and pigs.
These species don't pose an imminent danger, but monitoring them could help health officials head off an emerging coronavirus. The virus behind the current pandemic was detected only after it had infected humans.
"But if we know which hosts these viruses are being produced in — or could be produced in in the future — and we're putting the appropriate amount of surveillance on these specific hosts, then we'll get an early warning system," said Blagrove.
Of the seven coronaviruses known to infect humans, the three with serious health effects have emerged in the past two decades: severe acute respiratory syndrome (SARS) in 2003, Middle East respiratory syndrome (MERS) in 2012 and SARS coronavirus 2 (SARS-CoV-2), the source of the COVID-19 pandemic, in 2020.
The other four — HKU1, NL63, OC43 and 229E — cause milder symptoms in most patients, although they can advance to more serious conditions such as pneumonia.
The authors used a deep learning artificial intelligence to assign scores to virus-host combinations based on how likely they are to occur.
"It's a lot wider than we thought — a lot more potential hosts than we thought. But we think we've done a pretty good job of highlighting which ones they are so that we can guide the surveillance for them," said Blagrove.
The team next plans to look at habitats where the species live and identify potential geographical hotspots where future coronaviruses might emerge.