Scientists have discovered a bat coronavirus capable of entering human cells – and it could lead to another global pandemic.

An international team of researchers found an alphacoronavirus, called KY43, has the ability to bind to a cell receptor found in the human lung.

It originates in heart–nosed bats in East Africa, including parts of Kenya, eastern Sudan and northern Tanzania.

Preliminary testing suggests it has not yet spread into the local human population.

But the findings indicate it has the capability to trigger an infection – and could be the first step in another pandemic.

Commenting on the research Benjamin Neuman, professor of biology at Texas A&M University, said: 'This study shines a light on another of the depressingly many viruses lurking just outside public consciousness, awaiting a chance encounter that could open the door to spreading in people.

'Think of KY43 as one of a million viruses, poised for a one–in–a–million chance to make the leap from bats to people. History tells us that one virus will break through, but which, we cannot guess.

'When or if KY43 spreads in people, we can only guess – so for now, science does its job, studying and preparing, building a bulwark of knowledge against an uncertain future.'

Instead of working with 'live' viruses, the scientists used a database of known genetic sequences to select and synthesise alphacoronavirus 'spike' proteins.

They screened dozens of these spike proteins against a library of human receptors they could potentially bind to.

And they found one virus, KY43, could successfully enter our cells.

Study author Dr Dalan Bailey, from The Pirbright Institute, said: 'Before our study, it was assumed most alphacoronaviruses used just one or two possible receptors to enter their host, and the only difference was which species they could enter.

'We now know alphacoronaviruses might use a whole variety of additional receptors to get into cells.'

The researchers said the pandemic potential of alphacoronaviruses has so far remained relatively unchartered.

Dr James Nyagwange, KEMRI–Wellcome Trust Research Programme, who was part of the study, said: 'Our paper identifies the need for further study in East Africa to better understand the risk from the wider family of viruses that can use this human receptor.

'This will help humanity prepare for any spillover in the future and to start developing vaccines and antivirals.'

Professor Neuman said people who study human viruses usually have to play catch–up, responding to new outbreaks as they spread.

'This is a rare case, where a virus with a toolkit that would, at least in theory, make it possible to spread in people was spotted before it caused any harm, as far as we can tell,' he said.

'This virus is able to bind and potentially enter human cells, but to spread between people the virus would need to evade the immune system and a host of other intracellular factors.

'At present there is no evidence of immune evasion by these viruses. And we don't know what sort of disease it might cause, if any.'

Aris Katzourakis, Professor of Evolution and Genomics at the University of Oxford, was not involved in the study but said the findings act as a 'key early warning'.

'This work is important in flagging that these viruses could overcome one of the key hurdles that could lead to a future crossover event,' he said.

'Such possible crossover events could be the first step in future epidemics or even pandemics – though we are not at that stage yet and it isn't inevitable.

'We don't yet know if these viruses would successfully replicate in humans should a spillover occur, but we now have been forewarned that they can cross the first important barrier.'

The study, published in the journal Nature, was accompanied by a 'news and views' piece written by Professor Huan Yan from Wuhan University.

It reads: 'Coronaviruses are a vast and genetically diverse family, yet most of the molecular strategies that they use to enter host cells are unknown.

'This gap is especially evident for alphacoronavirus — one of the four major coronavirus genera — which circulates predominantly in bats.

'Understanding viral entry mechanisms matters because the recognition of receptor proteins in host cells is the main barrier that a virus must overcome to infect a new species.

'Once that barrier has been crossed in humans, animal viruses can spark outbreaks of disease, as seen with COVID–19.'