Emerging bat virus in China shows signs of another pandemic, scientists warn it's 'just a step away'

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A group of little-known bat viruses may be dangerously close to acquiring the ability to infect humans, raising alarms among virologists about the next potential spillover event. According to a new study published in the peer-reviewed journal Nature Communications, researchers in the United States have found that these viruses, which are closely related to the deadly MERS coronavirus, might need only a tiny genetic change to pose a serious threat to human health.

The viruses belong to a lesser-known subgroup of coronaviruses called merbecoviruses, a group that includes Middle East Respiratory Syndrome coronavirus (MERS-CoV). First detected in 2012, MERS-CoV is known for causing severe respiratory illness and carries a high fatality rate of around 34%. Unlike SARS-CoV-2, the virus responsible for COVID-19, MERS outbreaks have been relatively contained but far more lethal, particularly in hospital settings.

Now, scientists from Washington State University, Caltech, and the University of North Carolina are warning that a specific cluster within the merbecovirus family may be approaching a tipping point.

The study focused on a subgroup known as the HKU5 viruses, a lineage of bat coronaviruses that has largely flown under the radar of global surveillance and virological research. However, what the team discovered has triggered concern.

"HKU5 viruses haven't been studied much, but our research shows they have the machinery to infect cells. In fact, they might be only a single step away from being able to infect humans,” said Dr. Michael Letko, a virologist and lead author of the study.

Letko and his team conducted a series of experiments to examine how these viruses interact with cells, particularly looking at the viral spike proteins that enable coronaviruses to latch onto and enter host cells. What they found is that HKU5 viruses are already structurally equipped with many of the components needed to infect mammalian cells. In laboratory conditions, they were even able to bind to certain types of human cell receptors under specific circumstances, suggesting that only a small evolutionary nudge might allow them to jump species.

This warning echoes broader concerns in the scientific community about zoonotic spillover, the phenomenon in which viruses residing in animal reservoirs - particularly bats - mutate in ways that allow them to cross species barriers and infect humans. It’s the same process that is believed to have sparked the COVID-19 pandemic.