A new U.S. study warns that MERS-related bat coronaviruses, especially the lesser-known HKU5 group, may be only one mutation away from infecting humans, potentially sparking a future pandemic.
The viruses in question belong to the Merbecovirus subgenus—the same group that includes MERS-CoV, a deadly virus that emerged in 2012 and has a fatality rate of about 35%.
The study, published in Nature Communications, highlights the HKU5 virus, found in Pipistrellus abramus bats in Asia, as a potential zoonotic threat. While most viruses in this group don’t pose immediate risk to humans, researchers found that minor changes in the spike protein—the same mechanism used by viruses to enter cells—could enable human transmission.
“We found that HKU5 viruses might be just a small evolutionary step away from being able to infect humans,” said Michael Letko of Washington State University, who co-led the study.
Like SARS-CoV-2 (COVID-19), HKU5 viruses appear to target the ACE2 receptor, a key protein found in mammalian cells. The spike protein’s affinity for ACE2 was modeled using AlphaFold, Google Mind’s award-winning AI system capable of predicting 3D protein structures—a tool that won the 2024 Nobel Prize in Chemistry.
In a related study published in Cell, the HKU5-CoV strain was shown to already infect mink, raising red flags about its potential jump to humans.
“These viruses are close cousins of MERS. If they manage to cross over to humans, we should definitely be concerned,” Letko emphasized.
While MERS itself was originally traced to bats, it typically spreads to humans through camels. With HKU5 potentially bypassing that step, the global scientific community is urging for greater viral surveillance and preparedness for possible spillovers.