Researchers in China have identified a new bat coronavirus, HKU5-CoV-2, which is closely related to the highly lethal MERS virus (with a fatality rate of ~34%). Although HKU5 currently circulates only in bats, laboratory analyses show that a single amino-acid change in its spike protein could enable it to bind to the human ACE2 receptor, the same entry point SARS-CoV-2 uses in our throats, mouths, and noses.

At Washington State University, scientists engineered harmless “pseudoviruses” displaying the HKU5 spike. These mimics failed to infect human cells unless specific spike mutations were introduced, demonstrating that only minor adjustments are needed for HKU5 to latch onto ACE2 and enter human cells.

Experts warn that if HKU5 spills into an intermediate animal—such as minks or civets—it could naturally acquire those critical mutations. Unregulated wildlife trade and close contact between species in live-animal markets heighten the chance of such a host jump, increasing the likelihood of human exposure and onward transmission.

This study reignites debate over COVID-19’s origins. While some U.S. agencies (FBI, CIA) have pointed to a potential lab leak from the Wuhan Institute of Virology, others favor the wet-market hypothesis, where unsanitary conditions and mixed-species stalls may have enabled a different animal coronavirus to adapt and infect humans.

Published in Nature Communications, the work highlights that HKU5’s spike often remains in a “closed” conformation—making infection harder but not impossible. Given its MERS-like lethality and spillover potential, scientists stress the need for vigilant monitoring, further structural studies, and preparedness plans to mitigate any future pandemic threat.