But researchers say the pathogen’s potential to trigger a pandemic “should not be exaggerated”.
Researchers at the Wuhan Institute of Virology have identified a new coronavirus in bats that can enter human cells using the same mechanism as SARS-CoV-2, the virus responsible for COVID-19. While this discovery highlights the possibility of transmission to humans, the researchers emphasize that the new virus appears to be less virulent than the one that caused the recent pandemic.
Over the past five years, the enzyme ACE2 has gained global recognition as the binding site for SARS-CoV-2, allowing the virus to enter human cells. In 2006, researchers discovered a bat coronavirus called HKU5-CoV, which uses the bat version of ACE2 for infection but poses no threat to humans.
In the new study, researchers analyzed anal swab samples from Japanese house bats and identified a novel lineage of HKU5-CoV with the ability to bind to human ACE2. Named HKU5-CoV-2, the virus also appears capable of attaching to ACE2 in multiple mammalian species, raising concerns about its potential for cross-species transmission. Similar strains have been detected in farmed minks, suggesting the virus may already be spreading among different animal populations.
“These results indicate that the HKU5-CoV-2 may have a broader host range and a higher potential for interspecies infection [than the original HKU5-CoV strain],” the researchers explain.
To assess the threat posed by HKU5-CoV-2, scientists tested its ability to invade cultured human cells. The experiments showed that the virus successfully entered human cells expressing ACE2 but was unable to infect cells lacking this enzyme. This finding is concerning because it indicates that HKU5-CoV-2 uses the same entry mechanism as SARS-CoV-2.
Using models of the human respiratory and digestive systems, the researchers observed that the virus was able to replicate within these tissues.
Despite these findings, the researchers emphasize that HKU5-CoV-2 has a lower binding affinity for human ACE2 compared to SARS-CoV-2, along with other biological limitations that reduce its likelihood of sparking a pandemic. “Due to these suboptimal factors for human adaptation, the risk of [HKU5-CoV-2] emergence in human populations should not be exaggerated,” they state.
Encouragingly, further experiments identified several monoclonal antibodies that effectively neutralize the virus. Additionally, antiviral drugs such as remdesivir and nirmatrelvir successfully inhibited its activity. While the discovery warrants attention, researchers stress that there is no immediate cause for alarm.
The study has been published in the journal Cell.