The Wuhan Institute of Virology has just detected a new member of the coronavirus family, called HKU5-CoV-2. This variant of the HKU5-CoV virus, initially discovered in 2006 in small bats (P ipistrellus abramus) in Hong Kong, has particular characteristics, all compiled in the journal Cell on February 18. One has caught the attention of researchers: it can infect a wide range of mammals, including humans. Will it be the vector of the next pandemic feared by all virologists?
A new virus under surveillance
Laboratory experiments show that some strains of HKU5-CoV-2 interact effectively with the human ACE2 receptor to enter cells. This is a protein present on the surface of certain cells in the body that served as a gateway for SARS-CoV-2, responsible for the COVID-19 pandemic. This similarity in the mechanism of infection naturally worries specialists.
HKU5-CoV-2 is more closely related to the Middle East respiratory syndrome (MERS) virus than to SARS-CoV-2. The researchers also found that SARS-CoV-2-specific antibodies would likely provide only limited protection against this new virus.
However, scientists have also identified several factors that limit the ability of HKU5-CoV-2 to efficiently infect humans. These include structural incompatibilities with some human cellular co-receptors, less efficient viral entry mechanisms than SARS-CoV-2, and a reduced ability to evade innate immune defenses.
A fundamental point that was also underlined in their publication: “Because of these suboptimal factors for human adaptation, the risk of emergence of HKU5-CoV-2 in human populations should not be exaggerated.”
Coronaviruses: The Sword of Damocles of the 21st Century
While HKU5-CoV-2 may never infect humans, other similar viruses could eventually do so, which is why the WHO regularly compiles a list of priority pathogens.
Coronaviruses are a diverse group of viruses that infect mammals and birds, seven of which are currently known to affect humans. Four of them typically cause a mild cold, while the other three have caused more serious outbreaks: the original SARS in the early 2000s, MERS (a dangerous but limited zoonotic disease transmitted mainly from camels to humans), and finally SARS-CoV-2, which has caused the most devastating pandemic in a century, causing more than 20 million deaths worldwide since late 2019.
No human cases of HKU5-CoV-2 infection have been reported to date. Furthermore, the theoretical ability of a virus to cross the species barrier does not guarantee its subsequent human-to-human transmission – a phenomenon that remains exceptional in nature.
It was not until 2019 that scientists began to worry about the pandemic potential of coronaviruses, given their wide distribution in the animal kingdom: concerns that have now been reinforced by the discovery of HKU5-CoV-2.
In any case, whether it is a coronavirus, avian flu or some other as yet unknown pathogen, the conditions for the next pandemic are inevitably brewing. Even if HKU5-CoV-2 will not necessarily be responsible, we must be prepared: new global health crises will erupt in the decades to come.
Synopsis—
- • Chinese researchers have identified HKU5-CoV-2, a novel coronavirus capable of infecting several mammals, including humans.
- • The virus uses the ACE2 receptor to enter human cells, like SARS-CoV-2, but its ability to transmit remains limited.
- • While it does not pose an immediate threat, the discovery is a reminder that other pathogens could one day cause a new pandemic.
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