An international team of researchers has identified a bat-borne coronavirus from East Africa with the capacity to infect human cells. The findings of this study were featured in the journal Nature.
The virus, officially named Cardioderma bat coronavirus (CcCoV) KY43 or CcCoV-KY43, demonstrates the ability to attach to a receptor cell present in human lungs; however, investigations conducted in Kenya suggest it has not yet spread within the local populace.
Rather than working with “live” pathogens, the scientists utilized the publicly accessible Genbank database of known genetic sequences to select and synthesize the “spike” proteins of alphacoronaviruses. This involved 27 viruses initially isolated from bats, which were then tested against a library of coronavirus receptors found on human cells.
Spike proteins protrude from the surface of coronaviruses, SARS-CoV-2 included, and they connect with specific receptors on human cells, thereby initiating infection.
This collaborative research, integrating expertise from the UK and Kenya, established that CcCoV-KY43 binds to the human glycoprotein known as CEACAM6.
The research consortium—comprising members from the Pirbright Institute, the University of Cambridge, the KEMRI-Wellcome Trust research programme, the University of York, and the National Museums of Kenya—asserts that their data indicates alphacoronaviruses (alpha-CoV) possess the capability to employ a variety of receptors to breach human cells.
“Viral spike proteins function as keys that fit into the locks (host receptors) to open the door for cellular entry. Up to this point, we had identified just one receptor utilized by an alphacoronavirus. The next challenge is to discover the remainder,” commented study co-author Professor Stephen Graham from the Department of Pathology at the University of Cambridge.
“Prior to our work, the assumption was that all alphacoronaviruses relied on just one of two potential receptors for host invasion, with the only differentiation being which species they could enter. We now understand that alphacoronaviruses can utilize an array of different receptors to gain access to cells,” stated Dalan Bailey, a study co-author from the Pirbright Institute.
“Not only did we pinpoint a novel coronavirus receptor in human cells before the virus entered the human population, but we executed this investigation using only a fragment of the virus—the spike—instead of the entire pathogen. This approach eliminated the need to transport the live virus into the UK,” explained Julia Gallø, a co-author from the Pirbright Institute and the University of Cambridge.
CcCoV-KY43 was detected in the Cardioderma cor bat, an ecologically significant species predominantly inhabiting East Africa, encompassing regions such as eastern Sudan and northern Tanzania.
The researchers emphasize that the zoonotic (animal-to-human transmission) and pandemic potential of alphacoronaviruses remains largely unexplored; only two cellular receptors have been characterized for alpha-CoVs to date.
This paper highlights the necessity for further inquiry in East Africa to gain a better grasp of the risks associated with this viral family, given their ability to use this identified receptor for human cell entry. Such knowledge will better equip scientists to prepare for potential future human outbreaks and perhaps commence the development of human vaccines and antivirals. The team intends to apply the computational techniques pioneered in this study to search for other potential human pathogens and to decipher the broader determinants of zoonotic potential.
“We anticipate our findings will contribute to a clearer understanding of the risks posed by the viral family we identified that can exploit a human receptor—for instance, by mapping the virus’s prevalence among bats and investigating whether transmission has already occurred in at-risk populations,” concluded Graham.
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