Loss of FCoV-23 spike domain 0 enhances fusogenicity and entry kinetics.
Tortorici, M.A., Choi, A., Gibson, C.A., Lee, J., Brown, J.T., Stewart, C., Joshi, A., Harari, S., Willoughby, I., Treichel, C., Leaf, E.M., Bloom, J.D., King, N.P., Tait-Burkard, C., Whittaker, G.R., Veesler, D.(2025) Nature 645: 235-243
- PubMed: 40634609 
- DOI: https://doi.org/10.1038/s41586-025-09155-z
- Primary Citation of Related Structures:  
9DAZ, 9DB0, 9DB1, 9DB3, 9DBE, 9DBZ - PubMed Abstract: 
The ability of coronaviruses to recombine and cross species barriers affects human and animal health globally and is a pandemic threat 1,2 . FCoV-23 is a recently emerged, highly pathogenic recombinant coronavirus responsible for a widespread outbreak of feline infectious peritonitis. Here we report cryogenic electron microscopy structures of two FCoV-23 spike isoforms that correspond to the in-host loss of domain 0 observed in clinical samples. The loss of domain 0 markedly enhances the fusogenicity and kinetics of entry into cells and possibly enables biotype switching and lethality. We show that FCoV-23 can use several aminopeptidase N orthologues as receptors and reveal the molecular determinants of receptor species tropism, including a glycan that modulates human receptor engagement. We define antigenic relationships among alphacoronaviruses that infect humans and other mammalian species and identify a cross-reactive alphacoronavirus monoclonal antibody that inhibits FCoV-23 entry. Our results pave the way for the development of vaccines and therapeutics that target this highly pathogenic virus.
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
Organizational Affiliation: