Glycosylphosphatidylinositol biosynthesis functions as a conserved host defense pathway against coronaviruses via regulation of LY6E.

Coronaviruses, including SARS-CoV-2, rely on host factors for their replication and pathogenesis, while hosts deploy defense mechanisms to counteract viral infections. Although numerous host proviral factors have been identified, the landscape of host restriction factors and their underlying mechanisms remain less explored. Here, we conducted genome-wide CRISPR knockout screens using three distinct coronaviruses-SARS-CoV-2, HCoV-OC43 (a common cold human virus from the genus Betacoronavirus) and porcine epidemic diarrhea virus (Alphacoronavirus) to identify conserved host restriction factors. We identified glycosylphosphatidylinositol (GPI) biosynthesis as the pan-coronavirus host factor that restrict viral entry by disrupting spike protein-mediated membrane fusion at both endosomal and plasma membranes. GPI biosynthesis generates GPI moieties that covalently anchor proteins (GPI-anchored proteins [GPI-APs]) to the cell membrane, playing essential roles in various cellular processes. Through focused CRISPR knockout screens targeting 193 GPI-APs, we identified LY6E, a known pan-coronavirus restriction factor for viral entry, as the key downstream effector mediating the antiviral activity of the GPI biosynthesis pathway. These findings reveal the role for GPI biosynthesis as a conserved host defense mechanism against coronaviruses via regulation of downstream effectors.