Coronavirus entry is mediated by the spike protein that binds the receptor and mediates fusion after cleavage by host proteases. The proteases that mediate entry differ between cell lines, and it is currently unclear which proteases are relevant in vivo. A remarkable feature of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike is the presence of a multibasic cleavage site (MBCS), which is absent in the SARS-CoV spike. Here, we report that the SARS-CoV-2 spike MBCS increases infectivity on human airway organoids (hAOs). Compared with SARS-CoV, SARS-CoV-2 entered faster into Calu-3 cells and, more frequently, formed syncytia in hAOs. Moreover, the MBCS increased entry speed and plasma membrane serine protease usage relative to cathepsin-mediated endosomal entry. Blocking serine proteases, but not cathepsins, effectively inhibited SARS-CoV-2 entry and replication in hAOs. Our findings demonstrate that SARS-CoV-2 enters relevant airway cells using serine proteases, and suggest that the MBCS is an adaptation to this viral entry strategy.
【저자키워드】 COVID-19, SARS-CoV-2, SARS-CoV, virus, Airway organoids, serine proteases, multibasic cleavage site, 【초록키워드】 coronavirus, protease, viral entry, airway, Replication, Syncytia, cleavage, receptor, Calu-3 cell, in vivo, cell lines, host proteases, Organoid, endosomal entry, acute respiratory syndrome, Cathepsins, SARS-CoV-2 entry, serine protease, human airway, plasma membrane, MBCs, blocking, Cell, bind, inhibited, increase, faster, the spike protein, the SARS-CoV-2, 【제목키워드】 Organoid, Serine, SARS-CoV-2 entry, human airway, facilitated,