l entry.
Nonetheless, the two viruses were demonstrated by Xia to share also the membrane fusion mechanism, as strongly suggested by the impressive 89.9% sequence identity of S2 between SARS-CoV and SARS-CoV-2 (Xia et al., 2020a,b).
To date, the cell entry mechanism of SARS-CoV and SARS-CoV-2 has