ycans containing sialic acid [54,55]. S protein concentrated outside the virus contains the receptor binding domains (RBDs) at the N-terminal, such as MHV-CoV N-RBD and SARS C-RBD with their receptor (Fig. 2B–D) [7,56,57]. The coronavirus NL63 (CoV-NL63), and SARS-CoV use angiotensin-converti