3.1.5 Viral spike protein
The trimeric S glycoprotein responsible for the coronaviruses crown-like appearance, mediates attachment to the host receptor (Ou et al., 2020). Despite spike protein sequence similarity above 72% with SARS-CoV, a peculiar furin-like cleavage site at the S1/S2 position in the S-protein sequence of the 2019-nCoV was identified, lacking in the other SARS-like CoV (Coutard et al., 2020). Following the host cell attachment, entry is mediated by S protein priming by cellular protease. In some cases, the S protein is cleaved by a host cell furin-like protease. Blocking S protein attachment or furin-like cleavage sites are promising targets in drug discovery. Recently, Xia et al introduced a lipopeptide named EK1C4 effectively block 2019-nCoV infection at the cellular level in a dose-dependent manner with IC50 of 36.5 nM (Xia et al., 2020). The presence of three vaccine candidates in clinical phases accentuates the importance of this protein in the process of drug development (Thanh et al., 2020).