These include the spike or S glycoprotein, membrane or M protein, envelope or E protein, and nucleocapsid or N protein (associates with viral RNA genome; not shown). The current choice for vaccine generation is the S glycoprotein, which is capable of generating neutralizing antibody responses in addition to eliciting CD8+ and CD4+ T-cells. The spike protein exhibits a screw-like shape, composed of a larger head and a long, thin stalk.206 Three spike proteins interact to form a trimer that is held in place by a stalk (composed of S1 and S2 regions), which stands away from the viral surface and exhibits a host protease (furin) cleavage site, the role of which is explained in Figure 2. Adapted with permission from ref 206. Copyright 2020 CAS.