The spike is essential for both host specificity and viral infectivity.
The term 'peplomer' is typically used to refer to a grouping of heterologous proteins on the virus surface that function together.
The spike （S） glycoprotein of coronaviruses is known to be essential in the binding of the virus to the host cell at the advent of the infection process.
It's been reported that SARS-CoV-2 （COVID-19 coronavirus, 2019-nCoV） can infect the human respiratory epithelial cells through interaction with the human ACE2 receptor.
The spike protein is a large type I transmembrane protein containing two subunits, S1 and S2.
S1 mainly contains a receptor binding domain （RBD）, which is responsible for recognizing the cell surface receptor.
S2 contains basic elements needed for the membrane fusion.
The S protein plays key parts in the induction of neutralizing-antibody and T-cell responses, as well as protective immunity.
The main functions for the Spike protein are summarized as： Mediate receptor binding and membrane fusion; Defines the range of the hosts and specificity of the virus; Main component to bind with the neutralizing antibody; Key target for vaccine design; Can be transmitted between different hosts through gene recombination or mutation of the receptor binding domain （RBD）, leading to a higher mortality rate.
遺伝子構造：Recombinant SARS-CoV-2 S-trimer Protein is produced by our Mammalian expression system and the target gene encoding Cys15-Gln1208 is expressed with a 6His tag at the C-terminus. A67V, HV69-70del, T95I, G142D, VYY143-145del, N211del, L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K and L981F mutations were identified in the SARS-CoV-2 variant （known as Omicron/B.1.1.529 lineage） which emerged in South Africa. Two proline substitutions and furin cleavage site substitutions are introduced to stabilize the trimeric prefusion state of SARS-CoV-2 S protein and abolish the furin cleavage site, respectively.
