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Life cycle of Spike Protein

 Entering a Cell

After injection, the vaccine particles bump into cells and fuse to them, releasing mRNA. The cell’s molecules read its sequence and build spike proteins. The mRNA from the vaccine is eventually destroyed by the cell, leaving no permanent trace.



Spike protein coming outside the cell and bumping into antigen presenting cell



Helper T cell being activated


Helper T cell bumping in to B cell and B cell producing antibodies

The S protein is made up of 1,160 to 1,400 amino acids, depending upon the type of virus.

In addition to its role in penetrating cells, the S protein of viruses, particularly the SARS-CoV-2 virus, is a major inducer of neutralizing antibodies (NAbs). NAbs are protective antibodies that are naturally produced by our humoral immune system.

Functional S protein ALLOWS viruses like the novel SARS-CoV-2 to interact with receptors of potential host cells. As a result, the S protein represents an ideal target for vaccine and antiviral drug discovery.

Mechanistic studies indicated that I-S1 of spike protein crosses the blood-brain barrier by adsorptive transcytosis and that murine angiotensin-converting enzyme 2 is involved in brain and lung uptake, but not in kidney, liver or spleen uptake.


Ref:

1. Walls AC, Park YJ, Tortorici MA, Wall A, McGuire AT, Veesler D. Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein. Cell. 2020 Apr 16;181(2):281-292.e6. doi: 10.1016/j.cell.2020.02.058. Epub 2020 Mar 9. Erratum in: Cell. 2020 Dec 10;183(6):1735. PMID: 32155444; PMCID: PMC7102599.

2. Rhea EM, Logsdon AF, Hansen KM, Williams LM, Reed MJ, Baumann KK, Holden SJ, Raber J, Banks WA, Erickson MA. The S1 protein of SARS-CoV-2 crosses the blood-brain barrier in mice. Nat Neurosci. 2020 Dec 16. doi: 10.1038/s41593-020-00771-8. Epub ahead of print. PMID: 33328624.


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