The protein which allows the SARS-CoV-2 virus (the virus that causes COVID-19) to enter human cells (human cell entry protein) is 88% identical to that of the human cell entry protein in SARS-CoV (the virus that caused the 2003 SARS outbreak), the virus responsible for the 2003 SARS outbreak. This finding may provide a blueprint for the development of vaccines and therapies.
Walls, A. et al. Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein. Cell (2020). doi: 10.1016/j.cell.2020.02.058
16 April 2020
SARS-CoV-2, infects human cells by using a ‘spike’ protein (S protein) that binds to a protein found on human cells which helps to fuse the virus with the cell. This is similar to other related viruses within the coronavirus family which also use an S protein to enter target cells. Researchers investigated the similarity between the S proteins of SARS-CoV-2 and other related viruses to better understand how SARS-CoV-2 entry into human cells compares to the entry of other viruses into human cells. They found that the SARS-CoV-2 S protein shares 88% of the protein building blocks (amino acids) as well as other similar protein modifications making it quite similar to the SARS-CoV S protein. Due to the high degree of similarity, the researchers investigated whether immune responses developed against one virus could also protect against the other. Mice were first exposed to the S protein of SARS-CoV then given time to develop an immune response against the protein. Afterwards, they were exposed to the SARS-CoV-2 virus. The immune responses generated against the SARS-CoV protein had a ‘spillover’ effect in which they effectively protected against the SARS-CoV-2 infection and decreased the rate of infection by roughly 90%. These early findings in mice highlight that due to their similar structure, the exposure to one of these viruses may allow our body to initiate a protective response against the other as well.
Summary by: Jacob Ferguson