One of the biological characteristics of SARS-CoV-2, like several other viruses, is the presence of spike proteins, which allow these viruses to penetrate the host cell and cause infection.
Coronaviruses, such as the Middle East Respiratory Syndrome (MERS-CoV), which infected about 2,500 people by the end of 2019, as well as the emerging acute respiratory syndrome, SARS-CoV-2, are globular and coated viruses. The RNA genome of coronaviruses with an average length of 29Kb is the longest among RNA viruses.
Each component of the viral genome is packaged inside a helical nucleocapsid surrounded by a bilayer lipid membrane. Virus coat Coronaviruses are usually composed of three types of proteins:
Membrane protein (M), Envelope protein (E) and Spike protein (S).
Spike protein is a large, highly glycosylated transmembrane protein of type 1. Compared to proteins M and E, which are primarily involved in cell assembly, protein S plays a vital role in penetrating the host cell and initiating infection.
S proteins in coronaviruses are divided into two important functional subunits, in which the N-terminal subunit S1 forms the spherical head of the spike protein and the C-terminal subunit S2 forms the protein column, directly inside the virus coat. Is submerged.
When interacting with a susceptible host cell, the S1 subunit receptors the host cell and binds to it, while the S2 subunit, which is the most conserved component of the S protein, is responsible for integrating the virus coat with the host cell membrane. By connecting the S1 subunit, two major conformational changes occur in the S2 subunit to integrate with the host cell membrane.
When the change in conformations is complete, the fusion peptide attaches to the host cell membrane (anchor) and the virus can move closer to the cell membrane and eventually enter the nucleocapsid into the target cell.
S protein in viruses, especially in SARS-CoV-2 virus, is a major inducer of neutralizing antibodies (Nabs). Nabs are protective antibodies that are naturally produced by the humoral immune system. For antiviral function, Nabs bind to the epitope levels of viral particles and prevent them from entering the host cell.
The sensitivity of S protein in SARS-CoV-2 to Nabs has led many researchers to work in a field that can prevent the binding of S protein in SARS-CoV-2 to a host cell.
Without the S protein, viruses such as the new SARS-CoV-2 cannot interact with human and animal susceptible host cells and cause infections. As a result, S protein represents an ideal target for antiviral research as well as vaccine production.
New findings on the role of the spike protein in the corona virus
Scientists believe that SARS-CoV-2 virus spike proteins play a role in infecting the host by binding to healthy cells, and now, a new study shows that this part of the virus also plays a key role in the disease itself.
Research shows exactly how the SARS-CoV-2 virus damages the vascular system and attacks the cell surface. These findings, by explaining the different types of Covid 19, could be a window for new research into more effective treatments.
Researchers at the University of California have for the first time provided clear evidence of the mechanism by which proteins damage vascular cells. There is a consensus that SARS-CoV-2 affects the vascular system, but how to do this was not understood. Similarly, scientists have long studied various coronaviruses to believe that the spike protein is involved in damaging vascular endothelial cells, but this is the first time this process has been documented.
In this new study, researchers created a virus that, like the crown of the SARS-CoV-2 virus, was surrounded by spike proteins, but the virus was not real. Exposure to the virus caused damage to the lungs and arteries in an animal model, proving that spike protein alone is sufficient to cause disease.
The team then repeated the process in the laboratory, exposing healthy endothelial cells to spike protein. They showed that the spike protein damages cells by binding ACE2.
This binding disrupts the molecular signaling of ACE2 to the mitochondria of the organs that produce energy for the cells, causing damage and fragmentation of the mitochondria.