In the world of parasites, many bacterial or fungal pathogens can survive by themselves without infecting host cells. But viruses cannot. Instead, they must penetrate the cells to multiply, where they use their own biochemical mechanism to create new viral particles and extend to other cells or individuals. Like cell life, the coronaviruses themselves are surrounded by a fatty shell. To penetrate the cells, they use proteins (or glycoproteins, as they are often covered with slippery sugar molecules) to drain their own membrane with the cell membrane and thus capture the cell. One of these viral glycoproteins is the spike protein of coronaviruses. Given the emergence of new strains of Coronavirus SARS-COV-2, the interest of the general public to the spike squirrel has increased much. It turned out that new COVID-19 options carry several specific changes in the spike protein compared to other close-based options.
Spikes proteins
One of the key biological characteristics of Coronavirus SARS-COV-2, as well as some other viruses, is the presence of spiker proteins that allow these viruses to penetrate into the host cells and cause infection. As a rule, the virus sheath of coronaiviruses consists of three proteins that include a membrane protein (M), shell protein (E) and spike protein (S).
Selfed S or Square protein consists of 1160-1400 amino acids, depending on the type of virus. Compared with the M and E proteins, which are mainly involved in the assembly of the virus, S protein plays a crucial role in penetrating the host cells and the initiation of infection. It is noteworthy that it is the presence of S-proteins on coronavirus leads to the appearance of spike-shaped protrusions on their surface.
Specialists note that Coronavirus S-proteins can be divided into two important functional subunits, which include the N-terminal S1 subunit, forming the S-protein spherical head, and the C-terminal S2 region, directly built into the viral shell. When interacting with the potential host cell, the S1 subunit recognizes and binds to the receptors on the host cell, while the S2 subunit, which is the most conservative component of S protein, is responsible for the fusion of the virus shell with the host membrane.
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It is noteworthy that without protein s viruses like SARS-COV-2, could never interact with cells of potential owners, such as animals and people. It is for this reason that the protein S is an ideal target for the research of vaccines and antiviral drugs. In addition to its role in the cell, the virus s-protein, in particular COVID-19, is the main inducer of neutralizing antibodies (NABS). NABS is protective antibodies that are naturally produced by our immune system.
Spikels and vaccines
Our cells evolved to reflect the invasion of viruses. One of the main protective forces of cell life from the invaders is its outer shell, which consists of a fat layer containing all the enzymes, proteins and DNAs constituting the cell. Because of the biochemical nature of fats, the outer surface strongly repulses the viruses that should overcome this barrier to gain access to the cell.
Considering how important the spike protein for the virus is, the effect of many antiviral vaccines or drugs are aimed at viral glycoproteins. Vaccines against SARS-COV-2, produced by Pfizer / Biontech and Moderna, give instructions to our immune system to make their own version of the spike squirrel, which happens shortly after immunization. The production of spike protein inside our cells then launches the production of protective antibodies and T cells.
The virus causing Ebola fever has one spike protein, the influenza virus is two, and the virus is a simple herpes - five.
As the Conversation writes, one of the most important features of SARS-COV-2 spiker protein is how it moves or changes over time during the evolution of the virus. The protein coded in the viral genome can mutate and change its biochemical properties as the virus develops.
Most mutations do not benefit and either stop the operation of the spike protein, or do not affect its function. But some of them can cause changes that give a new version of the virus selective advantage, making it more transmitted or infectious. One of the ways to which this can happen is a mutation in a part of a spike squirrel that prevents the binding of protective antibodies with it. Another way is to make the spikes "more sticky" for our cells.
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That is why new mutations that change the functions of a spike squirrel or protein S are of particular concern - they may affect how we control the distribution of SARS-COV-2. New options recently discovered in the UK and South Africa have mutations in parts of the S protein, participating in penetration into your cells. Further research and laboratory experiments will help scientists find out if - and how - these mutations are significantly changed by the spike protein, and whether our current control measures remain effective.