What is an mRNA vaccine and how do mRNA vaccines work?
mRNA vaccines are based on messenger ribonucleic acid (mRNA) and are a novel technology that stimulates the body's own immune response. These vaccines contain information from the mRNA, including the “blueprint” or code of a specific virus trait (virus antigen). Based on the information, the body can produce this antigen itself: The mRNA transmits the information for the production of the antigen to our cell machinery, which produces proteins. When the cells in our body then present antigens on their surface, the desired specific immune responses are triggered. When the body is exposed to the coronavirus, the immune system recognizes specific antigens and can fight the virus well and thus the infection occurs quickly and in a targeted manner.
mRNA vaccines to fight the COVID-19 pandemic
In the case of the mRNA vaccine against COVID-19, the body, and thus the immune system, recognize the virus based on the spike protein of the coronavirus that is on the virus surface. mRNA vaccines against COVID-19 are designed to provide our bodies with the code to produce a non-infectious viral spike protein. In doing so, they instruct the cell machinery
to stimulate a natural immune response. This immune response is mainly achieved with the help of T cells and the production of neutralizing antibodies, to prevent SARS-CoV-2 infections and the associated disease COVID-19. If a vaccinated person later comes into contact with SARS-CoV-2, the immune system recognizes the surface structure, can fight and eliminate the virus. Neutralizing antibodies directed against SARS-CoV-2 circulate in your body and then immediately bind to the virus, "neutralize" it and prevent the virus from entering the cell. In this way, you will be protected from illness. T cells help the immune system fight intracellular infections, and they can also kill the infected cells directly.
In contrast to conventional vaccines, and mRNA vaccine does not contain any viral proteins itself, but only the information that our own cells need to produce a virus trait that triggers the desired immune response. The mRNA technology made the development of several vaccine candidates against COVID-19 possible.
How are traditional vaccines made?
Conventional vaccines usually contain weakened or inactivated pathogens or pathogen proteins (antigens) that stimulate the body's immune response, which means that it can react faster and more effectively if it is in contact with an infectious agent in the future.
The production of traditional viral vaccines in bioreactors is a common process, but it is lengthy and cumbersome: this process, which can take several months, involves several steps such as seed virus preparation, fermentation, harvest, and purification. Also, dealing with large amounts of live viruses is required.
How are mRNA vaccines made?
A different approach is used with mRNA vaccines: They take advantage of the process in which the cells themselves produce proteins from the information encoded in the messenger ribonucleic acid (mRNA). This “blueprint” is translated by the body to synthesize specific proteins (antigens).
An mRNA vaccine consists of a strand of mRNA that codes for a disease-specific protein (antigen). To improve the integration of this blueprint mRNA in the body cells and to increase the vaccine stability, the mRNA is enveloped by certain fatty substances (lipids): lipopolyplexes made of lipid nanoparticles.
Once the mRNA vaccine is injected into an individual, lipid nanoparticles protect the mRNA from degradation, which is very good, and help the mRNA to reach the cells. In these cells, the information contained in the mRNA strand is read and antigen proteins are produced, which ultimately triggers the desired immune response.
Interest in mRNA technology as a vaccine platform has increased over the last two decades. And an mRNA-based vaccine is faster to manufacture than many conventional vaccines for good, since only it has to produce blueprints and not antigens.
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