By Mia Schenenga
For almost a year, we have been living in a world plagued by COVID-19 and in a constant risk of exposure and quarantine. However, as new vaccines were announced and then eventually authorized by the FDA for emergency use, it’s as if we are finally seeing the light at the end of the tunnel. While this brings hope to many, it also marks the beginning of what could be a huge addition to science and medicine: using synthetic mRNA to vaccinate against illness.
Simply put, mRNA, or messenger RNA, is genetic material that carries instructions for making proteins within the cell. mRNA is used in all of our cells constantly, to direct the production of proteins by instructing the amino acids to be linked in the correct sequence. To begin, mRNA corresponds to a specific sequence of a gene, and then the ribosome within a cell “reads” these sequences. The process of transcription then takes place, which copies genes from the cell’s DNA into the mRNA. From there, the gene sequence in the mRNA is a three-base code that can be translated by tRNA, and each code corresponds to a specific amino acid. As the amino acids are put together using the code carried by the mRNA, it creates a protein, which is a very large and complex molecule that does the work within the body. These proteins are critical to the structure, function, and regulation of the body on the cellular level.
In a particle of SARS-CoV-2, the scientific name for the current coronavirus, there are 29 proteins. However, the mRNA vaccine focuses on one specific protein: the spike protein. This is the protein on the outside of the coronavirus particle and allows the virus to infect a healthy cell. Just as in a cell in the human body, mRNA is used to code the spike protein that can be found on the outside of the coronavirus particle. In order to create the vaccine, scientists were able to isolate the mRNA with the code for this specific spike protein. This mRNA was packaged into a lipid nanoparticle, which is how mRNA is delivered within the cell. So when a person receives the vaccine, they are being injected with what is known as synthetic mRNA, and codes for this specific spike protein that the coronavirus uses to infect a healthy cell in the human body. The lipid nanoparticle package allows for the mRNA to be delivered to the person’s cells, giving the person the genetic code to create the coronavirus spike protein.
Now, once the person has been vaccinated with the mRNA that codes for the spike protein, their cells can create the spike protein using amino acids exactly how they would create any other protein that was required for the body to function. The mRNA will bring a code that specifies that amino acids be linked in the specific order that creates the spike protein, as I described earlier. However, the body will recognize the newly create spike protein as an antigen, a foreign protein that causes the body’s immune system to activate. This immune response will consist of two types of cells within the lymphatic system: B-cells and T-cells. The B-cells will create antibodies against the antigen, which in this case is the spike protein, and the T-cells will gather the information to recognize the antigen in the future, allowing future protection from the virus. And so, if the person is later infected with the coronavirus, the T-cell will recognize the spike protein, and the immune system will direct the already-created antibodies to bind to the spike protein. The coronavirus particle will then be destroyed before it can infect the person’s cells.
Currently, two vaccines against SARS-CoV-2 have been approved for emergency use in the U.S. – the Pfizer-BioNTech COVID-19 Vaccine, and the Moderna COVID-19 Vaccine. Both vaccines have been created using mRNA technology, allowing the body to create, recognize, and generate antibodies against the coronavirus spike protein, giving the opportunity for the body to prepare for and prevent future infection in most cases. In clinical trials, the Pfizer-BioNTech vaccine had a 95% efficacy rate in preventing coronavirus infection in people with no prior infection, and the Moderna was found to be 94.1% effective under the same circumstances. While mRNA technology has been studied in medicine for the past decade or so, these COVID-19 vaccines mark the first widespread and successful use, paving the way for future improvements in its use in medicine, but also providing hope for immunity and an opportunity to find our way back to what our lives were like just a year ago.