COVID-19 mRNA Vaccine Production
Early in the COVID-19 pandemic, researchers used state-of-the-art genomic sequencers to quickly sequence the SARS-CoV-2 virus. This sequence was quickly shared with other researchers. This allowed researchers from across the globe to analyze the virus and better understand how it causes disease. The speed of this crucial first step enabled the immediate research and development of viable vaccine candidates.
Once researchers analyzed the viral sequence using cutting edge bioinformatics approaches, they selected the spike protein gene as their vaccine candidate. The spike protein is essential for the virus to attach to the host cell, thereby making it an effective antigen, or target for the immune system to recognize and attack. The genetic sequence is then optimized for the vaccine based on years of previous research on coronaviruses. Understanding the viral genome also allows researchers to update the vaccine if they detect new strains of the virus that may require a new versions of the vaccine.
The target spike protein gene is then synthetically manufactured and inserted into in a plasmid, or a small, circular piece of DNA. Plasmids are used in mRNA vaccine production because they are easy to replicate (copy) and reliably contain the target gene sequence. Once a sequence is selected, a new plasmid can be produced within a couple of weeks, allowing new mRNA vaccines to be tested and distributed rapidly.
Researchers then use established in-vitro (laboratory-based, such as in a test tube) protocols to create mRNA in a method that mimics our own biological processes. First, they separate the two strands of plasmid DNA. Then, RNA polymerase, the molecule that transcribes RNA from DNA, uses the spike protein gene to create a single mRNA molecule. This is nearly identical to the way genes in our bodies are transcribed. Finally, other molecules break down the rest of the plasmid to ensure that only the mRNA is packaged as a vaccine. The speed and efficiency of this process can make large amounts of mRNA in a short period of time.
mRNA is a fragile molecule, so researchers put it into a fatty lipid bilayer, which protects it while the vaccine is packaged, shipped and administered. This bilayer easily attaches to our cells once the vaccine is given, which efficiently delivers the mRNA and starts the immunization process. Currently, mRNA vaccines needs to be kept very cold or else they will degrade. This adds a layer of logistical complexity to the distribution mRNA vaccines.
Last updated: August 31, 2021