Biochemists Katalin Kariko and Drew Weissman have won the 2023 Nobel Prize in medicine/physiology. Why? Because they were the people behind the vaccines that just allowed us to control the worldwide COVID pandemic.
Usually, vaccine development takes about 5 to 10 years. However, more resources were put into the urgent battle of fighting the rapidly spreading COVID-19 than ever before: in record time, after the genetic sequence of the SARS-CoV-2 virus was discovered, several pharmaceutical companies, namely Moderna and Pfizer, created messenger RNA vaccines. Then, for the first time ever, the FDA approved mRNA vaccines.
Typical vaccines consist of weakened viruses or bacteria that provoke the immune system to make antibodies to protect against future infections:
As I learned in AP Bio class, once those weakened pathogens are allowed to get through the body’s innate defenses (skin, mucus, tears, saliva, etc.), macrophages and dendritic cells engulf the antigens of the foreign pathogens (the spike protein for coronavirus) through phagocytosis, which the phagocytes can display on the outside of their plasma membranes on MHC proteins, while simultaneously releasing chemical messengers called cytokines. Activated by the cytokines, certain T-helper cells then recognize the antigens displayed on certain MHC proteins and call for an appropriate response. If this process is in a cell, T-helper cells activate cytotoxic T cells and T-memory cells. However, if it is in the blood, T-helper cells activate B-plasma cells and B-memory cells. B-plasma cells are the cells that create antibodies, which effectively neutralize pathogens and B-memory cells remember how to create those antibodies significantly more effectively for better future protection.
However, it is a very costly and tedious process for scientists to get loads of the coronavirus and weaken it for vaccines. The way Pfizer and Moderna created working COVID vaccines so quickly, based on the research that Kariko and Weissman began in 2006, is by creating vaccines with mRNA that tells cells how to create weakened coronavirus proteins; this process is instead of scientists manually putting weakened proteins into vaccines and is significantly more efficient since our bodies are already good at making proteins based on DNA/RNA code.
The reason why mRNA vaccines have never been FDA approved before the COVID vaccines is because pumping mRNA into the body releases cytokines itself. As mentioned previously, in AP Bio we learned that cytokines trigger helper-T cells. If helper-T cells are triggered when they shouldn’t be, that could create many problems. So, to fix this problem, Kariko and Weissman slightly altered the structure of the RNA to lessen cytokine triggering. Additionally, they encased mRNA in bubbles of lipids. As I learned in AP Bio class, lipids are nonpolar, meaning they can travel through cell plasma membranes. This lipid bubble, therefore, allows the mRNA to travel directly to and inside the nuclei of cells without causing harm elsewhere. Then, the mRNA can tell ribosomes to create the certain weakened coronavirus proteins that trigger the immune response of creating antibodies as previously described.
With the help of the research of the very deserving 2023 medicine/physiology Nobel Prize winners, Weissman and Kariko, the problems with mRNA technologies have finally been resolved (for now). Thus, this more efficient — and may we call it, revolutionary — mRNA technology is now being looked at to potentially defend other viruses and even cancers. The opportunities for this technology seem extraordinary, but what other challenges will scientists and researchers face when trying to explore these opportunities?
I would argue it is time for them to explore and find out.