*Originally published June 24, 2021
First-generation vaccines for COVID-19
Vaccines are substances that train the body to respond to diseases; they help stimulate the production of antibodies. Approved by the Food and Drug Administration (FDA) for emergency use authorization, the mRNA vaccine sends a message to the cells to make a piece of a spike protein–this is found in the virus that causes COVID-19. This triggers an immune response where the body starts making antibodies (like what would happen if the SARS-CoV-2 virus entered the body).
Another type of COVID-19 vaccine is the viral vector vaccine. These work by using a modified virus (the vector) to tell our cells to make a spike protein (part of the virus that causes COVID-19). Then an immune response is triggered where antibodies are made.
Specifically, the spike protein has a cluster of amino acids at the end; that section is called the receptor-binding domain (RBD). Why is that important? It’s because the RBD is the main target for antibodies since they use a receptor to duplicate.
A Different Approach to Vaccines
Currently, vaccines introduce a spike protein to the body. The problem with this is that the crucial part of the spike protein, the RBD, is hidden within large folds of that protein. Therefore, there is only a moderate immune response that produces antibodies. Moreover, this vaccine can require larger doses as smaller ones can prove ineffective.
Lexi Walls, who did a doctorate in coronavirus structure in 2019, and others created a new approach for vaccines: the RBD tip should be used instead of the whole spike protein. However, RBD tends to not be isolated, so a group in the University of Washington’s Institute for Protein Design designed a synthetic nanoparticle core that the RBD could link to. Additionally, the RBD and the synthetic SARS-CoV-2 nanoparticle core were linked loosely. This allows antibodies to be made easily.
Some benefits: this technique would be easy to deliver to people, cheap, and fast to produce (as you don't have to use another virus).
Credit: Falconieri Visuals
Testing the Nanoparticle Virus
Some mice got high doses of spike protein (the first generation vaccine) and others got the nanoparticle vaccine in a test. Later they embedded all the mice’s blood with the pseudovirus (a safe version of the SARS-CoV-2 virus) to see if antibodies from the vaccine would neutralize the pseudovirus. The spike protein vaccine got moderate antibodies with moderate neutralizing, but the nanoparticle vaccine got extreme results; the neutralizing effect was 10 times the spike vaccine!
Testing was still required. In early 2021, they entered the last testing phase.
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