The SARS-CoV-2 virus that is causing the COVID-19 pandemic is just one of many different viruses in the coronavirus family.
Many of these are circulating in populations of animals like bats and have the potential to “jump” into the human population, just as SARS-CoV-2 did.
Scientists are working on developing vaccines for a wide range of related coronaviruses, with the aim of preventing future pandemics.
In a new study, researchers designed a protein-based 60-subunit nanoparticle onto which pieces of up to eight different types of coronavirus have been attached.
When injected into mice, this vaccine induces the production of antibodies that react to a variety of different coronaviruses—including similar viruses that were not presented on the nanoparticle.
The research was conducted by a team at the California Institute of Technology.
This vaccine platform, called a mosaic nanoparticle, was developed initially by collaborators at the University of Oxford.
The nanoparticle is shaped like a cage made up of 60 identical proteins, each of which has a small protein tag that functions as a piece of Velcro.
In the study, the team took fragments of the spike proteins of different coronaviruses (spike proteins play the biggest role in infection) and engineered each to have a protein tag that would bind to those on the cage—the other half of the piece of Velcro.
When these viral pieces were mixed together with the nanoparticle cage structure, each virus tag stuck to a tag on the cage, resulting in a nanoparticle presenting spikes representing different coronavirus strains on its surface.
Displaying eight different coronavirus spike fragments (known as receptor-binding domains or RBDs) with this particle platform generated a diverse antibody response, which is an advantage over traditional vaccine methods that present pieces from only a single type of virus.
After inoculation, the antibodies subsequently produced by mice were able to react to many different strains of coronavirus.
Importantly, the antibodies were reactive to related strains of coronavirus that were not present on the nanoparticle.
This suggests that, by presenting the immune system with multiple different coronavirus variants, the immune system learns to recognize common features of coronaviruses and thus could potentially react to a newly emerging coronavirus—not just a SARS-CoV-2 variant—that might cause another pandemic.
Although the team is still studying the mechanism underlying this phenomenon, the results are promising.
The next step is to examine whether immunization prevents viral infection and/or infection symptoms in animals making these antibodies.
One author of the study is Alex Cohen.
The study is published in Science.
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