Nanoparticle Technology Holds Promise for Protecting People Against Coronavirus Strains

This is the third coronavirus to emerge and cause serious human illness in the last 20 years, and it’s probably not the last, said Dr. Francis S. Collins, Director of the U.S. NIH.

With this in mind, I’m heartened by a new NIH-funded study showing the potential of a remarkably adaptable, nanoparticle-based approach to coronavirus vaccine development, continued Dr. Collins in a blog post on January 27, 2021.

Both COVID-19 vaccines currently authorized for human use by the Food and Drug Administration (FDA) work by using mRNA to instruct our cells to make an essential portion of the spike protein of SARS-CoV-2, which is the novel coronavirus that causes COVID-19.

As our immune system learns to recognize this protein fragment as foreign, it produces antibodies to attack SARS-CoV-2 and prevent COVID-19.

What makes the new vaccine technology so powerful is that it raises the possibility of training the immune system to recognize not just one coronavirus strain—but up to eight—with a single shot.

This approach has not yet been tested in people. Still, when a research team, led by Pamela Bjorkman, California Institute of Technology, Pasadena, injected this new type of vaccine into mice, it spurred the production of antibodies that react to various coronaviruses.

In fact, some of the mouse antibodies proved to be reactive to related strains of coronavirus that weren’t even represented in the vaccine.

These findings suggest that if presented with multiple different fragments of the spike protein’s receptor binding domain, which is what SARS-like coronaviruses use to infect human cells, the immune system may learn to recognize common features that might protect against as-yet-unknown, newly emerging coronaviruses.

This new analysis, published in the journal Science, utilizes a mosaic nanoparticle vaccine platform technology.

Initially developed by collaborators at the University of Oxford, United Kingdom, the platform’s nanoparticle component is a “cage” made up of 60 identical proteins. Each of those proteins has a small protein tag that functions much like a piece of Velcro®.

In their SARS-CoV-2 work, Bjorkman and her colleagues, including graduate student Alex A. Cohen, engineered multiple spike protein fragments, so each had its Velcro-like tag.

When mixed with the nanoparticle, the spike protein fragments stuck to the cage, resulting in a vaccine nanoparticle with spikes representing four to eight distinct coronavirus strains on its surface.

In this instance, the researchers chose spike protein fragments from several different strains of SARS-CoV-2, as well as from other related bat coronaviruses thought to pose a threat to humans.

The researchers then injected the vaccine nanoparticles into mice, and the results were encouraging. After inoculation, the mice began producing antibodies that could neutralize many different strains of coronavirus.

While more study is needed to understand the mechanisms, the antibodies responded to coronavirus strains that weren’t even represented on the mosaic nanoparticle.

Importantly, this broad antibody response came without apparent loss in the antibodies’ ability to respond to any particular coronavirus strain.

The findings raise the exciting possibility that this new vaccine technology could protect against many coronavirus strains with a single shot. Of course, far more study is needed to explore how well such vaccines work to protect animals against infection and whether they will prove to be safe and effective in people.

Our goal is not to replace the mRNA COVID-19 vaccines that scientists developed at such a remarkable pace over the last year but to provide much-needed vaccine strategies and tools to respond swiftly to the emerging coronavirus strains of the future.

As we double down on efforts to combat COVID-19, we must also come to grips that SARS-CoV-2 isn’t the first—and surely won’t be the last—novel coronavirus to cause disease in humans.

With continued research and development of new technologies such as this one, the hope is that we will come out of this terrible pandemic better prepared for future infectious disease threats, concluded Dr. Collins’s comments.

Dr. Collins was appointed the 16th Director of NIH by President Barack Obama and sworn in on August 17, 2009.

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