‘Simpler’ COVID-19 Vaccine Targets Only Part of Spike Protein

  • <<
  • >>

575846.jpg

 

With three vaccines currently approved in the U.S. to fight COVID-19, it may feel like we have beaten the pandemic. While great strides have been taken, we still have variants to contend with, as well as the long-term unknowns surrounding the novel coronavirus that may necessitate future booster shots.

Thus, vaccine development remains a top priority for scientists worldwide. Biomedical researcher Michael Cho has created a vaccine that is different than the three the U.S. currently has—one that is both easy to produce and easy to scale up.

"Just because we have vaccines now, that doesn't mean we won't need more in three or five years, maybe even longer," said Cho, a professor at Iowa State University. "I don't think our vaccine is too late to play a role."

Research has continually showed SARS-CoV-2's spike protein is the ideal target for vaccines. Both Pfizer/BioNTech’s mRNA vaccine and Moderna’s version target the spike protein, tricking the immune system into delivering a response against the not-present virus.

Cho’s vaccine also focuses on the spike protein, but not the entire thing. Instead, his version targets SARS-CoV-2's receptor-binding domain (RBD), which is the first step of the virus lifecycle. The RBD is the portion of the viral spike protein that binds to host cells to initiate infection. The antibodies produced by Cho’s experimental vaccine attack the RBD first, halting infection.

Cho likens the vaccine process to a how a lock and key operate

"The spike glycoprotein is the key that opens the lock, and the region of the key with all the peaks and valleys and grooves is the RBD," Cho said. "If antibodies attack the RBD, then the key won't work and the door will stay locked, preventing infection.”

Cho and his team successfully induced a potent antibody response with their RBD-targeting vaccine in mice over the course of three injections. The study, published in Frontiers in Immunology, did also demonstrate that one or two injections are sufficient, depending on the adjuvant used.

The next step would be testing the patent-pending vaccine, which is available for licensing from the Iowa State University Research Foundation, in human trials. For pharmaceutical manufacturers, the appeal is in the simplicity of the vaccine—production and scale up are minimal since it only requires a small portion of the virus’s spike protein. Additionally, the RBD-targeting vaccine is safe if/when administered multiple times, which could be necessary as herd immunity lags and new variants continue to emerge.

“The RBD plays a critical role in the very first step of the virus life cycle. Better understanding of where and how neutralizing antibodies bind the RBD should enable identification of sites of vulnerability and facilitate better vaccine design and formulation of immunotherapeutics,” the authors conclude.