MIT, Israel Scientists Develop Inexpensive COVID-19 Vaccine

A new protein subunit vaccine developed at MIT and Beth Israel Deaconess Medical Center may offer an inexpensive, easy-to-store, and effective alternative to RNA vaccines for COVID-19. The protein subunit vaccine, which can be manufactured using engineered yeast, has shown promise in preclinical studies, Anne Trafton reported for SciTechDaily.

Photo Insert: The MIT team designed the RBD protein so that it could be produced by the yeast Pichia pastoris, which is relatively easy to grow in an industrial bioreactor.

The vaccine, which comprises fragments of the SARS-CoV-2 spike protein arrayed on a virus-like particle, elicited a strong immune response and protected animals against viruses.

The vaccine was designed so that it can be produced by yeast, using fermentation facilities that already exist around the world. The Serum Institute of India, the world’s largest manufacturer of vaccines, is now producing large quantities of the vaccine and plans to run a clinical trial in Africa.

“There’s still a very large population that does not have access to COVID vaccines. Protein-based subunit vaccines are a low-cost, well-established technology that can provide a consistent supply and is accepted in many parts of the world,” says J. Christopher Love, the Raymond A. and Helen E. St. Laurent Professor of Chemical Engineering at MIT and a member of the Koch Institute for Integrative Cancer Research and the Ragon Institute of MGH, MIT, and Harvard.

Love and Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center (BIDMC) and a professor at Harvard Medical School, are the senior authors of the paper, which was published on March 16, 2022, in Science Advances.

For their subunit vaccine, the researchers decided to use a small piece of the SARS-CoV-2 spike protein, the receptor-binding domain (RBD). Studies among animals showed this protein fragment alone would not cause a strong immune response, thus the team decided to display many copies of the protein on a virus-like particle.

They chose the hepatitis B surface antigen as their scaffold. When coated with SARS-CoV-2 RBD fragments, this particle generated a much stronger response than the RBD protein on its own.

The MIT team designed the RBD protein so that it could be produced by the yeast Pichia pastoris, which is relatively easy to grow in an industrial bioreactor.

Each of the two vaccine components — the RBD protein fragment and the hepatitis B particle — can be produced separately in yeast. The researchers added a specialized peptide tag that binds with a tag found on the other component, allowing RBD fragments to be attached to the virus particles after each is produced.

Pichia pastoris is already used to produce vaccines worldwide. Once the researchers had their engineered yeast cells ready, they sent them to the Serum Institute, which ramped up production rapidly.

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