Caltech study offers hope for broad-spectrum coronavirus vaccine – Pasadena Now

In a groundbreaking study, Caltech researchers, in collaboration with scientists from Rockefeller University and the University of Washington, have demonstrated that a new vaccine candidate can provide protection against a range of coronaviruses, including SARS-CoV-2 and its variants. The research, conducted in the lab of Pamela Bjorkman, the David Baltimore Professor of Biology and Biological Engineering and Merkin Institute Professor at Caltech, offers hope for a broad defense against future pandemics.

Study published in the journal Room On August 27, attention focused on a vaccine called Mosaic-8. This innovative vaccine contains fragments of eight different sarbecoviruses, specifically regions of the virus’s spike protein called receptor-binding domains (RBDs).

The researchers were particularly interested in how Mosaic-8 would perform in individuals who already have immunity to SARS-CoV-2. This question is important because nearly all Americans have been exposed to the virus through infection or vaccination, potentially leading to a phenomenon called “original antigenic sin” (OAS).

“Current COVID-19 vaccines are not specifically designed to generate a broad antibody response that could provide better protection against variants or related viruses,” said Alexander Cohen, postdoctoral scholar and co-first author of the study.

The team used mice and non-human primate models that had previously been vaccinated with COVID-19 vaccines to mimic the immune state of most humans today. They immunized the animals with mRNA vaccines such as the Pfizer and Moderna vaccines or AstraZeneca's ChAdOx1 vaccine before giving them the Mosaic-8 vaccine.

Encouragingly, the results showed that Mosaic-8 generated broadly protective antibodies in both previously infected and immunologically naive animals. The vaccine not only boosted existing antibodies but also induced the formation of new antibodies by targeting regions specific to some of the sarbecovirus RBDs in seven animals.

Senior research scientist and co-first author Jennifer Keefe explained the vaccine’s mechanism: “Our goal is to preferentially boost those types of antibodies through the Mosaic-8 vaccine so that the body makes more of them, providing broader protection.”

The study's findings are particularly important given the possibility of future coronavirus outbreaks. Sarbecoviruses have caused two global health crises in the past two decades, highlighting the need for broad-spectrum protection.

Mosaic-8 works by targeting conserved regions of the virus's spike protein, specifically the RBD. By generating antibodies against these shared features, the vaccine aims to provide protection against multiple sarbecoviruses and SARS-CoV-2 variants.

The next step for the research team is to confirm these promising results in human trials. Phase 1 clinical trials for the Mosaic-8 vaccine are scheduled to begin in 2025, raising hopes for a more widespread defense against coronavirus threats in the future.

This study from the California Institute of Technology represents a significant advance in vaccine development, potentially offering a solution to the challenge of viral mutations and emerging coronavirus strains. As the world grapples with COVID-19, this research offers a glimpse into a much safer future.

The study was funded by Wellcome Leap, the National Institutes of Health, the Bill & Melinda Gates Foundation, the Coalition for Epidemic Preparedness Innovations, the Merkin Institute for Translational Research at the California Institute of Technology, and the Stavros Niarchos Foundation Institute.