Hybrid mRNA and protein vaccine induce 5x more antibodies in mice

Caltech scientists have developed a new type of vaccine that works like a hybrid of mRNA and protein nanoparticles. In tests in mice, the prototype produced five times more antibodies than existing COVID-19 vaccines, and could be put to work against a range of diseases.

The Caltech team has now developed a new technique that combines both methods into one vaccine. Known as ESCRT-and ALIX-binding region (EABR) technology, the vaccine uses mRNA to coax the recipient’s cells to make protein fragments, but also includes little “tails” on these proteins. These tails trigger cellular processes that lets some proteins clump together into virus-like particles and circulate through the body. In this way, they then function like protein-based vaccines.

“During a natural infection, the immune system encounters both infected cells and free virus particles,” said Magnus Hoffmann, lead author of the study. “Current mRNA vaccines mimic infected cells, while protein nanoparticle-based vaccines mimic free virus particles to stimulate immune responses. Our hybrid technology does both.”

The team tested the new technique as a COVID-19 vaccine in mice, and found that mice given the hybrid vaccine produced five times more antibodies than existing vaccines. Only two shots rather than three were needed to induce robust antibody levels against Omicron variants, and these antibodies were also effective against the original strain and the Delta variant.

Image source: Pamela Björkman / Caltech.