The big picture: Researchers from MIT and Caltech have developed an experimental nanoparticle vaccine designed to protect against a broad range of coronaviruses. This includes not only variants of the virus responsible for Covid-19 but also other coronaviruses currently circulating in animals that could potentially jump to humans in the future. In simple terms, scientists may have discovered a way to stay ahead of the next coronavirus outbreak before it even starts. Traditional vaccines typically focus on the most accessible parts of viruses, which are often the rapidly mutating receptor-binding domains. These RBDs enable the virus to latch onto and infect human cells. However, because these regions mutate frequently with each new replication of the virus, vaccines targeting them can quickly become ineffective unless updated promptly.Caltech researchers decided to take a different approach. Instead of targeting the highly variable RBDs, they focused on more conserved regions of the virus areas that remain relatively stable across different strains. They engineered a nanoparticle vaccine that displays 60 copies of RBDs from up to eight different coronaviruses. While these viruses share conserved regions, their variable regions differ, allowing the vaccine to prepare the immune system to respond to a broader range of potential threats.When injected, the nanoparticle exposes the immune system to all the distinct RBD shapes simultaneously. This prompts the body to produce antibodies targeting both the variable and conserved regions of the viruses.With this approach, the immune system gains a robust line of defense capable of neutralizing entire families of viruses, making it much harder for any single strain to evolve and bypass the vaccine's protection.In animal studies, a nanoparticle vaccine called "mosaic-7COM" outperformed earlier iterations, such as "mosaic-8," by generating strong antibody responses against seven different SARS-CoV-2 variants and four other related coronaviruses from the sarbecovirus family. The vaccine successfully prevented the virus from infecting the test animals. // Related StoriesRemarkably, mosaic-7COM also demonstrated near-equivalent effectiveness in animals that had previously received existing mRNA-based Covid-19 vaccines. This finding reflects a real-world scenario, where next-generation vaccines must enhance pre-existing immunity.Efforts are already underway to progress the mosaic-8 nanoparticle into clinical trials. Researchers also plan to test mosaic-7COM soon, given its superior performance in recent studies. Additionally, they are exploring ways to adapt the vaccines for mRNA delivery, a step that could simplify large-scale manufacturing.Image credit: Artem Podrez, Polina Tankilevitch