The SARS-CoV-2 rS vaccine is an intramuscularly delivered nanoparticle vaccine. The nanoparticles are created by infecting Sf9 insect cells with baculoviruses viral vectors that express the SARS-CoV-2 spike protein.
The proteins properly fold, undergo a series of programmed modifications, and are ultimately transported to the cell surface. Correctly folded and modified spike proteins are then extracted from the cell surface and purified to maintain their three-dimensional structure and biological activity, ultimately serving as the immunogenic molecule in the vaccine.
The vaccine is also being tested with Matrix M adjuvant, a saponin-based adjuvant that acts in part by stimulating the entry of antigen-presenting cells into the injection site and enhancing antigen presentation in the local lymph nodes.