Intranasal administration of a VLP-based vaccine against COVID-19 induces neutralizing antibodies against SARS-CoV-2 and Variants of Concerns

Background The highly contagious SARS-CoV-2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS-CoV-2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of COVID-19 vaccines. Methods In the current study, we tested in murine model the immunogenicity of a conventional vaccine platform based on virus-like particles (VLPs) displaying RBD of SARS-CoV-2 for intranasal vaccination. The candidate vaccine, CuMVTT-RBD, has been immunologically optimized to incorporate tetanus-toxin and is self-adjuvanted with TLR7/8 ligands. Results CuMVTT-RBD elicited strong RBD- and spike- specific systemic IgG and IgA antibody responses of high avidity. Local immune responses were assessed and results demonstrate strong mucosal antibody and plasma cell production in lung tissue. The induced systemic antibodies could efficiently recognize and neutralize different Variants of Concerns of mutated SARS-CoV-2 RBDs. Conclusion In summary, intranasal vaccination with CuMVTT-RBD shows high immunogenicity and induces protective systemic and local specific antibody response against SARS-CoV-2 and its variants. One sentence summary Evaluation of an intransal administrated conventional VLP-based vaccine against COVID-19 in a murine model. ### Competing Interest Statement M. F. Bachmann is a board member of Saiba AG and holds the patent of CuMVTT-VLPs. Senta A. Walton works for Saiba AG. Mona O. Mohsen received payments by Saiba AG to work on the development of a vaccine against Dengue Fever in the framework of a Eurostars grant. Martin F. Bachmann and Mona O Mohsen are shareholder of Saiba AG.