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Abstract 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 a vaccine against COVID‐19. Methods In the current study, we evaluated the immunogenicity of a traditional vaccine platform based on virus‐like particles (VLPs) displaying RBD of SARS‐CoV‐2 for intranasal administration in a murine model. The candidate vaccine platform, CuMV TT ‐RBD, has been optimized to incorporate a universal T helper cell epitope derived from tetanus‐toxin and is self‐adjuvanted with TLR7/8 ligands. Results CuMV TT ‐RBD vaccine elicited a strong systemic RBD‐ and spike‐IgG and IgA antibodies of high avidity. Local immune response was assessed, and our results demonstrate a strong mucosal antibody and plasma cell production in lung tissue. Furthermore, the induced systemic antibodies could efficiently recognize and neutralize different variants of concern (VOCs). Conclusion Our data demonstrate that intranasal administration of CuMV TT ‐RBD induces a protective systemic and local specific antibody response against SARS‐CoV‐2 and its VOCs.
Rothen et al. (Mon,) studied this question.