Coria, Lorena M.Saposnik, Lucas M.Pueblas Castro, CelesteCastro, Eliana F.Bruno, Laura A.Stone, William B.Perez, Paula S.Darriba, Maria LauraChemes, Lucia B.Alcain, JulietaMazzitelli, IgnacioVarese, AugustoSalvatori, MelinaAuguste, Albert J.alvarez, Diego E.Pasquevich, Karina A.Cassataro, Juliana2022-07-212022-07-212022-02-281664-3224844837http://hdl.handle.net/10919/111310In this work, we evaluated recombinant receptor binding domain (RBD)-based vaccine formulation prototypes with potential for further clinical development. We assessed different formulations containing RBD plus alum, AddaS03, AddaVax, or the combination of alum and U-Omp19: a novel Brucella spp. protease inhibitor vaccine adjuvant. Results show that the vaccine formulation composed of U-Omp19 and alum as adjuvants has a better performance: it significantly increased mucosal and systemic neutralizing antibodies in comparison to antigen plus alum, AddaVax, or AddaS03. Antibodies induced with the formulation containing U-Omp19 and alum not only increased their neutralization capacity against the ancestral virus but also cross-neutralized alpha, lambda, and gamma variants with similar potency. Furthermore, the addition of U-Omp19 to alum vaccine formulation increased the frequency of RBD-specific geminal center B cells and plasmablasts. Additionally, U-Omp19+alum formulation induced RBD-specific Th1 and CD8(+) T-cell responses in spleens and lungs. Finally, this vaccine formulation conferred protection against an intranasal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) challenge of K18-hACE2 mice.application/pdfenCreative Commons Attribution 4.0 Internationaladjuvantprotease inhibitorSARS- CoV-2U-Omp19germinal center cellsArticle - Refereedhttps://doi.org/10.3389/fimmu.2022.8448371335296091