Immunogenicity and protection of octavalent influenza vaccine candidates using adjuvanted proteins or mRNA-LNPs in naïve mice

João Paulo Portela Catani; Anouk Smet; Tine Ysenbaert; Laura Amelinck; Koen Sedeyn; Xavier Saelens; Thorsten U Vogel

doi:10.1038/s41541-026-01378-z

Immunogenicity and protection of octavalent influenza vaccine candidates using adjuvanted proteins or mRNA-LNPs in naïve mice

NPJ Vaccines. 2026 Jan 22;11(1):57. doi: 10.1038/s41541-026-01378-z.

Authors

João Paulo Portela Catani^{1

2}, Anouk Smet^{1

2}, Tine Ysenbaert^{1

2}, Laura Amelinck^{1

2}, Koen Sedeyn^{1

2}, Xavier Saelens^{3

4}, Thorsten U Vogel⁵

Affiliations

¹ VIB Center for Medical Biotechnology, VIB, Ghent, Belgium.
² Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.
³ VIB Center for Medical Biotechnology, VIB, Ghent, Belgium. Xavier.saelens@vib-ugent.be.
⁴ Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium. Xavier.saelens@vib-ugent.be.
⁵ Sanofi, Research North America, Cambridge, MA, USA. Thorsten.vogel@sanofi.com.

Abstract

Currently used influenza vaccines primarily induce antibody responses against hemagglutinin (HA). Neuraminidase (NA) has been proposed as a complementary antigen to improve and potentially expand the breadth of influenza vaccine protection. Here, we assessed the immunogenicity and protective potential of adjuvanted recombinant protein- and mRNA-LNP-based octavalent influenza vaccine formulations in naïve mice. The vaccine candidates contained HA and NA derived from the viruses recommended for the 2018-2019 Northern Hemisphere quadrivalent influenza vaccine. Both adjuvanted recombinant protein and mRNA-LNP formats fully protected mice against challenge with homologous H1N1, influenza B, and HxN2 viruses. However, the octavalent mRNA-LNP vaccine elicited higher serum IgG titers against both HA and NA compared with the adjuvanted octavalent recombinant protein vaccine in this animal model. Furthermore, the octavalent mRNA-LNP vaccine also protected mice against challenge with the historical H3N2 virus strains X31, X47, and X79. This protection correlated with the presence of HA cross-reactive serum antibodies and was confirmed by passive transfer of immune serum into unvaccinated mice.