Abstract Influenza is the cause of considerable morbidity and mortality globally. Despite immunization being the most effective and economical prophylactic approach, vaccines often provide less than optimal defense against an influenza virus infection and illness. While hemagglutinin (HA) is the primary target of influenza vaccines, it is also known that the other major surface protein, neuraminidases (NA) induces protective antibodies. This Direct to Phase 2 SBIR proposal continues our development and characterization of a unique vaccine platform that has been formulated by POP BIO. This platform consists of fabricating lipid bilayer nanoliposomes with a cobalt- porphyrin moiety intercalated into the bilayer (CoPoP) along with a monophosphoryl lipid A, a TLR4-based vaccine adjuvant, and a saponin QS-21. CoPoP enables spontaneous nanoliposome adjuvant particle formation (SNAP). When SNAP liposomes are combined with his-tagged recombinant trimeric HAs and tetrameric NAs, a mosaic nanoparticle vaccine candidate, SNAP-Flu is formed. The his-tag stably inserts into the bilayer by association with the cobalt producing nanoliposomes decorated with the immunogenic influenza antigens. In preliminary data, we have established that HA and NA protect mice from lethal H1N1, H3N2 and B strain inflenza virus challenge, while even better protection is observed with the multivalent SNAP-Flu nanoparticle vaccine. It has also been shown that this platform allows for the use of much less antigen in the vaccine (antigen sparing) in addition to the capacity for multiplexing with numerous antigens from different influenza strains. This study will involve POP BIO producing and characterizing the physical and chemical properties of SNAP-Flu. POP BIO will interact with the University at Buffalo, BIOQUAL, and Texas Biomedical Research Institute to assess the level of protection of SNAP-Flu against challenge with mouse-adapted strains of influenza in mice, human influenza strains in ferrets, and human influenza strains in non-human primates. The amount of antigen-sparing will be determined as will head-to-head comparison with other commercially available influenza vaccine formulations. This Direct to Phase 2 SBIR proposal will expand development of this platform to novel influenza antigen designs in preparation for clinical translation.