Adjuvanted influenza vaccine, Fluad, provides Pan-H1 protection through elicitation of non-HAI neutralizing antibodies 3586

Abstract Description The influenza virus infects millions each year and carries the potential to trigger global pandemics. Commercial influenza vaccines (CIV) primarily target the hemagglutinin (HA) protein, with antibody titers to HA serving as a key indicator of immune protection. The structural formulation of CIVs can vary, leading to differences in immune responses. Fluad, an adjuvanted vaccine, has been shown to present HA on unique disc-shaped particles, creating parallel arrays of HA above and below the disc that increase exposure of conserved HA stem epitopes. Here, we demonstrate that Fluad vaccination provides broad Pan-H1 protection (covering both seasonal (A/PuertoRico/08/1934) and pandemic (A/Michigan/45/2015) strains) in female mice. This protection is antibody-mediated, as passive transfer of Fluad sera successfully protected naïve mice. Additionally, the sera lacked hemagglutination inhibition (HAI) activity, suggesting that protection is due to stem-targeted antibodies. Fluad’s ability to elicit non-HAI neutralizing antibodies, which protect against both seasonal and pandemic-like H1 influenza viruses, highlights this structure as a display platform for elicitation of broadly reactive antibodies, critical in the development of a universal influenza vaccine platform. Funding Sources This work was supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases. Intramural award ZIAAI001180. Topic Categories Vaccines and Immunotherapy (VAC)