Intranasal vaccination with influenza HA/GO-PEI nanoparticles provides immune protection against homo- and heterologous strains

Significance A noninvasive intranasal (i.n.) influenza vaccine can induce mucosal immune responses in respiratory tracts, preventing infection at the portal of virus entry. However, the absence of appropriate mucosal adjuvants at present hinders the development of such a vaccine. Here, we developed polyethyleneimine-functionalized two-dimensional graphene oxide nanoparticles (GP) that showed high antigen-loading capacities and superior immunoenhancing properties. Robust and broadly reactive immune responses were induced with i.n. immunization with GP-HA nanoparticles, conferring protection against homologous and heterologous viruses. With versatility and flexibility, GP nanoparticles can be easily adapted for constructing mucosal vaccines of different respiratory pathogens. Intranasal (i.n.) immunization is a promising vaccination route for infectious respiratory diseases such as influenza. Recombinant protein vaccines can overcome the safety concerns and long production phase of virus-based influenza vaccines. However, soluble protein vaccines are poorly immunogenic if administered by an i.n. route. Here, we report that polyethyleneimine-functionalized graphene oxide nanoparticles (GP nanoparticles) showed high antigen-loading capacities and superior immunoenhancing properties. Via a facile electrostatic adsorption approach, influenza hemagglutinin (HA) was incorporated into GP nanoparticles and maintained structural integrity and antigenicity. The resulting GP nanoparticles enhanced antigen internalization and promoted inflammatory cytokine production and JAWS II dendritic cell maturation. Compared with soluble HA, GP nanoparticle formulations induced significantly enhanced and cross-reactive immune responses at both systemic sites and mucosal surfaces in mice after i.n. immunization. In the absence of any additional adjuvant, the GP nanoparticle significantly boosted antigen-specific humoral and cellular immune responses, comparable to the acknowledged potent mucosal immunomodulator CpG. The robust immune responses conferred immune protection against challenges by homologous and heterologous viruses. Additionally, the solid self-adjuvant effect of GP nanoparticles may mask the role of CpG when coincorporated. In the absence of currently approved mucosal adjuvants, GP nanoparticles can be developed into potent i.n. influenza vaccines, providing broad protection. With versatility and flexibility, the GP nanoplatform can be easily adapted for constructing mucosal vaccines for different respiratory pathogens.