An intranasally- and intramuscularly-deliverable nanostructured lipid carrier-replicon RNA vaccine drives protective systemic and mucosal immunity

A nucleic acid vaccine platform that could be flexibly administered either intranasally or intramuscularly could be a valuable new tool for epidemic and pandemic response, combining rapid antigen adaptability with optimal induction of systemic and/or mucosal immune responses most appropriate for a particular pathogen. However, such RNA vaccines have not yet been developed. We have developed and optimized dual intranasal and intramuscular deliverability of a proof-of-concept replicon vaccine expressing an H5 influenza antigen that uses a nanostructured lipid carrier (NLC) delivery system. A relationship was established between the RNA:NLC loading ratio, vaccine particle charge, RNA delivery to cells, and finally intranasal vaccine immunogenicity, allowing for identification of a single vaccine formulation that can be effectively administered via both intramuscular and intranasal routes. The vaccine induced systemic immunity when dosed intramuscularly or intranasally in an immunocompetent mouse model, whereas intranasal dosing uniquely stimulated a strong mucosal immune response. Moreover, a mixed intramuscular/intranasal dosing strategy stimulated a balanced systemic and mucosal immune response. Finally, we demonstrated the protective efficacy of an intranasally- and intramuscularly/intranasally-delivered H5 replicon-NLC vaccine against morbidity and mortality in a lethal H5N1 influenza challenge ferret model.