Nasal immunization with subunit proteosome influenza vaccines induces serum HAI, mucosal IgA and protection against influenza challenge

The immunogenicity of a mucosally delivered subunit influenza vaccine was a ssessed in mice. Split influenza virus vaccine (sFlu) was formulated with p roteosomes (Pr-sFlu), administered intranasally, and the induced immunity w as compared with the responses elicited by sFlu alone given either intramus cularly or intranasally. Intranasal (i.n.) immunization with Pr-sFlu induce d specific serum IgG and hemagglutination inhibition (HAI) titers comparabl e to or better than those induced by intramuscular (i.m.) sFlu, and in cont rast to sFlu alone, i.n. Pr-sFlu also induced high levels of influenza-spec ific IgA in lung and nasal washes. Mice receiving i.n. Pr-sFlu were complet ely protected against live virus challenge, as were mice immunized by injec tion with sFlu alone. The i.n. Pr-sFlu elicited cytokine responses polarize d towards a type 1 phenotype whereas those elicited by sFlu alone were of a mixed type 1/type 2 phenotype. The data strongly suggest that i.n. proteos ome-formulated influenza antigens are highly effective and are excellent ca ndidates for a non-invasive human vaccine. (C) 2001 Elsevier Science Ltd. A ll rights reserved.