TLR7 ligand-cyclodextrin conjugate is a promising adjuvant for intranasal influenza vaccine

The development of novel vaccine adjuvants with high efficacy remains an important issue in vaccine design. In this study, we examined a 1 V209-cyclodextrin (CD) conjugate that we have previously developed and evaluated its potential as an adjuvant for intranasal vaccines. Intranasal administration of the vaccines adjuvanted with 1 V209-CD conjugate enhanced both mucosal and systemic IgA and IgG responses against a model antigen, ovalbumin, recombinant hemagglutinin (rHA) from influenza virus strain A/Puerto Rico/8/1934 (H1N1), and a commercially available split influenza vaccine. In an influenza A virus challenge experiment, mice immunized with vaccines adjuvanted with the 1 V209-CD conjugate showed significantly improved survival and reduced lung tissue damage compared with non-adjuvanted controls, indicating that the 1 V209-CD conjugate promoted protective effects. These findings demonstrate that the 1 V209-CD conjugate effectively enhanced immunogenicity of the rHA or existing influenza split vaccine and may serve as a useful adjuvant for intranasal vaccines.