A variety of different vaccine types are available for H1N1 influenza A virus infections; however, their immunological mechanisms of action remain unclear. Here, we show that plasmacytoid dendritic cells (pDCs) and type I interferon (IFN)-mediated signaling delineate the immunogenicity of live attenuated virus, inactivated whole-virus (WV), and split-virus vaccines. Although Toll-like receptor 7 acted as the adjuvant receptor for the immunogenicity of both live virus and WV vaccines, the requirement for type I IFN production by pDCs for the immunogenicity of the vaccines was restricted to WV. A split vaccine commonly used in humans failed to immunize naïve mice, but a pDC-activating adjuvant could restore immunogenicity. In blood from human adults, however, split vaccine alone could recall memory T cell responses, underscoring the importance of this adjuvant pathway for primary, but not secondary, vaccination.

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Ken Ishii Lab

Contact:

Ken ISHII
Laboratory of Vaccine Science
Immunology Frontier Research Center (IFReC), Osaka University
TEL: +81-6-6879-8303
kenishii@biken.osaka-u.ac.jp

National Institute of Biomedical Innovation
TEL: +81-72-641-8043
kenishii@nibio.go.jp