title: A replication-incompetent virus possessing an uncleavable hemagglutinin as an influenza vaccine.
abstract: Vaccination is one of the most effective measures to protect against influenza virus infection. Inactivated and live-attenuated influenza vaccines are available; however, their efficacy is suboptimal. To develop a safe and more immunogenic vaccine, we produced a novel replication-incompetent influenza virus that possesses uncleavable hemagglutinin (HA) and tested its vaccine potential. The uncleavable HA was engineered by substituting the arginine at the C-terminus of HA1 with threonine, which prevents cleavage of HA into its HA1 and HA2 subunits, preventing fusion between the host and viral membranes. Although this fusion-deficient HA influenza virus that possesses uncleavable HA (uncleavable HA virus) could undergo multiple cycles of replication in only wild-type HA-expressing cells, it could infect normal cells and express viral proteins in infected cells, but could not generate infectious virus from infected cells due to the uncleavable HA. When C57BL/6 mice were intranasally immunized with the uncleavable HA virus, influenza-specific IgG and IgA antibodies were detected in nasal wash and bronchoalveolar lavage samples and in serum. In addition, influenza-specific CD8(+) T cells accumulated in the lungs of these mice. Moreover, mice immunized with the uncleavable HA virus were protected against a challenge of lethal doses of influenza virus, unlike mice immunized with a formalin-inactivated virus. These findings demonstrate that this fusion-deficient virus, which possesses uncleavable HA, is a suitable influenza vaccine candidate.
authors.affiliation: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan. kk096367@mgs.k.u-tokyo.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Katsura
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Iwatsuki-Horimoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukuyama
authors.forename: Shinji
authors.initials: S
authors.lastname: Watanabe
authors.forename: Saori
authors.initials: S
authors.lastname: Sakabe
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Hatta
authors.forename: Shin
authors.initials: S
authors.lastname: Murakami
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shimojima
authors.forename: Taisuke
authors.initials: T
authors.lastname: Horimoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kawaoka
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D004285:Dogs; D005260:Female; D057809:HEK293 Cells; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D009980:Influenza A virus / Q000472:pathogenicity / Q000502:physiology; D007252:Influenza Vaccines / Q000276:immunology*; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000276:immunology; D014779:Virus Replication
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D014613:Vaccines, Attenuated