title: Cross-Reactive Neuraminidase-Inhibiting Antibodies Elicited by Immunization with Recombinant Neuraminidase Proteins of H5N1 and Pandemic H1N1 Influenza A Viruses.
abstract: Neuraminidase (NA), an influenza virus envelope glycoprotein, removes sialic acid from receptors for virus release from infected cells. For this study, we used a baculovirus-insect cell expression system to construct and purify recombinant NA (rNA) proteins of H5N1 (A/Vietnam/1203/2004) and pandemic H1N1 (pH1N1) (A/Texas/05/2009) influenza viruses. BALB/c mice immunized with these proteins had high titers of NA-specific IgG and NA-inhibiting (NI) antibodies against H5N1, pH1N1, H3N2, and H7N9 viruses. H5N1 rNA immunization resulted in higher quantities of NA-specific antibody-secreting B cells against H5N1 and heterologous pH1N1 viruses in the spleen. H5N1 rNA and pH1N1 rNA immunizations both provided complete protection against homologous virus challenges, with H5N1 rNA immunization providing better protection against pH1N1 virus challenges. Cross-reactive NI antibodies were further dissected via pH1N1 rNA protein immunizations with I149V (NA with a change of Ile to Val at position 149), N344Y, and I365T/S366N NA mutations. The I365T/S366N mutation of pH1N1 rNA enhanced cross-reactive NI antibodies against H5N1, H3N2, and H7N9 viruses. It is our hope that these findings provide useful information for the development of an NA-based universal influenza vaccine.
  
  
  OBJECTIVE
  Neuraminidase (NA) is an influenza virus enzymatic protein that cleaves sialic acid linkages on infected cell surfaces, thus facilitating viral release and contributing to viral transmission and mucus infection. In currently available inactivated or live, attenuated influenza vaccines based on the antigenic content of hemagglutinin proteins, vaccine efficacy can be contributed partly through NA-elicited immune responses. We investigated the NA immunity of different recombinant NA (rNA) proteins associated with pH1N1 and H5N1 viruses. Our results indicate that H5N1 rNA immunization induced more potent cross-protective immunity than pH1N1 rNA immunization, and three mutated residues, I149V, I365T, and S366N, near the NA enzyme active site(s) are linked to enhanced cross-reactive NA-inhibiting antibodies against heterologous and heterosubtypic influenza A viruses. These findings provide useful information for the development of an NA-based universal influenza vaccine.
authors.affiliation: Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Wen-Chun
authors.initials: WC
authors.lastname: Liu
authors.affiliation: Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Yung-Ta
authors.initials: YT
authors.lastname: Tsou
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Jia-Tsrong
authors.initials: JT
authors.lastname: Jan
authors.affiliation: Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan Department of Medical Science, National Tsing Hua University, Hsinchu, Taiwan scwu@mx.nthu.edu.tw.
authors.forename: Suh-Chin
authors.initials: SC
authors.lastname: Wu
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D016367:Baculoviridae; D003429:Cross Reactions; D004195:Disease Models, Animal; D005260:Female; D005822:Genetic Vectors; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology*; D053118:Influenza A Virus, H1N1 Subtype / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D053124:Influenza A Virus, H5N1 Subtype / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D064766:Influenza A Virus, H7N9 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000517:prevention & control / Q000821:virology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D061987:Sf9 Cells; D018411:Spodoptera; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; C543345:H1N1 virus hemagglutinin; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C109963:hemagglutinin, avian influenza A virus