title: Emulsified nanoparticles containing inactivated influenza virus and CpG oligodeoxynucleotides critically influences the host immune responses in mice.
abstract: BACKGROUND
  Antigen sparing and cross-protective immunity are regarded as crucial in pandemic influenza vaccine development. Both targets can be achieved by adjuvantation strategy to elicit a robust and broadened immune response. We assessed the immunogenicity of an inactivated H5N1 whole-virion vaccine (A/Vietnam/1194/2004 NIBRG-14, clade 1) formulated with emulsified nanoparticles and investigated whether it can induce cross-clade protecting immunity.
  
  
  RESULTS
  After formulation with PELC, a proprietary water-in-oil-in-water nanoemulsion comprising of bioresorbable polymer/Span(R)85/squalene, inactivated virus was intramuscularly administered to mice in either one-dose or two-dose schedule. We found that the antigen-specific serum antibody responses elicited after two doses of non-adjuvanted vaccine were lower than those observed after a single dose of adjuvanted vaccine, PELC and the conventional alum adjuvant as well. Moreover, 5 microg HA of PELC-formulated inactivated virus were capable of inducing higher antibodies than those obtained from alum-adjuvanted vaccine. In single-dose study, we found that encapsulating inactivated virus into emulsified PELC nanoparticles could induce better antibody responses than those formulated with PELC-adsorbed vaccine. However, the potency was rather reduced when the inactivated virus and CpG (an immunostimulatory oligodeoxynucleotide containing unmethylated cytosine-guanosine motifs) were co-encapsulated within the emulsion. Finally, the mice who received PELC/CpG(adsorption)-vaccine could easily and quickly reach 100% of seroprotection against a homologous virus strain and effective cross-protection against a heterologous virus strain (A/Whooper swan/Mongolia/244/2005, clade 2.2).
  
  
  CONCLUSIONS
  Encapsulating inactivated H5N1 influenza virus and CpG into emulsified nanoparticles critically influences the humoral responses against pandemic influenza. These results demonstrated that the use of PELC could be as antigen-sparing in preparation for a potential shortage of prophylactic vaccines against local infectious diseases, in particular pandemic influenza. Moreover, the cross-clade neutralizing antibody responses data verify the potential of such adjuvanted H5N1 candidate vaccine as an effective tool in pre-pandemic preparedness.
authors.affiliation: Vaccine Research and Development Center, National Health Research Institutes, Zhunan Town, Taiwan. huangminghsi@nhri.org.tw
authors.forename: Ming-Hsi
authors.initials: MH
authors.lastname: Huang
authors.forename: Su-Chen
authors.initials: SC
authors.lastname: Lin
authors.forename: Chia-Hsin
authors.initials: CH
authors.lastname: Hsiao
authors.forename: Hsin-Ju
authors.initials: HJ
authors.lastname: Chao
authors.forename: Hung-Ren
authors.initials: HR
authors.lastname: Yang
authors.forename: Chien-Chun
authors.initials: CC
authors.lastname: Liao
authors.forename: Po-Wei
authors.initials: PW
authors.lastname: Chuang
authors.forename: Huang-Pi
authors.initials: HP
authors.lastname: Wu
authors.forename: Chiung-Yi
authors.initials: CY
authors.lastname: Huang
authors.forename: Chih-Hsiang
authors.initials: CH
authors.lastname: Leng
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Liu
authors.forename: Hsin-Wei
authors.initials: HW
authors.lastname: Chen
authors.forename: Ai-Hsiang
authors.initials: AH
authors.lastname: Chou
authors.forename: Alan Yung-Chih
authors.initials: AY
authors.lastname: Hu
authors.forename: Pele
authors.initials: P
authors.lastname: Chong
mesh_terms: D000276:Adjuvants, Immunologic / Q000235:genetics*; D000818:Animals; D000918:Antibody Specificity; D018899:CpG Islands; D004196:Disease Outbreaks; D004655:Emulsions; D005260:Female; D056724:Immunity, Humoral / Q000276:immunology*; D007117:Immunization, Secondary; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D051379:Mice; D053758:Nanoparticles / Q000737:chemistry*; D009838:Oligodeoxyribonucleotides / Q000235:genetics*; D015164:Vaccines, Inactivated / Q000737:chemistry / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D004655:Emulsions; D009838:Oligodeoxyribonucleotides; D015164:Vaccines, Inactivated
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