title: Novel chitosan derivative nanoparticles enhance the immunogenicity of a DNA vaccine encoding hepatitis B virus core antigen in mice.
abstract: BACKGROUND
  Chitosan has been shown to possess useful properties such as non-toxicity, high biocompatibility and non-antigenicity that offer advantages for vaccine delivery systems. In this study, we prepared novel chitosan derivative nanoparticles as DNA vaccine carriers and the potential and mechanism of the DNA-nanoparticle complexes in inducing augmented immune responses were explored.
  
  
  METHODS
  The pVAX(HBc)DNA-nanoparticle complexes as vaccine delivery systems were studied in several aspects: the protection against DNase I degradation was measured by an in vitro inhibition assay; the sustained expression of the plasmid in vivo was determined by RT-PCR; the elevated uptake efficiency by phagocytes was observed with confocal microscopy; the biocompatibility was evaluated by cytotoxicity and histology assay; the complexes were administrated to C57BL/6 mice and the humoral and cellular immune responses were evaluated by ELISA, IFN-gamma production and cytolytic T lymphocyte (CTL)-specific lysis assay.
  
  
  RESULTS
  The remaining relative activity of DNase I after inhibition varied from 32.3% to 77.6%. The complexes were observed with higher uptake efficiency by phagocytes than naked DNA. Three types of nanoparticles did not induce significant cytotoxicity at concentrations<or=400 microg/ml. No specific histological alteration related to the injection of the complexes was observed. The formulations of DNA-nanoparticle complexes significantly enhanced the immunogenicity in several parameters: elevated antibody production, higher level of IFN-gamma secretion, and augmented specific cell lysis.
  
  
  CONCLUSIONS
  This study demonstrated the potential of the novel chitosan derivative nanoparticles for safe and effective DNA vaccine delivery.
authors.affiliation: Department of Medical Genetics, The Second Military Medical University, 200433 Shanghai, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
authors.forename: Feng
authors.initials: F
authors.lastname: Qian
authors.forename: Xiaowen
authors.initials: X
authors.lastname: He
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Ding
authors.initials: D
authors.lastname: Ren
authors.forename: Ying
authors.initials: Y
authors.lastname: He
authors.forename: Ka
authors.initials: K
authors.lastname: Li
authors.forename: Shuhan
authors.initials: S
authors.lastname: Sun
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yin
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D048271:Chitosan / Q000737:chemistry / Q000276:immunology; D003850:Deoxyribonuclease I / Q000378:metabolism; D004337:Drug Carriers; D016503:Drug Delivery Systems; D006509:Hepatitis B / Q000276:immunology / Q000517:prevention & control; D006512:Hepatitis B Core Antigens / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007109:Immunity / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology; D053758:Nanoparticles; D019444:Vaccines, DNA / Q000276:immunology*
chemical_list: D004337:Drug Carriers; D006512:Hepatitis B Core Antigens; D019444:Vaccines, DNA; D048271:Chitosan; D003850:Deoxyribonuclease I