title: Intramuscular immunization with DNA construct containing Der p 2 and signal peptide sequences primed strong IgE production.
abstract: BACKGROUND
  Previous studies demonstrated that allergen gene vaccination induced TH1-skewed responses and inhibited IgE production. This study evaluated and characterized the immune responses induced by three DNA constructs encoding different forms of Der p 2 for safe and efficacious vaccination against mite allergy.
  
  
  METHODS
  Mice were immunized intramuscularly with DNA constructs encoding a major mite allergen, Der p 2, without a signal peptide (p2), with a signal peptide (p52), and with a signal peptide plus lysosomal-targeting sequence (p52-LA), respectively, followed by TH2-skewed protein challenge. Antibody and T-cell cytokine responses were assessed by ELISA. Primed dendritic cells (DCs) were adoptively transferred to naïve mice and humoral responses were examined after protein challenge. The circulating Der p 2 protein was detected by sandwich ELISA.
  
  
  RESULTS
  Mice immunized with p52-LA showed strong and clear-cut TH1-type response, as evident by high IFN-gamma production and elevated levels of Der p 2-specific IgG2a production whereas construct p2 induced only moderate levels of TH1 response. In contrast, mice immunized with construct p52 showed a mixed TH1/TH2 phenotype and produced substantial circulating Der p 2 protein. Mice adoptively transferred with DCs primed by p52 construct, but not by the p2 or p52-LA constructs, were sensitized to produce high levels of Der p 2-specific IgE.
  
  
  CONCLUSIONS
  Immunization with DNA construct encoding a signal peptide could potentially prime TH2-skewed responses and IgE production. The additional inclusion of lysosomal-targeting sequences to such construct could improve the safety and efficacy of DNA vaccination against allergy.
authors.affiliation: Department of Pediatrics, Yong Loo Lin School of Medicine, The National University of Singapore, Singapore.
authors.forename: Li Kiang
authors.initials: LK
authors.lastname: Tan
authors.forename: Chiung-Hui
authors.initials: CH
authors.lastname: Huang
authors.forename: I-Chun
authors.initials: IC
authors.lastname: Kuo
authors.forename: Lee Mei
authors.initials: LM
authors.lastname: Liew
authors.forename: Kaw Yan
authors.initials: KY
authors.lastname: Chua
mesh_terms: D000818:Animals; D039741:Antigens, Dermatophagoides / Q000008:administration & dosage / Q000276:immunology*; D060829:Arthropod Proteins; D003888:Desensitization, Immunologic; D005260:Female; D006967:Hypersensitivity / Q000517:prevention & control; D007114:Immunization / Q000379:methods; D007073:Immunoglobulin E / Q000097:blood*; D007273:Injections, Intramuscular; D052118:Lysosomal-Associated Membrane Protein 1; D051379:Mice; D008808:Mice, Inbred CBA; D008925:Mites / Q000276:immunology; D021382:Protein Sorting Signals / Q000235:genetics / Q000502:physiology*; D019444:Vaccines, DNA / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451163:Dermatophagoides pteronyssinus antigen p 2; D052118:Lysosomal-Associated Membrane Protein 1; D021382:Protein Sorting Signals; D019444:Vaccines, DNA; D007073:Immunoglobulin E