Intramuscular immunization with DNA construct containing Der p 2 and signal peptide sequences primed strong IgE production.
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.
Tan
Li Kiang
LK
Department of Pediatrics, Yong Loo Lin School of Medicine, The National University of Singapore, Singapore.
Huang
Chiung-Hui
CH
Kuo
I-Chun
IC
Liew
Lee Mei
LM
Chua
Kaw Yan
KY
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*
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