Transdermal immunization with low-pressure-gene-gun mediated chitosan-based DNA vaccines against Japanese encephalitis virus

DNA vaccine is a milestone in contemporary vaccine development. It has considerably offset many shortcomings in conventional vaccines. Although DNA vaccines applied through 'traditional' high-pressure gene guns generally elicit high titers of protective immunity, such a practice however requires enormous investment in daunting instruments that often discourage vaccines due to an inevitable pain-eliciting effect. In this study, we exploited a less expensive yet low-pressure-gene-gun that can alleviate such phobia of pain. DNA vaccines were prepared by using the associative feature of cationic chitosan and anionic DNAs. The optimized NIP ratio is 3. The formulized complex sizes to nano-scale. The vaccine complexes were tested in C3H/HeN mice. The expression of GFP reporter gene was observable and traceable in epidermis and spleen over 3 days. The expressions of GFP and the activation of dendritic cells (DCs) were evident and co-localized in hair follicles and epidermis. C3H/HeN mice immunized with the developed chitosan-JEV DNA vaccines can elicit desired JEV specific antibodies, whereby the mice maintained high survival rates against 50 x LD50 JEV challenge. The low-pressure-gene-gun mediated chitosan-based JEV DNA vaccines have proven to be convenient and efficacious, thereby with high capacity in deployment for future prophylaxis against JEV outbreaks. (C) 2009 Elsevier Ltd. All rights reserved.