title: Needle-free jet injection of a mixture of Japanese encephalitis DNA and protein vaccines: a strategy to effectively enhance immunogenicity of the DNA vaccine in a murine model.
abstract: Combined immunization with gene-based and protein-based vaccines can increase vaccine effectiveness. We previously demonstrated, using a murine model for Japanese encephalitis (JE), that simultaneous immunization with a DNA vaccine (pcJEME) by the intramuscular route and a protein vaccine consisting of subviral extracellular particles (EPs) by the subcutaneous route provided a synergistic increase in immunogenicities of these vaccines. Here, we investigated a novel immunization protocol consisting of a single inoculation with a mixture of DNA and protein vaccines using a needle-free jet injector. Immunization of ddY mice with 1 microg of pcJEME mixed with 1 microg of EPs or a 1/100 dose of commercial inactivated JE vaccine (JEVAX) induced neutralizing antibody titers of 1:40 to 1:80 (90% plaque reduction) 6 weeks after immunization, whereas immunization with DNA or protein alone only induced low titers (< or =1:10). Co-immunization with pcDNA3, a CpGcontaining vector of the vaccine plasmid, increased immunogenicity of JEVAX to some extent. IgG1/IgG2a isotype profiles supported increased production of EPs in pcJEME-inoculated mice by needle-free injection and an adjuvant effect of the vector on immunogenicity of JEVAX.
authors.affiliation: Department of Health Sciences, Kobe University School of Medicine, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142, Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Imoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Konishi
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D018899:CpG Islands / Q000276:immunology; D004195:Disease Models, Animal; D004338:Drug Combinations; D004664:Encephalitis Virus, Japanese / Q000235:genetics*; D004672:Encephalitis, Japanese / Q000097:blood / Q000276:immunology / Q000517:prevention & control*; D007277:Injections, Jet; D051379:Mice; D009500:Neutralization Tests; D014611:Vaccination; D019444:Vaccines, DNA / Q000008:administration & dosage*; D014614:Vaccines, Synthetic / Q000008:administration & dosage; D014765:Viral Vaccines / Q000008:administration & dosage*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D004338:Drug Combinations; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; D014765:Viral Vaccines