title: Protective efficacy and immune responses induced by a DNA vaccine encoding codon-optimized PPA1 against Photobacterium damselae subsp. piscicida in Japanese flounder.
abstract: Photobacterium damselae subsp. piscicida (Pdp) kills many cultured marine fish. As it evolves resistance to existing vaccines, new vaccines are needed. PPA1 is a major antigenic protein of Pdp. Here, DNA vaccines encoding wild-type PPA1 (pPPA1(wt)) and codon-optimized PPA1 (pPPA1(opt)) were constructed and tested against Pdp in Japanese flounder. The mRNA levels of the two antigenic genes at the vaccination site were not different, but the protein level was significantly higher in the pPPA1(opt)-vaccinated fish. In addition, after a bacterial challenge, the levels of interleukin (IL)-1β, IL-6 and IFN-γ mRNA significantly increased in the pPPA1(opt)-vaccinated fish but not in the pPPA1(wt)-vaccinated fish. The relative percent survival (RPS) after the challenge was higher in the pPPA1(opt)-vaccinated fish (90.9) than in the pPPA1(wt)-vaccinated fish (69.2). At the early stage of the infection after the challenge, the number of viable Pdp in the spleen was significantly lower in the pPPA1(opt)-vaccinated fish than in the pPPA1(wt)-vaccinated fish. These data show that codon-optimized DNA vaccine pPPA1(opt) had a strong immunogenicity and conferred protective efficacy against Pdp infection in Japanese flounder.
authors.affiliation: Laboratory of Genome Science, Graduate School of Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
authors.forename: Goshi
authors.initials: G
authors.lastname: Kato
authors.affiliation: Laboratory of Genome Science, Graduate School of Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
authors.forename: Kozue
authors.initials: K
authors.lastname: Yamashita
authors.affiliation: Laboratory of Genome Science, Graduate School of Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Laboratory of Genome Science, Graduate School of Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan. Electronic address: hirono@kaiyodai.ac.jp.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Hirono
mesh_terms: D000372:Agglutination Tests; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D005393:Fish Diseases / Q000276:immunology* / Q000401:mortality / Q000517:prevention & control*; D005432:Flounder; D015870:Gene Expression; D008969:Molecular Sequence Data; D010776:Photobacterium / Q000276:immunology*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D019444:Vaccines, DNA
keywords: Bacterial pseudotuberculosis; Codon optimization; Codon usage; Pasteurella piscicida; Pasteurellosis