title: Strategies to improve the immunogenicity of prM+E dengue virus type-2 DNA vaccine.
abstract: BACKGROUND
  An important goal for dengue vaccines is to induce a high and durable level of neutralizing antibody.
  
  
  OBJECTIVE
  Three strategies were investigated for improving the immunogenicity of a prM+E dengue serotype 2 (DENV-2) DNA vaccine: 1) expression in two different plasmids; 2) adjustment of dose; and, 3) introduction of the E sequence of Japanese encephalitis virus (JEV) at the carboxy-terminal portion of DENV-2 E.
  
  
  METHODS
  Expression cassettes were designed to encode a full-length prM+E sequence of DENV-2 virus employing human-preferred codons (D2prMEopt), or a chimeric prM+E sequence in which the 100-residue carboxy-terminal region of E was derived from JEV (D2prMEJE20opt). pHIS and pCMVkan in the presence and absence of CpG motif, respectively, were used for cassette expression. The immunogenicity was compared in mice.
  
  
  RESULTS
  Three injections of full-length-D2prMEopt in pHIS and pCMVkan induced a comparable neutralizing antibody titer at post-week-2-injection and post-week-4-injection. The 100-μg DNA dose induced a numerically but not statistically higher neutralizing antibody titer than the 10-μg dose. The chimeric-D2prMEJE20opt produced higher extracellular prM and E protein levels in transfected Vero cells, but had a tendency to induce a lower neutralizing antibody titer in mice when compared with the full-length-D2prMEopt. To optimize the immunogenicity of D2prMEopt-DNA candidate, both expression plasmids can be used to generate reproducible high neutralizing titer. A higher dose of DNA immunogen may induce a higher neutralizing antibody response.
  
  
  CONCLUSIONS
  The strategy of the C-terminal region chimeric counterpart with JE20 did not improve but may have reduced the induction of neutralizing antibodies.
authors.affiliation: Dengue Vaccine Research Unit, Chula Vaccine Research Center (Chula VRC), Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.|Department of Laboratory Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Chutitorn
authors.initials: C
authors.lastname: Ketloy
authors.affiliation: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Poonsook
authors.initials: P
authors.lastname: Keelapang
authors.affiliation: Dengue Vaccine Research Unit, Chula Vaccine Research Center (Chula VRC), Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Eakachai
authors.initials: E
authors.lastname: Prompetchara
authors.affiliation: Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand.
authors.forename: Amporn
authors.initials: A
authors.lastname: Suphatrakul
authors.affiliation: Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand.
authors.forename: Chunya
authors.initials: C
authors.lastname: Puttikhunt
authors.affiliation: Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.|Biomedical Technology Research Center, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand.
authors.forename: Watchara
authors.initials: W
authors.lastname: Kasinrerk
authors.affiliation: Department of International Health, Kobe University Graduate School of Health Sciences, Kobe, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Konishi
authors.affiliation: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.|Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand.
authors.forename: Nopporn
authors.initials: N
authors.lastname: Sittisombut
authors.affiliation: Dengue Vaccine Research Unit, Chula Vaccine Research Center (Chula VRC), Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.|Vaccine and Cellular Immunology Laboratory, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Kiat
authors.initials: K
authors.lastname: Ruxrungtham
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology*; D053059:Dengue Vaccines / Q000008:administration & dosage / Q000276:immunology*; D003716:Dengue Virus / Q000276:immunology; D004664:Encephalitis Virus, Japanese / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D007277:Injections, Jet; D051379:Mice; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology; D014759:Viral Envelope Proteins / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D053059:Dengue Vaccines; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; C072281:E protein TH Sman, Dengue virus