title: Induction of neutralizing antibody response against four dengue viruses in mice by intramuscular electroporation of tetravalent DNA vaccines.
abstract: DNA vaccine against dengue is an interesting strategy for a prime/boost approach. This study evaluated neutralizing antibody (NAb) induction of a dengue tetravalent DNA (TDNA) vaccine candidate administered by intramuscular-electroporation (IM-EP) and the benefit of homologous TDNA boosting in mice. Consensus humanized pre-membrane (prM) and envelope (E) of each serotypes, based on isolates from year 1962-2003, were separately cloned into a pCMVkan expression vector. ICR mice, five-six per group were immunized for three times (2-week interval) with TDNA at 100 µg (group I; 25 µg/monovalent) or 10 µg (group II; 2.5 µg/monovalent). In group I, mice received an additional TDNA boosting 13 weeks later. Plaque reduction neutralization tests (PRNT) were performed at 4 weeks post-last immunization. Both 100 µg and 10 µg doses of TDNA induced high NAb levels against all DENV serotypes. The median PRNT50 titers were comparable among four serotypes of DENV after TDNA immunization. Median PRNT50 titers ranged 240-320 in 100 µg and 160-240 in 10 µg groups (p = ns). A time course study of the 100 µg dose of TDNA showed detectable NAb at 2 weeks after the second injection. The NAb peaked at 4 weeks after the third injection then declined over time but remained detectable up to 13 weeks. An additional homologous TDNA boosting significantly enhanced the level of NAb from the nadir for at least ten-fold (p<0.05). Of interest, we have found that the use of more recent dengue viral strain for both vaccine immunogen design and neutralization assays is critical to avoid a mismatching outcome. In summary, this TDNA vaccine candidate induced good neutralizing antibody responses in mice; and the DNA/DNA prime/boost strategy is promising and warranted further evaluation in non-human primates.
authors.affiliation: Dengue Vaccine Research Unit, Chula Vaccine Research Center (ChulaVRC), Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Eakachai
authors.initials: E
authors.lastname: Prompetchara
authors.affiliation: Dengue Vaccine Research Unit, Chula Vaccine Research Center (ChulaVRC), 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: 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 (ChulaVRC), 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*; D000917:Antibody Formation / Q000276:immunology; D002460:Cell Line; D003715:Dengue / Q000276:immunology* / Q000517:prevention & control / Q000821:virology*; D053059:Dengue Vaccines / Q000276:immunology*; D003716:Dengue Virus / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007273:Injections, Intramuscular; D007700:Kinetics; D051379:Mice; D008813:Mice, Inbred ICR; D019444:Vaccines, DNA / Q000276:immunology*; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D057134:Antibodies, Neutralizing; D053059:Dengue Vaccines; D019444:Vaccines, DNA; D014764:Viral Proteins