title: An Epitope-Substituted DNA Vaccine Improves Safety and Immunogenicity against Dengue Virus Type 2.
abstract: Dengue virus (DENV), a global disease, is divided into four serotypes (DENV1-4). Cross-reactive and non-neutralizing antibodies against envelope (E) protein of DENV bind to the Fcγ receptors (FcγR) of cells, and thereby exacerbate viral infection by heterologous serotypes via antibody-dependent enhancement (ADE). Identification and modification of enhancing epitopes may mitigate enhancement of DENV infection. In this study, we characterized the cross-reactive DB21-6 and DB39-2 monoclonal antibodies (mAbs) against domain I-II of DENV; these antibodies poorly neutralized and potently enhanced DENV infection both in vitro and in vivo. In addition, two enhancing mAbs, DB21-6 and DB39-2, were observed to compete with sera antibodies from patients infected with dengue. The epitopes of these enhancing mAbs were identified using phage display, structural prediction, and mapping of virus-like particle (VLP) mutants. N8, R9, V12, and E13 are the reactive residues of DB21-6, while N8, R9, and E13 are the reactive residues of DB39-2. N8 substitution tends to maintain VLP secretion, and decreases the binding activity of DB21-6 and DB39-2. The immunized sera from N8 substitution (N8R) DNA vaccine exerted greater neutralizing and protective activity than wild-type (WT)-immunized sera, both in vitro and in vivo. Furthermore, treatment with N8R-immunized sera reduced the enhancement of mortality in AG129 mice. These results support identification and substitution of enhancing epitope as a novel strategy for developing safe dengue vaccines.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Chung-Tao
authors.initials: CT
authors.lastname: Tang
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Pi-Chun
authors.initials: PC
authors.lastname: Li
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: I-Ju
authors.initials: IJ
authors.lastname: Liu
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Mei-Ying
authors.initials: MY
authors.lastname: Liao
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Chiung-Yi
authors.initials: CY
authors.lastname: Chiu
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Day-Yu
authors.initials: DY
authors.lastname: Chao
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Han-Chung
authors.initials: HC
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D003429:Cross Reactions; D003715:Dengue / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D003716:Dengue Virus / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D018604:Epitope Mapping; D000939:Epitopes / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D019444:Vaccines, DNA / Q000009:adverse effects / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014759:Viral Envelope Proteins; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; D014764:Viral Proteins