An Epitope-Substituted DNA Vaccine Improves Safety and Immunogenicity against Dengue Virus Type 2.

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 enha...

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Bibliographic Details
Published in:PLOS Neglected Tropical Diseases
Main Authors: Chung-Tao Tang, Pi-Chun Li, I-Ju Liu, Mei-Ying Liao, Chiung-Yi Chiu, Day-Yu Chao, Han-Chung Wu
Format: Article in Journal/Newspaper
Language:English
Published: Public Library of Science (PLoS) 2015
Subjects:
Arctic medicine. Tropical medicine
RC955-962
Public aspects of medicine
RA1-1270
Arctic
Online Access:https://doi.org/10.1371/journal.pntd.0003903
https://doaj.org/article/4a7a10e8c138468ba810de9e1756d405
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Summary: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.

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