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Characterization of a Novel Dengue Serotype 4 Virus-Specific Neutralizing Epitope on the Envelope Protein Domain III.

ABSTRACT: The dengue virus (DENV) envelope protein domain III (ED3) has been suggested to contain receptor recognition sites and the critical neutralizing epitopes. Up to date, relatively little work has been done on fine mapping of neutralizing epitopes on ED3 for DENV4. In this study, a novel mouse type-specific neutralizing antibody 1G6 against DENV4 was obtained with both prophylactic and therapeutic effects. The epitope was mapped to residues 387-390 of DENV4 envelope protein. Furthermore, site-directed mutagenesis assay identified two critical residues (T388 and H390). The epitope is variable among different DENV serotypes but is highly conserved among four DENV4 genotypes. Affinity measurement showed that naturally occurring variations in ED3 outside the epitope region did not alter the binding of mAb 1G6. These findings expand our understanding of the interactions between neutralizing antibodies and the DENV4 and may be valuable for rational design of DENV vaccines and antiviral drugs.

SUBMITTER: Ji GH

PROVIDER: S-EPMC4592203 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Characterization of a Novel Dengue Serotype 4 Virus-Specific Neutralizing Epitope on the Envelope Protein Domain III.

Ji Guang-Hui GH Deng Yong-Qiang YQ Yu Xiao-Jie XJ Jiang Tao T Wang Hua-Jing HJ Shi Xin X Zhang Da-Peng DP Li Xiao-Feng XF Zhu Shun-Ya SY Zhao Hui H Dai Jian-Xin JX Qin Cheng-Feng CF Guo Ya-Jun YJ

PloS one 20151002 10

The dengue virus (DENV) envelope protein domain III (ED3) has been suggested to contain receptor recognition sites and the critical neutralizing epitopes. Up to date, relatively little work has been done on fine mapping of neutralizing epitopes on ED3 for DENV4. In this study, a novel mouse type-specific neutralizing antibody 1G6 against DENV4 was obtained with both prophylactic and therapeutic effects. The epitope was mapped to residues 387-390 of DENV4 envelope protein. Furthermore, site-direc ...[more]

PMID: 26430770

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Project description:The DENV envelope (E) and pre-membrane (prM) glycoproteins are primary targets of serologic immunity after infection and vaccination. Of these, serotype-specific (TS) antibodies typically target E domains, while serotype cross-reactive (CR) antibodies typically the target prM protein and conserved E regions. To identify and quantify E-domain TS neutralizing antibody responses in polyclonal sera, we developed a panel of chimeric DENV4/2 viruses that incorporate DENV2 envelope domain I, II, and III (DENV4/2-EDI, EDII, EDIII) into the DENV4 E glycoprotein. Chimeric DENV4/2 viruses were recovered, replicated efficiently, and displayed similar maturation states as parental viruses. The recovery of viable DENV4/2-EDII recombinants required the inclusion of chimeric DENV4/2 prM that maintained critical interactions with chimeric E. To assess structural integrity and epitope display of chimeric viruses, we examined neutralization of mature virions by monoclonal antibodies (mAbs) and heterotypic polyclonal sera. The ED-chimeric virions preserved epitopes of TS and envelope-dimer-epitope CR mAbs and had similar sensitivity to CR polyclonal responses as parental strains. Primary sera from natural infection and human challenge target a region centered on EDIII and secondarily target EDII and EDI. Sera from natural infection had a unique neutralization pattern compared to sera from human challenge, which included greater frequency and higher titer of responses against DENV EDII. In summary, DENV4/2 E recombinant viruses delineate the subdomain targets of TS antibodies after vaccination and primary infection, which may provide new correlates of protection or identify epitopes of neutralizing monoclonal antibodies.IMPORTANCEThe four dengue virus (DENV) serotypes infect several hundred million people each year. Although primary infection is generally mild, subsequent infection by differing serotypes increases the risk for symptomatic disease ranging from fever to life-threatening shock. Despite the availability of licensed vaccines, a comprehensive understanding of antibodies that target the viral envelope protein and protect from infection remains incomplete. In this manuscript, we develop a panel of recombinant viruses that graft each envelope domain of DENV2 onto the DENV4 envelope glycoprotein, revealing protein interactions important for virus viability. Furthermore, we map neutralizing antibody responses after primary DENV2 natural infection and a human challenge model to distinct domains on the viral envelope protein. The panel of recombinant viruses provides a new tool for dissecting the E domain-specific targeting of protective antibody responses, informing future DENV vaccine design.

Project description:Dengue is a viral disease spread to humans by mosquitoes. Notably, there are four serotypes of dengue viruses (DENV) that places ~40 % of the global population at risk of infection. However, lack of a suitable drug or a preventive vaccine exacerbates the matter further. Envelope domain-III (EDIII) antigen of dengue virus (DENV) has garnered much attention as a promising vaccine candidate for dengue, in addition to its use as a diagnostic intermediate. Hence developing a method for efficient production of high quality recombinant EDIII is important for research and industrial purpose.In this work, a Pichia pastoris system was optimized for the secretory over-expression of DENV serotype-3 EDIII under the control of methanol inducible AOX1 promoter. Temperature alone had a significant impact upon the amount of secretory EDIII, with 2.5-fold increase upon reducing the induction temperature from 30 to 20 °C. However surprisingly, supplementation of culture media with Casamino acids (CA), further augmented secretory EDIII titer, with a concomitant drop of intracellular EDIII levels at both temperatures. Though, reduction in intracellular retention of EDIII was more prominent at 20 °C than 30 °C. This suggests that CA supplementation facilitates overexpressing P. pastoris cells to secrete more EDIII by reducing the proportion retained intracellularly. Moreover, a bell-shaped correlation was observed between CA concentration and secretory EDIII titer. The maximum EDIII expression level of 187 mg/L was achieved under shake flask conditions with induction at 20 °C in the presence of 1 % CA. The overall increase in EDIII titer was ~9-fold compared to un-optimized conditions. Notably, mouse immune-sera, generated using this purified EDIII antigen, efficiently neutralized the DENV.The strategy described herein could enable fulfilling the mounting demand for recombinant EDIII as well as lay direction to future studies on secretory expression of recombinant proteins in P. pastoris with CA as a media supplement.

Dataset Information

Characterization of a Novel Dengue Serotype 4 Virus-Specific Neutralizing Epitope on the Envelope Protein Domain III.

Publications

Characterization of a Novel Dengue Serotype 4 Virus-Specific Neutralizing Epitope on the Envelope Protein Domain III.

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