Protection against Dengue Virus Infection in Mice by Administration of Antibodies against Modified Nonstructural Protein 1

Shu-Wen Wan,Hsiao-Sheng Liu,Yu-Ting Yen,Chiou-Feng Lin,Trai-Ming Yeh,Chia-Hui Huang,Yee-Shin Lin,Yi-Tien Lu,Betty A Wu-Hsieh,Robert Anderson

doi:10.1371/journal.pone.0092495

Shu-Wen Wan, Hsiao-Sheng Liu + Show 8 more

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https://doi.org/10.1371/journal.pone.0092495

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Abstract

BackgroundInfection with dengue virus (DENV) may cause life-threatening disease with thrombocytopenia and vascular leakage which are related to dysfunction of platelets and endothelial cells. We previously showed that antibodies (Abs) against DENV nonstructural protein 1 (NS1) cross-react with human platelets and endothelial cells, leading to functional disturbances. Based on sequence homology analysis, the C-terminal region of DENV NS1 protein contains cross-reactive epitopes. For safety in vaccine development, the cross-reactive epitopes of DENV NS1 protein should be deleted or modified.Methodology/Principal FindingsWe tested the protective effects of Abs against full-length DENV NS1, NS1 lacking the C-terminal amino acids (a.a.) 271-352 (designated ΔC NS1), and chimeric DJ NS1 consisting of N-terminal DENV NS1 (a.a. 1-270) and C-terminal Japanese encephalitis virus NS1 (a.a. 271-352). The anti-ΔC NS1 and anti-DJ NS1 Abs showed a lower binding activity to endothelial cells and platelets than that of anti-DENV NS1 Abs. Passive immunization with anti-ΔC NS1 and anti-DJ NS1 Abs reduced DENV-induced prolonged mouse tail bleeding time. Treatment with anti-DENV NS1, anti-ΔC NS1 and anti-DJ NS1 Abs reduced local skin hemorrhage, controlled the viral load of DENV infection in vivo, synergized with complement to inhibit viral replication in vitro, as well as abolished DENV-induced macrophage infiltration to the site of skin inoculation. Moreover, active immunization with modified NS1 protein, but not with unmodified DENV NS1 protein, reduced DENV-induced prolonged bleeding time, local skin hemorrhage, and viral load.Conclusions/SignificanceThese results support the idea that modified NS1 proteins may represent an improved strategy for safe and effective vaccine development against DENV infection.

Highlights

Dengue virus (DENV) belongs to the Flaviviridae family of enveloped, positive-strand RNA viruses, and is transmitted by Aedes mosquitoes
We previously found that anti-dengue virus (DENV) nonstructural protein 1 (NS1) Abs cross-react with platelets and endothelial cells [25,26] and the cross-reactive epitopes are located predominantly in the C-terminal region of the DENV NS1 protein [28,33]
We generated a chimeric DJ NS1 protein, which consists of N-terminal DENV NS1 (a.a. 1-270) and C-terminal Japanese encephalitis virus (JEV) NS1 (a.a. 271-352) (Figure 1A)

Summary

Introduction

Dengue virus (DENV) belongs to the Flaviviridae family of enveloped, positive-strand RNA viruses, and is transmitted by Aedes mosquitoes. The major clinical manifestations of DHF/DSS are thrombocytopenia and vascular leakage, additional symptoms, such as liver damage, may occur [1,2,3,4]. A dengue hemorrhage mouse model has been established which mimics the natural route of infection in humans. This model gives rise to severe thrombocytopenia, prolonged bleeding time, and increased numbers of circulating endothelial cells. The murine model can be used to test for many parameters of vaccine efficacy including hemorrhage which is a common clinical manifestation seen in DHF/DSS patients. Infection with dengue virus (DENV) may cause life-threatening disease with thrombocytopenia and vascular leakage which are related to dysfunction of platelets and endothelial cells. For safety in vaccine development, the cross-reactive epitopes of DENV NS1 protein should be deleted or modified

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Conclusion