C-Terminal Region of Dengue Virus Nonstructural Protein 1 Is Involved in Endothelial Cell Cross-Reactivity via Molecular Mimicry

Abstract

Infection with dengue virus (DV) causes diseases ranging from self-limited dengue fever to life-threatening dengue hemorrhagic fever and dengue shock syndrome. Vascular leakage, thrombocytopenia and bleeding are the clinical manifestations associated with dengue hemorrhage. We previously showed that anti-DV nonstructural protein 1 (NS1) antibodies (Abs) cross-reacted with endothelial cells. The potential target proteins on endothelial cell surface recognized by anti-DV NS1 Abs showed sequence homology with the C-terminal amino acids (a.a.) 311-352 of DV NS1. In this study, the role of NS1 C-terminal region in dengue autoimmunity was investigated. We deleted the a.a. 277-352 of DV NS1 to prepare truncated NS1 (tNS1) and generated anti-DV tNS1 Abs in mice. The endothelial cell-binding activity of anti-DV tNS1 Abs was lower than that of anti-DV NS1 Abs. In addition, the endothelial cell-binding activity of anti-DV NS1 Abs was inhibited by preabsorption with DV NS1 but not with DV tNS1 proteins. The anti-P311 (a.a. 311-330) and anti-P331 (a.a. 331-350) titers of dengue patient sera were positively correlated with their endothelial cell-binding activity. Dengue patient sera showed lower binding activity to DV tNS1 than to DV NS1 proteins. The endothelial cell-binding activity of dengue patient sera was inhibited by preabsorption with P311 and P331. This study helps to understand the molecular mechanisms of autoimmunity mediated by anti-DV NS1 Abs and to provide the potential implications of tNS1 in dengue vaccine strategies.

Correlation Between Serum Levels of Anti-Endothelial Cell Autoantigen and Anti-Dengue Virus Nonstructural Protein 1 Antibodies in Dengue Patients

“…There was no significant difference in both IgM and IgG titers of anti-P311-330 and anti-NS1 between different collection days (Supplemental Figure 3). Furthermore, consistent with our previous finding using a different source of patient sera, 42 the percentage of endothelial cells reactive with patient serum IgM correlated with anti-P311-330 IgM titers ( Figure 3C).…”

Deletion of the C-Terminal Region of Dengue Virus Nonstructural Protein 1 (NS1) Abolishes Anti-NS1-Mediated Platelet Dysfunction and Bleeding Tendency

“…Using sequence homology alignment, we found that the C-terminal region of DV NS1 protein contains cross-reactive epitopes with selfAgs (30,31). To explore the pathological role of cross-reactive epitopes in the hemorrhagic syndrome, we deleted the C-terminal region of DV NS1 protein to generate ⌬C NS1.…”

“…We previously found that anti-DV NS1 Abs cross-reacted with platelets and endothelial cells (21,22,34), and the C-terminal region of DV NS1 protein contained cross-reactive epitopes (30,31). We therefore deleted the C terminus of DV NS1 protein from aa 271 to 352 (⌬C NS1) ( Fig.…”

Anti–Dengue Virus Nonstructural Protein 1 Antibodies Cause NO-Mediated Endothelial Cell Apoptosis via Ceramide-Regulated Glycogen Synthase Kinase-3β and NF-κB Activation

“…Given the pathological effects reported for anti-NS1 Abs, the underlying mechanisms need to be characterized and the relevant epitopes identified. Considerable progress toward these goals has been achieved (30,(65)(66)(67)(68), raising the hope that safer NS1 candidate vaccines may be developed with modified or deleted harmful epitopes such as those involved in autoimmune responses.…”