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

Abstract

The mechanisms underlying dengue hemorrhagic disease are incompletely understood. We previously showed that anti-dengue virus (DV) nonstructural protein 1 (NS1) Abs cross-react with human platelets and inhibit platelet aggregation. Based on sequence homology alignment, the cross-reactive epitopes reside in the C-terminal region of DV NS1. In this study, we compared the effects of Abs against full-length DV NS1 and NS1 lacking the C-terminal aa 271 to 352 (designated ΔC NS1). Anti-ΔC NS1 Abs exhibited lower platelet binding activity than that of anti-full-length NS1. Anti-full-length NS1 but not anti-ΔC NS1 Abs inhibited platelet aggregation, which was shown to involve integrin αIIbβ3 inactivation. We found that the bleeding time in full-length NS1-hyperimmunized mice was longer than that in the normal control mice. By contrast, ΔC NS1-hyperimmunized mice showed a bleeding time similar to that of normal control mice. Passively administered anti-DV NS1, but not anti-ΔC NS1, Ab level decreased markedly in serum and this decrease was correlated with Ab binding to platelets. A transient platelet loss in the circulation was observed after anti-DV NS1, but not anti-ΔC NS1, Ab administration. In summary, platelet dysfunction and bleeding tendency are induced by anti-full-length DV NS1 but not by anti-ΔC NS1 Abs. These findings may be important not only for understanding dengue hemorrhagic disease pathogenesis but also for dengue vaccine development.

DENV-2 subunit proteins fused to CR2 receptor-binding domain (P28)-induces specific and neutralizing antibodies to the Dengue virus in mice

“…However, we were able to increase the immune response against DENV in a mouse model by targeting the domain III sequence to DEC-205 receptor of dendritic cells. 39 In parallel, we built 4 constructs based on the EIII, EII*, and NS1 antigens (Reported by Mellado-Sanchez et al 33 ). Two of these constructs were fused with P28 and were expressed in a Drosophila S2 cell system.…”

“…However, only the fragment responsible for protection (aa 57-130) was included, while its C-terminal region, involved in human crossreactivity, was omitted. 33 These four recombinant proteins were each generated in a Drosophila S2 system. In this study we show that all of these fusion proteins induced a robust response to wild virus in BALB/c mouse model with a predominance of the IgG1 isotype.…”

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.…”

Characterisation of B cell epitopes of dengue virus NS1 protein using bioinformatics approach

“…Collectively, the dengue group shared only a conservation level of 50 % with the NS1 protein from was interesting to note the carboxy terminal region (271-352aa) of the protein, which has been suggested to be pathologically important (Chen et al, 2009) being more understanding of the genetic variability or similarity among and within the serotypes of dengue virus as insight into the understanding of dengue pathogenesis.…”

“…EP20 on the other hand, is located in the C-terminal region of the protein, antibodies against which has been suggested to cross-react with the vascular endothelium. Since this has been proposed as a possible contributing factor for vascular leakage associated with severe dengue (Chen et al, 2009), the potential of EP20 as a vaccine target will be limited.…”