Facilitation of Cell Adhesion by Immobilized Dengue Viral Nonstructural Protein 1 (NS1): Arginine‐Glycine‐Aspartic Acid Structural Mimicry within the Dengue Viral NS1 Antigen

Abstract

Dengue virus infection causes life-threatening hemorrhagic fever. Increasing evidence implies that dengue viral nonstructural protein 1 (NS1) exhibits a tendency to elicit potentially hazardous autoantibodies, which show a wide spectrum of specificity against extracellular matrix and platelet antigens. How NS1 elicits autoantibodies remains unclear. To address the hypothesis that NS1 and matrix proteins may have structural and functional similarity, cell-matrix and cell-NS1 interactions were evaluated using a cell-adhesion assay. The present study showed that dengue NS1 immobilized on coverslips resulted in more cell adhesion than did the control proteins. This cell adhesion was inhibited by peptides containing arginine-glycine-aspartic acid (RGD), a motif important for integrin-mediated cell adhesion. In addition, anti-NS1 antibodies blocked RGD-mediated cell adhesion. Although there is no RGD motif in the NS1 protein sequence, these data indicate that RGD structural mimicry exists within the NS1 antigen.

Acquired coagulant factor VIII deficiency induced byBacillus anthracislethal toxin in mice

“…The LPS contamination was monitored using a Limulus Amoebocyte Lysate QCL -1000 kit (Lonza, Walkersville, MD, USA). 4,57 Batches of purified LT, in which LPS contamination was <1 endotoxin unit (EU)/mg LT, were used, because treatments of LPS at this level cannot elicit significant inflammatory cytokine IL-1b and TNF-a secretion in vitro and in vivo (data not shown). An anti-PA antibody that neutralizes the LT-mediated cytotoxicity was purified from rabbit sera that were immunized with PA (100 mg per cycle at 3-wk intervals for 6 cycles).…”

Endothelial Cell Sensitization by Death Receptor Fractions of an Anti–Dengue Nonstructural Protein 1 Antibody Induced Plasma Leakage, Coagulopathy, and Mortality in Mice

“…DHF cases were also defined according to these clinical manifestations as well as additional hemorrhagic manifestations, including positive tourniquet test results, hemoconcentration, and other signs of plasma leakage (24,25). According to previously described protocols (7,8), serum samples were collected from patients with DF and tested using at least two of the following four methods: 1) virus infection and isolation from mosquito C6/36 cells, 2) serotype-specific RT-PCR, 3) DENV-specific IgM or IgG measurement, and 4) a hemagglutination inhibition test. The serum samples were collected 3-7 d after the onset of illness.…”

“…Soluble recombinant DENV2-NS1 (rNS1) (7,8), TRAIL-R1 (rDR4), and rGST were obtained from engineered Escherichia coli using standard molecular biology technologies (7,8). When the recombinant protein formed inclusion bodies in E. coli, recombinant proteins were denatured and renatured according to a previously described method (8).…”

“…However, among all of the viruses examined, DENVs alone caused more severe disease during secondary infections, suggesting that DHF may not be fully explained by the ADE hypothesis. Another line of evidence revealed that DENV infection or exposure to nonstructural protein 1 (NS1) induces the production of autoantibodies against platelets and endothelial cells (7)(8)(9)(10)(11)(12)(13)(14)(15). Autoantibody titers are associated with the severity of disease in patients (11)(12)(13), providing an alternative explanation for DENVelicited immunopathogenesis.…”

West Nile Virus: Basic Principles, Replication Mechanism, Immune Response and Important Genetic Determinants of Virulence

“…NS1 protein functions as a cofactor for viral RNA replication and is the only nonstructural protein that is secreted in high levels (up to 50 g/ml) in the serum of WNV infected patients and has been connected with severe disease [19]. Many theories have been proposed regarding the contribution of NS1 to the pathogenic mechanism of WNV: it has been proposed to elicit hazardous autoantibodies [20] NS2A is a hydrophobic, multifunctional membrane-associated protein which plays an important role in RNA replication [24] and viral particles assembly [25,26]. NS2A is also the major suppressor of beta interferon (IFN-) transcription, thus inhibiting interferon response, one of the first lines of defense of the host [27].…”