Clinical and Virological Factors Influencing the Performance of a NS1 Antigen-Capture Assay and Potential Use as a Marker of Dengue Disease Severity

Dengue is the most prevalent arthropod-borne disease in tropical regions. The clinical manifestation may vary from asymptomatic to potentially fatal dengue shock syndrome. Early laboratory confirmation of dengue diagnosis is essential since many symptoms are not specific. Dengue non-structural protein 1 (NS1) may be used in simple antigen-capture ELISA for early detection of dengue virus infection. Our result demonstrated that the Platelia NS1 antigen detection kit had a quite low overall sensitivity. However, sensitivity rises significantly when used in combination with MAC-ELISA. When taking into account the various forms of dengue infection, the NS1 antigen detection was found relatively high in patients sampled during the first 3 days of fever onset, in patients with primary infection, DENV-1 infection, with high level of viremia and in mild form of dengue fever. In asymptomatically infected individuals, RT-PCR assay has proved to be more sensitive than NS1 antigen detection. Moreover, the NS1 antigen level correlated significantly with high viremia and low level of NS1 antigen was associated with more severe disease

Integrin αvβ5 is a primary receptor for adenovirus in CAR-negative cells

<p>Abstract</p> <p>Background</p> <p>Viruses bind to specific cellular receptors in order to infect their hosts. The specific receptors a virus uses are important factors in determining host range, cellular tropism, and pathogenesis. For adenovirus, the existing model of entry requires two receptor interactions. First, the viral fiber protein binds Coxsackie and Adenovirus Receptor (CAR), its primary cellular receptor, which docks the virus to the cell surface. Next, viral penton base engages cellular integrins, coreceptors thought to be required exclusively for internalization and not contributing to binding. However, a number of studies reporting data which conflicts with this simple model have been published. These observations have led us to question the proposed two-step model for adenovirus infection.</p> <p>Results</p> <p>In this study we report that cells which express little to no CAR can be efficiently transduced by adenovirus. Using competition experiments between whole virus and soluble viral fiber protein or integrin blocking peptides, we show virus binding is not dependent on fiber binding to cells but rather on penton base binding cellular integrins. Further, we find that binding to low CAR expressing cells is inhibited specifically by a blocking antibody to integrin αvβ5, demonstrating that in these cells integrin αvβ5 and not CAR is required for adenovirus attachment. The binding mediated by integrin αvβ5 is extremely high affinity, in the picomolar range.</p> <p>Conclusions</p> <p>Our data further challenges the model of adenovirus infection in which binding to primary receptor CAR is required in order for subsequent interactions between adenovirus and integrins to initiate viral entry. In low CAR cells, binding occurs through integrin αvβ5, a receptor previously thought to be used exclusively in internalization. We show for the first time that integrin αvβ5 can be used as an alternate binding receptor.</p

The dual role of the antibody response against the flavivirus non-structural protein 1 (NS1) in protection and immuno-pathogenesis

Dengue and Zika viruses are closely related mosquito-borne flaviviruses responsible for major public health problems in tropical and sub-tropical countries. The genomes of both, dengue and zika viruses encodes 10 genes that are translated into three structural proteins (C, prM, and E) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). The non-structural protein 1 (NS1) is a highly conserved glycoprotein of approximately 48–50 KDa. In infected cells, NS1 is found as a homodimer associated with intracellular membranes and replication complexes, serving as a scaffolding protein in virus replication and morphogenesis. NS1 is secreted efficiently from infected cells as a hexamer and is found in patient's sera during the acute phase of the disease. NS1 detection in sera is a valuable diagnostic marker and immunization with NS1 has been shown to protect animal models from lethal challenges with dengue and Zika viruses. Nevertheless, soluble NS1 has been associated with severe dengue and anti-NS1 antibodies have been reported to cross-react with host platelets and endothelial cells and thus presumably contribute to pathogenesis. Due to the implications of NS1 in arbovirus pathogenesis and its relevance as vaccine candidate, we discuss the dual role that anti-NS1 antibodies may play in protection and disease and the challenges that need to be overcome to develop safe and effective NS1-based vaccines against dengue and Zika

The dual role of the antibody response against the flavivirus non-structural protein 1 (NS1) in protection and immuno-pathogenesis

Dengue and Zika viruses are closely related mosquito-borne flaviviruses responsible for major public health problems in tropical and sub-tropical countries. The genomes of both, dengue and zika viruses encodes 10 genes that are translated into three structural proteins (C, prM, and E) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). The non-structural protein 1 (NS1) is a highly conserved glycoprotein of approximately 48–50 KDa. In infected cells, NS1 is found as a homodimer associated with intracellular membranes and replication complexes, serving as a scaffolding protein in virus replication and morphogenesis. NS1 is secreted efficiently from infected cells as a hexamer and is found in patient's sera during the acute phase of the disease. NS1 detection in sera is a valuable diagnostic marker and immunization with NS1 has been shown to protect animal models from lethal challenges with dengue and Zika viruses. Nevertheless, soluble NS1 has been associated with severe dengue and anti-NS1 antibodies have been reported to cross-react with host platelets and endothelial cells and thus presumably contribute to pathogenesis. Due to the implications of NS1 in arbovirus pathogenesis and its relevance as vaccine candidate, we discuss the dual role that anti-NS1 antibodies may play in protection and disease and the challenges that need to be overcome to develop safe and effective NS1-based vaccines against dengue and Zika

Structural Insights into Rotavirus Entry.

To initiate infection, non-enveloped viruses must recognize a target cell and penetrate the cell membrane by pore formation or membrane lysis. Rotaviruses are non-enveloped dsRNA viruses that infect the mature intestinal epithelium. They are major etiologic agents of diarrheal disease in human infants, as well as in young individuals of various avian and mammalian species. Rotavirus entry into the cell is a complex multistep process initiated by the interaction of the tip of the viral spike with glycan ligands at the cell surface, and driven by conformational changes of the proteins present in the outer protein capsid, the viral machinery for entry. This review feeds on the abundant structural information produced for rotavirus during the past 30 years and focuses on the structure and the dynamics of the rotavirus entry machinery. We survey the current models for rotavirus entry into cells.S