Influenza Virus Non-Structural Protein 1 (NS1) Disrupts Interferon Signaling

Type I interferons (IFNs) function as the first line of defense against viral infections by modulating cell growth, establishing an antiviral state and influencing the activation of various immune cells. Viruses such as influenza have developed mechanisms to evade this defense mechanism and during infection with influenza A viruses, the non-structural protein 1 (NS1) encoded by the virus genome suppresses induction of IFNs-α/β. Here we show that expression of avian H5N1 NS1 in HeLa cells leads to a block in IFN signaling. H5N1 NS1 reduces IFN-inducible tyrosine phosphorylation of STAT1, STAT2 and STAT3 and inhibits the nuclear translocation of phospho-STAT2 and the formation of IFN-inducible STAT1:1-, STAT1:3- and STAT3:3- DNA complexes. Inhibition of IFN-inducible STAT signaling by NS1 in HeLa cells is, in part, a consequence of NS1-mediated inhibition of expression of the IFN receptor subunit, IFNAR1. In support of this NS1-mediated inhibition, we observed a reduction in expression of ifnar1 in ex vivo human non-tumor lung tissues infected with H5N1 and H1N1 viruses. Moreover, H1N1 and H5N1 virus infection of human monocyte-derived macrophages led to inhibition of both ifnar1 and ifnar2 expression. In addition, NS1 expression induces up-regulation of the JAK/STAT inhibitors, SOCS1 and SOCS3. By contrast, treatment of ex vivo human lung tissues with IFN-α results in the up-regulation of a number of IFN-stimulated genes and inhibits both H5N1 and H1N1 virus replication. The data suggest that NS1 can directly interfere with IFN signaling to enhance viral replication, but that treatment with IFN can nevertheless override these inhibitory effects to block H5N1 and H1N1 virus infections

Influenza Virus H5N1 Non-structural Protein 1 Alters Interferon-alpha/beta Signaling

Type I interferons (IFNs) function as the first line of defense against viral infections by modulating numerous biological processes to establish an antiviral state and influencing the activation of various immune cells. During influenza A infection, the NS1 encoded by the virus genome disrupts many cellular processes to block type I IFN responses. We show that expression of H5N1 NS1 in HeLa cells reduces IFN-inducible activation of STAT proteins and its subsequent binding to DNA complexes. Subsequent analysis suggests NS1 blocks IFN signaling by inhibiting expression of type I IFN receptor subunit, IFNAR1, as well as up-regulating SOCS1 expression. Finally, we demonstrate that pretreatment of primary human lung tissue with IFN alfacon-1 inhibits H5N1 viral replication by up-regulating a number of interferon-stimulated genes. The data suggest that NS1 can directly interfere with Type I IFN signaling, and that pretreatment with IFN can inhibit H5N1 infection in primary human lung tissue.MAS

Building energy simulation and its application for building performance optimization: A review of methods, tools, and case studies

As one of the most important and advanced technology for carbon-mitigation in the building sector, building performance simulation (BPS) has played an increasingly important role with the powerful support of building energy modelling (BEM) technology for energy-efficient designs, operations, and retrofitting of buildings. Owing to its deep integration of multi-disciplinary approaches, the researchers, as well as tool developers and practitioners, are facing opportunities and challenges during the application of BEM at multiple scales and stages, e.g., building/system/community levels and planning/design/operation stages. By reviewing recent studies, this paper aims to provide a clear picture of how BEM performs in solving different research questions on varied scales of building phase and spatial resolution, with a focus on the objectives and frameworks, modelling methods and tools, applicability and transferability. To guide future applications of BEM for performance-driven building energy management, we classified the current research trends and future research opportunities into five topics that span through different stages and levels: (1) Simulation for performance-driven design for new building and retrofit design, (2) Model-based operational performance optimization, (3) Integrated simulation using data measurements for digital twin, (4) Building simulation supporting urban energy planning, and (5) Modelling of building-to-grid interaction for demand response. Additionally, future research recommendations are discussed, covering potential applications of BEM through integration with occupancy and behaviour modelling, integration with machine learning, quantification of model uncertainties, and linking to building monitoring systems

Treatment with IFN alfacon-1 inhibits <i>pandemic</i> H1N1 2009 virus replication in human lung tissue.

<p>Three different human surgical lung tissue explants were infected with pandemic H1N1 2009 virus for 24 hr, then either left untreated (▪) or treated with IFN alfacon-1 (1.2×104 U/mL) () for a further 48 hr. At the indicated times <b>A</b>) Viral titers (TCID₅₀) and <b>B</b>) Influenza A <i>m</i> gene expression were measured; Significant differences were determined by Student t-test: * ∼ p<0.05; ** ∼ p<0.01. <b>C</b>) Thin sections of infected human lung explants, either untreated (i) or IFN-treated (ii) were stained for influenza A nucleoprotein (pink).</p

Influenza virus infection reduces <i>ifnar1</i> and <i>ifnar2</i> expression at 24 hours post-infection in human monocyte-derived macrophages and <i>ex vivo</i> lung tissues.

<p>Human monocyte-derived macrophages were infected with A/HK/483/97 H5N1 or A/HK/54/98 H1N1 virus (Multiplicity of Infection (MOI)  = 2). RNA was extracted from the cells at <b>A</b>) 3 hr, <b>B</b>) 6 hr, and <b>C</b>) 24 hr post-infection. Following cDNA synthesis, <i>ifnar1</i> (▪) and <i>ifnar2</i> () expression was assayed by real-time PCR. Data shown are fold induction of gene expression relative to mock-infected control after normalizing to β-actin in each sample. Representative data of duplicate experiments with means of triplicate assays are shown; <b>D</b>) Human lung explant tissue was either mock-infected (PBS) or infected with A/HK/483/97 H5N1 or A/HK/54/98 H1N1 influenza A viruses, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013927#s2" target="_blank">Materials & Methods</a>. 18 hr post-infection tissue was processed to extract RNA. cDNA was synthesized and expression of <i>ifnar1</i>, <i>ifnar2</i> and <i>β-actin</i> gene expression was measured by RT-PCR analysis. Gene expression was calculated relative to <i>β-actin</i> gene expression and normalized to mock infected tissues. Data are representative of two independent experiments. Significant differences (asterisk) were determined by Student's t-test (p<0.05).</p

H5N1 NS1 expression inhibits IFN-inducible STAT:SIE complex formation.

<p><b>A</b>) HeLa cells transfected with either vector alone or HA-tagged NS1 plasmid were left untreated (−) or treated (+) with IFN-β (1×10³ U/mL) for 15 mins, 24 hr post-transfection. Nuclear extracts were isolated and equal amounts of protein were incubated with ³²P-labeled SIE probe. Complexes were resolved by native gel electrophoresis and visualized by autoradiography. Data are representative of two independent experiments. HeLa cells were treated with IFN-β (1×10³ U/mL) for 15 mins. Nuclear extracts were isolated and equal amount of protein were incubated with ³²P-labeled SIE probe in the presence or absence of 2 µg of anti-STAT1 and anti-STAT3 antibodies, as indicated. Complexes were resolved by native gel electrophoresis and visualized by autoradiography.</p