Influenza A virus-derived siRNAs increase in the absence of NS1 yet fail to inhibit virus replication
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ABSTRACT:
PROVIDER: PRJNA437453 | ENA |
REPOSITORIES: ENA
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Project description:While the issue of whether RNA interference (RNAi) ever forms part of the antiviral innate immune response in mammalian somatic cells remains controversial, there is considerable evidence demonstrating that few, if any, viral small interfering RNAs (siRNAs) are produced in infected cells. Moreover, total inhibition of RNAi by mutational inactivation of key RNAi factors, such as Dicer or Argonaut 2, has been shown to not enhance virus replication. One potential explanation for this lack of inhibitory effect is that mammalian viruses encode viral suppressors of RNAi (VSRs) that are so effective that viral siRNAs are not produced in infected cells. Indeed, a number of mammalian VSRs have been described of which the most prominent is the influenza A virus (IAV) NS1 protein, which has not only been reported to inhibit RNAi in plants and insects but also to prevent the production of viral siRNAs in IAV-infected human cells. Here, we confirm that an IAV mutant that lacks the viral NS1 protein indeed differs from wild type IAV in that it induces the production of readily detectable levels of Dicer-dependent viral siRNAs in infected human cells. However we also demonstrate that these siRNAs have little if any inhibitory effect on IAV gene expression.
2018-07-03 | GSE111572 | GEO
Project description:Influenza A virus (IAV) is an important human respiratory pathogen that causes significant seasonal epidemics and potential devastating pandemics. As part of its life cycle, IAV encodes the multifunctional protein NS1, that, among many roles, prevents immune detection and limits interferon (IFN) production. As different host immune pathways exert different selective pressures against IAV as replication progresses, we expect a prioritization in the host immune antagonism by NS1. In this work, we profiled bulk transcriptomic differences in a primary bronchial epithelial cell model facing IAV infections at distinct NS1 levels. We further demonstrated that the intracellular NS1 levels in-part shapes the host response heterogeneity at single cell level. We found that modulation of NS1 levels reveal a ranking in its inhibitory roles: modest NS1 expression is sufficient to inhibit immune detection, and thus the expression of pro-inflammatory cytokines (including IFNs), but higher levels are required to inhibit IFN signaling and ISG expression. Lastly, inhibition of chaperones related to the unfolded protein response requires the highest amount of NS1, often associated with later stages of viral replication. This work demystifies some of the multiple functions ascribed to IAV NS1, highlighting the prioritization of NS1 in antagonizing the different pathways involved in the host response to IAV infection.
2023-09-25 | GSE243730 | GEO
Project description: Not available
| S-EPMC6097656 | biostudies-literature
Project description:This SuperSeries is composed of the following subset Series: GSE39199: Gene Expression Response to Interferon Treatment at 12h and 24 in A549 cells GSE39200: The NS1 protein of influenza A virus suppresses interferon-regulated activation of antigen-presentation and immune-proteasome pathways Refer to individual Series
2012-07-09 | E-GEOD-39202 | biostudies-arrayexpress
Project description:Gene transcription effects of mutations in the infuenza virus A/Hong Kong/1/1968(H3N2) nonstructural 1 NS1 gene in infected human A549 (lung epithilium) cells Influenza A/Hong Kong/156/1997(H5N1) virus NS1 gene mutations F103L and M106I both increase IFN antagonism, virulence and cytoplasmic localization but differ in binding to RIG-I and CPSF30 (manuscript submitted to Virology Journal). Human cells were infected with influenza viruses mutants with specific gain of function mutations in the NS1 gene in order to assess the affects of each mutation on host gene expression. Human (A549) and mouse (M1) cells were infected at a multiplicity of infection of 2 (infectious viruses/cell) and incubated for 8 hr before collection of total RNA and microarray anlaysis using the Affymetrix platforms. Samples were compared in triplicate to mock PBS infected (uninfected) cells to detecte dysregulated genes for A/HK/1/1968(H3N2) wt, and the following NS1 gene mutants: F103L, M106I, M106V, and F103L + M106I. Background: The genetic basis for avian to mammalian host switching in influenza A virus is largely unknown. The human A/HK/156/1997(H5N1) virus that transmitted from poultry possesses NS1 gene mutations F103L + M106I that are virulence determinants in the mouse model of pneumonia; however their individual roles have not been determined. The emergent A/Shanghai/1/2013(H7N9)-like viruses also possess these mutations which may contribute to their virulence and ability to switch species. Methods: NS1 mutant viruses were constructed by reverse genetics and site directed mutagenesis on human and mouse-adapted backbones. Mouse infections assessed virulence, virus yield, tissue infection, and IFN induction. NS1 protein proprieties were assessed for subcellular distribution, IFN antagonism (mouse and human), CPSF30 and RIG-I domain binding, effect on host gene transcription (microarray); and the natural prevalence of 103L and 106I mutants was assessed. Results: Each of the F103L and M106I mutations contributes additively to virulence to reduce the lethal dose by >800 and >3,200 fold respectively by mediating alveolar tissue infection with >100 fold increased infectious yields. The 106I NS1 mutant lost CPSF binding but the 103L mutant maintained binding that correlated with an increased general decrease in host gene expression in human but not mouse cells. Each mutation positively modulated the inhibition of IFN induction in mouse cells and activation of the IFN-M-NM-2 promoter in human cells but not in combination in human cells indicating negative epistasis. Each of the F103L and M106I mutations restored a defect in cytoplasmic localization of H5N1 NS1 in mouse cells. Human H1N1 and H3N2 NS1 proteins bound to the CARD, helicase and RD RIG-I domains, whereas the H5N1 NS1 with the same consensus 103F and 106M mutations did not bind these domains, which was partially or totally restored by the F103L or M106I mutations respectively. Conclusions: The F103L and M106I mutations in the H5N1 NS1 protein each increased IFN antagonism and mediated interstitial pneumonia in mice that was associated with increased cytoplasmic localization and altered host factor binding. These mutations may contribute to the ability of previous HPAI H5N1 and recent LPAI H7N9 viruses to switch hosts and cause severe disease in mammals. Triplicate biological replicates of mock PBS treated (uninfected) cells to detecte dysregulated genes for A/HK/1/1968(H3N2) wt, and the following NS1 gene mutants: F103L, M106I, M106V, and F103L + M106I. Cells were infected at a multiplicty of infection of 2 and cells were incubated for 8 hr at 37 C for 8 hrs before RNA extraction and analysis of 3 biological replicates relative to mock PBS infected cells.
2013-06-22 | E-GEOD-48200 | biostudies-arrayexpress
Project description:The NS1 protein of influenza virus counters host antiviral defences primarily by antagonizing the type I interferon (IFN) response. Both the N-terminal dsRNA-binding domain and the C-terminal effector domain are required for optimal suppression of host responses during infection. To better understand the regulatory role of the NS1 effector domain, we used an NS1-truncated mutant virus derived from human H1N1 influenza isolate A/Texas/36/91 (Tx/91) and assessed global transcriptional profiles from two independent human lung cell-culture models.
2012-07-10 | GSE39200 | GEO
Project description:Gene transcription effects of mutations in the infuenza virus A/Hong Kong/1/1968(H3N2) nonstructural 1 NS1 gene in infected human A549 (lung epithilium) cells Influenza A/Hong Kong/156/1997(H5N1) virus NS1 gene mutations F103L and M106I both increase IFN antagonism, virulence and cytoplasmic localization but differ in binding to RIG-I and CPSF30 (manuscript submitted to Virology Journal). Human cells were infected with influenza viruses mutants with specific gain of function mutations in the NS1 gene in order to assess the affects of each mutation on host gene expression. Human (A549) and mouse (M1) cells were infected at a multiplicity of infection of 2 (infectious viruses/cell) and incubated for 8 hr before collection of total RNA and microarray anlaysis using the Affymetrix platforms. Samples were compared in triplicate to mock PBS infected (uninfected) cells to detecte dysregulated genes for A/HK/1/1968(H3N2) wt, and the following NS1 gene mutants: F103L, M106I, M106V, and F103L + M106I. Background: The genetic basis for avian to mammalian host switching in influenza A virus is largely unknown. The human A/HK/156/1997(H5N1) virus that transmitted from poultry possesses NS1 gene mutations F103L + M106I that are virulence determinants in the mouse model of pneumonia; however their individual roles have not been determined. The emergent A/Shanghai/1/2013(H7N9)-like viruses also possess these mutations which may contribute to their virulence and ability to switch species. Methods: NS1 mutant viruses were constructed by reverse genetics and site directed mutagenesis on human and mouse-adapted backbones. Mouse infections assessed virulence, virus yield, tissue infection, and IFN induction. NS1 protein proprieties were assessed for subcellular distribution, IFN antagonism (mouse and human), CPSF30 and RIG-I domain binding, effect on host gene transcription (microarray); and the natural prevalence of 103L and 106I mutants was assessed. Results: Each of the F103L and M106I mutations contributes additively to virulence to reduce the lethal dose by >800 and >3,200 fold respectively by mediating alveolar tissue infection with >100 fold increased infectious yields. The 106I NS1 mutant lost CPSF binding but the 103L mutant maintained binding that correlated with an increased general decrease in host gene expression in human but not mouse cells. Each mutation positively modulated the inhibition of IFN induction in mouse cells and activation of the IFN-β promoter in human cells but not in combination in human cells indicating negative epistasis. Each of the F103L and M106I mutations restored a defect in cytoplasmic localization of H5N1 NS1 in mouse cells. Human H1N1 and H3N2 NS1 proteins bound to the CARD, helicase and RD RIG-I domains, whereas the H5N1 NS1 with the same consensus 103F and 106M mutations did not bind these domains, which was partially or totally restored by the F103L or M106I mutations respectively. Conclusions: The F103L and M106I mutations in the H5N1 NS1 protein each increased IFN antagonism and mediated interstitial pneumonia in mice that was associated with increased cytoplasmic localization and altered host factor binding. These mutations may contribute to the ability of previous HPAI H5N1 and recent LPAI H7N9 viruses to switch hosts and cause severe disease in mammals.
2013-06-22 | GSE48200 | GEO
Project description:NS1 proteins from avian influenza viruses like the 1918 pandemic NS1 are capable of inhibiting the key signaling integrator c-Abl (Abl1), resulting in massive cytopathic cell alterations. In the current study, we addressed the consequences of NS1-mediated alteration of c-Abl on acute lung injury and pathogenicity. Comparing isogenic strains that differ only in their ability to inhibit c-Abl, we observed elevated pathogenicity for the c-Abl-inhibiting virus. NS1-mediated block of c-Abl resulted in severe lung pathology and massive edema formation and facilitated secondary bacterial pneumonia. This phenotype was independent of differences in replication and immune responses, defining it as an NS1 virulence mechanism distinct from its canonical functions. Microarray analysis revealed extensive down-regulation of genes involved in cell integrity and vascular endothelial regulation. In conclusion, NS1 protein-mediated blockade of c-Abl signaling drives acute lung injury and primes for bacterial co-infections revealing potential insights into the pathogenicity of the 1918 pandemic virus. Lung transcription analysis of Influenza A virus infected mice.
2014-11-03 | E-GEOD-62169 | biostudies-arrayexpress
Project description:Human respiratory syncytial virus (hRSV) is a major cause of morbidity and mortality in the pediatric, elderly, and immune compromised populations. A gap in our understanding of hRSVdisease pathology is the interplay between virally encoded immune antagonists and host components that limit hRSV replication. hRSV encodes for non-structural (NS) proteins that are important immune antagonists; however, the role of these proteins in viral pathogenesis is incompletely understood. Here we report the crystal structure of hRSV NS1 protein, which suggests that NS1 is a structural paralog of hRSV matrix (M) protein. Comparative analysis of the shared structural fold with M revealed regions unique to NS1. Studies on NS1 WT or mutant alone or in recombinant RSVs demonstrate that structural regions unique to NS1 contribute to modulation of host responses, including inhibition of type I IFN responses, suppression of dendritic cell maturation, and promotion of inflammatory responses. Transcriptional profiles of A549 cells infected with recombinant RSVs show significant differences in multiple host pathways, suggesting that NS1 may have a greater role in regulating host responses than previously appreciated. These results provide a framework to target NS1 for therapeutic development to limit hRSV associated morbidity and mortality.
2017-06-15 | GSE99298 | GEO
Project description:Dengue virus (DENV) is a major human pathogen that belongs to the flavivirus genus. Among non-structural viral proteins, NS1 is an enigmatic factor that is exclusively encoded by members of the flavivirus genus within the Flaviviridae family and accomplishes different functions during DENV infection. To gain insight into the molecular and cellular function of NS1 in viral replication, we generated a tagged NS1 DENV replicon and identified the associated host proteins during active viral replication. Replicons are self-replicating flavivirus RNAs containing large in-frame deletions in the structural genes and are useful tools to study translation and RNA amplification of several flaviviruses. To establish a global map of NS1-host protein interactions occurring during DENV replication, we stably expressed a DENV2 replicon encoding NS1 tagged with N-terminal FLAG and HA epitopes (FH-NS1) or the untagged version (WT) in three different human cell lines (Raji, HeLa and HAP1). Interactors of NS1 were identified by AP-MS/MS from these three different cell lines.
2017-11-29 | PXD008120 | Pride