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
ABSTRACT: 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. 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.
Project description:The NS1 protein of influenza A virus (IAV) is a multifunctional virulence factor. Mouse adaptive mutations in the NS1 protein of the human isolate A/Hong Kong/1/1968(H3N2) (HK) have been previously reported to increase virulence, viral fitness, and interferon antagonism, but differ in binding to post-transcriptional processing factor CPSF30. Because nuclear trafficking is a major genetic determinant of influenza virus host adaptation, we assessed subcellular localization and host gene expression of NS1 adaptive mutations. Recombinant HK viruses with adaptive mutations in the NS1 gene were assessed for NS1 protein subcellular localization in mouse and human cells using confocal microscopy and cellular fractionation. HK-wt virus NS1 partitioned equivalently between the cytoplasm and nucleus in human cells but was defective in cytoplasmic localization in mouse cells. The adaptive mutations either increased the proportion or abundance of NS1 in the cytoplasm, and/or the nucleus. NS1 mutations that increased cytoplasmic distribution identified a putative second nuclear export signal (NES) spanning aa positions 98-106 LSEDWFMLM, (mutation sites in bold); with the strongest effect seen for mutation M106I. The putative NES in the NS3 protein was associated with cytoplasmic localization. The host gene expression profile of the adaptive mutants was determined by microarray analysis of infected mouse cells to show either high or low gene regulation (HGR or LGR) phenotypes that mapped to the amino-terminal and the carboxy-terminal regions respectively. The HGR and LGR mutations were predominantly down regulating versus up regulating respectively. The greatest effect on host gene expression in the HGR group correlated with the ability of the NS1 protein to bind CPSF30. To our knowledge this is the first report of roles of adaptive NS1 mutations that affect intracellular localization and regulation of host gene expression. biological triplicates of mock infected mouse M1 cells; cells infected with A/HK/1/1968(H3N2) wt and NS1 mtuatn with mutaions, D2N, V23A, L98S, L98S + M106I, F103L, M106V, M106V + M124I, D125G, V180A, V226I, M106I, and R227K. Cells were infected at a multiplicty of infection of 2 and cels were incubated for 8 hr at 37 C for 8 hrs before RNA extraction and analysis relative to mock PBS infected cells.
Project description:Airway epithelial cells are the initial site of infection with influenza viruses. The innate immune responses of airway epithelial cells to infection have the potential to limit virus replication and induce effective adaptive immune responses. However, relatively little is known about the importance of this innate anti-viral response to infection. Avian influenza viruses are a potential source of future pandemics, therefore it is critical to examine the effectiveness of the host anti-viral system to different influenza viruses. We used a human influenza (H3N2) and a low pathogenic avian influenza (H11N9) to assess and compare the anti-viral responses of bronchial epithelial cells (BECs). After infection, the H3N2 virus replicated more effectively than the H11N9 strain in BECs. This was not due to differential expression of different sialic acid residues on BECs but was attributed to the interference of the host anti-viral responses by H3N2. The H3N2 strain induced a delay in anti-viral signaling and impaired release of type I and type III interferons (IFNs) compared to the H11N9 virus. We then transfected the gene encoding for non-structural (NS) 1 protein into the BECs and the H3N2 NS1 induced a greater inhibition of anti-viral responses compared to the H11N9 NS1. While the low pathogenic avian influenza virus was capable of infecting BECs, the human influenza virus replicated more effectively than avian influenza virus in BECs and this may be at least in part due to a differential ability of the two NS1 proteins to inhibit anti-viral responses. This suggests that the subversion of human anti-viral responses may be an important requirement for influenza viruses to adapt to the human host and induce disease. Overall design: One (2hr) or three (6hr, 24hr) replicates of each infection (H3N2, H11N9) and two replicates of media control samples (24hr) were performed and hybridized onto the beadchip. The supplementary file 'GSE19580.non-normalized.txt' file contains non-normalized data for Samples GSM487974-GSM487989.
Project description:Background. The pathogenesis of influenza A virus subtype H5N1 (hearafter, "H5N1") infection in humans is not completely understood, although hypercytokinemia is thought to play a role. We previously reported that most H5N1 viruses induce high cytokine responses in human macrophages, whereas some H5N1 viruses induce only a low level of cytokine production similar to that induced by seasonal viruses. Methods. To identify the viral molecular determinants for cytokine induction of H5N1 viruses in human macrophages, we generated a series of reassortant viruses between the high cytokine inducer A/Vietnam/UT3028II/03 clone 2 (VN3028IIcl2) and the low inducer A/Indonesia/UT3006/05 (IDN3006), and evaluated cytokine expression in human macrophages. Results. Viruses possessing the acidic polymerase (PA) gene of VN3028IIcl2 exhibited high levels of hypercytokinemia-related cytokine expression in human macrophages, compared with IDN3006, but showed no substantial differences in viral growth in these cells. Further, the PA gene of VN3028IIcl2 conferred enhanced virulence in mice. Conclusions. These results demonstrate that the PA gene of VN3028IIcl2 affects cytokine production in human macrophages and virulence in mice. These findings provide new insights into the cytokine-mediated pathogenesis of H5N1 infection in humans. Human monocyte-derived macrophages were mock-infected, or infected with IDN3006, VN3028IIcl2, or IDN3006/cl2PA at a multiplicity of infection (MOI) of 2. At 6 hours post-infection (hpi), the cells were harvested and subjected to microarray analysis (three technical replicates per each group).
Project description:Human tracheobronchial epithelial (HTBE) cells are considered to serve as a good correlate of influenza virus infection in the human respiratory tract. mRNA-Seq analysis was used to profile the cellular transcriptome of HTBE cells at multiple time points in response to infection with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), and A/Vietnam/1203/04 (H5N1) HALo virus. The Influenza A/Vietnam/1203/04 (H5N1) HALo mutant virus is an attenuated H5N1 virus generated from wild-type Influenza A/Vietnam/1203/04 (H5N1) virus as described in Steel, J., et al. J Virol. 2009 Feb; 83(4):1742-53. Overall design: Human tracheobronchial epithelial (HTBE) cells that have been isolated from normal donor airway epithelial tissue were infected with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), and A/Vietnam/1203/04 (H5N1) HALo virus at an MOI of 5. H3N2- and H5N1-infected samples and time-matched mock-infected samples were collected in duplicates at 3, 6, 12, and 18 hrs post infection for mRNA-Seq analysis. Sample from H1N1-infected cells and mock controls were collected at 3, 6, 12, 18, and 24 hrs.
Project description:Human monocyte-derived macrophages (MDM) serve as a model for resident alveolar macrophages (AM) in the human respiratory tract. mRNA-Seq analysis was used to profile the cellular transcriptome of MDM cells at multiple time points in response to infection with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), and A/Vietnam/1203/04 (H5N1) HALo virus. The Influenza A/Vietnam/1203/04 (H5N1) HALo mutant virus is an attenuated H5N1 virus generated from wild-type Influenza A/Vietnam/1203/04 (H5N1) virus as described in Steel, J., et al. J Virol. 2009 Feb; 83(4):1742-53. Overall design: Human monocyte-derived macrophages (MDM), obtained from healthy donor blood, were infected with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), or A/Vietnam/1203/04 (H5N1) HALo virus. Infected samples and time-matched mock-infected samples were collected in duplicates at 3, 6, 12, and 18 hrs post infection for mRNA-Seq analysis.
Project description:The highly pathogenic avian influenza (HPAI) H5N1 viruses continue to circulate in nature and threaten public health. Although several viral determinants and host factors that influence the virulence of HPAI H5N1 viruses in mammals have been identified, the detailed molecular mechanism remains poorly defined and requires further clarification. In our previous studies, we characterized two naturally isolated HPAI H5N1 viruses that had similar viral genomes but differed substantially in their lethality in mice. Here, we explored the molecular determinants and potential mechanism for this difference in virulence. By using reverse genetics, we found that a single amino acid at position 158 of the hemagglutinin (HA) protein substantially affected the systemic replication and pathogenicity of these H5N1 influenza viruses in mice. We further found that the G158N mutation introduced an N-linked glycosylation at sites 158–160 of the HA protein and that this N-linked glycosylation enhanced viral productivity in infected mammalian cells and induced stronger host immune and inflammatory responses to viral infection. These findings further our understanding of the determinants of pathogenicity of H5N1 viruses in mammals. Overall design: For all gene expression analyses, groups of three mice were inoculated with PBS or 106 EID50 of CK/1180 or CK/1180-1214HA. Total RNA was extracted from lung tissues on day 3 p.i. by using a QIAGEN RNeasy kit. The microarray assay was performed by using a Low RNA Input Linear Amplification Kit (Agilent Technologies, Santa Clara, CA) and Agilent’s Whole Mouse Genome Microarray Kit, 4×44 K (G4122F)
Project description:A novel avian-origin H7N9 influenza A virus (IAV) emerged in China in early 2013 causing mild to lethal human respiratory infections. H7N9 originated from multiple reassortment events between avian viruses and carries genetic markers of human adaptation. Determining whether H7N9 induces a host-response closer to human or avian IAV is important to better characterize this emerging virus. Here we compared the human lung epithelial cell response to infection with A/Anhui/01/13 (H7N9) or highly pathogenic avian-origin H5N1, H7N7, or human seasonal H3N2 IAV. Here, polarized confluent monolayers of Calu-3 cells were infected apically with the avian-origin IAVs A/Anhui/01/2013 (H7N9) [Anhui01], A/Netherland/219/2003 (H7N7) [NL219], A/Vietnam/1203/2004 (H5N1) [VN1203], or a human seasonal virus A/Panama/2007/1999 (H3N2) [Pan99] at an MOI of 1. Time-matched mocks were also included using the same cell stock as the rest of the samples. Culture medium (same as what the virus stock is in) was used for the mock infections. Quadruplicate wells were infected for each virus/timepoint. Measured timepoints were 3, 7, 12 and 24 hours post-inoculation and the RNA was used for transcriptional analysis via microarray.
Project description:The cellular transcriptome of C57BL/6 mouse lungs was profiled by mRNA-Seq analysis at multiple time points in response to infection with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), and A/Vietnam/1203/04 (H5N1) HALo virus. The Influenza A/Vietnam/1203/04 (H5N1) HALo mutant virus is an attenuated H5N1 virus generated from wild-type Influenza A/Vietnam/1203/04 (H5N1) virus as described in Steel, J., et al. J Virol. 2009 Feb; 83(4):1742-53. A/Wyoming/03/03 (H3N2) influenza virus replicates poorly in mice and lung tissue collected from mice inoculated with this virus did not carry viral loads detectable by plaque assay. Overall design: Six to eight week-old female C57BL/6 mice were infected with influenza A/California/04/09 (H1N1), A/Wyoming/03/03 (H3N2), or A/Vietnam/1203/04 (H5N1) HALo virus. Lungs from 3 infected mice per experimental group were collected at 12h, 1d, 2d, 3d and 4d post infection. Lungs of mice treated with PBS, collected after 4 d, served as mock control.
Project description:Analysis of gene expression in human macrophages infected with influenza A viruses expressing full length or truncated NS1 protein. The hypothesis tested was that C-terminal truncations of viral NS1 protein attenuate the capability of NS1 to limit activation of host antiviral and immune response genes. Cells were infected with influenza A/WSN/33 viruses expressing wild type NS1 protein (WSN-230), NS1 protein of 220 aa long (WSN-220) and NS1 protein of 202 aa long (WSN-202) on non-infected (Mock) Overall design: Total RNA isolated from macrophages after 8 hours of infection with wild type or mutant influenza A virus (multiplicity of infection = 2)
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. Primary human tracheobronchial epithelial (HTBE) cells were washed and infected with 4×10^6 p.f.u. Tx/91 or Tx/91 NS1 : 1–126 viruses per filter (m.o.i. of 20) for 1 h at 37 °C. Three replicate wells were infected for each condition per time point. Allantoic fluid was used for mock treatments. At 9.5 and 25 h p.i., cells were collected and resuspended in TRIzol reagent (Invitrogen) for total RNA extraction. A549 cells were infected with Tx/91 or Tx/91 NS1 : 1–126 viruses at an m.o.i. of 2 for 1 h at 4 °C. Three replicate wells were infected for each condition per time point. Allantoic fluid was used for mock treatments. A549 cells were collected and lysed in solution D (4 M guanidinium thiocyanate, 25 mM sodium citrate, 0.5 % sarcosyl, 0.1 M β-mercaptoethanol) at 12 and 24 h p.i. for total RNA extraction.