scholarly journals Identification of BPR3P0128 as an Inhibitor of Cap-Snatching Activities of Influenza Virus

2011 ◽  
Vol 56 (2) ◽  
pp. 647-657 ◽  
Author(s):  
John T.-A. Hsu ◽  
Jiann-Yih Yeh ◽  
Ta-Jen Lin ◽  
Mei-ling Li ◽  
Ming-Sian Wu ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Viral Replication ◽  
Influenza A ◽  
Large Scale ◽  
Mdck Cells ◽  
Enterovirus 71 ◽  
Dna Viruses ◽  
Polymerase Complex ◽  
Nuclear Extracts

ABSTRACTThe aim of this study was to identify the antiviral mechanism of a novel compound, BPR3P0128. From a large-scale screening of a library of small compounds, BPR3P compounds were found to be potent inhibitors of influenza viral replication in Madin–Darby canine kidney (MDCK) cells. BPR3P0128 exhibited inhibitory activity against both influenza A and B viruses. The 50% inhibitory concentrations were in the range of 51 to 190 nM in MDCK cells, as measured by inhibition-of-cytopathic-effect assays. BPR3P0128 appeared to target the viral replication cycle but had no effect on viral adsorption. The inhibition of cap-dependent mRNA transcription by BPR3P0128 was more prominent with a concurrent increase in cap-independent cRNA replication in a primer extension assay, suggesting a role of BPR3P0128 in switching transcription to replication. This reduction in mRNA expression resulted from the BPR3P-mediated inhibition of the cap-dependent endoribonuclease (cap-snatching) activities of nuclear extracts containing the influenza virus polymerase complex. No inhibition of binding of 5′ viral RNA to the viral polymerase complex by this compound was detected. BPR3P0128 also effectively inhibited other RNA viruses, such as enterovirus 71 and human rhinovirus, but not DNA viruses, suggesting that BPR3P0128 targets a cellular factor(s) associated with viral PB2 cap-snatching activity. The identification of this factor(s) could help redefine the regulation of viral transcription and replication and thereby provide a potential target for antiviral chemotherapeutics.

scholarly journals Influenza Virus Hemagglutinin (H3 Subtype) Requires Palmitoylation of Its Cytoplasmic Tail for Assembly: M1 Proteins of Two Subtypes Differ in Their Ability To Support Assembly

2005 ◽  
Vol 79 (21) ◽  
pp. 13673-13684 ◽  
Author(s):  
Benjamin J. Chen ◽  
Makoto Takeda ◽  
Robert A. Lamb
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Transmembrane Domain ◽  
Mdck Cells ◽  
Virus Assembly ◽  
Cytoplasmic Tail ◽  
Wild Type ◽  
Ha Gene

ABSTRACT The influenza A virus hemagglutinin (HA) transmembrane domain boundary region and the cytoplasmic tail contain three cysteines (residues 555, 562, and 565 for the H3 HA subtype) that are highly conserved among the 16 HA subtypes and which are each modified by the covalent addition of palmitic acid. Previous analysis of the role of these conserved cysteine residues led to differing data, suggesting either no role for HA palmitoylation or an important role for HA palmitoylation. To reexamine the role of these residues in the influenza virus life cycle, a series of cysteine-to-serine mutations were introduced into the HA gene of influenza virus A/Udorn/72 (Ud) (H3N2) by using a highly efficient reverse genetics system. Mutant viruses containing HA-C562S and HA-C565S mutations had reduced growth and failed to form plaques in MDCK cells but formed wild-type-like plaques in an MDCK cell line expressing wild-type HA. In cell-cell fusion assays, nonpalmitoylated H3 HA, in both cDNA-transfected and virus-infected cells, was fully competent for HA-mediated membrane fusion. When the HA cytoplasmic tail cysteine mutants were examined for lipid raft association, using as the criterion Triton X-100 insolubility, loss of raft association did not show a direct correlation with a reduction in virus replication. However, mutant virus assembly was reduced in parallel with reduced virus replication. Additionally, a reassortant of strain A/WSN/33 (WSN), containing the Ud HA gene with mutations C555S, C562S, and C565S, produced virus that could form plaques on regular MDCK cells and had only moderately decreased replication, suggesting differences in the interactions between Ud and WSN HA and internal viral proteins. Analysis of M1 mutants containing substitutions in the six residues that differ between the Ud and WSN M1 proteins indicated that a constellation of residues are responsible for the difference between the M1 proteins in their ability to support virus assembly with nonpalmitoylated H3 HA.

scholarly journals Virulence Determinants of Avian H5N1 Influenza A Virus in Mammalian and Avian Hosts: Role of the C-Terminal ESEV Motif in the Viral NS1 Protein

2010 ◽  
Vol 84 (20) ◽  
pp. 10708-10718 ◽  
Author(s):  
Florian Zielecki ◽  
Ilia Semmler ◽  
Donata Kalthoff ◽  
Daniel Voss ◽  
Susanne Mauel ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Viral Replication ◽  
Influenza A ◽  
Pdz Domain ◽  
Influenza Viruses ◽  
Dependent Manner ◽  
Ns1 Protein ◽  
H5n1 Influenza

ABSTRACT We assessed the prediction that access of the viral NS1 protein to cellular PDZ domain protein networks enhances the virulence of highly pathogenic avian influenza A viruses. The NS1 proteins of most avian influenza viruses bear the C-terminal ligand sequence Glu-Ser-Glu-Val (ESEV) for PDZ domains present in multiple host proteins, whereas no such motif is found in the NS1 homologues of seasonal human virus strains. Previous analysis showed that a C-terminal ESEV motif increases viral virulence when introduced into the NS1 protein of mouse-adapted H1N1 influenza virus. To examine the role of the PDZ domain ligand motif in avian influenza virus virulence, we generated three recombinants, derived from the prototypic H5N1 influenza A/Vietnam/1203/04 virus, expressing NS1 proteins that either have the C-terminal ESEV motif or the human influenza virus RSKV consensus or bear a natural truncation of this motif, respectively. Cell biological analyses showed strong control of NS1 nuclear migration in infected mammalian and avian cells, with only minor differences between the three variants. The ESEV sequence attenuated viral replication on cultured human, murine, and duck cells but not on chicken fibroblasts. However, all three viruses caused highly lethal infections in mice and chickens, with little difference in viral titers in organs, mean lethal dose, or intravenous pathogenicity index. These findings demonstrate that a PDZ domain ligand sequence in NS1 contributes little to the virulence of H5N1 viruses in these hosts, and they indicate that this motif modulates viral replication in a strain- and host-dependent manner.

Enterovirus 71 induces integrin β1/EGFR-Rac1-dependent oxidative stress in SK-N-SH cells: Role of HO-1/CO in viral replication

2011 ◽  
Vol 226 (12) ◽  
pp. 3316-3329 ◽  
Author(s):  
Wei-Hsuan Tung ◽  
Hsi-Lung Hsieh ◽  
I-Ta Lee ◽  
Chuen-Mao Yang
Keyword(s):  
Oxidative Stress ◽  
Viral Replication ◽  
Enterovirus 71 ◽  
Integrin Β1

scholarly journals Functional Analysis of PA Binding by Influenza A Virus PB1: Effects on Polymerase Activity and Viral Infectivity

2001 ◽  
Vol 75 (17) ◽  
pp. 8127-8136 ◽  
Author(s):  
Daniel R. Perez ◽  
Ruben O. Donis
Keyword(s):  
Amino Acids ◽  
Influenza Virus ◽  
Amino Acid ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Amino Acid Sequences ◽  
Influenza Viruses ◽  
Virus Growth ◽  
Transcription And Replication

ABSTRACT Influenza A virus expresses three viral polymerase (P) subunits—PB1, PB2, and PA—all of which are essential for RNA and viral replication. The functions of P proteins in transcription and replication have been partially elucidated, yet some of these functions seem to be dependent on the formation of a heterotrimer for optimal viral RNA transcription and replication. Although it is conceivable that heterotrimer subunit interactions may allow a more efficient catalysis, direct evidence of their essentiality for viral replication is lacking. Biochemical studies addressing the molecular anatomy of the P complexes have revealed direct interactions between PB1 and PB2 as well as between PB1 and PA. Previous studies have shown that the N-terminal 48 amino acids of PB1, termed domain α, contain the residues required for binding PA. We report here the refined mapping of the amino acid sequences within this small region of PB1 that are indispensable for binding PA by deletion mutagenesis of PB1 in a two-hybrid assay. Subsequently, we used site-directed mutagenesis to identify the critical amino acid residues of PB1 for interaction with PA in vivo. The first 12 amino acids of PB1 were found to constitute the core of the interaction interface, thus narrowing the previous boundaries of domain α. The role of the minimal PB1 domain α in influenza virus gene expression and genome replication was subsequently analyzed by evaluating the activity of a set of PB1 mutants in a model reporter minigenome system. A strong correlation was observed between a functional PA binding site on PB1 and P activity. Influenza viruses bearing mutant PB1 genes were recovered using a plasmid-based influenza virus reverse genetics system. Interestingly, mutations that rendered PB1 unable to bind PA were either nonviable or severely growth impaired. These data are consistent with an essential role for the N terminus of PB1 in binding PA, P activity, and virus growth.

scholarly journals Polymerase Acidic Subunit of H9N2 Polymerase Complex Induces Cell Apoptosis by Binding to PDCD 7 in A549 Cells

2020 ◽  
Author(s):  
Shaohua Wang ◽  
Na Li ◽  
Shugang Jin ◽  
Ruihua Zhang ◽  
Tong Xu
Keyword(s):  
Cell Death ◽  
Influenza Virus ◽  
Cell Apoptosis ◽  
Influenza A ◽  
A549 Cells ◽  
Influenza Virus Infection ◽  
Economic Loss ◽  
Poultry Production ◽  
H9n2 Influenza Virus

Abstract Background: H9N2 influenza virus, a subtype of influenza A virus, can spread across different species and induce the respiratory infectious disease in humans, leading to a severe public health risk and a huge economic loss to poultry production. Increasing studies have shown that polymerase acidic (PA) subunit of RNA polymerase in ribonucleoproteins complex of H9N2 involves in crossing the host species barriers, the replication and airborne transmission of H9N2.Methods: Here, to further investigate the role of PA subunit during the infection of H9N2 influenza virus, we employed mass spectrometry (MS) to search the potential binding proteins of PA subunit of H9N2. Our MS results showed that programmed cell death protein 7 (PDCD7) is a binding target of PA subunit. Co-immunoprecipitation and pull-down assays further confirmed the interaction between PDCD7 and PA subunit. Overexpression of PA subunit in A549 lung cells greatly increased the levels of PDCD7 in the nuclear and induced cell death assayed by MTT assay.Results: Flow cytometry analysis and Western blot results showed that PA subunit overexpression significantly increased the expression of pro-apoptotic protein, bax and caspase 3, and induced cell apoptosis. However, knockout of PDCD7 effectively attenuated the effects of PA overexpression in cell apoptosis.Conclusions: In conclusion, the PA subunit of H9N2 bind with PDCD7 and regulated cell apoptosis, which provide new insights in the role of PA subunit during H9N2 influenza virus infection.

scholarly journals NAction! How Can Neuraminidase-Based Immunity Contribute to Better Influenza Virus Vaccines?

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Florian Krammer ◽  
Ron A. M. Fouchier ◽  
Maryna C. Eichelberger ◽  
Richard J. Webby ◽  
Kathryn Shaw-Saliba ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Vaccine Development ◽  
Protective Role ◽  
National Institutes Of Health ◽  
Antigenic Drift ◽  
Centers Of Excellence ◽  
Open Questions ◽  
Infection Mechanisms

ABSTRACTNeuraminidase is one of the two surface glycoproteins of influenza A and B viruses. It has enzymatic activity that cleaves terminal sialic acid from glycans, and that activity is essential at several points in the virus life cycle. While neuraminidase is a major target for influenza antivirals, it is largely ignored in vaccine development. Current inactivated influenza virus vaccines might contain neuraminidase, but the antigen quantity and quality are varied and not standardized. While there are data that show a protective role of anti-neuraminidase immunity, many questions remain unanswered. These questions, among others, concern the targeted epitopes or antigenic sites, the potential for antigenic drift, and, connected to that, the breadth of protection, differences in induction of immune responses by vaccination versus infection, mechanisms of protection, the role of mucosal antineuraminidase antibodies, stability, and the immunogenicity of neuraminidase in vaccine formulations. Reagents for analysis of neuraminidase-based immunity are scarce, and assays are not widely used for clinical studies evaluating vaccines. However, efforts to better understand neuraminidase-based immunity have been made recently. A neuraminidase focus group, NAction!, was formed at a Centers of Excellence for Influenza Research and Surveillance meeting at the National Institutes of Health in Bethesda, MD, to promote research that helps to understand neuraminidase-based immunity and how it can contribute to the design of better and broadly protective influenza virus vaccines. Here, we review open questions and knowledge gaps that have been identified by this group and discuss how the gaps can be addressed, with the ultimate goal of designing better influenza virus vaccines.

scholarly journals Deep Mutational Scan of the Highly Conserved Influenza A Virus M1 Matrix Protein Reveals Substantial Intrinsic Mutational Tolerance

2019 ◽  
Vol 93 (13) ◽  
Author(s):  
Nancy Hom ◽  
Lauren Gentles ◽  
Jesse D. Bloom ◽  
Kelly K. Lee
Keyword(s):  
Cell Culture ◽  
Influenza Virus ◽  
Amino Acid ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Matrix Protein ◽  
Influenza Virus Infection ◽  
Sequence Diversity ◽  
Virus Protein

ABSTRACTInfluenza A virus matrix protein M1 is involved in multiple stages of the viral infectious cycle. Despite its functional importance, our present understanding of this essential viral protein is limited. The roles of a small subset of specific amino acids have been reported, but a more comprehensive understanding of the relationship between M1 sequence, structure, and virus fitness remains elusive. In this study, we used deep mutational scanning to measure the effect of every amino acid substitution in M1 on viral replication in cell culture. The map of amino acid mutational tolerance we have generated allows us to identify sites that are functionally constrained in cell culture as well as sites that are less constrained. Several sites that exhibit low tolerance to mutation have been found to be critical for M1 function and production of viable virions. Surprisingly, significant portions of the M1 sequence, especially in the C-terminal domain, whose structure is undetermined, were found to be highly tolerant of amino acid variation, despite having extremely low levels of sequence diversity among natural influenza virus strains. This unexpected discrepancy indicates that not all sites in M1 that exhibit high sequence conservation in nature are under strong constraint during selection for viral replication in cell culture.IMPORTANCEThe M1 matrix protein is critical for many stages of the influenza virus infection cycle. Currently, we have an incomplete understanding of this highly conserved protein’s function and structure. Key regions of M1, particularly in the C terminus of the protein, remain poorly characterized. In this study, we used deep mutational scanning to determine the extent of M1’s tolerance to mutation. Surprisingly, nearly two-thirds of the M1 sequence exhibits a high tolerance for substitutions, contrary to the extremely low sequence diversity observed across naturally occurring M1 isolates. Sites with low mutational tolerance were also identified, suggesting that they likely play critical functional roles and are under selective pressure. These results reveal the intrinsic mutational tolerance throughout M1 and shape future inquiries probing the functions of this essential influenza A virus protein.

scholarly journals RNA-Sequencing-Based Transcriptomic Analysis Reveals a Role for Annexin-A1 in Classical and Influenza A Virus-Induced Autophagy

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1399 ◽  
Author(s):  
Jianzhou Cui ◽  
Dhakshayini Morgan ◽  
Dao Han Cheng ◽  
Sok Lin Foo ◽  
Gracemary L. R. Yap ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Infection ◽  
Critical Role ◽  
Mtor Inhibitors ◽  
Influenza Viruses ◽  
Annexin A1 ◽  
Underlying Mechanisms

Influenza viruses have been shown to use autophagy for their survival. However, the proteins and mechanisms involved in the autophagic process triggered by the influenza virus are unclear. Annexin-A1 (ANXA1) is an immunomodulatory protein involved in the regulation of the immune response and Influenza A virus (IAV) replication. In this study, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 (CRISPR associated protein 9) deletion of ANXA1, combined with the next-generation sequencing, we systematically analyzed the critical role of ANXA1 in IAV infection as well as the detailed processes governing IAV infection, such as macroautophagy. A number of differentially expressed genes were uniquely expressed in influenza A virus-infected A549 parental cells and A549 ∆ANXA1 cells, which were enriched in the immune system and infection-related pathways. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed the role of ANXA1 in autophagy. To validate this, the effect of mechanistic target of rapamycin (mTOR) inhibitors, starvation and influenza infection on autophagy was determined, and our results demonstrate that ANXA1 enhances autophagy induced by conventional autophagy inducers and influenza virus. These results will help us to understand the underlying mechanisms of IAV infection and provide a potential therapeutic target for restricting influenza viral replication and infection.

scholarly journals Double-Edged Role of Interleukin 17A in Streptococcus pneumoniae Pathogenesis During Influenza Virus Coinfection

2019 ◽  
Vol 220 (5) ◽  
pp. 902-912 ◽  
Author(s):  
Ganesh Ambigapathy ◽  
Taylor Schmit ◽  
Ram Kumar Mathur ◽  
Suba Nookala ◽  
Saad Bahri ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Puerto Rico ◽  
Streptococcus Pneumoniae ◽  
Influenza A ◽  
Invasive Disease ◽  
Wild Type ◽  
Interleukin 17A ◽  
Influenza A H1n1 ◽  
Virus Influenza

AbstractBackgroundWe sought to determine the role of host interleukin 17A (IL-17A) response against colonizing Streptococcus pneumoniae, and its transition to a pathogen during coinfection with an influenza virus, influenza A H1N1 A/Puerto Rico/8/1934 (PR8).MethodWild-type (WT) C57BL/6 mice were intranasally inoculated with S. pneumoniae serotype 6A to establish colonization and later infected with the influenza strain, PR8, resulting in invasive S. pneumoniae disease. The role of the IL-17A response in colonization and coinfection was investigated in WT, RoRγt−/− and RAG1−/− mice with antibody-mediated depletion of IL-17A (WT) and CD90 cells (RAG1−/−).ResultsRAG1−/− mice did not clear colonization and IL-17A neutralization impaired 6A clearance in WT mice. RoRγt−/− mice also had reduced clearance. S. pneumoniae–PR8 coinfection elicited a robust IL-17A response in the nasopharynx; IL-17A neutralization reduced S. pneumoniae invasive disease. RoRγt−/− mice also had reduced S. pneumoniae disease in a coinfection model. Depletion of CD90+ cells suppressed the IL-17A response and reduced S. pneumoniae invasion in RAG1−/− mice.ConclusionOur data show that although IL-17A reduces S. pneumoniae colonization, coinfection with influenza virus elicits a robust innate IL-17A response that promotes inflammation and S. pneumoniae disease in the nasopharynx.

Sign in / Sign up

Export Citation Format

Share Document