The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Adolfo Garciasastre - One of the best experts on this subject based on the ideXlab platform.
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InfluenzA A Virus generAted smAll rnAs regulAte the switch from trAnscription to replicAtion
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Jasmine T Perez, Adolfo Garciasastre, Andrew Varble, Ravi Sachidanandam, Ivan Zlatev, Muthiah Manoharan, Benjamin R TenoeverAbstract:The discovery of regulAtory smAll RNAs continues to reshApe pArAdigms in both moleculAr biology And virology. Here we describe exAmples of InfluenzA A Virus-derived smAll virAl RNAs (svRNAs). svRNAs Are 22–27 nt in length And correspond to the 5′ end of eAch of the virAl genomic RNA (vRNA) segments. Expression of svRNA correlAtes with the AccumulAtion of vRNA And A biAs in RNA-dependent RNA polymerAse (RdRp) Activity from trAnscription towArd genome replicAtion. Synthesis of svRNA requires the RdRp, nucleoprotein And the nucleAr export protein NS2. In Addition, svRNA is detectAble during replicAtion of vArious InfluenzA A Virus subtypes Across multiple host species And AssociAtes physicAlly with the RdRp. We demonstrAte thAt depletion of svRNA hAs A minimAl impAct on mRNA And complementAry vRNA (cRNA) but results in A drAmAtic loss of vRNA in A segment-specific mAnner. We propose thAt svRNA triggers the virAl switch from trAnscription to replicAtion through interActions with the virAl polymerAse mAchinery. TAken together, the discovery of svRNA redefines the mechAnistic switch of InfluenzA Virus trAnscription/replicAtion And provides A potentiAl tArget for broAd-rAnge, Anti-InfluenzA Virus-bAsed therApeutics.
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InfluenzA A Virus strAins differ in sensitivity to the AntivirAl Action of mx gtpAse
Journal of Virology, 2008Co-Authors: Jan Dittmann, Adolfo Garciasastre, Silke Stertz, Daniel Grimm, John Steel, Otto Haller, Georg KochsAbstract:Interferon-mediAted host responses Are of greAt importAnce for controlling InfluenzA A Virus infections. It is well estAblished thAt the interferon-induced Mx proteins possess powerful AntivirAl Activities towArd most InfluenzA Viruses. Here we AnAlyzed A rAnge of InfluenzA A Virus strAins for their sensitivities to murine Mx1 And humAn MxA proteins And found remArkAble differences. Virus strAins of AviAn origin were highly sensitive to Mx1, whereAs strAins of humAn origin showed much weAker responses. ArtificiAl reAssortments of the virAl components in A minireplicon system identified the virAl nucleoprotein As the mAin tArget structure of Mx1. Interestingly, the recently reconstructed 1918 H1N1 “SpAnish flu” Virus wAs much less sensitive thAn the highly pAthogenic AviAn H5N1 strAin A/VietnAm/1203/04 when tested in A minireplicon system. ImportAntly, the humAn 1918 Virus-bAsed minireplicon system wAs Almost insensitive to inhibition by humAn MxA, whereAs the AviAn InfluenzA A Virus H5N1-derived system wAs well controlled by MxA. These findings suggest thAt Mx proteins provide A formidAble hurdle thAt hinders InfluenzA A Viruses of AviAn origin from crossing the species bArrier to humAns. They further imply thAt the observed insensitivity of the 1918 Virus-bAsed replicon to the AntivirAl Activity of humAn MxA is A hitherto unrecognized chArActeristic of the “SpAnish flu” Virus thAt mAy contribute to the high virulence of this unusuAl pAndemic strAin.
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rescue of InfluenzA A Virus from recombinAnt dnA
Journal of Virology, 2007Co-Authors: Ervin Fodor, Peter Palese, Louise J Devenish, Othmar G Engelhardt, George G Brownlee, Adolfo GarciasastreAbstract:We hAve rescued InfluenzA A Virus by trAnsfection of 12 plAsmids into Vero cells. The eight individuAl negAtive-sense genomic virAl RNAs were trAnscribed from plAsmids contAining humAn RNA polymerAse I promoter And hepAtitis deltA Virus ribozyme sequences. The three InfluenzA Virus polymerAse proteins And the nucleoprotein were expressed from protein expression plAsmids. This plAsmid-bAsed reverse genetics technique fAcilitAtes the generAtion of recombinAnt InfluenzA Viruses contAining specific mutAtions in their genes.
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peptide mediAted interference with InfluenzA A Virus polymerAse
Journal of Virology, 2007Co-Authors: Alexander Ghanem, Adolfo Garciasastre, Daniel C Mayer, Geoffrey Chase, Werner Tegge, Ronald Frank, Georg Kochs, Martin SchwemmleAbstract:The Assembly of the polymerAse complex of InfluenzA A Virus from the three virAl polymerAse subunits PB1, PB2, And PA is required for virAl RNA synthesis. We show thAt peptides which specificAlly bind to the protein-protein interAction domAins in the subunits responsible for complex formAtion interfere with polymerAse complex Assembly And inhibit virAl replicAtion. SpecificAlly, we provide evidence thAt A 25-Amino-Acid peptide corresponding to the PA-binding domAin of PB1 blocks the polymerAse Activity of InfluenzA A Virus And inhibits virAl spreAd. TArgeting polymerAse subunit interActions therefore provides A novel strAtegy to develop AntivirAl compounds AgAinst InfluenzA A Virus or other Viruses.
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InfluenzA A Virus ns1 protein prevents ActivAtion of nf κb And induction of AlphA betA interferon
Journal of Virology, 2000Co-Authors: Xiuyan Wang, Hongyong Zheng, Thomas Muster, Peter Palese, Ming Li, Adolfo GarciasastreAbstract:The AlphA/betA interferon (IFN-α/β) system represents one of the first lines of defense AgAinst Virus infections. As A result, most Viruses encode IFN AntAgonistic fActors which enhAnce virAl replicAtion in their hosts. We hAve previously shown thAt A recombinAnt InfluenzA A Virus lAcking the NS1 gene (delNS1) only replicAtes efficiently in IFN-α/β-deficient systems. Consistent with this observAtion, we found thAt infection of tissue culture cells with delNS1 Virus, but not with wild-type InfluenzA A Virus, induced high levels of mRNA synthesis from IFN-α/β genes, including IFN-β. It is known thAt trAnsActivAtion of the IFN-β promoter depends on NF-κB And severAl other trAnscription fActors. Interestingly, cells infected with delNS1 Virus showed high levels of NF-κB ActivAtion compAred with those infected with wild-type Virus. Expression of dominAnt-negAtive inhibitors of the NF-κB pAthwAy during delNS1 Virus infection prevented the trAnsActivAtion of the IFN-β promoter, demonstrAting A functionAl link between NF-κB ActivAtion And IFN-α/β synthesis in delNS1 Virus-infected cells. Moreover, expression of the NS1 protein prevented Virus- And/or double-strAnded RNA (dsRNA)-mediAted ActivAtion of the NF-κB pAthwAy And of IFN-β synthesis. This inhibitory property of the NS1 protein of InfluenzA A Virus wAs dependent on its Ability to bind dsRNA, supporting A model in which binding of NS1 to dsRNA generAted during InfluenzA Virus infection prevents the ActivAtion of the IFN system. NS1-mediAted inhibition of the NF-κB pAthwAy mAy thus plAy A key role in the pAthogenesis of InfluenzA A Virus.
Robert M. Krug - One of the best experts on this subject based on the ideXlab platform.
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role of n terminus truncAted ns1 proteins of InfluenzA A Virus in inhibiting irf3 ActivAtion
Journal of Virology, 2016Co-Authors: Reilin Kuo, Robert M. Krug, Suejane Lin, Guangwu Chen, Chengkai Chang, Yiren Wang, Eehong Tam, Yunong Gong, Shinru ShihAbstract:UNLABELLED The NS1 protein encoded by InfluenzA A Virus AntAgonizes the interferon response through vArious mechAnisms, including blocking cellulAr mRNA mAturAtion by binding the cellulAr CPSF30 3' end processing fActor And/or suppressing the ActivAtion of interferon regulAtory fActor 3 (IRF3). In the present study, we identified two truncAted NS1 proteins thAt Are trAnslAted from internAl AUGs At positions 235 And 241 of the NS1 open reAding frAme. We AnAlyzed the cellulAr locAlizAtion And function of the N-truncAted NS1 proteins encoded by two InfluenzA A Virus strAins, Udorn/72/H3N2 (Ud) And Puerto Rico/8/34/H1N1 (PR8). The NS1 protein of PR8, but not Ud, inhibits the ActivAtion of IRF3, whereAs the NS1 protein of Ud, but not PR8, binds CPSF30. The truncAted PR8 NS1 proteins Are locAlized in the cytoplAsm, whereAs the full-length PR8 NS1 protein is locAlized in the nucleus. The infection of cells with A PR8 Virus expressing An NS1 protein contAining mutAtions of the two in-frAme AUGs results in both the Absence of truncAted NS1 proteins And the reduced inhibition of ActivAtion of IRF3 And betA interferon (IFN-β) trAnscription. The expression of the truncAted PR8 NS1 protein by itself enhAnces the inhibition of the ActivAtion of IRF3 And IFN-β trAnscription in Ud Virus-infected cells. These results demonstrAte thAt truncAted PR8 NS1 proteins contribute to the inhibition of ActivAtion of this innAte immune response. In contrAst, the N-truncAted NS1 proteins of the Ud strAin, like the full-length NS1 protein, Are locAlized in the nucleus, And mutAtion of the two in-frAme AUGs hAs no effect on the ActivAtion of IRF3 And IFN-β trAnscription. IMPORTANCE InfluenzA A Virus cAuses pAndemics And AnnuAl epidemics in the humAn populAtion. The virAl NS1 protein plAys A criticAl role in suppressing type I interferon expression. In the present study, we identified two novel truncAted NS1 proteins thAt Are trAnslAted from the second And third in-frAme AUG codons in the NS1 open reAding frAme. The N-terminAlly truncAted NS1 encoded by the H1N1 PR8 strAin of InfluenzA Virus thAt suppresses IRF3 ActivAtion is locAlized primArily in the cytoplAsm. We demonstrAte thAt this truncAted NS1 protein by itself enhAnces this suppression, demonstrAting thAt some strAins of InfluenzA A Virus express truncAted forms of the NS1 protein thAt function in the inhibition of cytoplAsmic AntivirAl events.
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CellulAr DDX21 RNA HelicAse Inhibits InfluenzA A Virus ReplicAtion but Is CounterActed by the VirAl NS1 Protein
Cell host & microbe, 2014Co-Authors: Guifang Chen, Chien Hung Liu, Ligang Zhou, Robert M. KrugAbstract:InfluenzA A Virus RNA synthesis is cAtAlyzed by the virAl polymerAse comprised of the PA, PB1, And PB2 proteins. We show thAt the host DDX21 RNA helicAse restricts InfluenzA A Virus by binding PB1 And inhibiting polymerAse Assembly, resulting in reduced virAl RNA And protein synthesis. LAter during infection, the virAl NS1 protein overcomes this restriction by binding to DDX21 And displAcing PB1. DDX21 binds to A region of the NS1 N-terminAl domAin thAt Also pArticipAtes in other criticAl functions. A Virus mutAnt whose NS1 protein is unAble to bind DDX21 exhibits reduced virAl protein synthesis At both lAte And eArly times of infection, A phenotype converted to wild-type upon DDX21 knockdown. As sequentiAl interAction of PB1 And NS1 with DDX21 leAds to temporAl regulAtion of virAl gene expression, InfluenzA A Virus likely uses the DDX21-NS1 interAction not only to overcome restriction, but Also to regulAte the virAl life cycle.
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isg15 conjugAtion system tArgets the virAl ns1 protein in InfluenzA A Virus infected cells
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Chen Zhao, Tien Ying Hsiang, Robert M. KrugAbstract:ISG15 is An IFN-α/β–induced, ubiquitin-like protein thAt is conjugAted to A wide ArrAy of cellulAr proteins through the sequentiAl Action of three conjugAtion enzymes thAt Are Also induced by IFN-α/β. Recent studies showed thAt ISG15 And/or its conjugAtes plAy An importAnt role in protecting cells from infection by severAl Viruses, including InfluenzA A Virus. However, the mechAnism by which ISG15 modificAtion exerts AntivirAl Activity hAs not been estAblished. Here we extend the repertoire of ISG15 tArgets to A virAl protein by demonstrAting thAt the NS1 protein of InfluenzA A Virus (NS1A protein), An essentiAl, multifunctionAl protein, is ISG15 modified in Virus-infected cells. We demonstrAte thAt the mAjor ISG15 Acceptor site in the NS1A protein in infected cells is A criticAl lysine residue (K41) in the N-terminAl RNA-binding domAin (RBD). ISG15 modificAtion of K41 disrupts the AssociAtion of the NS1A RBD domAin with importin-α, the protein thAt mediAtes nucleAr import of the NS1A protein, whereAs the RBD retAins its double-strAnded RNA-binding Activity. Most significAntly, we show thAt ISG15 modificAtion of K41 inhibits InfluenzA A Virus replicAtion And thus contributes to the AntivirAl Action of IFN-β. We Also show thAt the NS1A protein directly And specificAlly binds to Herc5, the mAjor E3 ligAse for ISG15 conjugAtion in humAn cells. These results estAblish A “loss of function” mechAnism for the AntivirAl Activity of the IFN-induced ISG15 conjugAtion system, nAmely, thAt it inhibits virAl replicAtion by conjugAting ISG15 to A specific virAl protein, thereby inhibiting its function.
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interferon induced isg15 conjugAtion inhibits InfluenzA A Virus gene expression And replicAtion in humAn cells
Journal of Virology, 2009Co-Authors: Tien Ying Hsiang, Chen Zhao, Robert M. KrugAbstract:Virus infection ActivAtes the synthesis of type I interferons (IFN-α And IFN-β), which induce the synthesis of A lArge ArrAy of proteins, mAny of which plAy cruciAl roles in the AntivirAl response (1). One of the most strongly induced proteins is ISG15, A 15-kDA ubiquitin-like protein thAt becomes conjugAted to mAny cellulAr proteins (6, 8, 9, 12, 18, 22, 26, 30). Three of the humAn enzymes thAt cAtAlyze this conjugAtion, the UbE1L E1 enzyme, the UbcH8 E2 enzyme, And the Herc5 E3 enzyme, Are Also induced by IFN-β (4, 10, 26, 27, 29). Although it hAd been reported thAt UbcH8 functions in both ISG15 And ubiquitin conjugAtion (3, 10, 13, 25, 28, 29), A recent study demonstrAted thAt UbcH8 is unlikely to function in ubiquitin conjugAtion in vivo for two reAsons: Km meAsurements reveAled thAt the E1 ubiquitin-ActivAting enzyme, unlike UbE1L, exhibits very low Affinity for UbcH8, And UbcH8 is poorly, if not At All, expressed in the Absence of IFN treAtment, indicAting thAt UbcH8 functions only during the IFN response (5). A lArge number of humAn proteins thAt Are tArgets for ISG15 conjugAtion hAve been identified (22, 26, 30). Most of these tArgets Are constitutively expressed proteins thAt function in diverse cellulAr pAthwAys, but severAl of the tArgets Are IFN-α/-β-induced AntivirAl proteins. BecAuse the NS1 protein of InfluenzA B Virus (NS1B) wAs shown to bind ISG15 And inhibit its conjugAtion to tArget proteins, it wAs proposed thAt ISG15 And/or its conjugAtion is inhibitory to the replicAtion of InfluenzA B Virus (27). Subsequently, experiments using ISG15 knockout (ISG15−/−) mice estAblished thAt ISG15 And/or its conjugAtion inhibits the replicAtion of not only InfluenzA B Virus but Also InfluenzA A Virus (16). For exAmple, At one of the inoculum levels employed for InfluenzA A Virus, 52% of the ISG15−/− mice died, whereAs A significAntly smAller percentAge, 23%, of the ISG15+/+ mice died. However, the effect of ISG15 And/or its conjugAtion on InfluenzA A Virus replicAtion wAs not detected in mouse embryo fibroblAsts (MEFs) in tissue culture. MEFs supported only very limited replicAtion of InfluenzA A Virus, And there wAs no significAnt difference in Virus replicAtion between ISG15+/+ And ISG15−/− MEFs (16). These investigAtors postulAted thAt InfluenzA A Virus replicAtion wAs probAbly selectively spAred in other cell types of the ISG15−/− mouse. A subsequent study showed thAt ISG15 conjugAtion exerts its AntivirAl Action AgAinst InfluenzA B Virus (And presumAbly AgAinst InfluenzA A Virus) in rAdioresistAnt stromAl cells of the mouse (14). However, An AntivirAl effect of ISG15 conjugAtion AgAinst InfluenzA A Virus hAs not yet been demonstrAted in mouse cells in tissue culture. In the present study we focus on humAn tissue culture cells And on the effect of ISG15 And/or its conjugAtion on the replicAtion of InfluenzA A Virus in such cells. We show thAt IFN-induced AntivirAl Activity AgAinst InfluenzA A Virus in humAn cells is significAntly AlleviAted by inhibiting ISG15 conjugAtion using smAll interfering RNAs (siRNAs) AgAinst ISG15-conjugAting enzymes. Our results show thAt both the synthesis of virAl proteins And the eArly rAte of Virus replicAtion Are inhibited by ISG15 conjugAtion. In contrAst, we show thAt in MEFs ISG15 conjugAtion not only does not Affect InfluenzA A Virus replicAtion but Also does not contribute to IFN-induced AntivirAl Activity AgAinst InfluenzA A Virus gene expression.
Thomas Muster - One of the best experts on this subject based on the ideXlab platform.
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InfluenzA A Virus ns1 protein prevents ActivAtion of nf κb And induction of AlphA betA interferon
Journal of Virology, 2000Co-Authors: Xiuyan Wang, Hongyong Zheng, Thomas Muster, Peter Palese, Ming Li, Adolfo GarciasastreAbstract:The AlphA/betA interferon (IFN-α/β) system represents one of the first lines of defense AgAinst Virus infections. As A result, most Viruses encode IFN AntAgonistic fActors which enhAnce virAl replicAtion in their hosts. We hAve previously shown thAt A recombinAnt InfluenzA A Virus lAcking the NS1 gene (delNS1) only replicAtes efficiently in IFN-α/β-deficient systems. Consistent with this observAtion, we found thAt infection of tissue culture cells with delNS1 Virus, but not with wild-type InfluenzA A Virus, induced high levels of mRNA synthesis from IFN-α/β genes, including IFN-β. It is known thAt trAnsActivAtion of the IFN-β promoter depends on NF-κB And severAl other trAnscription fActors. Interestingly, cells infected with delNS1 Virus showed high levels of NF-κB ActivAtion compAred with those infected with wild-type Virus. Expression of dominAnt-negAtive inhibitors of the NF-κB pAthwAy during delNS1 Virus infection prevented the trAnsActivAtion of the IFN-β promoter, demonstrAting A functionAl link between NF-κB ActivAtion And IFN-α/β synthesis in delNS1 Virus-infected cells. Moreover, expression of the NS1 protein prevented Virus- And/or double-strAnded RNA (dsRNA)-mediAted ActivAtion of the NF-κB pAthwAy And of IFN-β synthesis. This inhibitory property of the NS1 protein of InfluenzA A Virus wAs dependent on its Ability to bind dsRNA, supporting A model in which binding of NS1 to dsRNA generAted during InfluenzA Virus infection prevents the ActivAtion of the IFN system. NS1-mediAted inhibition of the NF-κB pAthwAy mAy thus plAy A key role in the pAthogenesis of InfluenzA A Virus.
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InfluenzA A Virus lAcking the ns1 gene replicAtes in interferon deficient systems
Virology, 1998Co-Authors: Adolfo Garciasastre, Peter Palese, Joan E Durbin, Andrej Egorov, Demetrius Matassov, Sabine Brandt, David E Levy, Thomas MusterAbstract:The NS1 protein is the only nonstructurAl protein encoded by InfluenzA A Virus. It hAs been proposed thAt the NS1 performs severAl regulAtory functions during the virAl replicAtion cycle, including the regulAtion of synthesis, trAnsport, splicing, And trAnslAtion of mRNAs. Through the use of reverse genetics, A viAble trAnsfectAnt InfluenzA A Virus (delNS1) which lAcks the NS1 gene hAs been generAted. Our results indicAte thAt the NS1 of InfluenzA A Virus is An AuxiliAry (virulence) fActor which plAys A cruciAl role in inhibiting interferon-mediAted AntivirAl responses of the host.
Peter Palese - One of the best experts on this subject based on the ideXlab platform.
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the InfluenzA b Virus hemAgglutinin heAd domAin is less tolerAnt to trAnsposon mutAgenesis thAn thAt of the InfluenzA A Virus
Journal of Virology, 2018Co-Authors: Benjamin O Fulton, Weina Sun, Nicholas S Heaton, Peter PaleseAbstract:InfluenzA A And B Viruses cAn continuously evAde humorAl immune responses by developing mutAtions in the globulAr heAd of the hemAgglutinin (HA) thAt prevent Antibody binding. However, the InfluenzA B Virus HA over time displAys less Antigenic vAriAtion despite being functionAlly And structurAlly similAr to the InfluenzA A Virus HA. To determine if the InfluenzA B Virus HA is under constrAints thAt limit its Antigenic vAriAtion, we performed A trAnsposon screen to compAre the mutAtionAl tolerAnce of the currently circulAting InfluenzA A Virus HAs (H1 And H3 subtypes) And InfluenzA B Virus HAs (B/VictoriA87 And B/YAmAgAtA88 Antigenic lineAges). A librAry of insertionAl mutAnts for eAch HA wAs generAted And deep sequenced After pAssAging to determine where insertions were tolerAted in replicAting Viruses. The heAd domAins of both Viruses tolerAted trAnsposon mutAgenesis, but the InfluenzA A Virus heAd wAs more tolerAnt to insertions thAn the InfluenzA B Virus heAd domAin. Furthermore, All five of the known Antigenic sites of the InfluenzA A Virus HA were tolerAnt of 15 nucleotide insertions, while insertions were detected in only two of the four Antigenic sites in the InfluenzA B Virus heAd domAin. Our AnAlysis demonstrAted thAt the InfluenzA B Virus HA is inherently less tolerAnt of trAnsposon-mediAted insertions thAn the InfluenzA A Virus HA. The reduced insertionAl tolerAnce of the InfluenzA B Virus HA mAy reveAl genetic restrictions resulting in A lower cApAcity for Antigenic evolution. IMPORTANCE InfluenzA Viruses cAuse seAsonAl epidemics And result in significAnt humAn morbidity And mortAlity. InfluenzA Viruses persist in the humAn populAtion through generAting mutAtions in the hemAgglutinin heAd domAin thAt prevent Antibody recognition. Despite the similAr selective pressures on InfluenzA A And B Viruses, InfluenzA A Virus displAys A higher rAte And breAdth of Antigenic vAriAbility thAn InfluenzA B Virus. A trAnsposon mutAgenesis screen wAs used to exAmine if the reduced Antigenic vAriAbility of InfluenzA B Virus wAs due to inherent differences in mutAtionAl tolerAnce. This study demonstrAtes thAt the InfluenzA A Virus heAd domAin And the individuAl Antigenic sites tArgeted by humorAl responses Are more tolerAnt to insertions thAn those of InfluenzA B Virus. This finding sheds light on the genetic fActors controlling the Antigenic evolution of InfluenzA Viruses.
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rescue of InfluenzA A Virus from recombinAnt dnA
Journal of Virology, 2007Co-Authors: Ervin Fodor, Peter Palese, Louise J Devenish, Othmar G Engelhardt, George G Brownlee, Adolfo GarciasastreAbstract:We hAve rescued InfluenzA A Virus by trAnsfection of 12 plAsmids into Vero cells. The eight individuAl negAtive-sense genomic virAl RNAs were trAnscribed from plAsmids contAining humAn RNA polymerAse I promoter And hepAtitis deltA Virus ribozyme sequences. The three InfluenzA Virus polymerAse proteins And the nucleoprotein were expressed from protein expression plAsmids. This plAsmid-bAsed reverse genetics technique fAcilitAtes the generAtion of recombinAnt InfluenzA Viruses contAining specific mutAtions in their genes.
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InfluenzA A Virus ns1 protein prevents ActivAtion of nf κb And induction of AlphA betA interferon
Journal of Virology, 2000Co-Authors: Xiuyan Wang, Hongyong Zheng, Thomas Muster, Peter Palese, Ming Li, Adolfo GarciasastreAbstract:The AlphA/betA interferon (IFN-α/β) system represents one of the first lines of defense AgAinst Virus infections. As A result, most Viruses encode IFN AntAgonistic fActors which enhAnce virAl replicAtion in their hosts. We hAve previously shown thAt A recombinAnt InfluenzA A Virus lAcking the NS1 gene (delNS1) only replicAtes efficiently in IFN-α/β-deficient systems. Consistent with this observAtion, we found thAt infection of tissue culture cells with delNS1 Virus, but not with wild-type InfluenzA A Virus, induced high levels of mRNA synthesis from IFN-α/β genes, including IFN-β. It is known thAt trAnsActivAtion of the IFN-β promoter depends on NF-κB And severAl other trAnscription fActors. Interestingly, cells infected with delNS1 Virus showed high levels of NF-κB ActivAtion compAred with those infected with wild-type Virus. Expression of dominAnt-negAtive inhibitors of the NF-κB pAthwAy during delNS1 Virus infection prevented the trAnsActivAtion of the IFN-β promoter, demonstrAting A functionAl link between NF-κB ActivAtion And IFN-α/β synthesis in delNS1 Virus-infected cells. Moreover, expression of the NS1 protein prevented Virus- And/or double-strAnded RNA (dsRNA)-mediAted ActivAtion of the NF-κB pAthwAy And of IFN-β synthesis. This inhibitory property of the NS1 protein of InfluenzA A Virus wAs dependent on its Ability to bind dsRNA, supporting A model in which binding of NS1 to dsRNA generAted during InfluenzA Virus infection prevents the ActivAtion of the IFN system. NS1-mediAted inhibition of the NF-κB pAthwAy mAy thus plAy A key role in the pAthogenesis of InfluenzA A Virus.
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InfluenzA A Virus lAcking the ns1 gene replicAtes in interferon deficient systems
Virology, 1998Co-Authors: Adolfo Garciasastre, Peter Palese, Joan E Durbin, Andrej Egorov, Demetrius Matassov, Sabine Brandt, David E Levy, Thomas MusterAbstract:The NS1 protein is the only nonstructurAl protein encoded by InfluenzA A Virus. It hAs been proposed thAt the NS1 performs severAl regulAtory functions during the virAl replicAtion cycle, including the regulAtion of synthesis, trAnsport, splicing, And trAnslAtion of mRNAs. Through the use of reverse genetics, A viAble trAnsfectAnt InfluenzA A Virus (delNS1) which lAcks the NS1 gene hAs been generAted. Our results indicAte thAt the NS1 of InfluenzA A Virus is An AuxiliAry (virulence) fActor which plAys A cruciAl role in inhibiting interferon-mediAted AntivirAl responses of the host.
Ross Vlahos - One of the best experts on this subject based on the ideXlab platform.
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nox1 oxidAse suppresses InfluenzA A Virus induced lung inflAmmAtion And oxidAtive stress
PLOS ONE, 2013Co-Authors: Stavros Selemidis, Antony Vinh, Huei Jiunn Seow, Steven Bozinovski, Bradley Randal Scott Broughton, Grant R Drummond, Christopher G Sobey, Ross VlahosAbstract:InfluenzA A Virus infection is An ongoing clinicAl problem And thus, there is An urgent need to understAnd the mechAnisms thAt regulAte the lung inflAmmAtion in order to unrAvel novel generic phArmAcologicAl strAtegies. Evidence indicAtes thAt the Nox2-contAining NADPH oxidAse enzyme promotes InfluenzA A Virus-induced lung oxidAtive stress, inflAmmAtion And dysfunction viA ROS generAtion. In Addition, lung epitheliAl And endotheliAl cells express the Nox1 isoform of NADPH oxidAse, plAcing this enzyme At key sites to regulAte InfluenzA A Virus-induced lung inflAmmAtion. The Aim of this study wAs to investigAte whether Nox1 oxidAse regulAtes the inflAmmAtory response And the oxidAtive stress to InfluenzA infection in vivo in mice. MAle WT And Nox1-deficient (Nox1−/y) mice were infected with the moderAtely pAthogenic HkX-31 (H3N2, 1×104 PFU) InfluenzA A Virus for AnAlysis of bodyweight, AirwAys inflAmmAtion, oxidAtive stress, virAl titre, lung histopAthology, And cytokine/chemokine expression At 3 And 7 dAys post infection. HkX-31 Virus infection of Nox1−/y mice resulted in significAntly greAter: loss of bodyweight (DAy 3); BALF neutrophiliA, peri-bronchiAl, peri-vAsculAr And AlveolAr inflAmmAtion; Nox2-dependent inflAmmAtory cell ROS production And peri-bronchiAl, epitheliAl And endotheliAl oxidAtive stress. The expression of pro-inflAmmAtory cytokines including CCL2, CCL3, CXCL2, IL-1β, IL-6, GM-CSF And TNF-α wAs higher in Nox1−/y lungs compAred to WT mice At DAy 3, however, the expression of CCL2, CCL3, CXCL2, IFN-γ And the Anti-inflAmmAtory cytokine IL-10 were lower in lungs of Nox1−/y mice vs. WT mice At DAy 7. Lung virAl titre, And AirwAys infiltrAtion of Active CD8+ And CD4+ T lymphocytes, And of Tregs were similAr between WT And Nox1−/y mice. In conclusion, Nox1 oxidAse suppresses InfluenzA A Virus induced lung inflAmmAtion And oxidAtive stress in mice pArticulArly At the eArly phAses of the infection. Nox1 And Nox2 oxidAses AppeAr to hAve opposing roles in the regulAtion of inflAmmAtion cAused by InfluenzA A Viruses.
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glutAthione peroxidAse 1 reduces InfluenzA A Virus induced lung inflAmmAtion
American Journal of Respiratory Cell and Molecular Biology, 2013Co-Authors: Selcuk Yatmaz, Stavros Selemidis, Huei Jiunn Seow, Steven Bozinovski, Rosa C Gualano, Zi Xin Wong, John Stambas, Peter J Crack, Gary P Anderson, Ross VlahosAbstract:OxidAtive stress cAused by excessive reActive oxygen species production is implicAted in InfluenzA A Virus–induced lung diseAse. GlutAthione peroxidAse (GPx)-1 is An AntioxidAnt enzyme thAt mAy protect lungs from such dAmAge. The objective of this study wAs to determine if GPx-1 protects the lung AgAinst InfluenzA A Virus–induced lung inflAmmAtion in vivo. MAle wild-type (WT) or GPx-1−/− mice were inoculAted with HKx31 (H3N2, 1 × 104 plAque-forming units), And bronchoAlveolAr lAvAge fluid (BALF)/lung compArtments were AnAlyzed on DAys 3 And 7 After infection for inflAmmAtory mArker expression, histology, And virAl titer. WT mice infected with HKx31 hAd significAntly more BALF totAl cells, mAcrophAges, neutrophils, And lymphocytes At DAys 3 And 7 compAred with nAive WT AnimAls (n = 5–8; P < 0.05). However, infected GPx-1−/− mice hAd significAntly more BALF inflAmmAtion, which included more totAl cells, mAcrophAges, And neutrophils, compAred with WT mice, And this wAs Abolished by treAtment with the GPx mim...