scholarly journals Structural basis of influenza virus fusion inhibition by the antiviral drug Arbidol

2016 ◽  
Vol 114 (2) ◽  
pp. 206-214 ◽  
Author(s):  
Rameshwar U. Kadam ◽  
Ian A. Wilson
Keyword(s):  
Influenza Virus ◽  
Broad Spectrum ◽  
Hydrophobic Interactions ◽  
Antiviral Drug ◽  
Binding Mode ◽  
Influenza Viruses ◽  
Structural Basis ◽  
Salt Bridges ◽  
Fusion Inhibition ◽  
Conformational Rearrangements

The broad-spectrum antiviral drug Arbidol shows efficacy against influenza viruses by targeting the hemagglutinin (HA) fusion machinery. However, the structural basis of the mechanism underlying fusion inhibition by Arbidol has remained obscure, thereby hindering its further development as a specific and optimized influenza therapeutic. We determined crystal structures of Arbidol in complex with influenza virus HA from pandemic 1968 H3N2 and recent 2013 H7N9 viruses. Arbidol binds in a hydrophobic cavity in the HA trimer stem at the interface between two protomers. This cavity is distal to the conserved epitope targeted by broadly neutralizing stem antibodies and is ∼16 Å from the fusion peptide. Arbidol primarily makes hydrophobic interactions with the binding site but also induces some conformational rearrangements to form a network of inter- and intraprotomer salt bridges. By functioning as molecular glue, Arbidol stabilizes the prefusion conformation of HA that inhibits the large conformational rearrangements associated with membrane fusion in the low pH of the endosome. This unique binding mode compared with the small-molecule inhibitors of other class I fusion proteins enhances our understanding of how small molecules can function as fusion inhibitors and guides the development of broad-spectrum therapeutics against influenza virus.

scholarly journals Discovery of a novel specific inhibitor targeting influenza A nucleoprotein with pleiotropic inhibitory effects on various steps of viral life cycle

2021 ◽  
Author(s):  
Fang Yang ◽  
Bo Pang ◽  
Kin Kui Lai ◽  
Nam Nam Cheung ◽  
Jun Dai ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Broad Spectrum ◽  
Influenza A ◽  
Recurrent Events ◽  
Antiviral Drug ◽  
Influenza Virus Infection ◽  
Specific Inhibitor ◽  
Influenza Viruses ◽  
Novel Influenza A

Influenza viruses (IAV) continue to pose an imminent threat to human due to annual influenza epidemics outbreak and episodic pandemics with high mortality. In this context, the suboptimal vaccine coverage and efficacy, coupled with recurrent events of viral resistance against a very limited antiviral portfolio, emphasize an urgent need for new additional prophylactic and therapeutic options, including new antiviral targets and drugs with new mechanisms of action to prevent and treat influenza infection. Here we characterized a novel influenza A nucleoprotein (NP) inhibitor FA-6005 that inhibited a broad spectrum of human pandemic, seasonal influenza A and B viruses in vitro and protects mice against lethal influenza A virus challenge. The small molecule FA-6005 targeted a conserved NP I41 domain and acted as a potential broad, multi-mechanistic anti-influenza virus therapeutic since FA-6005 suppressed influenza virus replication and perturbed intracellular trafficking of viral ribonucleoproteins (vRNP) from early to late stage. Cocrystal structures of the NP/FA-6005 complex reconciled well with concurrent mutational studies. This study provides the first line of direct evidence suggesting that the newly-identified NP I41 pocket as an attractive target for drug development that inhibit the multiple functions of NP. Our results also highlighted FA-6005 as a promising candidate for further development as an antiviral drug for the treatment of IAV infection and provide chemical-level details for inhibitor optimization. Importance Current influenza antivirals have limitations with regard to their effectiveness and the potential emergence of resistance. Therefore, there is an urgent need for broad-spectrum inhibitors to address the considerable challenges posed by the rapid evolution of influenza viruses that limit the effectiveness of vaccines and the emergence of antiviral drug resistance. Herein we identified a novel influenza A virus NP antagonist FA-6005 with broad-spectrum efficacy against influenza viruses and our study presented a comprehensive study of mode of action of FA-6005 with the crystal structure of the compound in complex with NP. The influenza inhibitor holds promise as an urgently sought-after therapeutic option offering a complementary mechanism of action to existing antiviral drugs for the treatment of influenza virus infection, and that should further aid development of universal therapeutics.

scholarly journals Thapsigargin Is a Broad-Spectrum Inhibitor of Major Human Respiratory Viruses: Coronavirus, Respiratory Syncytial Virus and Influenza A Virus

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 234
Author(s):  
Sarah Al-Beltagi ◽  
Cristian Alexandru Preda ◽  
Leah V. Goulding ◽  
Joe James ◽  
Juan Pu ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Respiratory Syncytial Virus ◽  
Influenza A Virus ◽  
Broad Spectrum ◽  
Influenza A ◽  
Respiratory Viruses ◽  
Influenza Viruses ◽  
Virus Challenge ◽  
2009 H1n1 ◽  
Syncytial Virus

The long-term control strategy of SARS-CoV-2 and other major respiratory viruses needs to include antivirals to treat acute infections, in addition to the judicious use of effective vaccines. Whilst COVID-19 vaccines are being rolled out for mass vaccination, the modest number of antivirals in use or development for any disease bears testament to the challenges of antiviral development. We recently showed that non-cytotoxic levels of thapsigargin (TG), an inhibitor of the sarcoplasmic/endoplasmic reticulum (ER) Ca2+ ATPase pump, induces a potent host innate immune antiviral response that blocks influenza A virus replication. Here we show that TG is also highly effective in blocking the replication of respiratory syncytial virus (RSV), common cold coronavirus OC43, SARS-CoV-2 and influenza A virus in immortalized or primary human cells. TG’s antiviral performance was significantly better than remdesivir and ribavirin in their respective inhibition of OC43 and RSV. Notably, TG was just as inhibitory to coronaviruses (OC43 and SARS-CoV-2) and influenza viruses (USSR H1N1 and pdm 2009 H1N1) in separate infections as in co-infections. Post-infection oral gavage of acid-stable TG protected mice against a lethal influenza virus challenge. Together with its ability to inhibit the different viruses before or during active infection, and with an antiviral duration of at least 48 h post-TG exposure, we propose that TG (or its derivatives) is a promising broad-spectrum inhibitor against SARS-CoV-2, OC43, RSV and influenza virus.

scholarly journals A recombinant protein containing influenza viral conserved epitopes and superantigen induces broad-spectrum protection

2021 ◽  
Author(s):  
Yansheng Li ◽  
Mingkai Xu ◽  
Yongqiang Li ◽  
Wu Gu ◽  
Gulinare Halimu ◽  
...  
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
Recombinant Protein ◽  
Broad Spectrum ◽  
Influenza Pandemic ◽  
Influenza Virus Infection ◽  
Influenza Viruses ◽  
Lung Damage ◽  
Potential Candidate ◽  
Universal Vaccine

Influenza pandemic poses public health threats annually for lacking vaccine which provides cross-protection against novel and emerging influenza viruses. Combining conserved antigens inducing cross-protective antibody response with epitopes activating cross-protective cytotoxic T-cells would offer an attractive strategy for developing universal vaccine. In this study, we constructed a recombinant protein NMHC consisting of influenza viral conserved epitopes and superantigen fragment. NMHC promoted the mature of bone marrow-derived dendritic cells and induced CD4+ T cells to differentiate into Th1, 32 Th2 and Th17 subtypes. Mice vaccinated with NMHC produced high level of immunoglobulins which cross-bound to HA fragments from six influenza virus subtypes with high antibody titers. Anti-NMHC serum showed potent hemagglutinin inhibition effects to highly divergent group 1 (H1 subtypes) and group 2 (H3 subtype) influenza virus strains. And purified anti-NMHC antibodies could bind to multiple HAs with high affinities. NMHC vaccination effectively protected the mice from infection and lung damage challenged by two subtypes of H1N1 influenza virus. Moreover, NMHC vaccination elicited CD4+ and CD8+ T-cell responses to clear the virus from infected tissue and prevent virus spreading. In conclusion, this study provided proof of concept for triggering both B cells and T cells immune responses against multiple influenza virus infection, and NMHC may be a potential candidate of universal broad-spectrum vaccine for various influenza virus prevention and therapy.

scholarly journals Discovery of Allopregnanolone Against Influenza Virus With Broad Spectrum in Vitro

2021 ◽  
Author(s):  
yuqi Wang ◽  
Yanyan Wang ◽  
Hong Cao
Keyword(s):  
Natural Products ◽  
Influenza Virus ◽  
Viral Replication ◽  
Broad Spectrum ◽  
Influenza A ◽  
Influenza Virus Infection ◽  
Influenza Viruses ◽  
Wild Type Virus ◽  
Dependent Manner ◽  
Viral Yield

Abstract Background: Influenza virus infection with seasonal or occasional but devastating morbidity and mortality, is a severe threat to public health. The frequent emergence of resistant viral strains limited application of current antivirals and posing an urgent need for novel antiviral therapies. Natural products offered a broad prospect in the screening and development of new influenza inhibitors.Methods: In this research, a high-throughput antiviral screening for 891 natural products was performed based on a recombinant reporter influenza A virus. According to the cytotoxicity assay and dose-response relationship, alloprogesterone (ALLO), as the positive hit was selected, and verified by viral titer reduction assay and immunofluorescence using a wild-type virus. Followingly, we explored its antiviral potency of counteracting with IAV and IBV, and preliminary investigated the mechanism of ALLO through time-of-addition assay and mini-replicon system.Results: Under the criteria of 80% inhibition and 70% cell viability, ALLO was screened out and confirmed antiviral activity in varied cells. The inhibitory effect of ALLO against influenza virus with a dose-dependent manner and significantly reduced viral yield of five different influenza viruses in the presence of 40 µM ALLO, including oseltamivir-resistant virus. Moreover, ALLO exhibited no influence on IAV entry or release during the viral replication cycle, but obviously interfered with the genome replication regarding post-infection 2 hrs to 6 hrs, which is consistent with the evidence of decreased polymerase activity.Conclusions: In summary, we firstly identified a new pharmacological activity of ALLO, as a broad spectrum inhibitor for treatment influenza infections, targeting viral replication stage and possessing great value of further development.

scholarly journals A recombinant protein containing influenza viral conserved epitopes and superantigen induces broad-spectrum protection

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Yansheng Li ◽  
Mingkai Xu ◽  
Yongqiang Li ◽  
Wu Gu ◽  
Gulinare Halimu ◽  
...  
Keyword(s):  
Influenza Virus ◽  
T Cell ◽  
Recombinant Protein ◽  
Broad Spectrum ◽  
T Cell Responses ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Lung Damage ◽  
Universal Vaccine ◽  
Cell Responses

Influenza pandemics pose public health threats annually for lacking vaccine which provides cross-protection against novel and emerging influenza viruses. Combining conserved antigens that induce cross-protective antibody responses with epitopes that activate cross-protective T cell responses might be an attractive strategy for developing a universal vaccine. In this study, we constructed a recombinant protein named NMHC which consist of influenza viral conserved epitopes and a superantigen fragment. NMHC promoted the maturation of bone marrow-derived dendritic cells and induced CD4+ T cells to differentiate into Th1, Th2, and Th17 subtypes. Mice vaccinated with NMHC produced high levels of immunoglobulins that cross-bound to HA fragments from six influenza virus subtypes with high antibody titers. Anti-NMHC serum showed potent hemagglutinin inhibition effects to highly divergent group 1 (H1 subtype) and group 2 (H3 subtype) influenza virus strains. Furthermore, purified anti-NMHC antibodies bound to multiple HAs with high affinities. NMHC vaccination effectively protected mice from infection and lung damage when exposed to two subtypes of H1N1 influenza virus. Moreover, NMHC vaccination elicited CD4+ and CD8+ T cell responses that cleared the virus from infected tissues and prevented virus spread. In conclusion, this study provides proof of concept that NMHC vaccination triggers B and T cell immune responses against multiple influenza virus infections. Therefore, NMHC might be a candidate universal broad-spectrum vaccine for the prevention and treatment of multiple influenza viruses.

The cap-binding site of influenza virus protein PB2 as a drug target

2016 ◽  
Vol 72 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Chelsea Severin ◽  
Tales Rocha de Moura ◽  
Yong Liu ◽  
Keqin Li ◽  
Xiaofeng Zheng ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Binding Site ◽  
Structural Changes ◽  
Hydrophobic Interactions ◽  
Influenza Viruses ◽  
Virus Protein ◽  
Mrna Transcription ◽  
Viral Mrnas ◽  
Multiple Strains ◽  
Virus Strains

The RNA polymerase of influenza virus consists of three subunits: PA, PB1 and PB2. It uses a unique `cap-snatching' mechanism for the transcription of viral mRNAs. The cap-binding domain of the PB2 subunit (PB2cap) in the viral polymerase binds the cap of a host pre-mRNA molecule, while the endonuclease of the PA subunit cleaves the RNA 10–13 nucleotides downstream from the cap. The capped RNA fragment is then used as the primer for viral mRNA transcription. The structure of PB2cap from influenza virus H1N1 A/California/07/2009 and of its complex with the cap analog m7GTP were solved at high resolution. Structural changes are observed in the cap-binding site of this new pandemic influenza virus strain, especially the hydrophobic interactions between the ligand and the target protein. m7GTP binds deeper in the pocket than some other virus strains, much deeper than the host cap-binding proteins. Analysis of the new H1N1 structures and comparisons with other structures provide new insights into the design of small-molecule inhibitors that will be effective against multiple strains of both type A and type B influenza viruses.

scholarly journals Structural basis of client specificity in mitochondrial membrane-protein chaperones

2020 ◽  
Author(s):  
Iva Sučec ◽  
Yong Wang ◽  
Ons Dakhlaoui ◽  
Katharina Weinhäupl ◽  
Tobias Jores ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Integral Membrane Proteins ◽  
Structural Basis ◽  
Salt Bridges ◽  
Mitochondrial Carrier ◽  
Poorly Soluble ◽  
Dynamics Simulations ◽  
Fine Tune ◽  
Mitochondrial Membrane Protein ◽  
Hydrophilic Domain

Chaperones are essential for assisting protein folding, and for transferring poorly soluble proteins to their functional locations within cells. Hydrophobic interactions drive promiscuous chaperone–client binding, but our understanding how additional interactions enable client specificity is sparse. Here we decipher what determines binding of two chaperones (TIM8·13, TIM9·10) to different integral membrane proteins, the alltransmembrane mitochondrial carrier Ggc1, and Tim23 which has an additional disordered hydrophilic domain. Combining NMR, SAXS and molecular dynamics simulations, we determine the structures of Tim23/TIM8·13 and Tim23/TIM9·10 complexes. TIM8·13 uses transient salt bridges to interact with the hydrophilic part of its client, but its interactions to the trans-membrane part are weaker than in TIM9·10. Consequently, TIM9·10 is outcompeting TIM8·13 in binding hydrophobic clients, while TIM8·13 is tuned to few clients with both hydrophilic and hydrophobic parts. Our study exemplifies how chaperones fine-tune the balance of promiscuity vs. specificity.

scholarly journals Drug repositioning of Clopidogrel or Triamterene to inhibit influenza virus replication in vitro

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259129
Author(s):  
Nichole Orr-Burks ◽  
Jackelyn Murray ◽  
Kyle V. Todd ◽  
Abhijeet Bakre ◽  
Ralph A. Tripp
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Drug Repositioning ◽  
Antiviral Drug ◽  
Influenza Viruses ◽  
Influenza Virus Replication ◽  
Approved Drugs ◽  
Multiple Strains ◽  
Tract Infections

Influenza viruses cause respiratory tract infections and substantial health concerns. Infection may result in mild to severe respiratory disease associated with morbidity and some mortality. Several anti-influenza drugs are available, but these agents target viral components and are susceptible to drug resistance. There is a need for new antiviral drug strategies that include repurposing of clinically approved drugs. Drugs that target cellular machinery necessary for influenza virus replication can provide a means for inhibiting influenza virus replication. We used RNA interference screening to identify key host cell genes required for influenza replication, and then FDA-approved drugs that could be repurposed for targeting host genes. We examined the effects of Clopidogrel and Triamterene to inhibit A/WSN/33 (EC50 5.84 uM and 31.48 uM, respectively), A/CA/04/09 (EC50 6.432 uM and 3.32 uM, respectively), and B/Yamagata/16/1988 (EC50 0.28 uM and 0.11 uM, respectively) replication. Clopidogrel and Triamterene provide a druggable approach to influenza treatment across multiple strains and subtypes.

scholarly journals Molecular basis of SARS-CoV-2 Omicron variant receptor engagement and antibody evasion and neutralization

2022 ◽  
Author(s):  
Qin Hong ◽  
Wenyu Han ◽  
Jiawei Li ◽  
Shiqi Xu ◽  
Yifan Wang ◽  
...  
Keyword(s):  
Surface Properties ◽  
Immune Evasion ◽  
Broad Spectrum ◽  
Molecular Basis ◽  
Structural Basis ◽  
Salt Bridges ◽  
High Importance ◽  
Closed State ◽  
Open States

The SARS-CoV-2 Omicron variant exhibits striking immune evasion and is spreading globally at an unprecedented speed. Understanding the underlying structural basis of the high transmissibility and greatly enhanced immune evasion of Omicron is of high importance. Here through cryo-EM analysis, we present both the closed and open states of the Omicron spike, which appear more compact than the counterparts of the G614 strain, potentially related to the Omicron substitution induced enhanced protomer-protomer and S1-S2 interactions. The closed state showing dominant population may indicate a conformational masking mechanism of immune evasion for Omicron spike. Moreover, we capture two states for the Omicron S/ACE2 complex with S binding one or two ACE2s, revealing that the substitutions on the Omicron RBM result in new salt bridges/H-bonds and more favorable electrostatic surface properties, together strengthened interaction with ACE2, in line with the higher ACE2 affinity of the Omicron relative to the G614 strain. Furthermore, we determine cryo-EM structures of the Omicron S/S3H3 Fab, an antibody able to cross-neutralize major variants of concern including Omicron, elucidating the structural basis for S3H3-mediated broad-spectrum neutralization. Our findings shed new lights on the high transmissibility and immune evasion of the Omicron variant and may also inform design of broadly effective vaccines against emerging variants.

scholarly journals Determining the Mutation Bias of Favipiravir in Influenza Virus Using Next-Generation Sequencing

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Daniel H. Goldhill ◽  
Pinky Langat ◽  
Hongyao Xie ◽  
Monica Galiano ◽  
Shahjahan Miah ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Next Generation Sequencing ◽  
Broad Spectrum ◽  
Influenza Pandemic ◽  
Antiviral Drug ◽  
Sequence Information ◽  
Next Generation ◽  
Mutation Bias ◽  
Next Generation Sequencing Ngs ◽  
Generation Sequencing

ABSTRACT Favipiravir is a broad-spectrum antiviral drug that may be used to treat influenza. Previous research has identified that favipiravir likely acts as a mutagen, but the precise mutation bias that favipiravir induces in influenza virus RNAs has not been described. Here, we use next-generation sequencing (NGS) with barcoding of individual RNA molecules to accurately and quantitatively detect favipiravir-induced mutations and to sample orders of magnitude more mutations than would be possible through Sanger sequencing. We demonstrate that favipiravir causes mutations and show that favipiravir primarily acts as a guanine analogue and secondarily as an adenine analogue resulting in the accumulation of transition mutations. We also use a standard NGS pipeline to show that the mutagenic effect of favipiravir can be measured by whole-genome sequencing of virus. IMPORTANCE New antiviral drugs are needed as a first line of defense in the event of a novel influenza pandemic. Favipiravir is a broad-spectrum antiviral which is effective against influenza. The exact mechanism of how favipiravir works to inhibit influenza is still unclear. We used next-generation sequencing (NGS) to demonstrate that favipiravir causes mutations in influenza RNA. The greater depth of NGS sequence information over traditional sequencing methods allowed us to precisely determine the bias of particular mutations caused by favipiravir. NGS can also be used in a standard diagnostic pipeline to show that favipiravir is acting on the virus by revealing the mutation bias pattern typical to the drug. Our work will aid in testing whether viruses are resistant to favipiravir and may help demonstrate the effect of favipiravir on viruses in a clinical setting. This will be important if favipiravir is used during a future influenza pandemic.

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