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Lieber CM, Aggarwal M, Yoon JJ, Cox RM, Kang HJ, Sourimant J, Toots M, Johnson SK, Jones CA, Sticher ZM, Kolykhalov AA, Saindane MT, Tompkins SM, Planz O, Painter GR, Natchus MG, Sakamoto K, Plemper RK. 4'-Fluorouridine mitigates lethal infection with pandemic human and highly pathogenic avian influenza viruses. PLoS Pathog 2023; 19:e1011342. [PMID: 37068076 PMCID: PMC10138230 DOI: 10.1371/journal.ppat.1011342] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/27/2023] [Accepted: 04/03/2023] [Indexed: 04/18/2023] Open
Abstract
Influenza outbreaks are associated with substantial morbidity, mortality and economic burden. Next generation antivirals are needed to treat seasonal infections and prepare against zoonotic spillover of avian influenza viruses with pandemic potential. Having previously identified oral efficacy of the nucleoside analog 4'-Fluorouridine (4'-FlU, EIDD-2749) against SARS-CoV-2 and respiratory syncytial virus (RSV), we explored activity of the compound against seasonal and highly pathogenic influenza (HPAI) viruses in cell culture, human airway epithelium (HAE) models, and/or two animal models, ferrets and mice, that assess IAV transmission and lethal viral pneumonia, respectively. 4'-FlU inhibited a panel of relevant influenza A and B viruses with nanomolar to sub-micromolar potency in HAE cells. In vitro polymerase assays revealed immediate chain termination of IAV polymerase after 4'-FlU incorporation, in contrast to delayed chain termination of SARS-CoV-2 and RSV polymerase. Once-daily oral treatment of ferrets with 2 mg/kg 4'-FlU initiated 12 hours after infection rapidly stopped virus shedding and prevented transmission to untreated sentinels. Treatment of mice infected with a lethal inoculum of pandemic A/CA/07/2009 (H1N1)pdm09 (pdmCa09) with 4'-FlU alleviated pneumonia. Three doses mediated complete survival when treatment was initiated up to 60 hours after infection, indicating a broad time window for effective intervention. Therapeutic oral 4'-FlU ensured survival of animals infected with HPAI A/VN/12/2003 (H5N1) and of immunocompromised mice infected with pdmCa09. Recoverees were protected against homologous reinfection. This study defines the mechanistic foundation for high sensitivity of influenza viruses to 4'-FlU and supports 4'-FlU as developmental candidate for the treatment of seasonal and pandemic influenza.
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Affiliation(s)
- Carolin M Lieber
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Megha Aggarwal
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Jeong-Joong Yoon
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Robert M Cox
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Hae-Ji Kang
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Julien Sourimant
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Mart Toots
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
| | - Scott K Johnson
- Center for Vaccines and Immunology, University of Georgia, Athens, Georgia, United States of America
| | - Cheryl A Jones
- Center for Vaccines and Immunology, University of Georgia, Athens, Georgia, United States of America
| | - Zachary M Sticher
- Emory Institute for Drug Development, Emory University, Atlanta, Georgia, United States of America
| | - Alexander A Kolykhalov
- Emory Institute for Drug Development, Emory University, Atlanta, Georgia, United States of America
| | - Manohar T Saindane
- Emory Institute for Drug Development, Emory University, Atlanta, Georgia, United States of America
| | - Stephen M Tompkins
- Center for Vaccines and Immunology, University of Georgia, Athens, Georgia, United States of America
| | - Oliver Planz
- Department of Immunology, Interfaculty Institute for Cell Biology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - George R Painter
- Emory Institute for Drug Development, Emory University, Atlanta, Georgia, United States of America
| | - Michael G Natchus
- Emory Institute for Drug Development, Emory University, Atlanta, Georgia, United States of America
| | - Kaori Sakamoto
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Richard K Plemper
- Center for Translational Antiviral Research, Georgia State University Institute for Biomedical Sciences, Atlanta, Georgia, United States of America
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2
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Sourimant J, Lieber CM, Yoon JJ, Toots M, Govindarajan M, Udumula V, Sakamoto K, Natchus MG, Patti J, Vernachio J, Plemper RK. Orally efficacious lead of the AVG inhibitor series targeting a dynamic interface in the respiratory syncytial virus polymerase. SCIENCE ADVANCES 2022; 8:eabo2236. [PMID: 35749502 PMCID: PMC9232112 DOI: 10.1126/sciadv.abo2236] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Respiratory syncytial virus (RSV) is a leading cause of lower respiratory infections in infants and the immunocompromised, yet no efficient therapeutic exists. We have identified the AVG class of allosteric inhibitors of RSV RNA synthesis. Here, we demonstrate through biolayer interferometry and in vitro RNA-dependent RNA polymerase (RdRP) assays that AVG compounds bind to the viral polymerase, stalling the polymerase in initiation conformation. Resistance profiling revealed a unique escape pattern, suggesting a discrete docking pose. Affinity mapping using photoreactive AVG analogs identified the interface of polymerase core, capping, and connector domains as a molecular target site. A first-generation lead showed nanomolar potency against RSV in human airway epithelium organoids but lacked in vivo efficacy. Docking pose-informed synthetic optimization generated orally efficacious AVG-388, which showed potent efficacy in the RSV mouse model when administered therapeutically. This study maps a druggable target in the RSV RdRP and establishes clinical potential of the AVG chemotype against RSV disease.
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Affiliation(s)
- Julien Sourimant
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Carolin M. Lieber
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Jeong-Joong Yoon
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Mart Toots
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | | | - Venkata Udumula
- Emory Institute for Drug Development, Emory University, Atlanta, GA 30322, USA
| | - Kaori Sakamoto
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Michael G. Natchus
- Emory Institute for Drug Development, Emory University, Atlanta, GA 30322, USA
| | - Joseph Patti
- Aviragen Therapeutics Inc, Alpharetta, GA 30009, USA
| | | | - Richard K. Plemper
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
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3
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Treatment of Respiratory Viral Coinfections. EPIDEMIOLGIA (BASEL, SWITZERLAND) 2022; 3:81-96. [PMID: 36417269 PMCID: PMC9620919 DOI: 10.3390/epidemiologia3010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/18/2022] [Accepted: 02/01/2022] [Indexed: 12/14/2022]
Abstract
With the advent of rapid multiplex PCR, physicians have been able to test for multiple viral pathogens when a patient presents with influenza-like illness. This has led to the discovery that many respiratory infections are caused by more than one virus. Antiviral treatment of viral coinfections can be complex because treatment of one virus will affect the time course of the other virus. Since effective antivirals are only available for some respiratory viruses, careful consideration needs to be given on the effect treating one virus will have on the dynamics of the other virus, which might not have available antiviral treatment. In this study, we use mathematical models of viral coinfections to assess the effect of antiviral treatment on coinfections. We examine the effect of the mechanism of action, relative growth rates of the viruses, and the assumptions underlying the interaction of the viruses. We find that high antiviral efficacy is needed to suppress both infections. If high doses of both antivirals are not achieved, then we run the risk of lengthening the duration of coinfection or even of allowing a suppressed virus to replicate to higher viral titers.
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Bu L, Chen B, Xing L, Cai X, Liang S, Zhang L, Wang X, Song W. Generation of a pdmH1N1 2018 Influenza A Reporter Virus Carrying a mCherry Fluorescent Protein in the PA Segment. Front Cell Infect Microbiol 2022; 11:827790. [PMID: 35127568 PMCID: PMC8811159 DOI: 10.3389/fcimb.2021.827790] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/31/2021] [Indexed: 11/13/2022] Open
Abstract
Influenza A virus (IAV) is a major human pathogen associated with significant morbidity and mortality worldwide. Through serial passage in mice, we generated a recombinant pdmH1N1 2009 IAV, A/Guangdong/GLW/2018 (GLW/18-MA), which encodes an mCherry gene fused to the C-terminal of a polymerase acidic (PA) segment and demonstrated comparable growth kinetics to the wild-type. Nine mutations were identified in the GLW/18-MA genome: PA (I61M, E351G, and G631S), NP (E292G), HA1 (T164I), HA2 (N117S and P160S), NA (W61R), and NEP (K44R). The recombinant IAV reporter expresses mCherry, a red fluorescent protein, at a high level and maintains its genetic integrity after five generations of serial passages in Madin-Darby Canine Kidney cells (MDCK) cells. Moreover, the imaging is noninvasive and permits the monitoring of infection in living mice. Treatment with oseltamivir or baicalin followed by infection with the reporter IAV led to a decrease in fluorescent protein signal in living mice. This result demonstrates that the IAV reporter virus is a powerful tool to study viral pathogenicity and transmission and to develop and evaluate novel anti-viral drugs, inhibitors, and vaccines in the future.
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Affiliation(s)
- Ling Bu
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Boqian Chen
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lei Xing
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xuejun Cai
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Shuhua Liang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Liying Zhang
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, China
| | - Xinhua Wang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenjun Song
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Integration of Traditional and Western Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- State Key Laboratory for Emerging Infectious Diseases, Department of Microbiology, and the Research Center of Infection and Immunology, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
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5
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Froggatt HM, Burke KN, Chaparian RR, Miranda HA, Zhu X, Chambers BS, Heaton NS. Influenza A virus segments five and six can harbor artificial introns allowing expanded coding capacity. PLoS Pathog 2021; 17:e1009951. [PMID: 34570829 PMCID: PMC8496794 DOI: 10.1371/journal.ppat.1009951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 10/07/2021] [Accepted: 09/08/2021] [Indexed: 12/30/2022] Open
Abstract
Influenza A viruses encode their genomes across eight, negative sense RNA segments. The six largest segments produce mRNA transcripts that do not generally splice; however, the two smallest segments are actively spliced to produce the essential viral proteins NEP and M2. Thus, viral utilization of RNA splicing effectively expands the viral coding capacity without increasing the number of genomic segments. As a first step towards understanding why splicing is not more broadly utilized across genomic segments, we designed and inserted an artificial intron into the normally nonsplicing NA segment. This insertion was tolerated and, although viral mRNAs were incompletely spliced, we observed only minor effects on viral fitness. To take advantage of the unspliced viral RNAs, we encoded a reporter luciferase gene in frame with the viral ORF such that when the intron was not removed the reporter protein would be produced. This approach, which we also show can be applied to the NP encoding segment and in different viral genetic backgrounds, led to high levels of reporter protein expression with minimal effects on the kinetics of viral replication or the ability to cause disease in experimentally infected animals. These data together show that the influenza viral genome is more tolerant of splicing than previously appreciated and this knowledge can be leveraged to develop viral genetic platforms with utility for biotechnology applications. Unlike most host mRNAs, some viral mRNAs encode multiple discrete, functional proteins. One method influenza A viruses use to increase the protein products from two of their eight RNA genome segments is splicing. Splicing requires host machinery to remove part of the viral mRNA, the intron, to generate a different mRNA product. Although only certain influenza viral segments naturally splice, we were interested in whether additional segments could splice to produce multiple proteins. We inserted artificial introns harboring reporter genes into otherwise nonsplicing genomic segments of an H1N1 influenza A virus and found that this modification was well tolerated by the virus. We further demonstrated that an unrelated H3N2 influenza A virus could similarly support splicing and express a reporter protein from an artificial intron. These findings have implications for our understanding of how viruses expand their coding capacity with a limited genome. Additionally, encoding reporter proteins in spliced intronic sequences also represents a new method of generating reporter viruses requiring limited manipulation of the viral RNA.
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Affiliation(s)
- Heather M. Froggatt
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Kaitlyn N. Burke
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Ryan R. Chaparian
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Hector A. Miranda
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Xinyu Zhu
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Benjamin S. Chambers
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
| | - Nicholas S. Heaton
- Department of Molecular Genetics and Microbiology Duke University School of Medicine Durham, North Carolina, United States of America
- Duke Human Vaccine Institute Duke University School of Medicine Durham, North Carolina, United States of America
- * E-mail:
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6
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Identification and Characterization of a Small-Molecule Rabies Virus Entry Inhibitor. J Virol 2020; 94:JVI.00321-20. [PMID: 32321812 DOI: 10.1128/jvi.00321-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/13/2020] [Indexed: 12/25/2022] Open
Abstract
Rabies virus (RABV) causes a severe and fatal neurological disease, but morbidity is vaccine preventable and treatable prior to the onset of clinical symptoms. However, immunoglobulin (IgG)-based rabies postexposure prophylaxis (PEP) is expensive, restricting access to life-saving treatment, especially for patients in low-income countries where the clinical need is greatest, and does not confer cross-protection against newly emerging phylogroup II lyssaviruses. Toward identifying a cost-effective replacement for the IgG component of rabies PEP, we developed and implemented a high-throughput screening protocol utilizing a single-cycle RABV reporter strain. A large-scale screen and subsequent direct and orthogonal counterscreens identified a first-in-class direct-acting RABV inhibitor, GRP-60367, with a specificity index (SI) of >100,000. Mechanistic characterization through time-of-addition studies, transient cell-to-cell fusion assays, and chimeric vesicular stomatitis virus (VSV) recombinants expressing the RABV glycoprotein (G) demonstrated that GRP-60367 inhibits entry of a subset of RABV strains. Resistance profiling of the chemotype revealed hot spots in conserved hydrophobic positions of the RABV G protein fusion loop that were confirmed in transient cell-to-cell fusion assays. Transfer of RABV G genes with signature resistance mutations into a recombinant VSV backbone resulted in the recovery of replication-competent virions with low susceptibility to the inhibitor. This work outlines a tangible strategy for mechanistic characterization and resistance profiling of RABV drug candidates and identified a novel, well-behaved molecular probe chemotype that specifically targets the RABV G protein and prevents G-mediated viral entry.IMPORTANCE Rabies PEP depends on anti-RABV IgG, which is expensive and in limited supply in geographical areas with the highest disease burden. Replacing the IgG component with a cost-effective and shelf-stable small-molecule antiviral could address this unmet clinical need by expanding access to life-saving medication. This study has established a robust protocol for high-throughput anti-RABV drug screens and identified a chemically well-behaved, first-in-class hit with nanomolar anti-RABV potency that blocks RABV G protein-mediated viral entry. Resistance mapping revealed a druggable site formed by the G protein fusion loops that has not previously emerged as a target for neutralizing antibodies. Discovery of this RABV entry inhibitor establishes a new molecular probe to advance further mechanistic and structural characterization of RABV G that may aid in the design of a next-generation clinical candidate against RABV.
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Orienti I, Gentilomi GA, Farruggia G. Pulmonary Delivery of Fenretinide: A Possible Adjuvant Treatment In COVID-19. Int J Mol Sci 2020; 21:E3812. [PMID: 32471278 PMCID: PMC7312074 DOI: 10.3390/ijms21113812] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/18/2020] [Accepted: 05/26/2020] [Indexed: 02/08/2023] Open
Abstract
At present, there is no vaccine or effective standard treatment for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection (or coronavirus disease-19 (COVID-19)), which frequently leads to lethal pulmonary inflammatory responses. COVID-19 pathology is characterized by extreme inflammation and amplified immune response with activation of a cytokine storm. A subsequent progression to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can take place, which is often followed by death. The causes of these strong inflammatory responses in SARS-CoV-2 infection are still unknown. As uncontrolled pulmonary inflammation is likely the main cause of death in SARS-CoV-2 infection, anti-inflammatory therapeutic interventions are particularly important. Fenretinide N-(4-hydroxyphenyl) retinamide is a bioactive molecule characterized by poly-pharmacological properties and a low toxicity profile. Fenretinide is endowed with antitumor, anti-inflammatory, antiviral, and immunomodulating properties other than efficacy in obesity/diabetic pathologies. Its anti-inflammatory and antiviral activities, in particular, could likely have utility in multimodal therapies for the treatment of ALI/ARDS in COVID-19 patients. Moreover, fenretinide administration by pulmonary delivery systems could further increase its therapeutic value by carrying high drug concentrations to the lungs and triggering a rapid onset of activity. This is particularly important in SARS-CoV-2 infection, where only a narrow time window exists for therapeutic intervention.
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Affiliation(s)
- Isabella Orienti
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Via S. Donato 19/2, 40127 Bologna, Italy;
| | - Giovanna Angela Gentilomi
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Via Massarenti 9, 40138 Bologna, Italy;
- Unit of Microbiology, Alma Mater Studiorum-University of Bologna, S. Orsola-Malpighi Hospital, 40138 Bologna, Italy
| | - Giovanna Farruggia
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Via S. Donato 19/2, 40127 Bologna, Italy;
- Biostructures and Biosystems National Institute (BBNI), 00136 Roma, Italy
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8
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Aggarwal M, Plemper RK. Structural Insight into Paramyxovirus and Pneumovirus Entry Inhibition. Viruses 2020; 12:E342. [PMID: 32245118 PMCID: PMC7150754 DOI: 10.3390/v12030342] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 01/04/2023] Open
Abstract
Paramyxoviruses and pneumoviruses infect cells through fusion (F) protein-mediated merger of the viral envelope with target membranes. Members of these families include a range of major human and animal pathogens, such as respiratory syncytial virus (RSV), measles virus (MeV), human parainfluenza viruses (HPIVs), and highly pathogenic Nipah virus (NiV). High-resolution F protein structures in both the metastable pre- and the postfusion conformation have been solved for several members of the families and a number of F-targeting entry inhibitors have progressed to advanced development or clinical testing. However, small-molecule RSV entry inhibitors have overall disappointed in clinical trials and viral resistance developed rapidly in experimental settings and patients, raising the question of whether the available structural information may provide a path to counteract viral escape through proactive inhibitor engineering. This article will summarize current mechanistic insight into F-mediated membrane fusion and examine the contribution of structural information to the development of small-molecule F inhibitors. Implications are outlined for future drug target selection and rational drug engineering strategies.
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Affiliation(s)
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA;
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9
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Identification and Characterization of Novel Compounds with Broad-Spectrum Antiviral Activity against Influenza A and B Viruses. J Virol 2020; 94:JVI.02149-19. [PMID: 31941776 DOI: 10.1128/jvi.02149-19] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 12/24/2019] [Indexed: 12/23/2022] Open
Abstract
Influenza A (IAV) and influenza B (IBV) viruses are highly contagious pathogens that cause fatal respiratory disease every year, with high economic impact. In addition, IAV can cause pandemic infections with great consequences when new viruses are introduced into humans. In this study, we evaluated 10 previously described compounds with antiviral activity against mammarenaviruses for their ability to inhibit IAV infection using our recently described bireporter influenza A/Puerto Rico/8/34 (PR8) H1N1 (BIRFLU). Among the 10 tested compounds, eight (antimycin A [AmA], brequinar [BRQ], 6-azauridine, azaribine, pyrazofurin [PF], AVN-944, mycophenolate mofetil [MMF], and mycophenolic acid [MPA]), but not obatoclax or Osu-03012, showed potent anti-influenza virus activity under posttreatment conditions [median 50% effective concentration (EC50) = 3.80 nM to 1.73 μM; selective index SI for 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, >28.90 to 13,157.89]. AmA, 6-azauridine, azaribine, and PF also showed potent inhibitory effect in pretreatment (EC50 = 0.14 μM to 0.55 μM; SI-MTT = 70.12 to >357.14) or cotreatment (EC50 = 34.69 nM to 7.52 μM; SI-MTT = 5.24 to > 1,441.33) settings. All of the compounds tested inhibited viral genome replication and gene transcription, and none of them affected host cellular RNA polymerase II activities. The antiviral activity of the eight identified compounds against BIRFLU was further confirmed with seasonal IAVs (A/California/04/2009 H1N1 and A/Wyoming/3/2003 H3N2) and an IBV (B/Brisbane/60/2008, Victoria lineage), demonstrating their broad-spectrum prophylactic and therapeutic activity against currently circulating influenza viruses in humans. Together, our results identified a new set of antiviral compounds for the potential treatment of influenza viral infections.IMPORTANCE Influenza viruses are highly contagious pathogens and are a major threat to human health. Vaccination remains the most effective tool to protect humans against influenza infection. However, vaccination does not always guarantee complete protection against drifted or, more noticeably, shifted influenza viruses. Although U.S. Food and Drug Administration (FDA) drugs are approved for the treatment of influenza infections, influenza viruses resistant to current FDA antivirals have been reported and continue to emerge. Therefore, there is an urgent need to find novel antivirals for the treatment of influenza viral infections in humans, a search that could be expedited by repurposing currently approved drugs. In this study, we assessed the influenza antiviral activity of 10 compounds previously shown to inhibit mammarenavirus infection. Among them, eight drugs showed antiviral activities, providing a new battery of drugs that could be used for the treatment of influenza infections.
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10
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Xu L, Jiang W, Jia H, Zheng L, Xing J, Liu A, Du G. Discovery of Multitarget-Directed Ligands Against Influenza A Virus From Compound Yizhihao Through a Predictive System for Compound-Protein Interactions. Front Cell Infect Microbiol 2020; 10:16. [PMID: 32117796 PMCID: PMC7026480 DOI: 10.3389/fcimb.2020.00016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/14/2020] [Indexed: 12/27/2022] Open
Abstract
Influenza A virus (IAV) is a threat to public health due to its high mutation rate and resistance to existing drugs. In this investigation, 15 targets selected from an influenza virus–host interaction network were successfully constructed as a multitarget virtual screening system for new drug discovery against IAV using Naïve Bayesian, recursive partitioning, and CDOCKER methods. The predictive accuracies of the models were evaluated using training sets and test sets. The system was then used to predict active constituents of Compound Yizhihao (CYZH), a Chinese medicinal compound used to treat influenza. Twenty-eight compounds with multitarget activities were selected for subsequent in vitro evaluation. Of the four compounds predicted to be active on neuraminidase (NA), chlorogenic acid, and orientin showed inhibitory activity in vitro. Linarin, sinensetin, cedar acid, isoliquiritigenin, sinigrin, luteolin, chlorogenic acid, orientin, epigoitrin, and rupestonic acid exhibited significant effects on TNF-α expression, which is almost consistent with predicted results. Results from a cytopathic effect (CPE) reduction assay revealed acacetin, indirubin, tryptanthrin, quercetin, luteolin, emodin, and apigenin had protective effects against wild-type strains of IAV. Quercetin, luteolin, and apigenin had good efficacy against resistant IAV strains in CPE reduction assays. Finally, with the aid of Gene Ontology biological process analysis, the potential mechanisms of CYZH action were revealed. In conclusion, a compound-protein interaction-prediction system was an efficient tool for the discovery of novel compounds against influenza, and the findings from CYZH provide important information for its usage and development.
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Affiliation(s)
- Lvjie Xu
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Wen Jiang
- The Sixth Clinical Hospital of Xinjiang Medical University, Ürümqi, China
| | - Hao Jia
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Lishu Zheng
- Chinese Center for Disease Control and Prevention, National Institute for Viral Disease Control and Prevention, Beijing, China
| | - Jianguo Xing
- Xinjiang Institute of Materia Medica, Ürümqi, China
| | - Ailin Liu
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Guanhua Du
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
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11
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Chen RP, Gaynor AS, Chen W. Synthetic biology approaches for targeted protein degradation. Biotechnol Adv 2019; 37:107446. [DOI: 10.1016/j.biotechadv.2019.107446] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/03/2019] [Accepted: 09/06/2019] [Indexed: 12/12/2022]
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12
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Shi Z, Zou J, Zhang Z, Zhao X, Noriega J, Zhang B, Zhao C, Ingle H, Bittinger K, Mattei LM, Pruijssers AJ, Plemper RK, Nice TJ, Baldridge MT, Dermody TS, Chassaing B, Gewirtz AT. Segmented Filamentous Bacteria Prevent and Cure Rotavirus Infection. Cell 2019; 179:644-658.e13. [PMID: 31607511 PMCID: PMC7525827 DOI: 10.1016/j.cell.2019.09.028] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 05/23/2019] [Accepted: 09/23/2019] [Indexed: 12/21/2022]
Abstract
Rotavirus (RV) encounters intestinal epithelial cells amidst diverse microbiota, opening possibilities of microbes influencing RV infection. Although RV clearance typically requires adaptive immunity, we unintentionally generated RV-resistant immunodeficient mice, which, we hypothesized, reflected select microbes protecting against RV. Accordingly, such RV resistance was transferred by co-housing and fecal transplant. RV-protecting microbiota were interrogated by heat, filtration, and antimicrobial agents, followed by limiting dilution transplant to germ-free mice and microbiome analysis. This approach revealed that segmented filamentous bacteria (SFB) were sufficient to protect mice against RV infection and associated diarrhea. Such protection was independent of previously defined RV-impeding factors, including interferon, IL-17, and IL-22. Colonization of the ileum by SFB induced changes in host gene expression and accelerated epithelial cell turnover. Incubation of RV with SFB-containing feces reduced infectivity in vitro, suggesting direct neutralization of RV. Thus, independent of immune cells, SFB confer protection against certain enteric viral infections and associated diarrheal disease.
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Affiliation(s)
- Zhenda Shi
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Jun Zou
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Zhan Zhang
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Xu Zhao
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Juan Noriega
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Benyue Zhang
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Chunyu Zhao
- Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Harshad Ingle
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kyle Bittinger
- Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Lisa M Mattei
- Gastroenterology, Hepatology, and Nutrition, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Andrea J Pruijssers
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Timothy J Nice
- Department of Microbiology and Immunology, Oregon Health Sciences University, Portland, OR, USA
| | - Megan T Baldridge
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Terence S Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine and UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Benoit Chassaing
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA; Neuroscience Institute, GSU, Atlanta, GA, USA
| | - Andrew T Gewirtz
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA.
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13
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Wang L, Cui Q, Zhao X, Li P, Wang Y, Rong L, Du R. Generation of a Reassortant Influenza A Subtype H3N2 Virus Expressing Gaussia Luciferase. Viruses 2019; 11:v11070665. [PMID: 31330768 PMCID: PMC6669691 DOI: 10.3390/v11070665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/19/2019] [Accepted: 07/19/2019] [Indexed: 12/22/2022] Open
Abstract
Reporter influenza A viruses (IAVs) carrying fluorescent or luminescent genes provide a powerful tool for both basic and translational research. Most reporter IAVs are based on the backbone of either subtype H1N1 viruses, A/Puerto Rico/8/1934 (PR8) or A/WSN/1933, but no reporter subtype H3N2 virus is currently available to our knowledge. Since the IAV subtype H3N2 co-circulates with H1N1 among humans causing annual epidemics, a reporter influenza A subtype H3N2 virus would be highly valuable. In this study, the segments of A/Wyoming/3/03 (NY, H3N2) virus encoding hemagglutinin and neuraminidase, respectively, were reassorted with the six internal genes of PR8 where the NS gene was fused with a Gaussia luciferase (Gluc) gene. Using reverse genetics, NY-r19-Gluc, a replication competent reassortant influenza A subtype H3N2 virus expressing reporter Gluc was successfully generated. This reporter virus is stable during replication in Madin-Darby canine kidney (MDCK) cells, and preliminary studies demonstrated it as a useful tool to evaluate antivirals. In addition, NY-r19-Gluc virus will be a powerful tool in other studies including the application of diagnostic and therapeutic antibodies as well as the evaluation of novel vaccines.
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Affiliation(s)
- Lin Wang
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
| | - Qinghua Cui
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
- Shandong Provincial Collaborative Innovation Center for Antiviral Traditional Chinese Medicine, Jinan 250355, China
- Qingdao Academy of Chinese Medicinal Sciences, Shandong University of Traditional Chinese Medicine, Qingdao 266122, China
| | - Xiujuan Zhao
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
| | - Ping Li
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
| | - Yanyan Wang
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
| | - Lijun Rong
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Ruikun Du
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
- Shandong Provincial Collaborative Innovation Center for Antiviral Traditional Chinese Medicine, Jinan 250355, China.
- Qingdao Academy of Chinese Medicinal Sciences, Shandong University of Traditional Chinese Medicine, Qingdao 266122, China.
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14
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Engineered Small-Molecule Control of Influenza A Virus Replication. J Virol 2018; 93:JVI.01677-18. [PMID: 30282710 DOI: 10.1128/jvi.01677-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 09/26/2018] [Indexed: 01/01/2023] Open
Abstract
Influenza A virus (IAV) remains a global health concern despite the availability of a seasonal vaccine. It is difficult to predict which strains will circulate during influenza season, and therefore, it is extremely challenging to test novel vaccines in the human population. To overcome this obstacle, new vaccines must be tested in challenge studies. This approach poses significant safety problems, since current pharmacological interventions for IAV are poorly efficacious. New methods are needed to enhance the safety of these challenge studies. In this study, we have generated a virus expressing a small-molecule-assisted shutoff (SMASh) tag as a safety switch for IAV replication. The addition of the SMASh tag to an essential IAV protein allows for small-molecule-mediated inhibition of replication. Treatment with this drug controls the replication of a SMASh-tagged virus in vitro and in vivo This model for restriction of viral replication has potential for broad applications in vaccine studies, virotherapy, and basic virus research.IMPORTANCE Influenza A virus (IAV) causes significant morbidity and mortality annually worldwide, despite the availability of new formulations of the vaccine each season. There is a critical need to develop more-efficacious vaccines. However, testing novel vaccines in the human population in controlled studies is difficult due to the limited availability and efficacy of intervention strategies should the vaccine fail. There are also significant safety concerns for work with highly pathogenic IAV strains in the laboratory. Therefore, novel strategies are needed to improve the safety of vaccine studies and of research on highly pathogenic IAV. In this study, we developed an IAV strain engineered to contain a small-molecule-mediated safety switch. This tag, when attached to an essential viral protein, allows for the regulation of IAV replication in vitro and in vivo This strategy provides a platform for the regulation of virus replication without targeting viral proteins directly.
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15
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Cockerill GS, Good JAD, Mathews N. State of the Art in Respiratory Syncytial Virus Drug Discovery and Development. J Med Chem 2018; 62:3206-3227. [DOI: 10.1021/acs.jmedchem.8b01361] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- G. Stuart Cockerill
- ReViral Ltd., Stevenage Bioscience Catalyst, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2FX, United Kingdom
| | - James A. D. Good
- ReViral Ltd., Stevenage Bioscience Catalyst, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2FX, United Kingdom
| | - Neil Mathews
- ReViral Ltd., Stevenage Bioscience Catalyst, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2FX, United Kingdom
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16
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Cox RM, Toots M, Yoon JJ, Sourimant J, Ludeke B, Fearns R, Bourque E, Patti J, Lee E, Vernachio J, Plemper RK. Development of an allosteric inhibitor class blocking RNA elongation by the respiratory syncytial virus polymerase complex. J Biol Chem 2018; 293:16761-16777. [PMID: 30206124 DOI: 10.1074/jbc.ra118.004862] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/10/2018] [Indexed: 12/22/2022] Open
Abstract
Respiratory syncytial virus (RSV) represents a significant health threat to infants and to elderly or immunocompromised individuals. There are currently no vaccines available to prevent RSV infections, and disease management is largely limited to supportive care, making the identification and development of effective antiviral therapeutics against RSV a priority. To identify effective chemical scaffolds for managing RSV disease, we conducted a high-throughput anti-RSV screen of a 57,000-compound library. We identified a hit compound that specifically blocked activity of the RSV RNA-dependent RNA polymerase (RdRp) complex, initially with moderate low-micromolar potency. Mechanistic characterization in an in vitro RSV RdRp assay indicated that representatives of this compound class block elongation of RSV RNA products after initial extension by up to three nucleotides. Synthetic hit-to-lead exploration yielded an informative 3D quantitative structure-activity relationship (3D-QSAR) model and resulted in analogs with more than 20-fold improved potency and selectivity indices (SIs) of >1,000. However, first-generation leads exhibited limited water solubility and poor metabolic stability. A second optimization strategy informed by the 3D-QSAR model combined with in silico pharmacokinetics (PK) predictions yielded an advanced lead, AVG-233, that demonstrated nanomolar activity against both laboratory-adapted RSV strains and clinical RSV isolates. This anti-RSV activity extended to infection of established cell lines and primary human airway cells. PK profiling in mice revealed 34% oral bioavailability of AVG-233 and sustained high drug levels in the circulation after a single oral dose of 20 mg/kg. This promising first-in-class lead warrants further development as an anti-RSV drug.
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Affiliation(s)
- Robert M Cox
- From the Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30303
| | - Mart Toots
- From the Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30303
| | - Jeong-Joong Yoon
- From the Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30303
| | - Julien Sourimant
- From the Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30303
| | - Barbara Ludeke
- the Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, and
| | - Rachel Fearns
- the Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, and
| | | | - Joseph Patti
- Aviragen Therapeutics, Alpharetta, Georgia 30009
| | - Edward Lee
- Aviragen Therapeutics, Alpharetta, Georgia 30009
| | | | - Richard K Plemper
- From the Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30303,
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17
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Directed Evolution of an Influenza Reporter Virus To Restore Replication and Virulence and Enhance Noninvasive Bioluminescence Imaging in Mice. J Virol 2018; 92:JVI.00593-18. [PMID: 29899096 DOI: 10.1128/jvi.00593-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/06/2018] [Indexed: 02/06/2023] Open
Abstract
Reporter viruses provide a powerful tool to study infection, yet incorporating a nonessential gene often results in virus attenuation and genetic instability. Here, we used directed evolution of a luciferase-expressing pandemic H1N1 (pH1N1) 2009 influenza A virus in mice to restore replication kinetics and virulence, increase the bioluminescence signal, and maintain reporter gene expression. An unadapted pH1N1 virus with NanoLuc luciferase inserted into the 5' end of the PA gene segment grew to titers 10-fold less than those of the wild type in MDCK cells and in DBA/2 mice and was less virulent. For 12 rounds, we propagated DBA/2 lung samples with the highest bioluminescence-to-titer ratios. Every three rounds, we compared in vivo replication, weight loss, mortality, and bioluminescence. Mouse-adapted virus after 9 rounds (MA-9) had the highest relative bioluminescence signal and had wild-type-like fitness and virulence in DBA/2 mice. Using reverse genetics, we discovered fitness was restored in virus rPB2-MA9/PA-D479N by a combination of PA-D479N and PB2-E158G amino acid mutations and PB2 noncoding mutations C1161T and C1977T. rPB2-MA9/PA-D479N has increased mRNA transcription, which helps restore wild-type-like phenotypes in DBA/2 and BALB/c mice. Overall, the results demonstrate that directed evolution that maximizes foreign-gene expression while maintaining genetic stability is an effective method to restore wild-type-like in vivo fitness of a reporter virus. Virus rPB2-MA9/PA-D479N is expected to be a useful tool for noninvasive imaging of pH1N1 influenza virus infection and clearance while analyzing virus-host interactions and developing new therapeutics and vaccines.IMPORTANCE Influenza viruses contribute to 290,000 to 650,000 deaths globally each year. Infection is studied in mice to learn how the virus causes sickness and to develop new drugs and vaccines. During experiments, scientists have needed to euthanize groups of mice at different times to measure the amount of infectious virus in mouse tissues. By inserting a foreign gene that causes infected cells to light up, scientists could see infection spread in living mice. Unfortunately, adding an extra gene not needed by the virus slowed it down and made it weaker. Here, we used a new strategy to restore the fitness and lethality of an influenza reporter virus; we adapted it to mouse lungs and selected for variants that had the greatest light signal. The adapted virus can be used to study influenza virus infection, immunology, and disease in living mice. The strategy can also be used to adapt other viruses.
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18
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Orally Efficacious Broad-Spectrum Ribonucleoside Analog Inhibitor of Influenza and Respiratory Syncytial Viruses. Antimicrob Agents Chemother 2018; 62:AAC.00766-18. [PMID: 29891600 DOI: 10.1128/aac.00766-18] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 05/31/2018] [Indexed: 01/29/2023] Open
Abstract
Morbidity and mortality resulting from influenza-like disease are a threat, especially for older adults. To improve case management, next-generation broad-spectrum antiviral therapeutics that are efficacious against major drivers of influenza-like disease, including influenza viruses and respiratory syncytial virus (RSV), are urgently needed. Using a dual-pathogen high-throughput screening protocol for influenza A virus (IAV) and RSV inhibitors, we have identified N4-hydroxycytidine (NHC) as a potent inhibitor of RSV, influenza B viruses, and IAVs of human, avian, and swine origins. Biochemical in vitro polymerase assays and viral RNA sequencing revealed that the ribonucleotide analog is incorporated into nascent viral RNAs in place of cytidine, increasing the frequency of viral mutagenesis. Viral passaging in cell culture in the presence of an inhibitor did not induce robust resistance. Pharmacokinetic profiling demonstrated dose-dependent oral bioavailability of 36 to 56%, sustained levels of the active 5'-triphosphate anabolite in primary human airway cells and mouse lung tissue, and good tolerability after extended dosing at 800 mg/kg of body weight/day. The compound was orally efficacious against RSV and both seasonal and highly pathogenic avian IAVs in mouse models, reducing lung virus loads and alleviating disease biomarkers. Oral dosing reduced IAV burdens in a guinea pig transmission model and suppressed virus spread to uninfected contact animals through direct transmission. Based on its broad-spectrum efficacy and pharmacokinetic properties, NHC is a promising candidate for future clinical development as a treatment option for influenza-like diseases.
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19
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Pan W, Dong J, Chen P, Zhang B, Li Z, Chen L. Development and application of bioluminescence imaging for the influenza A virus. J Thorac Dis 2018; 10:S2230-S2237. [PMID: 30116602 DOI: 10.21037/jtd.2018.02.35] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Influenza A viruses (IAVs) cause seasonal epidemics and intermittent pandemics which threaten human health. Conventional assays cannot meet the demands for rapid and sensitive detection of viral spread and pathogenesis in real time cannot be used for high-throughput screens of novel antivirals. Bioluminescence imaging (BLI) has emerged as a powerful tool in the study of infectious diseases in animal models. The advent of influenza reverse genetics has enabled the incorporation of bioluminescent reporter proteins into replication-competent IAVs. This review briefly describes the current development and applications of bioluminescence in the study of viral infections and antiviral therapeutics for IAVs. BLI is expected to substantially accelerate the basic and applied research of IAV both in vitro and in vivo.
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Affiliation(s)
- Weiqi Pan
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510182, China
| | - Ji Dong
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510182, China
| | - Peihai Chen
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.,Institute of Health Sciences, Anhui University, Hefei 230601, China
| | - Beiwu Zhang
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Zhixia Li
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Ling Chen
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510182, China.,Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
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20
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Generation and application of replication-competent Venus-expressing H5N1, H7N9, and H9N2 influenza A viruses. Sci Bull (Beijing) 2018; 63:176-186. [PMID: 36659003 DOI: 10.1016/j.scib.2018.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/27/2017] [Accepted: 12/28/2017] [Indexed: 01/21/2023]
Abstract
The generation and application of replication-competent influenza A virus (IAV) expressing a reporter gene represent a valuable tool to elucidate the mechanism of viral pathogenesis and establish new countermeasures to combat the threat of influenza. Here, replication-competent IAVs with a neuraminidase (NA) segment harboring a fluorescent reporter protein, Venus, were generated in the background of H5N1, H7N9, and H9N2 influenza viruses, the three subtypes of viruses with imminent pandemic potential. All three reporter viruses maintained virion morphology, replicated with similar or slightly reduced titers relative to their parental viruses, and stably expressed the fluorescent signal for at least two passages in embryonated chicken eggs. As a proof of concept, we demonstrated that these reporter viruses, used in combination with a high-content imaging system, can serve as a convenient and rapid tool for the screening of antivirals and host factors involved in the virus life cycle. Moreover, the reporter viruses demonstrated similar growth properties and tissue tropism as their parental viruses in mice, among which the H7N9 NA-Venus virus could potentially be used in ex vivo studies to better understand H7N9 pathogenesis or to develop novel therapeutics.
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21
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Construction and Characterization of a Recombinant Human Respiratory Syncytial Virus Encoding Enhanced Green Fluorescence Protein for Antiviral Drug Screening Assay. BIOMED RESEARCH INTERNATIONAL 2018; 2018:8431243. [PMID: 29568767 PMCID: PMC5820570 DOI: 10.1155/2018/8431243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/25/2017] [Accepted: 12/04/2017] [Indexed: 11/17/2022]
Abstract
Human respiratory syncytial virus (RSV) is the single most important cause of lower respiratory tract disease in infants and young children and a major viral agent responsible for respiratory tract disease in immunosuppressed individuals and the elderly, but no vaccines and antiviral drugs are available. Herein the recombinant RSV (rRSV) encoding enhanced green fluorescence protein (EGFP, rRSV-EGFP) was constructed and the potential for screening anti-RSV drugs was investigated. The recombinant plasmid of pBRATm-rRSV-EGFP, containing T7 transcription cassette composed of T7 promoter, RSV antigenomic cDNA with EGFP gene, HDV ribozyme (δ), and T7 terminator in the order of 5' to 3', was constructed and cotransfected into BHK/T7-9 cells together with helper plasmids encoding N, P, L, and M2-1 gene, respectively. The rescued rRSV-EGFP was confirmed by increasing expression of EGFP over blind passages and by RT-PCR. rRSV-EGFP was comparable to the other two recombinant RSVs encoding red fluorescent protein (RFP, rRSV-RFP) or luciferase (Luc, rRSV-Luc) in the growth kinetic, and there was a difference in sensitivity between them for screening anti-RSV agents based on infection of HEp-2 cells. The EGFP-encoding rRSV has been constructed and rescued successfully and has the potential for high-throughput anti-RSV drug screening in vitro.
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22
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Karlsson EA, Meliopoulos VA, Tran V, Savage C, Livingston B, Schultz-Cherry S, Mehle A. Measuring Influenza Virus Infection Using Bioluminescent Reporter Viruses for In Vivo Imaging and In Vitro Replication Assays. Methods Mol Biol 2018; 1836:431-459. [PMID: 30151586 DOI: 10.1007/978-1-4939-8678-1_21] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To streamline standard virological assays, we developed bioluminescent replication-competent influenza reporter viruses that mimic their parental counterparts. These reporter viruses provide a rapid and quantitative readout of viral infection and replication. Moreover, they permit real-time in vivo measures of viral load, tissue distribution, and transmission in the same cohort of animals over the entire course of infection-measurements that were not previously possible. Here we provide detailed protocols using bioluminescent reporter viruses for in vivo imaging in mice and ferrets. We also describe cell culture-based techniques using reporter viruses for quantification of viral titers and performing microneutralization assays. The ease, speed, and adaptability of these approaches have the potential to accelerate multiple areas of influenza virus research.
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Affiliation(s)
- Erik A Karlsson
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
- Virology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Victoria A Meliopoulos
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Vy Tran
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
| | - Chandra Savage
- Animal Resource Center, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Brandi Livingston
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Stacey Schultz-Cherry
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA.
| | - Andrew Mehle
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
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23
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Pandemic 2009 H1N1 Influenza Venus reporter virus reveals broad diversity of MHC class II-positive antigen-bearing cells following infection in vivo. Sci Rep 2017; 7:10857. [PMID: 28883436 PMCID: PMC5589842 DOI: 10.1038/s41598-017-11313-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 08/22/2017] [Indexed: 12/17/2022] Open
Abstract
Although it is well established that Influenza A virus infection is initiated in the respiratory tract, the sequence of events and the cell types that become infected or access viral antigens remains incompletely understood. In this report, we used a novel Influenza A/California/04/09 (H1N1) reporter virus that stably expresses the Venus fluorescent protein to identify antigen-bearing cells over time in a mouse model of infection using flow cytometry. These studies revealed that many hematopoietic cells, including subsets of monocytes, macrophages, dendritic cells, neutrophils and eosinophils acquire influenza antigen in the lungs early post-infection. Surface staining of the viral HA revealed that most cell populations become infected, most prominently CD45neg cells, alveolar macrophages and neutrophils. Finally, differences in infection status, cell lineage and MHC class II expression by antigen-bearing cells correlated with differences in their ability to re-stimulate influenza-specific CD4 T cells ex vivo. Collectively, these studies have revealed the cellular heterogeneity and complexity of antigen-bearing cells within the lung and their potential as targets of antigen recognition by CD4 T cells.
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24
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Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein. J Virol 2017; 91:JVI.00184-17. [PMID: 28468888 DOI: 10.1128/jvi.00184-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/27/2017] [Indexed: 01/15/2023] Open
Abstract
Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication.IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are able to protect infants from severe disease, if administered prophylactically. However, antibody responses established after natural RSV infections are poorly protective against reinfection, and high levels of antibodies do not always correlate with protection. Therefore, RSV might be capable of interfering, at least partially, with antibody-induced neutralization. In this study, a process through which surface-expressed RSV F proteins are internalized after interaction with RSV-specific antibodies is described. One the one hand, this antigen-antibody complex internalization could result in an antiviral effect, since it may interfere with virus particle formation and virus production. On the other hand, this mechanism may also reduce the efficacy of antibody-mediated effector mechanisms toward infected cells.
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Jiménez-Somarribas A, Mao S, Yoon JJ, Weisshaar M, Cox RM, Marengo JR, Mitchell DG, Morehouse ZP, Yan D, Solis I, Liotta DC, Natchus MG, Plemper RK. Identification of Non-Nucleoside Inhibitors of the Respiratory Syncytial Virus Polymerase Complex. J Med Chem 2017; 60:2305-2325. [PMID: 28245119 DOI: 10.1021/acs.jmedchem.6b01568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Respiratory syncytial virus (RSV) represents a threat to infants, the elderly, and the immunocompromised. RSV entry blockers are in clinical trials, but escape mutations challenge their potential. In search of RSV inhibitors, we have integrated a signature resistance mutation into a recombinant RSV virus and applied the strain to high-throughput screening. Counterscreening of candidates returned 14 confirmed hits with activities in the nano- to low-micromolar range. All blocked RSV polymerase activity in minigenome assays. Compound 1a (GRP-74915) was selected for development based on activity (EC50 = 0.21 μM, selectivity index (SI) 40) and scaffold. Resynthesis confirmed the potency of the compound, which suppressed viral RNA synthesis in infected cells. However, metabolic testing revealed a short half-life in the presence of mouse hepatocyte fractions. Metabolite tracking and chemical elaboration combined with 3D-quantitative structure-activity relationship modeling yielded analogues (i.e., 8n: EC50 = 0.06 μM, SI 500) that establish a platform for the development of a therapeutic candidate.
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Affiliation(s)
| | - Shuli Mao
- Emory Institute for Drug Development, Emory University , Atlanta, Georgia 30329, United States
| | - Jeong-Joong Yoon
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Marco Weisshaar
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Robert M Cox
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Jose R Marengo
- Emory Institute for Drug Development, Emory University , Atlanta, Georgia 30329, United States
| | - Deborah G Mitchell
- Emory Institute for Drug Development, Emory University , Atlanta, Georgia 30329, United States
| | - Zachary P Morehouse
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Dan Yan
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Ivan Solis
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
| | - Dennis C Liotta
- Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| | - Michael G Natchus
- Emory Institute for Drug Development, Emory University , Atlanta, Georgia 30329, United States
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University , Atlanta, Georgia 30303, United States
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26
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Abstract
Protein homeostasis networks are highly regulated systems responsible for maintaining the health and productivity of cells. Whereas therapeutics have been developed to disrupt protein homeostasis, more recently identified techniques have been used to repurpose homeostatic networks to effect degradation of disease-relevant proteins. Here, we review recent advances in the use of small molecules to degrade proteins in a selective manner. First, we highlight all-small-molecule techniques with direct clinical application. Second, we describe techniques that may find broader acceptance in the biomedical research community that require little or no synthetic chemistry. In addition to serving as innovative research tools, these new approaches to control intracellular protein levels offer the potential to develop novel therapeutics targeting proteins that are not currently pharmaceutically vulnerable.
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Affiliation(s)
- Daniel P Bondeson
- Department of Molecular, Cellular, and Developmental Biology, Department of Chemistry, and Department of Pharmacology, Yale University, New Haven, Connecticut 06511;
| | - Craig M Crews
- Department of Molecular, Cellular, and Developmental Biology, Department of Chemistry, and Department of Pharmacology, Yale University, New Haven, Connecticut 06511;
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27
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Weisshaar M, Cox R, Morehouse Z, Kyasa SK, Yan D, Oberacker P, Mao S, Golden JE, Lowen AC, Natchus MG, Plemper RK. Identification and Characterization of Influenza Virus Entry Inhibitors through Dual Myxovirus High-Throughput Screening. J Virol 2016; 90:7368-7387. [PMID: 27252534 PMCID: PMC4984618 DOI: 10.1128/jvi.00898-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 05/26/2016] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Influenza A virus (IAV) infections cause major morbidity and mortality, generating an urgent need for novel antiviral therapeutics. We recently established a dual myxovirus high-throughput screening protocol that combines a fully replication-competent IAV-WSN strain and a respiratory syncytial virus reporter strain for the simultaneous identification of IAV-specific, paramyxovirus-specific, and broad-spectrum inhibitors. In the present study, this protocol was applied to a screening campaign to assess a diverse chemical library with over 142,000 entries. Focusing on IAV-specific hits, we obtained a hit rate of 0.03% after cytotoxicity testing and counterscreening. Three chemically distinct hit classes with nanomolar potency and favorable cytotoxicity profiles were selected. Time-of-addition, minigenome, and viral entry studies demonstrated that these classes block hemagglutinin (HA)-mediated membrane fusion. Antiviral activity extends to an isolate from the 2009 pandemic and, in one case, another group 1 subtype. Target identification through biolayer interferometry confirmed binding of all hit compounds to HA. Resistance profiling revealed two distinct escape mechanisms: primary resistance, associated with reduced compound binding, and secondary resistance, associated with unaltered binding. Secondary resistance was mediated, unusually, through two different pairs of cooperative mutations, each combining a mutation eliminating the membrane-proximal stalk N-glycan with a membrane-distal change in HA1 or HA2. Chemical synthesis of an analog library combined with in silico docking extracted a docking pose for the hit classes. Chemical interrogation spotlights IAV HA as a major druggable target for small-molecule inhibition. Our study identifies novel chemical scaffolds with high developmental potential, outlines diverse routes of IAV escape from entry inhibition, and establishes a path toward structure-aided lead development. IMPORTANCE This study is one of the first to apply a fully replication-competent third-generation IAV reporter strain to a large-scale high-throughput screen (HTS) drug discovery campaign, allowing multicycle infection and screening in physiologically relevant human respiratory cells. A large number of potential druggable targets was thus chemically interrogated, but mechanistic characterization, positive target identification, and resistance profiling demonstrated that three chemically promising and structurally distinct hit classes selected for further analysis all block HA-mediated membrane fusion. Viral escape from inhibition could be achieved through primary and secondary resistance mechanisms. In silico docking predicted compound binding to a microdomain located at the membrane-distal site of the prefusion HA stalk that was also previously suggested as a target site for chemically unrelated HA inhibitors. This study identifies an unexpected chemodominance of the HA stalk microdomain for small-molecule inhibitors in IAV inhibitor screening campaigns and highlights a novel mechanism of cooperative resistance to IAV entry blockers.
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Affiliation(s)
- Marco Weisshaar
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Robert Cox
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Zachary Morehouse
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Shiva K Kyasa
- Emory Institute for Drug Development, Emory University, Atlanta, GA, USA
| | - Dan Yan
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Phil Oberacker
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Shuli Mao
- Emory Institute for Drug Development, Emory University, Atlanta, GA, USA
| | - Jennifer E Golden
- Department of Pharmacology, University of Wisconsin, Madison, WI, USA
| | - Anice C Lowen
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Michael G Natchus
- Emory Institute for Drug Development, Emory University, Atlanta, GA, USA
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
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28
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Fluorescent and Bioluminescent Reporter Myxoviruses. Viruses 2016; 8:v8080214. [PMID: 27527209 PMCID: PMC4997576 DOI: 10.3390/v8080214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/08/2016] [Accepted: 07/11/2016] [Indexed: 12/16/2022] Open
Abstract
The advent of virus reverse genetics has enabled the incorporation of genetically encoded reporter proteins into replication-competent viruses. These reporters include fluorescent proteins which have intrinsic chromophores that absorb light and re-emit it at lower wavelengths, and bioluminescent proteins which are luciferase enzymes that react with substrates to produce visible light. The incorporation of these reporters into replication-competent viruses has revolutionized our understanding of molecular virology and aspects of viral tropism and transmission. Reporter viruses have also enabled the development of high-throughput assays to screen antiviral compounds and antibodies and to perform neutralization assays. However, there remain technical challenges with the design of replication-competent reporter viruses, and each reporter has unique advantages and disadvantages for specific applications. This review describes currently available reporters, design strategies for incorporating reporters into replication-competent paramyxoviruses and orthomyxoviruses, and the variety of applications for which these tools can be utilized both in vitro and in vivo.
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Breen M, Nogales A, Baker SF, Martínez-Sobrido L. Replication-Competent Influenza A Viruses Expressing Reporter Genes. Viruses 2016; 8:v8070179. [PMID: 27347991 PMCID: PMC4974514 DOI: 10.3390/v8070179] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 06/16/2016] [Accepted: 06/19/2016] [Indexed: 12/12/2022] Open
Abstract
Influenza A viruses (IAV) cause annual seasonal human respiratory disease epidemics. In addition, IAV have been implicated in occasional pandemics with inordinate health and economic consequences. Studying IAV, in vitro or in vivo, requires the use of laborious secondary methodologies to identify virus-infected cells. To circumvent this requirement, replication-competent IAV expressing an easily traceable reporter protein can be used. Here we discuss the development and applications of recombinant replication-competent IAV harboring diverse fluorescent or bioluminescent reporter genes in different locations of the viral genome. These viruses have been employed for in vitro and in vivo studies, such as the screening of neutralizing antibodies or antiviral compounds, the identification of host factors involved in viral replication, cell tropism, the development of vaccines, or the assessment of viral infection dynamics. In summary, reporter-expressing, replicating-competent IAV represent a powerful tool for the study of IAV both in vitro and in vivo.
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Affiliation(s)
- Michael Breen
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Steven F Baker
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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Cox R, Plemper RK. Structure-guided design of small-molecule therapeutics against RSV disease. Expert Opin Drug Discov 2016; 11:543-556. [PMID: 27046051 PMCID: PMC5074927 DOI: 10.1517/17460441.2016.1174212] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION In the United States, respiratory syncytial virus (RSV) is responsible for the majority of infant hospitalizations resulting from viral infections, as well as a leading source of pneumonia and bronchiolitis in young children and the elderly. In the absence of vaccine prophylaxis or an effective antiviral for improved disease management, the development of novel anti-RSV therapeutics is critical. Several advanced drug development campaigns of the past decade have focused on blocking viral infection. These efforts have returned a chemically distinct panel of small-molecule RSV entry inhibitors, but binding sites and molecular mechanism of action appeared to share a common mechanism, resulting in comprehensive cross-resistance and calling for alternative druggable targets such as viral RNA-dependent RNA-polymerase complex. Areas Covered: In this review, the authors discuss the current status of the mechanism of action of RSV entry inhibitors. They also provide the recent structural insight into the organization of the polymerase complex that have revealed novel drug targets sites, and outline a path towards the discovery of next-generation RSV therapeutics. Expert opinion: Considering the tremendous progress experienced in our structural understanding of RSV biology in recent years and encouraging early results of a nucleoside analog inhibitor in clinical trials, there is high prospect that new generations of much needed effective anti-RSV therapeutics will become available for clinical use in the foreseeable future.
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Affiliation(s)
- Robert Cox
- Institute for Biomedical Sciences, Georgia State University, 100 Piedmont Av, Atlanta, Georgia 30303-3222 USA
| | - Richard K Plemper
- Institute for Biomedical Sciences, Georgia State University, 100 Piedmont Av, Atlanta, Georgia 30303-3222 USA
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31
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Replication-Competent Influenza A and B Viruses Expressing a Fluorescent Dynamic Timer Protein for In Vitro and In Vivo Studies. PLoS One 2016; 11:e0147723. [PMID: 26809059 PMCID: PMC4725730 DOI: 10.1371/journal.pone.0147723] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/07/2016] [Indexed: 01/13/2023] Open
Abstract
Influenza A and B viruses (IAV and IBV, respectively) cause annual seasonal human respiratory disease epidemics. In addition, IAVs have been implicated in occasional pandemics with inordinate health and economic consequences. Studying influenza viruses in vitro or in vivo requires the use of laborious secondary methodologies to identify infected cells. To circumvent this requirement, replication-competent infectious influenza viruses expressing an easily traceable fluorescent reporter protein can be used. Timer is a fluorescent protein that undergoes a time-dependent color emission conversion from green to red. The rate of spectral change is independent of Timer protein concentration and can be used to chronologically measure the duration of its expression. Here, we describe the generation of replication-competent IAV and IBV where the viral non-structural protein 1 (NS1) was fused to the fluorescent dynamic Timer protein. Timer-expressing IAV and IBV displayed similar plaque phenotypes and growth kinetics to wild-type viruses in tissue culture. Within infected cells, Timer’s spectral shift can be used to measure the rate and cell-to-cell spread of infection using fluorescent microscopy, plate readers, or flow cytometry. The progression of Timer-expressing IAV infection was also evaluated in a mouse model, demonstrating the feasibility to characterize IAV cell-to-cell infections in vivo. By providing the ability to chronologically track viral spread, Timer-expressing influenza viruses are an excellent option to evaluate the in vitro and in vivo dynamics of viral infection.
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