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Genoyer E, Wilson J, Ames JM, Stokes C, Moreno D, Etzyon N, Oberst A, Gale M. Exposure of negative-sense viral RNA in the cytoplasm initiates innate immunity to West Nile virus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.07.597966. [PMID: 38895355 PMCID: PMC11185705 DOI: 10.1101/2024.06.07.597966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
For many RNA viruses, immunity is triggered when RIG-I-like receptors (RLRs) detect viral RNA. However, only a minority of infected cells undergo innate immune activation. By examining these "first responder" cells during West Nile virus infection, we found that specific accumulation of anti- genomic negative-sense viral RNA (-vRNA) underlies innate immune activation and that RIG-I preferentially interacts with -vRNA. However, flaviviruses sequester -vRNA into membrane-bound replication compartments away from cytosolic sensors. We found that single-stranded -vRNA accumulates outside of replication compartments in "first responder" cells, rendering it accessible to RLRs. Exposure of this -vRNA occurs at late timepoints of infection, is linked to viral assembly, and depends on the expression of viral structural proteins. These findings reveal that while most infected cells replicate high levels of vRNA, release of -vRNA from replication compartments during assembly occurs at low frequency and is critical for initiation of innate immunity during flavivirus infection.
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Cai HL, Huang YW. Reverse genetics systems for SARS-CoV-2: Development and applications. Virol Sin 2023; 38:837-850. [PMID: 37832720 PMCID: PMC10786661 DOI: 10.1016/j.virs.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 10/07/2023] [Indexed: 10/15/2023] Open
Abstract
The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused serious harm to human health and struck a blow to global economic development. Research on SARS-CoV-2 has greatly benefited from the use of reverse genetics systems, which have been established to artificially manipulate the viral genome, generating recombinant and reporter infectious viruses or biosafety level 2 (BSL-2)-adapted non-infectious replicons with desired modifications. These tools have been instrumental in studying the molecular biological characteristics of the virus, investigating antiviral therapeutics, and facilitating the development of attenuated vaccine candidates. Here, we review the construction strategies, development, and applications of reverse genetics systems for SARS-CoV-2, which may be applied to other CoVs as well.
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Affiliation(s)
- Hou-Li Cai
- Department of Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Yao-Wei Huang
- Department of Veterinary Medicine, Zhejiang University, Hangzhou, 310058, China; State Key Laboratory for Animal Disease Control and Prevention, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China.
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The Antifungal Itraconazole Is a Potent Inhibitor of Chikungunya Virus Replication. Viruses 2022; 14:v14071351. [PMID: 35891332 PMCID: PMC9317443 DOI: 10.3390/v14071351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/14/2022] [Accepted: 06/17/2022] [Indexed: 12/04/2022] Open
Abstract
Chikungunya virus (CHIKV) is the causative agent of chikungunya fever, a disabling disease that can cause long-term severe arthritis. Since the last large CHIKV outbreak in 2015, the reemergence of the virus represents a serious public health concern. The morbidity associated with viral infection emphasizes the need for the development of specific anti-CHIKV drugs. Herein, we describe the development and characterization of a CHIKV reporter replicon cell line and its use in replicon-based screenings. We tested 960 compounds from MMV/DNDi Open Box libraries and identified four candidates with interesting antiviral activities, which were confirmed in viral infection assays employing CHIKV-nanoluc and BHK-21 cells. The most noteworthy compound identified was itraconazole (ITZ), an orally available, safe, and cheap antifungal, that showed high selectivity indexes of >312 and >294 in both replicon-based and viral infection assays, respectively. The antiviral activity of this molecule has been described against positive-sense single stranded RNA viruses (+ssRNA) and was related to cholesterol metabolism that could affect the formation of the replication organelles. Although its precise mechanism of action against CHIKV still needs to be elucidated, our results demonstrate that ITZ is a potent inhibitor of the viral replication that could be repurposed as a broad-spectrum antiviral.
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Zhang JW, Wang H, Liu J, Ma L, Hua RH, Bu ZG. Generation of A Stable GFP-reporter Zika Virus System for High-throughput Screening of Zika Virus Inhibitors. Virol Sin 2021; 36:476-489. [PMID: 33231855 PMCID: PMC8257822 DOI: 10.1007/s12250-020-00316-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/18/2020] [Indexed: 01/15/2023] Open
Abstract
Zika virus (ZIKV) is associated with severe birth defects and Guillain-Barré syndrome and no approved vaccines or specific therapies to combat ZIKV infection are currently available. To accelerate anti-ZIKV therapeutics research, we developed a stable ZIKV GFP-reporter virus system with considerably improved GFP visibility and stability. In this system a BHK-21 cell line expressing DC-SIGNR was established to facilitate the proliferation of GFP-reporter ZIKV. Using this reporter virus system, we established a high-throughput screening assay and screened a selected plant-sourced compounds library for their ability to block ZIKV infection. More than 31 out of 974 tested compounds effectively decreased ZIKV reporter infection. Four selected compounds, homoharringtonine (HHT), bruceine D (BD), dihydroartemisinin (DHA) and digitonin (DGT), were further validated to inhibit wild-type ZIKV infection in cells of BHK-21 and human cell line A549. The FDA-approved chronic myeloid leukemia treatment drug HHT and BD were identified as broad-spectrum flavivirus inhibitors. DHA, another FDA-approved antimalarial drug effectively inhibited ZIKV infection in BHK-21 cells. HHT, BD and DHA inhibited ZIKV infection at a post-entry stage. Digitonin was found to have inhibitory activity in the early stage of viral infection. Our research provides an efficient high-throughput screening assay for ZIKV inhibitors. The active compounds identified in this study represent potential therapies for the treatment of ZIKV infection.
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Affiliation(s)
- Jing-Wei Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China
| | - Han Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China
| | - Jing Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China
| | - Le Ma
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China
| | - Rong-Hong Hua
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China.
| | - Zhi-Gao Bu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150069, China.
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou 225009, China.
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5
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Zhang X, Liu Y, Liu J, Bailey AL, Plante KS, Plante JA, Zou J, Xia H, Bopp NE, Aguilar PV, Ren P, Menachery VD, Diamond MS, Weaver SC, Xie X, Shi PY. A trans-complementation system for SARS-CoV-2 recapitulates authentic viral replication without virulence. Cell 2021; 184:2229-2238.e13. [PMID: 33691138 PMCID: PMC7901297 DOI: 10.1016/j.cell.2021.02.044] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/11/2021] [Accepted: 02/19/2021] [Indexed: 12/25/2022]
Abstract
The biosafety level 3 (BSL-3) requirement to culture severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a bottleneck for research. Here, we report a trans-complementation system that produces single-round infectious SARS-CoV-2 that recapitulates authentic viral replication. We demonstrate that the single-round infectious SARS-CoV-2 can be used at BSL-2 laboratories for high-throughput neutralization and antiviral testing. The trans-complementation system consists of two components: a genomic viral RNA containing ORF3 and envelope gene deletions, as well as mutated transcriptional regulator sequences, and a producer cell line expressing the two deleted genes. Trans-complementation of the two components generates virions that can infect naive cells for only one round but does not produce wild-type SARS-CoV-2. Hamsters and K18-hACE2 transgenic mice inoculated with the complementation-derived virions exhibited no detectable disease, even after intracranial inoculation with the highest possible dose. Thus, the trans-complementation platform can be safely used at BSL-2 laboratories for research and countermeasure development.
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Affiliation(s)
- Xianwen Zhang
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Yang Liu
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Jianying Liu
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Adam L Bailey
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - Kenneth S Plante
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, TX, USA
| | - Jessica A Plante
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, TX, USA
| | - Jing Zou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Hongjie Xia
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Nathen E Bopp
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Patricia V Aguilar
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Ping Ren
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Vineet D Menachery
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Michael S Diamond
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, USA; Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA; Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Scott C Weaver
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; World Reference Center for Emerging Viruses and Arboviruses, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, USA
| | - Xuping Xie
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
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Zhang X, Liu Y, Liu J, Bailey AL, Plante KS, Plante JA, Zou J, Xia H, Bopp N, Aguilar P, Ren P, Menachery VD, Diamond MS, Weaver SC, Xie X, Shi PY. A trans -complementation system for SARS-CoV-2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 33501436 DOI: 10.1101/2021.01.16.426970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The biosafety level-3 (BSL-3) requirement to culture severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a bottleneck for research and countermeasure development. Here we report a trans -complementation system that produces single-round infectious SARS-CoV-2 that recapitulates authentic viral replication. We demonstrate that the single-round infectious SARS-CoV-2 can be used at BSL-2 laboratories for high-throughput neutralization and antiviral testing. The trans -complementation system consists of two components: a genomic viral RNA containing a deletion of ORF3 and envelope gene, and a producer cell line expressing the two deleted genes. Trans- complementation of the two components generates virions that can infect naive cells for only one round, but does not produce wild-type SARS-CoV-2. Hamsters and K18-hACE2 transgenic mice inoculated with the complementation-derived virions exhibited no detectable disease, even after intracranial inoculation with the highest possible dose. The results suggest that the trans -complementation platform can be safely used at BSL-2 laboratories for research and countermeasure development.
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7
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Balakrishnan A, Mun AB. Ribavirin inhibits Chandipura virus replication in Vero cells. J Med Virol 2020; 92:2969-2975. [PMID: 32543712 DOI: 10.1002/jmv.26184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 06/10/2020] [Indexed: 01/04/2023]
Abstract
Chandipura virus (CHPV) is an emerging tropical pathogen in India. The virus has been reported to be associated with an acute encephalitis syndrome in young children with a case fatality rate of 55% to 75%. Clinical management with symptomatic treatment is the only option available to treat infected patients. No vaccines are available for prophylaxis. In light of the prophylactic limitations, antiviral therapy would play an important role in control of CHPV infection. In the present study, ribavirin (RBV), an antiviral drug widely accepted for human use and having an antiviral effect on many RNA and DNA viruses, was tested against the CHPV. A screening assay that scores for the virus-mediated plaque formation in the cultured Vero cells was used. RBV exhibited 50% inhibitory concentration (IC50 ) at 89.84 ± 1.8 µM. The drug was very effective when the cells were treated either within an hour postinfection or 4 to 6 hours before infection. The plaque morphology was different in RBV treated cells; the plaques were smaller in size as compared with the plaques in the virus infected cells. The study reports the antiviral activity of RBV against CHPV, and hence, suggests the possible utility of RBV in CHPV infected patients to mitigate the disease. A further clinical trial is needed before introducing the drug for human use against CHPV infection.
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Affiliation(s)
| | - Amol B Mun
- ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
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Autonomously Replicating RNAs of Bungowannah Pestivirus: E RNS Is Not Essential for the Generation of Infectious Particles. J Virol 2020; 94:JVI.00436-20. [PMID: 32404522 DOI: 10.1128/jvi.00436-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 05/04/2020] [Indexed: 12/31/2022] Open
Abstract
Autonomously replicating subgenomic Bungowannah virus (BuPV) RNAs (BuPV replicons) with deletions of the genome regions encoding the structural proteins C, ERNS, E1, and E2 were constructed on the basis of an infectious cDNA clone of BuPV. Nanoluciferase (Nluc) insertion was used to compare the replication efficiencies of all constructs after electroporation of in vitro-transcribed RNA from the different clones. Deletion of C, E1, E2, or the complete structural protein genome region (C-ERNS-E1-E2) prevented the production of infectious progeny virus, whereas deletion of ERNS still allowed the generation of infectious particles. However, those ΔERNS viral particles were defective in virus assembly and/or egress and could not be further propagated for more than three additional passages in porcine SK-6 cells. These "defective-in-third-cycle" BuPV ΔERNS mutants were subsequently used to express the classical swine fever virus envelope protein E2, the N-terminal domain of the Schmallenberg virus Gc protein, and the receptor binding domain of the Middle East respiratory syndrome coronavirus spike protein. The constructs could be efficiently complemented and further passaged in SK-6 cells constitutively expressing the BuPV ERNS protein. Importantly, BuPVs are able to infect a wide variety of target cell lines, allowing expression in a very wide host spectrum. Therefore, we suggest that packaged BuPV ΔERNS replicon particles have potential as broad-spectrum viral vectors.IMPORTANCE The proteins NPRO and ERNS are unique for the genus Pestivirus, but only NPRO has been demonstrated to be nonessential for in vitro growth. While this was also speculated for ERNS, it has always been previously shown that pestivirus replicons with deletions of the structural proteins ERNS, E1, or E2 did not produce any infectious progeny virus in susceptible host cells. Here, we demonstrated for the first time that BuPV ERNS is dispensable for the generation of infectious virus particles but still important for efficient passaging. The ERNS-defective BuPV particles showed clearly limited growth in cell culture but were capable of several rounds of infection, expression of foreign genes, and highly efficient trans-complementation to rescue virus replicon particles (VRPs). The noncytopathic characteristics and the absence of preexisting immunity to BuPV in human populations and livestock also provide a significant benefit for a possible use, e.g., as a vector vaccine platform.
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9
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Vicenti I, Dragoni F, Giannini A, Giammarino F, Spinicci M, Saladini F, Boccuto A, Zazzi M. Development of a Cell-Based Immunodetection Assay for Simultaneous Screening of Antiviral Compounds Inhibiting Zika and Dengue Virus Replication. SLAS DISCOVERY 2020; 25:506-514. [PMID: 32186426 DOI: 10.1177/2472555220911456] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Practical cell-based assays can accelerate anti-Zika (ZIKV) and anti-dengue (DENV) virus drug discovery. We developed an immunodetection assay (IA), using a pan-flaviviral monoclonal antibody recognizing a conserved envelope domain. The final protocol includes a direct virus yield reduction assay (YRA) carried out in the human Huh7 cell line, followed by transfer of the supernatant to a secondary Huh7 culture to characterize late antiviral effects. Sofosbuvir and ribavirin were used to validate the assay, while celgosivir was used to evaluate the ability to discriminate between early and late antiviral activity. In the direct YRA, at 100, 50, and 25 TCID50, sofosbuvir IC50 values were 5.0 ± 1.5, 2.7 ± 0.5, 2.5 ± 1.1 µM against ZIKV and 16.6 ± 2.8, 4.6 ± 1.4, 2.6 ± 2.2 µM against DENV; ribavirin IC50 values were 6.8 ± 4.0, 3.8 ± 0.6, 4.5 ± 1.4 µM against ZIKV and 17.3 ± 4.6, 7.6 ± 1.2, 4.1 ± 2.3 µM against DENV. Sofosbuvir and ribavirin IC50 values determined in the secondary YRA were reproducible and comparable with those obtained by direct YRA and plaque reduction assay (PRA). In agreement with the proposed mechanism of late action, celgosivir was active against DENV only in the secondary YRA (IC50 11.0 ± 1.0 µM) and in PRA (IC50 10.1 ± 1.1 µM). The assay format overcomes relevant limitations of the gold standard PRA, allowing concurrent analysis of candidate antiviral compounds against different viruses and providing preliminary information about early versus late antiviral activity.
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Affiliation(s)
- Ilaria Vicenti
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Filippo Dragoni
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Alessia Giannini
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | | | - Michele Spinicci
- Unit of Infectious Diseases, Careggi University Hospital, Florence, Toscana, Italy
| | - Francesco Saladini
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Adele Boccuto
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Maurizio Zazzi
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
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10
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Zou J, Shi PY. Strategies for Zika drug discovery. Curr Opin Virol 2019; 35:19-26. [PMID: 30852345 DOI: 10.1016/j.coviro.2019.01.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/23/2019] [Accepted: 01/28/2019] [Indexed: 12/15/2022]
Abstract
Zika virus (ZIKV) can cause devastating congenital syndrome in fetuses from pregnant women and autoimmune disorder Guillain-Barré syndrome in adults. No clinically approved vaccine or drug is currently available for ZIKV. This unmet medical need has motivated a global effort to develop countermeasures. Several promising ZIKV vaccine candidates have already entered clinical trials. In contrast, antiviral development of ZIKV is lagging behind. Here, we review the overall strategies for ZIKV drug discovery, including (i) repurposing of clinically approved drugs, (ii) viral replication-based phenotypic screening for inhibitors, and (iii) targeted drug discovery of viral proteins. Along with vaccines, the development of antiviral treatment will provide a complementary means to control ZIKV infections.
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Affiliation(s)
- Jing Zou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Department of Phamarcology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, USA.
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11
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Meutiawati F, Bezemer B, Strating JRPM, Overheul GJ, Žusinaite E, van Kuppeveld FJM, van Cleef KWR, van Rij RP. Posaconazole inhibits dengue virus replication by targeting oxysterol-binding protein. Antiviral Res 2018; 157:68-79. [PMID: 29981375 DOI: 10.1016/j.antiviral.2018.06.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/08/2018] [Accepted: 06/30/2018] [Indexed: 11/30/2022]
Abstract
Dengue virus (DENV) is associated with an estimated 390 million infections per year, occurring across approximately 100 countries in tropical and sub-tropical regions. To date, there are no antiviral drugs or specific therapies to treat DENV infection. Posaconazole and itraconazole are potent antifungal drugs that inhibit ergosterol biosynthesis in fungal cells, but also target a number of human proteins. Here, we show that itraconazole and posaconazole have antiviral activity against DENV. Posaconazole inhibited replication of multiple serotypes of DENV and the related flavivirus Zika virus, and reduced viral RNA replication, but not translation of the viral genome. We used a combination of knockdown and drug sensitization assays to define the molecular target of posaconazole that mediates its antiviral activity. We found that knockdown of oxysterol-binding protein (OSBP) inhibited DENV replication. Moreover, knockdown of OSBP, but not other known targets of posaconazole, enhanced the inhibitory effect of posaconazole. Our findings imply OSBP as a potential target for the development of antiviral compounds against DENV.
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Affiliation(s)
- Febrina Meutiawati
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands; Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bodine Bezemer
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands; Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen R P M Strating
- Virology Division, Department of Infectious Diseases & Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Gijs J Overheul
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands; Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eva Žusinaite
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Frank J M van Kuppeveld
- Virology Division, Department of Infectious Diseases & Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Koen W R van Cleef
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands; Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands; Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands.
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12
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Establishment and Application of Flavivirus Replicons. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1062:165-173. [PMID: 29845532 DOI: 10.1007/978-981-10-8727-1_12] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Dengue virus (DENV) and Zika virus (ZIKV) are enveloped, positive-strand RNA viruses belonging to the genus Flavivirus in the family Flaviviridae. The genome of ~11 kb length encodes one long open reading frame flanked by a 5' and a 3' untranslated region (UTR). The 5' end is capped and the 3' end lacks a poly(A) tail. The encoded single polyprotein is cleaved co-and posttranslationally by cellular and viral proteases. The first one-third of the genome encodes the structural proteins (C-prM-E), whereas the nonstructural (NS) proteins NS1-NS2A-NS3-NS4A-2K-NS4B-NS5 are encoded by the remaining two-thirds of the genome.Research on flaviviruses was driven forward by the ability to produce recombinant viruses using reverse genetics technology. It is known that the purified RNA of flaviviruses is per se infectious, which allows initiation of a complete viral life cycle by transfecting the genomic RNA into susceptible cells. In 1989, the first infectious flavivirus RNA was transcribed from full-length cDNA templates of yellow fever virus (YFV) facilitating molecular genetic analyses of this virus. In addition to the production of infectious recombinant viruses, reverse genetics can also be used to establish non-infectious replicons. Replicons contain an in-frame deletion in the structural protein genes but still encode all nonstructural proteins and contain the UTRs necessary to mediate efficient replication, a factor that enables their analyses under Biosafety Level (BSL) 1 conditions. This is particularly important since many flaviviruses are BSL3 agents.The review will cover strategies for generating flavivirus replicons, including the establishment of bacteriophage (T7 or SP6) promoter-driven constructs as well as cytomegalovirus (CMV) promoter-driven constructs. Furthermore, different reporter replicons or replicons expressing selectable marker proteins will be outlined using examples of their application to answer basic questions of the flavivirus replication cycle, to select and test antiviral compounds or to produce virus replicon particles. The establishment and application of flavivirus replicons will further be exemplified by my own data using an established YFV reporter replicon to study the role of YFV NS2A in the viral life cycle. In addition, we established a reporter replicon of a novel insect-specific flavivirus, namely Niénokoué virus (NIEV), to define the barrier(s) involved in host range restriction.
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Development of Virus-Like-Particle Vaccine and Reporter Assay for Zika Virus. J Virol 2017; 91:JVI.00834-17. [PMID: 28794019 DOI: 10.1128/jvi.00834-17] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/31/2017] [Indexed: 12/31/2022] Open
Abstract
Recent worldwide outbreaks of Zika virus (ZIKV) infection and the lack of an approved vaccine raise serious concerns regarding preparedness to combat this emerging virus. We used a virus-like particle (VLP)-based approach to develop a vaccine and a microneutralization assay for ZIKV. A synthetic capsid-premembrane-envelope (C-prM-E) gene construct of ZIKV was used to generate reporter virus particles (RVPs) that package a green fluorescent protein (GFP) reporter-expressing West Nile virus (WNV) replicon. The assay was adapted to a 96-well format, similar to the plaque reduction neutralization test (PRNT), and showed high reproducibility with specific detection of ZIKV neutralizing antibodies. Furthermore, C-prM-E and prM-E VLPs were tested as vaccine candidates in mice and compared to DNA vaccination. While the ZIKV prM-E construct alone was sufficient for generating VLPs, efficient VLP production from the C-prM-E construct could be achieved in the presence of the WNV NS2B-3 protease, which cleaves C from prM, allowing virus release. Immunization studies in mice showed that VLPs generated higher neutralizing antibody titers than those with the DNA vaccines, with C-prM-E VLPs giving slightly higher titers than those with prM-E VLPs. The superiority of C-prM-E VLPs suggests that inclusion of capsid may have benefits for ZIKV and other flaviviral VLP vaccines. To facilitate the VLP platform, we generated a stable cell line expressing high levels of ZIKV prM-E proteins that constitutively produce VLPs as well as a cell line expressing ZIKV C-prM-E proteins for RVP production. While several vaccine platforms have been proposed for ZIKV, this study describes a safe, effective, and economical VLP-based vaccine against ZIKV.IMPORTANCE To address the growing Zika virus epidemic, we undertook this study with two objectives: first, to develop a safe, effective, and economical vaccine for ZIKV, and second, to develop a rapid and versatile assay to detect the anti-ZIKV immune response. We generated a cell line stably expressing ZIKV prM-E that produces large amounts of VLPs in the supernatant and a ZIKV C-prM-E cell line that produces reporter virus particles upon transfection with a GFP replicon plasmid. The prM-E VLPs induced a strong neutralizing antibody response in mice that was better when the capsid was included. VLP-based vaccines showed significantly better neutralizing antibody responses than those with their DNA counterparts. The RVP-based microneutralization assay worked similarly to the PRNT assay, with a rapid GFP readout in a 96-well format. Our VLP-based platform provides a source for a ZIKV vaccine and diagnosis that can rapidly be adapted to current outbreaks.
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Zhang QY, Li XD, Liu SQ, Deng CL, Zhang B, Ye HQ. Development of a stable Japanese encephalitis virus replicon cell line for antiviral screening. Arch Virol 2017; 162:3417-3423. [PMID: 28779235 DOI: 10.1007/s00705-017-3508-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 06/21/2017] [Indexed: 12/27/2022]
Abstract
Japanese encephalitis virus (JEV), an important pathogen in Eastern and Southern Asia and the Pacific, has spread to Australia and other territories in recent years. Although the vaccine for JEV has been used in some countries, development of efficient antiviral drugs is still an urgent requirement. Replicon systems have been widely used in the research of viral replication and antiviral screening for West Nile virus (WNV), yellow fever virus (YFV) and dengue virus (DENV). Here, a novel JEV replicon harboring the Rluc and Pac gene (JEV-Pac-Rluc-Rep) was constructed. Furthermore, we established a BHK-21 cell line harboring JEV-Pac-Rluc-Rep (BHK-21/PAC/Rluc cell line) through continuous puromycin selection. Characterization of cell line stability showed that the replicon RNA could persistently replicate in this cell line for at least up to 10 rounds of passage. Using a known flavivirus inhibitor, the JEV replicon cell line was validated for antiviral screening. The JEV replicon cell line will be a valuable tool for both compound screening and viral replication studies.
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Affiliation(s)
- Qiu-Yan Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao-Dan Li
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Si-Qing Liu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Cheng-Lin Deng
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Bo Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Han-Qing Ye
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
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15
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Li W, Ma L, Guo LP, Wang XL, Zhang JW, Bu ZG, Hua RH. West Nile virus infectious replicon particles generated using a packaging-restricted cell line is a safe reporter system. Sci Rep 2017; 7:3286. [PMID: 28607390 PMCID: PMC5468312 DOI: 10.1038/s41598-017-03670-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/03/2017] [Indexed: 11/09/2022] Open
Abstract
West Nile virus (WNV) is a neurotropic pathogen which causes zoonotic disease in humans. Recently, there have been an increasing number of infected cases and there are no clinically approved vaccines or effective drugs to treat WNV infections in humans. The purpose of this study was to facilitate vaccine and antiviral drug discovery by developing a packaging cell line-restricted WNV infectious replicon particle system. We constructed a DNA-based WNV replicon lacking the C-prM-E coding region and replaced it with a GFP coding sequence. To produce WNV replicon particles, cell lines stably-expressing prM-E and C-prM-E were constructed. When the WNV replicon plasmid was co-transfected with a WNV C-expressing plasmid into the prM-E-expressing cell line or directly transfected the C-prM-E expressing cell line, the replicon particle was able to replicate, form green fluorescence foci, and exhibit cytopathic plaques similar to that induced by the wild type virus. The infectious capacity of the replicon particles was restricted to the packaging cell line as the replicons demonstrated only one round of infection in other permissive cells. Thus, this system provides a safe and convenient reporter WNV manipulating tool which can be used to study WNV viral invasion mechanisms, neutralizing antibodies and antiviral efficacy.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China
| | - Le Ma
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China
| | - Li-Ping Guo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China
| | - Xiao-Lei Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China
| | - Jing-Wei Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China
| | - Zhi-Gao Bu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China.
| | - Rong-Hong Hua
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, 150001, China.
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16
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Zhang HL, Ye HQ, Deng CL, Liu SQ, Shi PY, Qin CF, Yuan ZM, Zhang B. Generation and characterization of West Nile pseudo-infectious reporter virus for antiviral screening. Antiviral Res 2017; 141:38-47. [DOI: 10.1016/j.antiviral.2017.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 02/10/2017] [Accepted: 02/11/2017] [Indexed: 01/27/2023]
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17
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Xie X, Zou J, Shan C, Yang Y, Kum DB, Dallmeier K, Neyts J, Shi PY. Zika Virus Replicons for Drug Discovery. EBioMedicine 2016; 12:156-160. [PMID: 27658737 PMCID: PMC5078599 DOI: 10.1016/j.ebiom.2016.09.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/09/2016] [Accepted: 09/13/2016] [Indexed: 01/08/2023] Open
Abstract
The current epidemic of Zika virus (ZIKV) has underscored the urgency to establish experimental systems for studying viral replication and pathogenesis, and countermeasure development. Here we report two ZIKV replicon systems: a luciferase replicon that can differentiate between viral translation and RNA synthesis; and a stable luciferase replicon carrying cell line that can be used to screen and characterize inhibitors of viral replication. The transient replicon was used to evaluate the effect of an NS5 polymerase mutation on viral RNA synthesis and to analyze a known ZIKV inhibitor. The replicon cell line was developed into a 96-well format for antiviral testing. Compare with virus infection-based assay, the replicon cell line allows antiviral screening without using infectious virus. Collectively, the replicon systems have provided critical tools for both basic and translational research. A Zika virus replicon has been developed to study antivirals and to differentiate between viral translation and replication. A cell line carrying Zika virus replicon has been developed to screen and characterize antiviral inhibitors.
Experimental systems are urgently needed to study Zika virus and to develop countermeasures. In this communication, we report the development of Zika virus replicon systems that can be used to study viral replication and pathogenesis as well as to screen and characterize antiviral inhibitors.
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Affiliation(s)
- Xuping Xie
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Jing Zou
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Chao Shan
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Yujiao Yang
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Dieudonné Buh Kum
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, University of Leuven, Leuven, Belgium
| | - Kai Dallmeier
- Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, University of Leuven, Leuven, Belgium
| | - Johan Neyts
- Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, University of Leuven, Leuven, Belgium
| | - Pei-Yong Shi
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Department of Pharmacology & Toxicology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
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18
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Live Cell Reporter Systems for Positive-Sense Single Strand RNA Viruses. Appl Biochem Biotechnol 2016; 178:1567-85. [PMID: 26728654 PMCID: PMC7091396 DOI: 10.1007/s12010-015-1968-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/22/2015] [Indexed: 01/09/2023]
Abstract
Cell-based reporter systems have facilitated studies of viral replication and pathogenesis, virus detection, and drug susceptibility testing. There are three types of cell-based reporter systems that express certain reporter protein for positive-sense single strand RNA virus infections. The first type is classical reporter system, which relies on recombinant virus, reporter virus particle, or subgenomic replicon. During infection with the recombinant virus or reporter virus particle, the reporter protein is expressed and can be detected in real time in a dose-dependent manner. Using subgenomic replicon, which are genetically engineered viral RNA molecules that are capable of replication but incapable of producing virions, the translation and replication of the replicon could be tracked by the accumulation of reporter protein. The second type of reporter system involves genetically engineered cells bearing virus-specific protease cleavage sequences, which can sense the incoming viral protease. The third type is based on viral replicase, which can report the specific virus infection via detection of the incoming viral replicase. This review specifically focuses on the major technical breakthroughs in the design of cell-based reporter systems and the application of these systems to the further understanding and control of viruses over the past few decades.
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19
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Mukherjee S, Pierson TC, Dowd KA. Pseudo-infectious reporter virus particles for measuring antibody-mediated neutralization and enhancement of dengue virus infection. Methods Mol Biol 2014; 1138:75-97. [PMID: 24696332 DOI: 10.1007/978-1-4939-0348-1_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This chapter outlines methods for the production of dengue virus (DENV) reporter virus particles (RVPs) and their use in assays that measure antibody-mediated neutralization and enhancement of DENV infection. RVPs are pseudo-infectious virions produced by complementation of a self-replicating flavivirus replicon with the DENV structural genes in trans. RVPs harvested from transfected cells are capable of only a single round of infection and encapsidate replicon RNA that encodes a reporter gene used to enumerate infected cells. RVPs may be produced using the structural genes of different DENV serotypes, genotypes, and mutants by changing plasmids used for complementation. Further modifications are possible including generating RVPs with varying levels of uncleaved prM protein, which resemble either the immature or mature form of the virus. Neutralization potency is measured by incubating RVPs with serial dilutions of antibody, followed by infection of target cells that express DENV attachment factors. Enhancement of infection is measured similarly using Fc receptor-expressing cells capable of internalizing antibody-virus complexes.
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Affiliation(s)
- Swati Mukherjee
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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20
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Li XD, Li XF, Ye HQ, Deng CL, Ye Q, Shan C, Shang BD, Xu LL, Li SH, Cao SB, Yuan ZM, Shi PY, Qin CF, Zhang B. Recovery of a chemically synthesized Japanese encephalitis virus reveals two critical adaptive mutations in NS2B and NS4A. J Gen Virol 2013; 95:806-815. [PMID: 24362961 DOI: 10.1099/vir.0.061838-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A full-length genome infectious clone is a powerful tool for functional assays in virology. In this study, using a chemical synthesized complete genome of Japanese encephalitis virus (JEV) strain SA14 (GenBank accession no. U14163), we constructed a full-length genomic cDNA clone of JEV. The recovered virus from the cDNA clone replicated poorly in baby hamster kidney (BHK-21) cells and in suckling mice brain. Following serial passage in BHK-21 cells, adaptive mutations within the NS2B and NS4A proteins were recovered in the passaged viruses leading to viruses with a large-plaque phenotype. Mutagenesis analysis, using a genome-length RNA and a replicon of JEV, demonstrated that the adaptive mutations restored replication to different degrees, and the restoration efficiencies were in the order: NS2B-T102M<NS4A-R79K<NS2B-T102M+NS4A-R79K. An in vivo virulence assay in mice showed that the recombinant virus containing double mutations showed similar virulence to the WT SA14 (GenBank accession no. M55506). This study reports the first chemically synthesized JEV. A reverse genetics assay demonstrated that substitutions of NS2B-T102M and NS4A-R79K altered JEV replication.
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Affiliation(s)
- Xiao-Dan Li
- University of Chinese Academy of Sciences, Beijing 100049, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Xiao-Feng Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Han-Qing Ye
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Cheng-Lin Deng
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Qing Ye
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Chao Shan
- University of Chinese Academy of Sciences, Beijing 100049, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Bao-Di Shang
- University of Chinese Academy of Sciences, Beijing 100049, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Lin-Lin Xu
- University of Chinese Academy of Sciences, Beijing 100049, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Shi-Hua Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Sheng-Bo Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Zhi-Ming Yuan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Pei-Yong Shi
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Cheng-Feng Qin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Bo Zhang
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.,Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
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21
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Shang B, Deng C, Ye H, Xu W, Yuan Z, Shi PY, Zhang B. Development and characterization of a stable eGFP enterovirus 71 for antiviral screening. Antiviral Res 2012; 97:198-205. [PMID: 23267829 DOI: 10.1016/j.antiviral.2012.12.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/06/2012] [Accepted: 12/15/2012] [Indexed: 11/18/2022]
Abstract
Enterovirus 71 (EV71) is one of the major causative agents for hand, foot, and mouth disease. There is currently no clinically approved vaccine or antiviral treatment for EV71 infection. To facilitate antiviral drug discovery, we developed an infectious cDNA clone of an epidemic strain of EV71 and a stable eGFP reporter EV71. The reporter virus was generated by engineering the eGFP gene between the 5' untranslated region and VP4 gene of the EV71 genome. Vero cells transfected with the cDNA clone-derived RNA generated high titers (>10(6)PFU/ml) of the eGFP reporter virus. The reporter virus was infectious to Vero cells, producing robust eGFP fluorescence signals. Compared with the wild type virus, the reporter virus replicated slower in cell culture. To examine the stability of the reporter virus, we continuously passaged the virus on Vero cells for five rounds. The passaged viruses maintained the eGFP gene, demonstrating the stability of the reporter virus. Using a known EV71 inhibitor, we demonstrate that the reporter virus could be used for antiviral screening. The infectious cDNA clones of the wild type virus and the eGFP reporter viruses will be useful for antiviral research as well as for studying viral replication and pathogenesis of EV71.
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Affiliation(s)
- Baodi Shang
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Science, China
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22
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Leardkamolkarn V, Sirigulpanit W, Chotiwan N, Kumkate S, Huang CYH. Development of Dengue type-2 virus replicons expressing GFP reporter gene in study of viral RNA replication. Virus Res 2011; 163:552-62. [PMID: 22197424 DOI: 10.1016/j.virusres.2011.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 11/19/2022]
Abstract
Insertion of green fluorescent protein (GFP) encoding-gene into virus genes has provided a valuable tool for flavivirus research. This study aimed to develop dengue virus (DENV) replicons expressing GFP reporter that would provide a fast in vitro system to analyze functional roles of specific DENV sequences in viral replication. Two classes of recombinant replicon constructs were generated; one was a RNA-launched replicon with a GFP gene directly inserted into a full-length DENV genome (FL-DENV/GFP), and the other consisted of 4 types of DNA-launched DENV subgenomic replicons with GFP replacement at various structural genes (Δ-DENV/GFP). The FL-DENV/GFP resulted in GFP expression in transfected cells with no viable DENV being recovered from the transfection. The Δ-DENV/GFP constructs with partial structural gene deletion (ΔC-, ΔCprM/M-, ΔprM/M-, or ΔE-) expressed bright and long lasting GFP. The GFP expression intensity in living cells correlated well with the level of RNA replication. Various mutations in the 5'noncoding region of DENV-2 previously shown to be important genetic determinants for virus replication and mouse virulence were incorporated into the 5 different replicon constructs. Characterizations of 29 mutants demonstrated that these replicons can provide a useful platform for a quick and powerful in vitro system to analyze genetic determinants of DENV replication. These constructs can also be useful for development of vectors expressing foreign genes for various researches.
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23
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A DNA-based West Nile virus replicon elicits humoral and cellular immune responses in mice. J Virol Methods 2011; 178:87-93. [DOI: 10.1016/j.jviromet.2011.08.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 08/13/2011] [Accepted: 08/17/2011] [Indexed: 01/08/2023]
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Moritoh K, Maeda A, Nishino T, Sasaki N, Agui T. Development and application of West Nile virus subgenomic replicon RNA expressing secreted alkaline phosphatase. J Vet Med Sci 2010; 73:683-6. [PMID: 21187681 DOI: 10.1292/jvms.10-0495] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have developed a West Nile virus (WNV) subgenomic replicon harboring the secreted alkaline phosphatase (SEAP) reporter gene instead of viral structural genes (designated repWNV/SEAP). The repWNV/SEAP allowed easy evaluation of viral replication efficiency by direct measurement of SEAP secretion in the cell culture medium in physical containment level 2 facilities. Furthermore, we validated the availability of this system using a known anti-flavivirus gene, mouse oligoadenylate synthetase 1b (Oas1b). The Oas1b-transfected cells were more resistant to repWNV/SEAP replication than the original cells. Thus, this system not only affords a useful tool for identification/evaluation of anti-flavivirus genes/drugs in terms of safety, ease of use and reliability, but should be able to reduce or replace the bioassay using laboratory animals.
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Affiliation(s)
- Kanako Moritoh
- Laboratory of Laboratory Animal Science and Medicine, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita, Nishi, Kita-ku Sapporo, Hokkaido, Japan
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25
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Shiryaev SA, Cheltsov AV, Gawlik K, Ratnikov BI, Strongin AY. Virtual ligand screening of the National Cancer Institute (NCI) compound library leads to the allosteric inhibitory scaffolds of the West Nile Virus NS3 proteinase. Assay Drug Dev Technol 2010; 9:69-78. [PMID: 21050032 DOI: 10.1089/adt.2010.0309] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Viruses of the genus Flavivirus are responsible for significant human disease and mortality. The N-terminal domain of the flaviviral nonstructural (NS)3 protein codes for the serine, chymotrypsin-fold proteinase (NS3pro). The presence of the nonstructural (NS)2B cofactor, which is encoded by the upstream gene in the flaviviral genome, is necessary for NS3pro to exhibit its proteolytic activity. The two-component NS2B-NS3pro functional activity is essential for the viral polyprotein processing and replication. Both the structure and the function of NS2B-NS3pro are conserved in the Flavivirus family. Because of its essential function in the posttranslational processing of the viral polyprotein precursor, NS2B-NS3pro is a promising target for anti-flavivirus drugs. To identify selective inhibitors with the reduced cross-reactivity and off-target effects, we focused our strategy on the allosteric inhibitors capable of targeting the NS2B-NS3pro interface rather than the NS3pro active site. Using virtual ligand screening of the diverse, ∼275,000-compound library and the catalytic domain of the two-component West Nile virus (WNV) NS2B-NS3pro as a receptor, we identified a limited subset of the novel inhibitory scaffolds. Several of the discovered compounds performed as allosteric inhibitors and exhibited a nanomolar range potency in the in vitro cleavage assays. The inhibitors were also potent in cell-based assays employing the sub-genomic, luciferase-tagged WNV and Dengue viral replicons. The selectivity of the inhibitors was confirmed using the in vitro cleavage assays with furin, a human serine proteinase, the substrate preferences of which are similar to those of WNV NS2B-NS3pro. Conceptually, the similar in silico drug discovery strategy may be readily employed for the identification of inhibitors of other flaviviruses.
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Affiliation(s)
- Sergey A Shiryaev
- Inflammatory and Infectious Disease Center, Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
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26
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Massé N, Davidson A, Ferron F, Alvarez K, Jacobs M, Romette JL, Canard B, Guillemot JC. Dengue virus replicons: Production of an interserotypic chimera and cell lines from different species, and establishment of a cell-based fluorescent assay to screen inhibitors, validated by the evaluation of ribavirin's activity. Antiviral Res 2010; 86:296-305. [DOI: 10.1016/j.antiviral.2010.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 03/08/2010] [Accepted: 03/16/2010] [Indexed: 10/19/2022]
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27
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Establishment and characterization of a Madin-Darby canine kidney reporter cell line for influenza A virus assays. J Clin Microbiol 2010; 48:2515-23. [PMID: 20504984 DOI: 10.1128/jcm.02286-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza virus diagnosis has traditionally relied on virus isolation in chicken embryo or cell cultures. Many laboratories have adopted rapid molecular methods for detection of influenza viruses and discontinued routine utilization of the relatively slow viral culture methods. We describe an influenza A virus reporter cell line that contributes to more efficient viral detection in cell culture. Madin-Darby canine kidney (MDCK) cells were engineered to constitutively produce an influenza virus genome-like luciferase reporter RNA driven by the canine RNA polymerase I promoter. Induction of a high level of luciferase activity was detected in the Luc9.1 cells upon infection with various strains of influenza A virus, including 2009 H1N1 pandemic and highly pathogenic H5N1 virus. In contrast, infection with influenza B virus or human adenovirus type 5 did not induce significant levels of reporter expression. The reporter Luc9.1 cells were evaluated in neutralizing antibody assays with convalescent H3N2 ferret serum, yielding a neutralization titer comparable to that obtained by the conventional microneutralization assay, suggesting that the use of the reporter cell line might simplify neutralization assays by facilitating the establishment of infectious virus endpoints. Luc9.1 cells were also used to determine the susceptibility of influenza A viruses to a model antiviral drug. The equivalence to conventional antiviral assay results indicated that the Luc9.1 cells could provide an alternative cell-based platform for high-throughput drug discovery screens. In summary, the MDCK-derived Luc9.1 reporter cell line is highly permissive for influenza A virus replication and provides a very specific and sensitive approach for simultaneous detection and isolation of influenza A viruses as well as functional evaluation of antibodies and antiviral molecules.
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HTS-driven discovery of new chemotypes with West Nile Virus inhibitory activity. Molecules 2010; 15:1690-704. [PMID: 20336008 PMCID: PMC4839297 DOI: 10.3390/molecules15031690] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 02/20/2010] [Accepted: 03/08/2010] [Indexed: 11/17/2022] Open
Abstract
West Nile virus (WNV) is a positive sense, single-stranded RNA virus that can cause illness in humans when transmitted via mosquito vectors. Unfortunately, no antivirals or vaccines are currently available, and therefore efficient and safe antivirals are urgently needed. We developed a high throughput screen to discover small molecule probes that inhibit virus infection of Vero E6 cells. A primary screen of a 13,001 compound library at a 10 microM final concentration was conducted using the 384-well format. Z' values ranged from 0.54-0.83 with a median of 0.74. Average S/B was 17 and S/N for each plate ranged from 10.8 to 23.9. Twenty-six compounds showed a dose response in the HT screen and were further evaluated in a time of addition assay and in a titer reduction assay. Seven compounds showed potential as small molecule probes directed at WNV. The hit rate from the primary screen was 0.185% (24 compounds out of 13,001 compounds) and from the secondary screens was 0.053% (7 out of 13,001 compounds) respectively.
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Castel G, Tordo N. [New strategies for the development of antiviral molecules]. REVUE FRANCOPHONE DES LABORATOIRES : RFL 2009; 2009:91-100. [PMID: 32288807 PMCID: PMC7140268 DOI: 10.1016/s1773-035x(09)70313-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 09/30/2009] [Indexed: 11/29/2022]
Abstract
Antiviral research is a recent discipline and the number of molecules available to fight against viral infections remains still insufficient. However, both diseases caused by emerging endemic viruses and the existence of resistance from some viruses against antiviral make necessary a constant search for new antiviral drugs. Parallel to the development of traditional molecules such as nucleoside analogues, whose effectiveness is well demonstrated, pharmaceutical industry is now turning to new solutions such as antiviral peptides, which constitute a new exploration field in therapy. The recent progress in disciplines such as genomics, proteomics and structural biology have improved our fundamental understanding of the viral world. These advances can be used to efficiently create new drugs more selective and more effective. Identification and development of these molecules require the use of newer techniques such as high-throughput screening of combinatorial compound libraries and the use of new bioinformatics tools. This review aims to present some recent methods for the development of antiviral molecules.
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Affiliation(s)
- Guillaume Castel
- Unité postulante des stratégies antivirales – CNRS URA-3015, Institut Pasteur, 25, rue du Docteur-Roux, 75724 Paris cedex 15
| | - Noël Tordo
- Unité postulante des stratégies antivirales – CNRS URA-3015, Institut Pasteur, 25, rue du Docteur-Roux, 75724 Paris cedex 15
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Abstract
Superinfection exclusion is the ability of an established viral infection to interfere with a second viral infection. Using West Nile virus (WNV) as a model, we show that replicating replicons in BHK-21 cells suppress subsequent WNV infection. The WNV replicon also suppresses superinfections of other flaviviruses but not nonflaviviruses. Mode-of-action analysis indicates that the exclusion of WNV superinfection occurs at the step of RNA synthesis. The continuous culturing of WNV in the replicon-containing cells generated variants that could overcome the superinfection exclusion. The sequencing of the selected viruses revealed mutations in structural (prM S90R or envelope E138K) and nonstructural genes (NS4a K124R and peptide 2K V9M). Mutagenesis analysis showed that the mutations in structural genes nonselectively enhance viral infection in both naïve and replicon-containing BHK-21 cells; in contrast, the mutations in nonstructural genes more selectively enhance viral replication in the replicon-containing cells than in the naïve cells. Mechanistic analysis showed that the envelope mutation functions through the enhancement of virion attachment to BHK-21 cells, whereas the 2K mutation (and, to a lesser extent, the NS4a mutation) functions through the enhancement of viral RNA synthesis. Furthermore, we show that WNV superinfection exclusion is reversible by the treatment of the replicon cells with a flavivirus inhibitor. The preestablished replication of the replicon could be suppressed by infecting the cells with the 2K mutant WNV but not with the wild-type virus. These results suggest that WNV superinfection exclusion is a result of competition for intracellular host factors that are required for viral RNA synthesis.
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Cyclosporine inhibits flavivirus replication through blocking the interaction between host cyclophilins and viral NS5 protein. Antimicrob Agents Chemother 2009; 53:3226-35. [PMID: 19451286 DOI: 10.1128/aac.00189-09] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Although flaviviruses cause significant human diseases, no effective therapy is currently available. Host factors essential for viral replication are potential targets for antiviral development. Here we report that cyclophilins (CyPs), a family of cellular peptidyl-prolyl isomerases (PPIases), play a role in flavivirus replication. Huh-7.5 cells with knockdown of different isoforms of CyP were less efficient than parental cells in supporting flavivirus replication, including West Nile virus (WNV), dengue virus, and yellow fever virus. The low viral replication in CyP A (CyPA) knockdown cells could be rescued by trans supplying of a wild-type CyPA but not by trans supplying of a mutant CyPA (defective in the PPIase activity), indicating that the isomerase activity of CyPA is critical for viral replication. Immunoprecipitation and biochemical pulldown analyses showed that CyPA interacts with WNV genomic RNA and viral NS5 protein in the replication complex. Furthermore, antiviral experiments demonstrated that cyclosporine (Cs; an 11-amino-acid cyclic peptide known to block the PPIase activity of CyPA) inhibits flavivirus replication in cell culture at nontoxic concentrations. Time-of-addition and transient replicon results indicated that Cs inhibits flavivirus at the step of viral RNA synthesis. Biochemical analysis showed that Cs directly blocks the interaction between CyPA and WNV NS5 protein. Our results suggest that host CyPA is a component of flavivirus replication complex and could be targeted for potential antiviral development.
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Abstract
AbstractA rapid real-time polymerase chain reaction (RT-PCR) for detecting West Nile virus (WNV) was established. Primers were designed according to the sequence of the capsid protein gene of WNV by Primer Premier 5.0. In this way, an inexpensive assay using the intercalating dye SYBR Green I was developed and validated. The amplifying curve showed that this method could successfully amplify 102 copies/μl of the WNV gene, while reference to Japanese encephalitis virus (JEV) and blank control were all negative. Tenfold successive dilutions of positive WNV DNA were used to measure the sensitivity of RT-PCR. The assay system showed high reproducibility with coefficient of variation (CV) <2%. Thus the newly established RT-PCR assay was shown to be a rapid, sensitive and specific test for detecting WNV.
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Identification and characterization of inhibitors of West Nile virus. Antiviral Res 2009; 83:71-9. [PMID: 19501258 DOI: 10.1016/j.antiviral.2009.03.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 03/10/2009] [Accepted: 03/23/2009] [Indexed: 12/11/2022]
Abstract
Although flaviviruses cause significant human diseases, no antiviral therapy is currently available for clinical treatment of these pathogens. To identify flavivirus inhibitors, we performed a high-throughput screening of compound libraries using cells containing luciferase-reporting replicon of West Nile viruses (WNV). Five novel small molecular inhibitors of WNV were identified from libraries containing 96,958 compounds. The inhibitors suppress epidemic strain of WNV in cell culture, with EC(50) (50% effective concentration) values of <10microM and TI (therapeutic index) values of >10. Viral titer reduction assays, using various flaviviruses and nonflaviviruses, showed that the compounds have distinct antiviral spectra. Mode-of-action analysis showed that the inhibitors block distinct steps of WNV replication: four compounds inhibit viral RNA syntheses, while the other compound suppresses both viral translation and RNA syntheses. Biochemical enzyme assays showed that two compounds selectively inhibit viral RNA-dependent RNA polymerase (RdRp), while another compound specifically inhibits both RdRp and methyltransferase. The identified compounds could potentially be developed for treatment of flavivirus infections.
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Novel Therapeutics Against West Nile Virus. WEST NILE ENCEPHALITIS VIRUS INFECTION 2009. [PMCID: PMC7122128 DOI: 10.1007/978-0-387-79840-0_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
No effective therapy is currently available for clinical treatment of flavivirus infections. Recent advances in the structural and molecular biology of flaviviruses have provided new opportunities for the development of antiviral therapies. This chapter summarizes the current status of West Nile virus (WNV) therapeutics. First, strategies for identifying and characterizing small molecular inhibitors are reviewed. These strategies include structure-based rational design, biochemical enzyme-based screening, and reverse genetic system-based screening. Second, known WNV inhibitors are summarized. Both small and macromolecular inhibitors have been identified to inhibit WNV. The macromolecular inhibitors include WNV antibodies, interferon, and nucleic acid-based agents (i.e., antisense oligomer and siRNA). Since the antibody-based therapy is reviewed elsewhere in this book, this chapter emphasizes the nonantibody macromolecular and small molecular inhibitors. Finally, new potential antiviral targets and issues related to WNV therapeutics are discussed.
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A single-amino acid substitution in West Nile virus 2K peptide between NS4A and NS4B confers resistance to lycorine, a flavivirus inhibitor. Virology 2008; 384:242-52. [PMID: 19062063 PMCID: PMC5388927 DOI: 10.1016/j.virol.2008.11.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2008] [Revised: 10/19/2008] [Accepted: 11/04/2008] [Indexed: 11/23/2022]
Abstract
Lycorine potently inhibits flaviviruses in cell culture. At 1.2-microM concentration, lycorine reduced viral titers of West Nile (WNV), dengue, and yellow fever viruses by 10(2)- to 10(4)-fold. However, the compound did not inhibit an alphavirus (Western equine encephalitis virus) or a rhabdovirus (vesicular stomatitis virus), indicating a selective antiviral spectrum. The compound exerts its antiviral activity mainly through suppression of viral RNA replication. A Val-->Met substitution at the 9th amino acid position of the viral 2K peptide (spanning the endoplasmic reticulum membrane between NS4A and NS4B proteins) confers WNV resistance to lycorine, through enhancement of viral RNA replication. Initial chemistry synthesis demonstrated that modifications of the two hydroxyl groups of lycorine can increase the compound's potency, while reducing its cytotoxicity. Taken together, the results have established lycorine as a flavivirus inhibitor for antiviral development. The lycorine-resistance results demonstrate a direct role of the 2K peptide in flavivirus RNA synthesis.
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Identification and biochemical characterization of small-molecule inhibitors of west nile virus serine protease by a high-throughput screen. Antimicrob Agents Chemother 2008; 52:3385-93. [PMID: 18606844 DOI: 10.1128/aac.01508-07] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
West Nile virus and dengue virus are mosquito-borne flaviviruses that cause a large number of human infections each year. No vaccines or chemotherapeutics are currently available. These viruses encode a serine protease that is essential for polyprotein processing, a required step in the viral replication cycle. In this study, a high-throughput screening assay for the West Nile virus protease was employed to screen approximately 32,000 small-molecule compounds for identification of inhibitors. Lead inhibitor compounds with three distinct core chemical structures (1 to 3) were identified. In a secondary screening of selected compounds, two compounds, belonging to the 8-hydroxyquinoline family (compounds A and B) and containing core structure 1, were identified as potent inhibitors of the West Nile virus protease, with K(i) values of 3.2 +/- 0.3 microM and 3.4 +/- 0.6 microM, respectively. These compounds inhibited the dengue virus type 2 protease with K(i) values of 28.6 +/- 5.1 microM and 30.2 +/- 8.6 microM, respectively, showing some selectivity in the inhibition of these viral proteases. However, the compounds show no inhibition of cellular serine proteases, trypsin, or factor Xa. Kinetic analysis and molecular docking of compound B onto the known crystal structure of the West Nile virus protease indicate that the inhibitor binds in the substrate-binding cleft. Furthermore, compound B was capable of inhibiting West Nile virus RNA replication in cultured Vero cells (50% effective concentration, 1.4 +/- 0.4 microM; selectivity index, 100), presumably by inhibition of polyprotein processing.
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Dong H, Zhang B, Shi PY. Flavivirus methyltransferase: a novel antiviral target. Antiviral Res 2008; 80:1-10. [PMID: 18571739 DOI: 10.1016/j.antiviral.2008.05.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 04/30/2008] [Accepted: 05/02/2008] [Indexed: 12/17/2022]
Abstract
Many flaviviruses are significant human pathogens. No effective antiviral therapy is currently available for treatment of flavivirus infections. Development of antiviral treatment against these viruses is urgently needed. The flavivirus methyltransferase (MTase) responsible for N-7 and 2'-O methylation of the viral RNA cap has recently been mapped to the N-terminal region of nonstructural protein 5. Structural and functional studies suggest that the MTase represents a novel antiviral target. Here we review current understanding of flavivirus RNA cap methylation and its implications for development of antivirals. The 5' end of the flavivirus plus-strand RNA genome contains a type 1 cap structure (m(7)GpppAmG). Flaviviruses encode a single MTase domain that catalyzes two sequential methylations of the viral RNA cap, GpppA-RNA-->m(7)GpppA-RNA-->m(7)GpppAm-RNA, using S-adenosyl-L-methionine (SAM) as the methyl donor. The two reactions require different viral RNA elements and distinct biochemical assay conditions. Despite exhibiting two distinct methylation activities, flavivirus MTase contains a single binding site for SAM in its crystal structure. Therefore, substrate GpppA-RNA must be re-positioned to accept the N-7 and 2'-O methyl groups from SAM during the two methylation reactions. Structure-guided mutagenesis studies indeed revealed two distinct sets of amino acids on the enzyme surface that are specifically required for N-7 and 2'-O methylation. In the context of virus, West Nile viruses (WNVs) defective in N-7 methylation are non-replicative; however, WNVs defective in 2'-O methylation are attenuated and can protect mice from subsequent wild-type WNV challenge. Collectively, the results demonstrate that the N-7 MTase represents a novel target for flavivirus therapy.
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Affiliation(s)
- Hongping Dong
- Wadsworth Center, New York State Department of Health, State University of New York, Albany, NY 12201, USA
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38
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Green N, Ott RD, Isaacs RJ, Fang H. Cell-based Assays to Identify Inhibitors of Viral Disease. Expert Opin Drug Discov 2008; 3:671-676. [PMID: 19750206 DOI: 10.1517/17460441.3.6.671] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND: Antagonizing the production of infectious virus inside cells requires drugs that can cross the cell membrane without harming host cells. OBJECTIVE: It is therefore advantageous to establish intracellular potency of anti-viral drug candidates early in the drug-discovery pipeline. METHODS: To this end, cell-based assays are being developed and employed in high-throughput drug screening, ranging from assays that monitor replication of intact viruses to those that monitor activity of specific viral proteins. While numerous cell-based assays have been developed and investigated, rapid counter screens are also needed to define the specific viral targets of identified inhibitors and to eliminate nonspecific screening hits. RESULTS/CONCLUSIONS: Here, we describe the types of cell-based assays being used in antiviral drug screens and evaluate the equally important counter screens that are being employed to reach the full potential of cell-based high-throughput screening.
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Affiliation(s)
- Neil Green
- Chief Scientific Officer, Microbial Novoteqs, 111 10 Avenue South, Suite 110, Nashville, TN 37203
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Orlinger KK, Kofler RM, Heinz FX, Hoenninger VM, Mandl CW. Selection and analysis of mutations in an encephalomyocarditis virus internal ribosome entry site that improve the efficiency of a bicistronic flavivirus construct. J Virol 2007; 81:12619-29. [PMID: 17855533 PMCID: PMC2168969 DOI: 10.1128/jvi.01017-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flaviviruses have a positive-stranded RNA genome, which simultaneously serves as an mRNA for translation of the viral proteins. All of the structural and nonstructural proteins are translated from a cap-dependent cistron as a single polyprotein precursor. In an earlier study (K. K. Orlinger, V. M. Hoenninger, R. M. Kofler, and C. W. Mandl, J. Virol. 80:12197-12208, 2006), it was demonstrated that an artificial bicistronic flavivirus genome, TBEV-bc, in which the region coding for the viral surface glycoproteins prM and E from tick-borne encephalitis virus (TBEV) had been removed from its natural context and inserted into the 3' noncoding region under the control of an internal ribosome entry site (IRES) from encephalomyocarditis virus (EMCV) produces viable, infectious virus when cells are transfected with this RNA. The rates of RNA replication and infectious particle formation were significantly lower with TBEV-bc, however, than with wild-type TBEV. In this study, we have identified two types of mutations, selected by passage in BHK-21 cells, that enhance the growth properties of TBEV-bc. The first type occurred in the E protein, and these most likely increase the affinity of the virus for heparan sulfate on the cell surface. The second type occurred in the inserted EMCV IRES, in the oligo(A) loop of the J-K stem-loop structure, a binding site for the eukaryotic translation initiation factor 4G. These included single-nucleotide substitutions as well as insertions of additional adenines in this loop. An A-to-C substitution in the oligo(A) loop decreased the efficiency of the IRES itself but nevertheless resulted in improved rates of virus particle formation and overall replication efficiency. These results demonstrate the need for proper balance in the competition for free template RNA between the viral RNA replication machinery and the cellular translation machinery at the two different start sites and also identify specific target sites for the improvement of bicistronic flavivirus expression vectors.
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Affiliation(s)
- Klaus K Orlinger
- Clinical Institute of Virology, Medical University of Vienna, Kinderspitalgasse 15, A-1095, Vienna, Austria
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40
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Lai CY, Hu HP, King CC, Wang WK. Incorporation of dengue virus replicon into virus-like particles by a cell line stably expressing precursor membrane and envelope proteins of dengue virus type 2. J Biomed Sci 2007; 15:15-27. [PMID: 17768670 DOI: 10.1007/s11373-007-9204-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 08/08/2007] [Indexed: 11/26/2022] Open
Abstract
While virus-like particles (VLPs) containing subgenomic replicons, which can transduce replicons into target cells efficiently for studying viral replication and vectors of gene therapy and vaccine, have been established for several flaviviruses, none has been reported for the four serotypes of dengue virus, the causal agent of the most important arboviral diseases in this century. In this study, we successfully established a cell line stably expressing the precursor membrane/envelope (PrM/E) proteins of dengue virus type 2 (DENV2), which can package a DENV2 replicon with deletion of PrM/E genes and produce single-round infectious VLPs. Moreover, it can package a similar replicon of different serotype, dengue virus type 4, and produce infectious chimeric VLPs. To our knowledge, this study reports for the first time replicon-containing VLPs of dengue virus. Moreover, this convenient system has potential as a valuable tool to study encapsidation of dengue virus and to develop novel chimeric VLPs containing dengue virus replicon as vaccine in the future.
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Affiliation(s)
- Chih-Yun Lai
- Institute of Microbiology, College of Medicine, National Taiwan University, No.1 Sec.1 Jen-Ai Rd, Taipei, Taiwan
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Rossi SL, Fayzulin R, Dewsbury N, Bourne N, Mason PW. Mutations in West Nile virus nonstructural proteins that facilitate replicon persistence in vitro attenuate virus replication in vitro and in vivo. Virology 2007; 364:184-95. [PMID: 17382364 DOI: 10.1016/j.virol.2007.02.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 01/09/2007] [Accepted: 02/07/2007] [Indexed: 12/25/2022]
Abstract
West Nile virus (WNV) infections in vertebrates are generally acute but persistent infections have been observed. To investigate the ability of WNV to produce persistent infections, we forced subgenomic WNV replicons to replicate within a cell without causing cell death. Detailed analyses of these cell-adapted genomes revealed mutations within the nonstructural protein genes NS2A (D73H, M108K), NS3 (117Kins), NS4B (E249G) and NS5 (P528H). WNV replicons and WNVs harboring a subset of NS2A or NS3 mutations showed a reduction in genome replication, a reduction in antigen accumulation, a decrease in cytopathic effect, an increased ability to persist in cell culture and/or attenuation in vivo. Taken together, these data indicate that WNV with a defect in replication and an increased potential to persist within the host cell can be generated by point mutations at multiple independent loci, suggesting that persistent viruses could arise in nature.
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Affiliation(s)
- Shannan L Rossi
- Department of Pathology, 3.206B Mary Moody Northen Pavilion, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0436, USA
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Puig-Basagoiti F, Tilgner M, Bennett CJ, Zhou Y, Muñoz-Jordán JL, García-Sastre A, Bernard KA, Shi PY. A mouse cell-adapted NS4B mutation attenuates West Nile virus RNA synthesis. Virology 2006; 361:229-41. [PMID: 17178141 PMCID: PMC1952232 DOI: 10.1016/j.virol.2006.11.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Revised: 11/04/2006] [Accepted: 11/09/2006] [Indexed: 01/09/2023]
Abstract
An adaptive mutation (E249G) within West Nile virus (WNV) NS4B gene was consistently recovered from replicon RNAs in C3H/He mouse cells. The E249G is located at the C-terminal tail of NS4B predicted to be on the cytoplasmic side of the endoplasmic reticulum membrane. The E249G substitution reduced replicon RNA synthesis. Compared with the wild-type NS4B, the E249G mutant protein exhibited a similar efficiency in evasion of interferon-beta response. Recombinant E249G virus exhibited smaller plaques, slower growth kinetics, and lower RNA synthesis than the wild-type virus in a host-dependent manner, with the greatest difference in rodent cells (C3H/He and BHK-21) and the least difference in mosquito cells (C3/36). Selection of revertants of E249G virus identified a second site mutation at residue 246, which could compensate for the low replication phenotype in cell culture. These results demonstrate that distinct residues within the C-terminal tail of flavivirus NS4B are critical for viral replication.
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Affiliation(s)
| | - Mark Tilgner
- Wadsworth Center, New York State Department of Health, Albany, New York 12201
| | - Corey J. Bennett
- Wadsworth Center, New York State Department of Health, Albany, New York 12201
| | - Yangsheng Zhou
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, New York 12201
| | - Jorge L. Muñoz-Jordán
- Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases, Dengue Branch, San Juan, Puerto Rico 00920-3860
| | - Adolfo García-Sastre
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029
| | - Kristen A. Bernard
- Wadsworth Center, New York State Department of Health, Albany, New York 12201
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, New York 12201
| | - Pei-Yong Shi
- Wadsworth Center, New York State Department of Health, Albany, New York 12201
- Department of Biomedical Sciences, University at Albany, State University of New York, Albany, New York 12201
- *Corresponding author. Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12208, E-mail address: (P.-Y. Shi)
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Ge F, Luo Y, Liew PX, Hung E. Derivation of a novel SARS-coronavirus replicon cell line and its application for anti-SARS drug screening. Virology 2006; 360:150-8. [PMID: 17098272 PMCID: PMC7103326 DOI: 10.1016/j.virol.2006.10.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 08/30/2006] [Accepted: 10/01/2006] [Indexed: 11/26/2022]
Abstract
The severe acute respiratory syndrome (SARS) outbreak in 2002, which had a high morbidity rate and caused worldwide alarm, remains untreated today even though SARS was eventually isolated and controlled. Development and high-throughput screening of efficacious drugs is therefore critical. However, currently there remains a lack of such a safe system. Here, the generation and characterization of the first selectable, SARS–coronavirus (SARS–CoV)-based replicon cell line which can be used for screening is described. Partial SARS–CoV cDNAs and antibiotic resistance/reporter gene DNA were generated and assembled in vitro to produce the replicon transcription template, which was then transcribed in vitro to generate the replicon RNA. The latter was introduced into a mammalian cell line and the transfected cells were selected for by antibiotic application. For the antibiotic-resistant cell lines thus generated, the expression of reporter gene was ensured by continued monitoring using fluorescent microscopy and flow cytometry. The suitability of this replicon cell line in drug screening was demonstrated by testing the inhibitory effect of several existing drugs and the results demonstrate that the SARS–CoV replicon cell lines provide a safe tool for the identification of SARS–CoV replicase inhibitors. The replicon cell lines thus developed can be applied to high-throughput screening for anti-SARS drugs without the need to grow infectious SARS–CoV.
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Affiliation(s)
- Feng Ge
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD4, 5 Science Drive 2 Singapore 117597, Republic of Singapore.
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Yocupicio-Monroy M, Padmanabhan R, Medina F, del Angel RM. Mosquito La protein binds to the 3' untranslated region of the positive and negative polarity dengue virus RNAs and relocates to the cytoplasm of infected cells. Virology 2006; 357:29-40. [PMID: 16962153 DOI: 10.1016/j.virol.2006.07.042] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 03/13/2006] [Accepted: 07/10/2006] [Indexed: 02/05/2023]
Abstract
The untranslated regions (UTRs) of the positive and negative strand RNAs of several viruses are major binding sites for cellular and viral proteins. Human La autoantigen is one of the cellular proteins that interacts with various positive strand RNA viral genomes including that of dengue virus (DEN) within the 5'- and 3'-UTRs of positive (+) and the 3'-UTR of negative strand (-) RNA, and with the nonstructural proteins NS3 and NS5, that form DEN replicase complex. Since DEN replicates in human and mosquito cells, some functional interactions have to be conserved in both hosts. In the present report, we demonstrate that mosquito La protein interacts with the 3'-UTRs of (+) and (-) polarity viral RNAs. The localization of La protein, examined by confocal microscopy, indicates that La protein is redistributed in DEN-infected cells. Furthermore, the presence of La protein in an in vitro replication system inhibited RNA synthesis in a dose-dependent manner, suggesting that La protein plays an important role in dengue virus replicative cycle.
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Affiliation(s)
- Martha Yocupicio-Monroy
- Posgrado en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, México City 03100, México
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Takhampunya R, Ubol S, Houng HS, Cameron CE, Padmanabhan R. Inhibition of dengue virus replication by mycophenolic acid and ribavirin. J Gen Virol 2006; 87:1947-1952. [PMID: 16760396 DOI: 10.1099/vir.0.81655-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dengue viruses (DEN), mosquito-borne members of the family Flaviviridae, are human pathogens of global significance. The effects of mycophenolic acid (MPA) and ribavirin (RBV) on DEN replication in monkey kidney (LLC-MK2) cells were examined. MPA (IC(50)=0.4+/-0.3 microM) and RBV (IC(50)=50.9+/-18 microM) inhibited DEN2 replication. Quantitative real-time RT-PCR of viral RNA and plaque assays of virions from DEN2-infected and MPA (10 microM)- and RBV (> or =200 microM)-treated cells showed a fivefold increase in defective viral RNA production by cells treated with each drug. Moreover, a dramatic reduction of intracellular viral replicase activity was seen by in vitro replicase assays. Guanosine reversed the inhibition of these compounds, suggesting that one mode of antiviral action of MPA and RBV is by inhibition of inosine monophosphate dehydrogenase and thereby depletion of the intracellular GTP pool. In addition, RBV may act by competing with guanine-nucleotide precursors in viral RNA translation, replication and 5' capping.
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Affiliation(s)
- Ratree Takhampunya
- Department of Microbiology, Faculty of Science, Mahidol University, 272 Rama VI Road, Bangkok 10400, Thailand
- Department of Microbiology and Immunology, Georgetown University School of Medicine, 3900 Reservoir Road, Washington, DC 20057, USA
| | - Sukathida Ubol
- Department of Microbiology, Faculty of Science, Mahidol University, 272 Rama VI Road, Bangkok 10400, Thailand
| | - Huo-Shu Houng
- Department of Virus Diseases, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Radhakrishnan Padmanabhan
- Department of Microbiology and Immunology, Georgetown University School of Medicine, 3900 Reservoir Road, Washington, DC 20057, USA
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Puig-Basagoiti F, Tilgner M, Forshey BM, Philpott SM, Espina NG, Wentworth DE, Goebel SJ, Masters PS, Falgout B, Ren P, Ferguson DM, Shi PY. Triaryl pyrazoline compound inhibits flavivirus RNA replication. Antimicrob Agents Chemother 2006; 50:1320-9. [PMID: 16569847 PMCID: PMC1426921 DOI: 10.1128/aac.50.4.1320-1329.2006] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Triaryl pyrazoline {[5-(4-chloro-phenyl)-3-thiophen-2-yl-4,5-dihydro-pyrazol-1-yl]-phenyl-methanone} inhibits flavivirus infection in cell culture. The inhibitor was identified through high-throughput screening of a compound library using a luciferase-expressing West Nile (WN) virus infection assay. The compound inhibited an epidemic strain of WN virus without detectable cytotoxicity (a 50% effective concentration of 28 microM and a compound concentration of >or=300 microM required to reduce 50% cell viability). Besides WN virus, the compound also inhibited other flaviviruses (dengue, yellow fever, and St. Louis encephalitis viruses), an alphavirus (Western equine encephalitis virus), a coronavirus (mouse hepatitis virus), and a rhabdovirus (vesicular stomatitis virus). However, the compound did not suppress an orthomyxovirus (influenza virus) or a retrovirus (human immunodeficiency virus type 1). Mode-of-action analyses in WN virus showed that the compound did not inhibit viral entry or virion assembly but specifically suppressed viral RNA synthesis. To examine the mechanism of inhibition of dengue virus, we developed two replicon systems for dengue type 1 virus: (i) a stable cell line that harbored replicons containing a luciferase reporter and a neomycin phosphotransferase selection marker and (ii) a luciferase-expressing replicon that could differentiate between viral translation and RNA replication. Analyses of the compound in the dengue type 1 virus replicon systems showed that it weakly suppressed viral translation but significantly inhibited viral RNA synthesis. Overall, the results demonstrate that triaryl pyrazoline exerts a broad spectrum of antiflavivirus activity through potent inhibition of viral RNA replication. This novel inhibitor could be developed for potential treatment of flavivirus infection.
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Fredericksen BL, Gale M. West Nile virus evades activation of interferon regulatory factor 3 through RIG-I-dependent and -independent pathways without antagonizing host defense signaling. J Virol 2006; 80:2913-23. [PMID: 16501100 PMCID: PMC1395472 DOI: 10.1128/jvi.80.6.2913-2923.2006] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The ability of viruses to control and/or evade the host antiviral response is critical to the establishment of a productive infection. We have previously shown that West Nile virus NY (WNV-NY) delays activation of interferon regulatory factor 3 (IRF-3), a transcription factor critical to the initiation of the antiviral response. Here we demonstrate that the delayed activation of IRF-3 is essential for WNV-NY to achieve maximum virus production. Furthermore, WNV-NY utilizes a unique mechanism to control activation of IRF-3. In contrast to many other viruses that impose a nonspecific block to the IRF-3 pathway, WNV-NY eludes detection by the host cell at early times postinfection. To better understand this process, we assessed the role of the pathogen recognition receptor (PRR) retinoic acid-inducible gene I (RIG-I) in sensing WNV-NY infection. RIG-I null mouse embryo fibroblasts (MEFs) retained the ability to respond to WNV-NY infection; however, the onset of the host response was delayed compared to wild-type (WT) MEFs. This suggests that RIG-I is involved in initially sensing WNV-NY infection, while other PRRs sustain and/or amplify the host response later in infection. The delayed initiation of the host response correlated with an increase in WNV-NY replication in RIG-I null MEFs compared to WT MEFs. Our data suggest that activation of the host response by RIG-I early in infection is important for controlling replication of WNV-NY. Furthermore, pathogenic strains of WNV may have evolved to circumvent stimulation of the host response until after replication is well under way.
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Affiliation(s)
- Brenda L Fredericksen
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, USA
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Puig-Basagoiti F, Deas TS, Ren P, Tilgner M, Ferguson DM, Shi PY. High-throughput assays using a luciferase-expressing replicon, virus-like particles, and full-length virus for West Nile virus drug discovery. Antimicrob Agents Chemother 2006; 49:4980-8. [PMID: 16304161 PMCID: PMC1315944 DOI: 10.1128/aac.49.12.4980-4988.2005] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Many flaviviruses cause significant human disease worldwide. The development of flavivirus chemotherapy requires reliable high-throughput screening (HTS) assays. Although genetic systems have been developed for many flaviviruses, their usage in antiviral HTS assays has not been well explored. Here we compare three cell-based HTS assays for West Nile virus (WNV) drug discovery: (i) an assay that uses a cell line harboring a persistently replicating subgenomic replicon (containing a deletion of viral structural genes), (ii) an assay that uses packaged virus-like particles containing replicon RNA, and (iii) an assay that uses a full-length reporting virus. A Renilla luciferase gene was engineered into the replicon or into the full-length viral genome to monitor viral replication. Potential inhibitors could be identified through suppression of luciferase signals upon compound incubation. The antiviral assays were optimized in a 96-well format, validated with known WNV inhibitors, and proved useful in identifying a new inhibitor(s) through HTS of a compound library. In addition, because each assay encompasses multiple but discrete steps of the viral life cycle, the three systems could potentially be used to discriminate the mode of action of any inhibitor among viral entry (detected by assays ii and iii but not by assay i), replication (including viral translation and RNA synthesis; detected by assays i to iii), and virion assembly (detected by assay iii but not by assays i and ii). The approaches described in this study should be applicable to the development of cell-based assays for other flaviviruses.
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Affiliation(s)
- Francesc Puig-Basagoiti
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, New York 12208, USA
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Lutz A, Dyall J, Olivo PD, Pekosz A. Virus-inducible reporter genes as a tool for detecting and quantifying influenza A virus replication. J Virol Methods 2005; 126:13-20. [PMID: 15847914 PMCID: PMC1698269 DOI: 10.1016/j.jviromet.2005.01.016] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 01/08/2005] [Accepted: 01/20/2005] [Indexed: 11/23/2022]
Abstract
The use of influenza A virus-inducible reporter gene segments in detecting influenza A virus replication was investigated. The RNA polymerase I promoter/terminator cassette was used to express RNA transcripts encoding green fluorescence protein or firefly luciferase flanked by the untranslated regions of the influenza A/WSN/33 nucleoprotein (NP) segment. Reporter gene activity was detected after reconstitution of the influenza A virus polymerase complex from cDNA or after virus infection, and was influenza A virus-specific. Reporter gene activity could be detected as early as 6 h post-infection and was virus dose-dependent. Inhibitory effects of antibodies or amantadine could be detected and quantified rapidly, providing a means of not only identifying influenza A virus-specific replication, but also of determining the antigenic subtype as well as antiviral drug susceptibility. Induction of virus-specific reporter genes provides a rapid, sensitive method for detecting virus replication, quantifying virus titers and assessing antiviral sensitivity as well as antigenic subtype.
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Affiliation(s)
- Andrew Lutz
- Department of Molecular Microbiology and Pathology & Immunology, Washington University in St, Louis, St. Louis, MO 63110
| | | | | | - Andrew Pekosz
- Department of Molecular Microbiology and Pathology & Immunology, Washington University in St, Louis, St. Louis, MO 63110
- *Corresponding author: Departments of Molecular Microbiology and Pathology & Immunology, Washington University School of Medicine, Campus Box 8230, 660 S. Euclid Ave., St. Louis, MO 63110, , tel: 314.747.2132, fax: 314.362.3203
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