1
|
Zhang L, Shao Y, Wang Y, Yang Q, Guo J, Gao GF, Deng T. Twenty natural amino acid substitution screening at the last residue 121 of influenza A virus NS2 protein reveals the critical role of NS2 in promoting virus genome replication by coordinating with viral polymerase. J Virol 2024; 98:e0116623. [PMID: 38054704 PMCID: PMC10804943 DOI: 10.1128/jvi.01166-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/20/2023] [Indexed: 12/07/2023] Open
Abstract
Both influenza A virus genome transcription (vRNA→mRNA) and replication (vRNA→cRNA→vRNA), catalyzed by the influenza RNA polymerase (FluPol), are dynamically regulated across the virus life cycle. It has been reported that the last amino acid I121 of the viral NS2 protein plays a critical role in promoting viral genome replication in influenza mini-replicon systems. Here, we performed a 20 natural amino acid substitution screening at residue NS2-I121 in the context of virus infection. We found that the hydrophobicity of the residue 121 is essential for virus survival. Interestingly, through serial passage of the rescued mutant viruses, we further identified adaptive mutations PA-K19E and PB1-S713N on FluPol which could effectively compensate for the replication-promoting defect caused by NS2-I121 mutation in the both mini-replicon and virus infection systems. Structural analysis of different functional states of FluPol indicates that PA-K19E and PB1-S713N could stabilize the replicase conformation of FluPol. By using a cell-based NanoBiT complementary reporter assay, we further demonstrate that both wild-type NS2 and PA-K19E/PB1-S713N could enhance FluPol dimerization, which is necessary for genome replication. These results reveal the critical role NS2 plays in promoting viral genome replication by coordinating with FluPol.IMPORTANCEThe intrinsic mechanisms of influenza RNA polymerase (FluPol) in catalyzing viral genome transcription and replication have been largely resolved. However, the mechanisms of how transcription and replication are dynamically regulated remain elusive. We recently reported that the last amino acid of the viral NS2 protein plays a critical role in promoting viral genome replication in an influenza mini-replicon system. Here, we conducted a 20 amino acid substitution screening at the last residue 121 in virus rescue and serial passage. Our results demonstrate that the replication-promoting function of NS2 is important for virus survival and efficient multiplication. We further show evidence that NS2 and NS2-I121 adaptive mutations PA-K19E/PB1-S713N regulate virus genome replication by promoting FluPol dimerization. This work highlights the coordination between NS2 and FluPol in fulfilling efficient genome replication. It further advances our understanding of the regulation of viral RNA synthesis for influenza A virus.
Collapse
Affiliation(s)
- Lei Zhang
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- />Institute of Pediatrics, Shenzhen Children’s Hospital, Shenzhen, China
| | - Yuekun Shao
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yingying Wang
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Qiuxian Yang
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jiamei Guo
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - George F. Gao
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Tao Deng
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
2
|
Ogasawara S, Ebashi S. RNA Overwriting of Cellular mRNA by Cas13b-Directed RNA-Dependent RNA Polymerase of Influenza A Virus. Int J Mol Sci 2023; 24:10000. [PMID: 37373148 DOI: 10.3390/ijms241210000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/05/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
Dysregulation of mRNA processing results in diseases such as cancer. Although RNA editing technologies attract attention as gene therapy for repairing aberrant mRNA, substantial sequence defects arising from mis-splicing cannot be corrected by existing techniques using adenosine deaminase acting on RNA (ADAR) due to the limitation of adenosine-to-inosine point conversion. Here, we report an RNA editing technology called "RNA overwriting" that overwrites the sequence downstream of a designated site on the target RNA by utilizing the RNA-dependent RNA polymerase (RdRp) of the influenza A virus. To enable RNA overwriting within living cells, we developed a modified RdRp by introducing H357A and E361A mutations in the polymerase basic 2 of RdRp and fusing the C-terminus with catalytically inactive Cas13b (dCas13b). The modified RdRp knocked down 46% of the target mRNA and further overwrote 21% of the mRNA. RNA overwriting is a versatile editing technique that can perform various modifications, including addition, deletion, and mutation introduction, and thus allow for repair of the aberrant mRNA produced by dysregulation of mRNA processing, such as mis-splicing.
Collapse
Affiliation(s)
- Shinzi Ogasawara
- Department of Biology, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Nagano, Japan
| | - Sae Ebashi
- Department of Biology, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Nagano, Japan
| |
Collapse
|
3
|
Whelan M, Pelchat M. Role of RNA Polymerase II Promoter-Proximal Pausing in Viral Transcription. Viruses 2022; 14:v14092029. [PMID: 36146833 PMCID: PMC9503719 DOI: 10.3390/v14092029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/09/2022] [Accepted: 09/11/2022] [Indexed: 11/16/2022] Open
Abstract
The promoter-proximal pause induced by the binding of the DRB sensitivity-inducing factor (DSIF) and the negative elongation factor (NELF) to RNAP II is a key step in the regulation of metazoan gene expression. It helps maintain a permissive chromatin landscape and ensures a quick transcriptional response from stimulus-responsive pathways such as the innate immune response. It is also involved in the biology of several RNA viruses such as the human immunodeficiency virus (HIV), the influenza A virus (IAV) and the hepatitis delta virus (HDV). HIV uses the pause as one of its mechanisms to enter and maintain latency, leading to the creation of viral reservoirs resistant to antiretrovirals. IAV, on the other hand, uses the pause to acquire the capped primers necessary to initiate viral transcription through cap-snatching. Finally, the HDV RNA genome is transcribed directly by RNAP II and requires the small hepatitis delta antigen to displace NELF from the polymerase and overcome the transcriptional block caused by RNAP II promoter-proximal pausing. In this review, we will discuss the RNAP II promoter-proximal pause and the roles it plays in the life cycle of RNA viruses such as HIV, IAV and HDV.
Collapse
|
4
|
Ogasawara S, Yamada A. RNA Editing with Viral RNA-Dependent RNA Polymerase. ACS Synth Biol 2022; 11:46-52. [PMID: 34978432 DOI: 10.1021/acssynbio.1c00332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RNA editing is currently attracting attention as a method for editing genetic information without injury to the genome. The most common approach to edit RNA sequences involves the induction of an A-to-I change by adenosine deaminase acting on RNA (ADAR). However, this method only allows point editing. Here, we report a highly flexible RNA editing method called "RNA overwriting" that employs the influenza A virus RNA-dependent RNA polymerase (RdRp) comprising PA, PB1, and PB2 subunits. RdRp binds to the 5'-cap structure of the host mRNA and cleaves at the AG site, followed by transcription of the viral RNA; this process is called cap-snatching. We engineered a targeting snatch system wherein the target RNA is cleaved and extended at any site addressed by guide RNA (gRNA). We constructed five recombinant RdRps containing a PB2 mutant and demonstrated the editing capability of RdRp mutants by using short RNAs in vitro. PB2-480-containing RdRp exhibited good performance in both cleavage and extension assays; we succeeded in RNA overwriting using PB2-480-containing RdRp. In principle, this method allows RNA editing of any type including mutation, addition, and deletion, by changing the sequence of the template RNA to the sequence of interest; hence, the use of viral RdRp could open new avenues in RNA editing and be a powerful tool in life science.
Collapse
Affiliation(s)
- Shinzi Ogasawara
- Department of Biology, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Ai Yamada
- Department of Biology, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
| |
Collapse
|
5
|
Abstract
Influenza infection causes severe illness in 3 to 5 million people annually, with up to an estimated 650,000 deaths per annum. As such, it represents an ongoing burden to health care systems and human health. Severe acute respiratory infection can occur, resulting in respiratory failure requiring intensive care support. Herein we discuss diagnostic approaches, including development of CLIA-waived point of care tests that allow rapid diagnosis and treatment of influenza. Bacterial and fungal coinfections in severe influenza pneumonia are associated with worse outcomes, and we summarize the approach and treatment options for diagnosis and treatment of bacterial and Aspergillus coinfection. We discuss the available drug options for the treatment of severe influenza, and treatments which are no longer supported by the evidence base. Finally, we describe the supportive management and ventilatory approach to patients with respiratory failure as a result of severe influenza in the intensive care unit.
Collapse
Affiliation(s)
- Liam S O'Driscoll
- Department of Intensive Care Medicine, St. James's University Hospital, Multidisciplinary Intensive Care Research Organization (MICRO), Trinity Centre for Health Sciences, Dublin, Ireland
| | - Ignacio Martin-Loeches
- Department of Intensive Care Medicine, St. James's University Hospital, Multidisciplinary Intensive Care Research Organization (MICRO), Trinity Centre for Health Sciences, Dublin, Ireland.,Respiratory Medicine, Hospital Clinic, IDIBAPS, Universidad de Barcelona, CIBERes, Barcelona, Spain
| |
Collapse
|
6
|
Equine Influenza Virus and Vaccines. Viruses 2021; 13:v13081657. [PMID: 34452521 PMCID: PMC8402878 DOI: 10.3390/v13081657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 01/01/2023] Open
Abstract
Equine influenza virus (EIV) is a constantly evolving viral pathogen that is responsible for yearly outbreaks of respiratory disease in horses termed equine influenza (EI). There is currently no evidence of circulation of the original H7N7 strain of EIV worldwide; however, the EIV H3N8 strain, which was first isolated in the early 1960s, remains a major threat to most of the world's horse populations. It can also infect dogs. The ability of EIV to constantly accumulate mutations in its antibody-binding sites enables it to evade host protective immunity, making it a successful viral pathogen. Clinical and virological protection against EIV is achieved by stimulation of strong cellular and humoral immunity in vaccinated horses. However, despite EI vaccine updates over the years, EIV remains relevant, because the protective effects of vaccines decay and permit subclinical infections that facilitate transmission into susceptible populations. In this review, we describe how the evolution of EIV drives repeated EI outbreaks even in horse populations with supposedly high vaccination coverage. Next, we discuss the approaches employed to develop efficacious EI vaccines for commercial use and the existing system for recommendations on updating vaccines based on available clinical and virological data to improve protective immunity in vaccinated horse populations. Understanding how EIV biology can be better harnessed to improve EI vaccines is central to controlling EI.
Collapse
|
7
|
Kumar G, Cuypers M, Webby RR, Webb TR, White SW. Structural insights into the substrate specificity of the endonuclease activity of the influenza virus cap-snatching mechanism. Nucleic Acids Res 2021; 49:1609-1618. [PMID: 33469660 PMCID: PMC7897473 DOI: 10.1093/nar/gkaa1294] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 01/01/2023] Open
Abstract
The endonuclease activity within the influenza virus cap-snatching process is a proven therapeutic target. The anti-influenza drug baloxavir is highly effective, but is associated with resistance mutations that threaten its clinical efficacy. The endonuclease resides within the N-terminal domain of the PA subunit (PAN) of the influenza RNA dependent RNA polymerase, and we report here complexes of PAN with RNA and DNA oligonucleotides to understand its specificity and the structural basis of baloxavir resistance mutations. The RNA and DNA oligonucleotides bind within the substrate binding groove of PAN in a similar fashion, explaining the ability of the enzyme to cleave both substrates. The individual nucleotides occupy adjacent conserved pockets that flank the two-metal active site. However, the 2′ OH of the RNA ribose moieties engage in additional interactions that appear to optimize the binding and cleavage efficiency for the natural substrate. The major baloxavir resistance mutation at position 38 is at the core of the substrate binding site, but structural studies and modeling suggest that it maintains the necessary virus fitness via compensating interactions with RNA. These studies will facilitate the development of new influenza therapeutics that spatially match the substrate and are less likely to elicit resistance mutations.
Collapse
Affiliation(s)
| | - Maxime Cuypers
- Department of Structural Biology, Memphis, TN 38105, USA
| | - Richard R Webby
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Thomas R Webb
- Wildflower Biopharma, Inc., 8650 Genesee Ave. STE 214, San Diego, CA 92122, USA.,Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | | |
Collapse
|
8
|
Gregor J, Radilová K, Brynda J, Fanfrlík J, Konvalinka J, Kožíšek M. Structural and Thermodynamic Analysis of the Resistance Development to Pimodivir (VX-787), the Clinical Inhibitor of Cap Binding to PB2 Subunit of Influenza A Polymerase. Molecules 2021; 26:molecules26041007. [PMID: 33673017 PMCID: PMC7917969 DOI: 10.3390/molecules26041007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/20/2021] [Accepted: 02/12/2021] [Indexed: 01/06/2023] Open
Abstract
Influenza A virus (IAV) encodes a polymerase composed of three subunits: PA, with endonuclease activity, PB1 with polymerase activity and PB2 with host RNA five-prime cap binding site. Their cooperation and stepwise activation include a process called cap-snatching, which is a crucial step in the IAV life cycle. Reproduction of IAV can be blocked by disrupting the interaction between the PB2 domain and the five-prime cap. An inhibitor of this interaction called pimodivir (VX-787) recently entered the third phase of clinical trial; however, several mutations in PB2 that cause resistance to pimodivir were observed. First major mutation, F404Y, causing resistance was identified during preclinical testing, next the mutation M431I was identified in patients during the second phase of clinical trials. The mutation H357N was identified during testing of IAV strains at Centers for Disease Control and Prevention. We set out to provide a structural and thermodynamic analysis of the interactions between cap-binding domain of PB2 wild-type and PB2 variants bearing these mutations and pimodivir. Here we present four crystal structures of PB2-WT, PB2-F404Y, PB2-M431I and PB2-H357N in complex with pimodivir. We have thermodynamically analysed all PB2 variants and proposed the effect of these mutations on thermodynamic parameters of these interactions and pimodivir resistance development. These data will contribute to understanding the effect of these missense mutations to the resistance development and help to design next generation inhibitors.
Collapse
Affiliation(s)
- Jiří Gregor
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
- First Faculty of Medicine, Charles University, Kateřinská 1660/32, 12108 Prague 2, Czech Republic
| | - Kateřina Radilová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
- First Faculty of Medicine, Charles University, Kateřinská 1660/32, 12108 Prague 2, Czech Republic
| | - Jiří Brynda
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
| | - Jindřich Fanfrlík
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
| | - Jan Konvalinka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 8, 12800 Prague 2, Czech Republic
- Correspondence: (J.K.); (M.K.); Tel.: +420-220-183-218 (J.K.)
| | - Milan Kožíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 16610 Prague 6, Czech Republic; (J.G.); (K.R.); (J.B.); (J.F.)
- Correspondence: (J.K.); (M.K.); Tel.: +420-220-183-218 (J.K.)
| |
Collapse
|
9
|
Qin Z, Qu X, Lei L, Xu L, Pan Z. Y-Box-Binding Protein 3 (YBX3) Restricts Influenza A Virus by Interacting with Viral Ribonucleoprotein Complex and Imparing its Function. J Gen Virol 2020; 101:385-398. [DOI: 10.1099/jgv.0.001390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Zhenqiao Qin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Xiao Qu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Lei Lei
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Lulai Xu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Zishu Pan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| |
Collapse
|
10
|
Hu A, Li J, Tang W, Liu G, Zhang H, Liu C, Chen X. Anthralin Suppresses the Proliferation of Influenza Virus by Inhibiting the Cap-Binding and Endonuclease Activity of Viral RNA Polymerase. Front Microbiol 2020; 11:178. [PMID: 32132985 PMCID: PMC7040080 DOI: 10.3389/fmicb.2020.00178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 01/24/2020] [Indexed: 11/23/2022] Open
Abstract
Influenza virus RNA-dependent RNA polymerase (vRdRp) does not have capping activity and relies on the capped RNAs produced by the host RNA polymerase II (RNAPII). The viral polymerases process the capped RNAs to produce short capped RNA fragments that are used as primers to initiate the transcription of viral mRNAs. This process, known as cap-snatching, can be targeted by antiviral therapeutics. Here, anthralin was identified as an inhibitor against influenza a virus (IAV) infection by targeting the cap-snatching activity of the viral polymerase. Anthralin, an FDA-approved drug used in the treatment of psoriasis, shows antiviral activity against IAV infection in vitro and in vivo. Importantly, anthralin significantly reduces weight loss, lung injury, and mortality caused by IAV infection in mice. The mechanism of action study revealed that anthralin inhibits the cap-binding function of PB2 subunit and endonuclease activity of PA. As a result, viral mRNA transcription is blocked, leading to the decreases in viral RNA replication and viral protein expression. In conclusion, anthralin has been demonstrated to have the potential of an alternative antiviral against influenza virus infection. Also, targeting the captive pocket structure that includes the N-terminus of PA endonuclease domain and the C-terminal of PB2 cap-binding domain of IAV RdRp may be an excellent strategy for developing anti-influenza drugs.
Collapse
Affiliation(s)
- Ao Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jing Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Wei Tang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Ge Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Haiwei Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Chunlan Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xulin Chen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China.,Guangdong Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| |
Collapse
|
11
|
The R251K Substitution in Viral Protein PB2 Increases Viral Replication and Pathogenicity of Eurasian Avian-like H1N1 Swine Influenza Viruses. Viruses 2020; 12:v12010052. [PMID: 31906472 PMCID: PMC7019279 DOI: 10.3390/v12010052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/29/2019] [Accepted: 12/31/2019] [Indexed: 12/21/2022] Open
Abstract
The Eurasian avian-like swine (EA) H1N1 virus has affected the Chinese swine industry, and human infection cases have been reported occasionally. However, little is known about the pathogenic mechanism of EA H1N1 virus. In this study, we compared the mouse pathogenicity of A/swine/Guangdong/YJ4/2014 (YJ4) and A/swine/Guangdong/MS285/2017 (MS285) viruses, which had similar genotype to A/Hunan/42443/2015 (HuN-like). None of the mice inoculated with 106 TCID50 of YJ4 survived at 7 days post infection, while the survival rate of the MS285 group was 100%. Therefore, a series of single fragment reassortants in MS285 background and two rescued wild-type viruses were generated by using the reverse genetics method, and the pathogenicity analysis revealed that the PB2 gene contributed to the high virulence of YJ4 virus. Furthermore, there were 11 amino acid differences in PB2 between MS285 and YJ4 identified by sequence alignment, and 11 single amino acid mutant viruses were generated in the MS285 background. We found that the R251K mutation significantly increased the virulence of MS285 in mice, contributed to high polymerase activity and enhanced viral genome transcription and replication. These results indicate that PB2-R251K contributes to the virulence of the EA H1N1 virus and provide new insight into future molecular epidemiological surveillance strategies.
Collapse
|
12
|
Suttie A, Deng YM, Greenhill AR, Dussart P, Horwood PF, Karlsson EA. Inventory of molecular markers affecting biological characteristics of avian influenza A viruses. Virus Genes 2019; 55:739-768. [PMID: 31428925 PMCID: PMC6831541 DOI: 10.1007/s11262-019-01700-z] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 08/09/2019] [Indexed: 12/20/2022]
Abstract
Avian influenza viruses (AIVs) circulate globally, spilling over into domestic poultry and causing zoonotic infections in humans. Fortunately, AIVs are not yet capable of causing sustained human-to-human infection; however, AIVs are still a high risk as future pandemic strains, especially if they acquire further mutations that facilitate human infection and/or increase pathogenesis. Molecular characterization of sequencing data for known genetic markers associated with AIV adaptation, transmission, and antiviral resistance allows for fast, efficient assessment of AIV risk. Here we summarize and update the current knowledge on experimentally verified molecular markers involved in AIV pathogenicity, receptor binding, replicative capacity, and transmission in both poultry and mammals with a broad focus to include data available on other AIV subtypes outside of A/H5N1 and A/H7N9.
Collapse
Affiliation(s)
- Annika Suttie
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, 5 Monivong Blvd, PO Box #983, Phnom Penh, Cambodia
- School of Health and Life Sciences, Federation University, Churchill, Australia
- World Health Organization Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Yi-Mo Deng
- World Health Organization Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Andrew R Greenhill
- School of Health and Life Sciences, Federation University, Churchill, Australia
| | - Philippe Dussart
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, 5 Monivong Blvd, PO Box #983, Phnom Penh, Cambodia
| | - Paul F Horwood
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | - Erik A Karlsson
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, 5 Monivong Blvd, PO Box #983, Phnom Penh, Cambodia.
| |
Collapse
|
13
|
A Parallel Phenotypic Versus Target-Based Screening Strategy for RNA-Dependent RNA Polymerase Inhibitors of the Influenza A Virus. Viruses 2019; 11:v11090826. [PMID: 31491939 PMCID: PMC6783926 DOI: 10.3390/v11090826] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 12/19/2022] Open
Abstract
Influenza A virus infections cause significant morbidity and mortality, and novel antivirals are urgently needed. Influenza RNA-dependent RNA polymerase (RdRp) activity has been acknowledged as a promising target for novel antivirals. In this study, a phenotypic versus target-based screening strategy was established to identify the influenza A virus inhibitors targeting the virus RNA transcription/replication steps by sequentially using an RdRp-targeted screen and a replication-competent reporter virus-based approach using the same compounds. To demonstrate the utility of this approach, a pilot screen of a library of 891 compounds derived from natural products was carried out. Quality control analysis indicates that the primary screen was robust for identification of influenza A virus inhibitors targeting RdRp activity. Finally, two hit candidates were identified, and one was validated as a putative RdRp inhibitor. This strategy can greatly reduce the number of false positives and improve the accuracy and efficacy of primary screening, thereby providing a powerful tool for antiviral discovery.
Collapse
|
14
|
Walker AP, Fodor E. Interplay between Influenza Virus and the Host RNA Polymerase II Transcriptional Machinery. Trends Microbiol 2019; 27:398-407. [PMID: 30642766 PMCID: PMC6467242 DOI: 10.1016/j.tim.2018.12.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 11/30/2018] [Accepted: 12/20/2018] [Indexed: 12/12/2022]
Abstract
The influenza virus RNA-dependent RNA polymerase (RdRP) cleaves the 5' end of nascent capped host RNAs and uses the capped RNA fragment to prime viral transcription in a mechanism called 'cap snatching'. Cap snatching requires an intimate association between influenza RdRP and cellular RNA polymerase II (Pol II), which is the source of nascent capped host RNAs targeted by influenza virus. Recent structural studies have revealed how influenza RdRP binds to Pol II and how this binding promotes the initiation of viral transcription by influenza RdRP. In this review we focus on these recent insights into the mechanism of cap snatching by influenza virus and the impact of cap snatching on host gene expression during influenza virus infection.
Collapse
Affiliation(s)
- Alexander P Walker
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
| |
Collapse
|
15
|
Xiong J, Wang J, Hu G, Zhao W, Li J. Design, synthesis and biological evaluation of novel, orally bioavailable pyrimidine-fused heterocycles as influenza PB2 inhibitors. Eur J Med Chem 2019; 162:249-265. [DOI: 10.1016/j.ejmech.2018.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 10/29/2018] [Accepted: 11/06/2018] [Indexed: 02/05/2023]
|
16
|
Shin WJ, Seong BL. Novel antiviral drug discovery strategies to tackle drug-resistant mutants of influenza virus strains. Expert Opin Drug Discov 2018; 14:153-168. [PMID: 30585088 DOI: 10.1080/17460441.2019.1560261] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION The emergence of drug-resistant influenza virus strains highlights the need for new antiviral therapeutics to combat future pandemic outbreaks as well as continuing seasonal cycles of influenza. Areas covered: This review summarizes the mechanisms of current FDA-approved anti-influenza drugs and patterns of resistance to those drugs. It also discusses potential novel targets for broad-spectrum antiviral drugs and recent progress in novel drug design to overcome drug resistance in influenza. Expert opinion: Using the available structural information about drug-binding pockets, research is currently underway to identify molecular interactions that can be exploited to generate new antiviral drugs. Despite continued efforts, antivirals targeting viral surface proteins like HA, NA, and M2, are all susceptible to developing resistance. Structural information on the internal viral polymerase complex (PB1, PB2, and PA) provides a new avenue for influenza drug discovery. Host factors, either at the initial step of viral infection or at the later step of nuclear trafficking of viral RNP complex, are being actively pursued to generate novel drugs with new modes of action, without resulting in drug resistance.
Collapse
Affiliation(s)
- Woo-Jin Shin
- a Department of Molecular Microbiology and Immunology, Keck School of Medicine , University of Southern California , Los Angeles , CA , USA
| | - Baik L Seong
- b Department of Biotechnology , College of Life Science and Biotechnology, Yonsei University , Seoul , South Korea.,c Vaccine Translational Research Center , Yonsei University , Seoul , South Korea
| |
Collapse
|
17
|
Moravej H, Moravej Z, Yazdanparast M, Heiat M, Mirhosseini A, Moosazadeh Moghaddam M, Mirnejad R. Antimicrobial Peptides: Features, Action, and Their Resistance Mechanisms in Bacteria. Microb Drug Resist 2018; 24:747-767. [PMID: 29957118 DOI: 10.1089/mdr.2017.0392] [Citation(s) in RCA: 170] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In recent years, because of increased resistance to conventional antimicrobials, many researchers have started to study the synthesis of new antibiotics to control the disease-causing effects of infectious pathogens. Antimicrobial peptides (AMPs) are among the newest antibiotics; these peptides are integral compounds in all kinds of organisms and play a significant role in microbial ecology, and critically contribute to the innate immunity of organisms by destroying invading microorganisms. Moreover, AMPs may encourage cells to produce chemokines, stimulate angiogenesis, accelerate wound healing, and influence programmed cell death in multicellular organisms. Bacteria differ in their inherent susceptibility and resistance mechanisms to these peptides when responding to the antimicrobial effects of AMPs. Generally, the development of AMP resistance mechanisms is driven by direct competition between bacterial species, and host and pathogen interactions. Several studies have shown diverse mechanisms of bacterial resistance to AMPs, for example, some bacteria produce proteases and trapping proteins; some modify cell surface charge, change membrane fluidity, and activate efflux pumps; and some species make use of biofilms and exopolymers, and develop sensing systems by selective gene expression. A closer understanding of bacterial resistance mechanisms may help in developing novel therapeutic approaches for the treatment of infections caused by pathogenic organisms that are successful in developing extensive resistance to AMPs. Based on these observations, this review discusses the properties of AMPs, their targeting mechanisms, and bacterial resistance mechanisms against AMPs.
Collapse
Affiliation(s)
- Hoda Moravej
- 1 Molecular Biology Research Center, Systems Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences , Tehran, Iran
| | - Zahra Moravej
- 2 Department of Hepatitis and AIDS, Pasteur Institute of Iran , Tehran, Iran
| | - Maryam Yazdanparast
- 3 Department of Pharmacology, Experimental Medicine Research Center, School of Medicine, Tehran University of Medical Sciences , Tehran, Iran
| | - Mohammad Heiat
- 4 Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences , Tehran, Iran
| | - Ali Mirhosseini
- 5 Applied Microbiology Research Center, Systems Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences , Tehran, Iran
| | | | - Reza Mirnejad
- 1 Molecular Biology Research Center, Systems Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences , Tehran, Iran
| |
Collapse
|
18
|
Chaisri U, Chaicumpa W. Evolution of Therapeutic Antibodies, Influenza Virus Biology, Influenza, and Influenza Immunotherapy. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9747549. [PMID: 29998138 PMCID: PMC5994580 DOI: 10.1155/2018/9747549] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/19/2018] [Accepted: 03/31/2018] [Indexed: 02/07/2023]
Abstract
This narrative review article summarizes past and current technologies for generating antibodies for passive immunization/immunotherapy. Contemporary DNA and protein technologies have facilitated the development of engineered therapeutic monoclonal antibodies in a variety of formats according to the required effector functions. Chimeric, humanized, and human monoclonal antibodies to antigenic/epitopic myriads with less immunogenicity than animal-derived antibodies in human recipients can be produced in vitro. Immunotherapy with ready-to-use antibodies has gained wide acceptance as a powerful treatment against both infectious and noninfectious diseases. Influenza, a highly contagious disease, precipitates annual epidemics and occasional pandemics, resulting in high health and economic burden worldwide. Currently available drugs are becoming less and less effective against this rapidly mutating virus. Alternative treatment strategies are needed, particularly for individuals at high risk for severe morbidity. In a setting where vaccines are not yet protective or available, human antibodies that are broadly effective against various influenza subtypes could be highly efficacious in lowering morbidity and mortality and controlling unprecedented epidemic/pandemic. Prototypes of human single-chain antibodies to several conserved proteins of influenza virus with no Fc portion (hence, no ADE effect in recipients) are available. These antibodies have high potential as a novel, safe, and effective anti-influenza agent.
Collapse
Affiliation(s)
- Urai Chaisri
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| |
Collapse
|
19
|
Zhou Z, Liu T, Zhang J, Zhan P, Liu X. Influenza A virus polymerase: an attractive target for next-generation anti-influenza therapeutics. Drug Discov Today 2018; 23:503-518. [PMID: 29339107 DOI: 10.1016/j.drudis.2018.01.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/31/2017] [Accepted: 01/05/2018] [Indexed: 12/20/2022]
Abstract
The influenza RNA-dependent RNA polymerase (RdRP) is conserved among different types of influenza virus, playing an important part in transcription and replication. In this regard, influenza RdRP is an attractive target for novel anti-influenza drug discovery. Herein, we will introduce the structural and functional information of influenza polymerase; and an overview of inhibitors targeting the PA endonuclease and PB2 cap-binding site is provided, along with the approaches utilized for identification of these inhibitors. The protein-protein interactions (PPIs) of the three polymerase subunits: PA, PB1 and PB2, are described based on the published crystal structures, and inhibitors targeting the PA-PB1 interaction are introduced briefly.
Collapse
Affiliation(s)
- Zhongxia Zhou
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, 250012 Jinan, Shandong, China
| | - Tao Liu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, 250012 Jinan, Shandong, China
| | - Jian Zhang
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, 250012 Jinan, Shandong, China
| | - Peng Zhan
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, 250012 Jinan, Shandong, China.
| | - Xinyong Liu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, 250012 Jinan, Shandong, China.
| |
Collapse
|
20
|
Synergistic effect of PB2 283M and 526R contributes to enhanced virulence of H5N8 influenza viruses in mice. Vet Res 2017; 48:67. [PMID: 29070059 PMCID: PMC5657129 DOI: 10.1186/s13567-017-0471-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 10/09/2017] [Indexed: 12/14/2022] Open
Abstract
Highly pathogenic avian influenza (HPAI) H5N8 virus has caused considerable economic losses to poultry industry and poses a great threat to public health. Our previous study revealed two genetically similar HPAI H5N8 viruses displaying completely different virulence in mice. However, the molecular basis for viral pathogenicity to mammals remains unknown. Herein, we generated a series of reassortants between the two viruses and evaluated their virulence in mice. We demonstrated that 283M in PB2 is a new mammalian virulence marker for H5 viruses and that synergistic effect of amino acid residues 283M and 526R in PB2 is responsible for high virulence of the HPAI H5N8 virus. Analysis of available PB2 sequences showed that PB2 283M is highly conserved among influenza A viruses, while PB2 526R presents in most of human H3N2 and H5N1 isolates. Further study confirmed that the residues 283M and 526R had similar impacts on an HPAI H5N1 virus, suggesting that influenza viruses with both residues may replicate well in mammalian hosts. Together, these results present new insights for synergistic effect of 283M and 526R in PB2 of H5 HPAI virus on virulence to mammalian host, furthering our understanding of the pathogenesis of influenza A virus.
Collapse
|
21
|
Chen W, Xu Q, Zhong Y, Yu H, Shu J, Ma T, Li Z. Genetic variation and co-evolutionary relationship of RNA polymerase complex segments in influenza A viruses. Virology 2017; 511:193-206. [PMID: 28866238 DOI: 10.1016/j.virol.2017.07.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 11/19/2022]
Abstract
The RNA polymerase complex (RNApc) in influenza A viruses (IVs) is composed of the PB2, PB1 and PA subunits, which are encoded by the three longest genome segments (Seg1-3) and are responsible for the replication of vRNAs and transcription of viral mRNAs. However, the co-evolutionary relationships of the three segments from the known 126 subtypes IVs are unclear. In this study, we performed a detailed analysis based on a total number of 121,191 nucleotide sequences. Three segment sequences were aligned before the repeated, incomplete and mixed sequences were removed for homologous and phylogenetic analyses. Subsequently, the estimated substitution rates and TMRCAs (Times for Most Recent Common Ancestor) were calculated by 175 representative IVs. Tracing the cladistic distribution of three segments from these IVs, co-evolutionary patterns and trajectories could be inferred. The further correlation analysis of six internal protein coding segments reflect the RNApc segments have the closer correlation than others during continuous reassortments. This global approach facilitates the establishment of a fast antiviral strategy and monitoring of viral variation.
Collapse
Affiliation(s)
- Wentian Chen
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Qi Xu
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Yaogang Zhong
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Hanjie Yu
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Jian Shu
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Tianran Ma
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China
| | - Zheng Li
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an 710069, PR China.
| |
Collapse
|
22
|
Bera BC, Virmani N, Kumar N, Anand T, Pavulraj S, Rash A, Elton D, Rash N, Bhatia S, Sood R, Singh RK, Tripathi BN. Genetic and codon usage bias analyses of polymerase genes of equine influenza virus and its relation to evolution. BMC Genomics 2017; 18:652. [PMID: 28830350 PMCID: PMC5568313 DOI: 10.1186/s12864-017-4063-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 08/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Equine influenza is a major health problem of equines worldwide. The polymerase genes of influenza virus have key roles in virus replication, transcription, transmission between hosts and pathogenesis. Hence, the comprehensive genetic and codon usage bias of polymerase genes of equine influenza virus (EIV) were analyzed to elucidate the genetic and evolutionary relationships in a novel perspective. RESULTS The group - specific consensus amino acid substitutions were identified in all polymerase genes of EIVs that led to divergence of EIVs into various clades. The consistent amino acid changes were also detected in the Florida clade 2 EIVs circulating in Europe and Asia since 2007. To study the codon usage patterns, a total of 281,324 codons of polymerase genes of EIV H3N8 isolates from 1963 to 2015 were systemically analyzed. The polymerase genes of EIVs exhibit a weak codon usage bias. The ENc-GC3s and Neutrality plots indicated that natural selection is the major influencing factor of codon usage bias, and that the impact of mutation pressure is comparatively minor. The methods for estimating host imposed translation pressure suggested that the polymerase acidic (PA) gene seems to be under less translational pressure compared to polymerase basic 1 (PB1) and polymerase basic 2 (PB2) genes. The multivariate statistical analysis of polymerase genes divided EIVs into four evolutionary diverged clusters - Pre-divergent, Eurasian, Florida sub-lineage 1 and 2. CONCLUSIONS Various lineage specific amino acid substitutions observed in all polymerase genes of EIVs and especially, clade 2 EIVs underwent major variations which led to the emergence of a phylogenetically distinct group of EIVs originating from Richmond/1/07. The codon usage bias was low in all the polymerase genes of EIVs that was influenced by the multiple factors such as the nucleotide compositions, mutation pressure, aromaticity and hydropathicity. However, natural selection was the major influencing factor in defining the codon usage patterns and evolution of polymerase genes of EIVs.
Collapse
Affiliation(s)
- Bidhan Ch Bera
- National Research Centre on Equines, Sirsa Road, Hisar, Haryana, India
| | - Nitin Virmani
- National Research Centre on Equines, Sirsa Road, Hisar, Haryana, India.
| | - Naveen Kumar
- National Institute of High Security Animal Diseases, Hathai Kheda Dam Road, Anand Nagar, Bhopal, Madhya Pradesh, India
| | - Taruna Anand
- National Research Centre on Equines, Sirsa Road, Hisar, Haryana, India
| | - S Pavulraj
- National Research Centre on Equines, Sirsa Road, Hisar, Haryana, India
| | - Adam Rash
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK
| | - Debra Elton
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK
| | - Nicola Rash
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK
| | - Sandeep Bhatia
- National Institute of High Security Animal Diseases, Hathai Kheda Dam Road, Anand Nagar, Bhopal, Madhya Pradesh, India
| | - Richa Sood
- National Institute of High Security Animal Diseases, Hathai Kheda Dam Road, Anand Nagar, Bhopal, Madhya Pradesh, India
| | - Raj Kumar Singh
- Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh, India
| | | |
Collapse
|
23
|
Meng B, Bentley K, Marriott AC, Scott PD, Dimmock NJ, Easton AJ. Unexpected complexity in the interference activity of a cloned influenza defective interfering RNA. Virol J 2017; 14:138. [PMID: 28738877 PMCID: PMC5525295 DOI: 10.1186/s12985-017-0805-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 07/14/2017] [Indexed: 02/02/2023] Open
Abstract
Background Defective interfering (DI) viruses are natural antivirals made by nearly all viruses. They have a highly deleted genome (thus being non-infectious) and interfere with the replication of genetically related infectious viruses. We have produced the first potential therapeutic DI virus for the clinic by cloning an influenza A DI RNA (1/244) which was derived naturally from genome segment 1. This is highly effective in vivo, and has unexpectedly broad-spectrum activity with two different modes of action: inhibiting influenza A viruses through RNA interference, and all other (interferon-sensitive) respiratory viruses through stimulating interferon type I. Results We have investigated the RNA inhibitory mechanism(s) of DI 1/244 RNA. Ablation of initiation codons does not diminish interference showing that no protein product is required for protection. Further analysis indicated that 1/244 DI RNA interferes by replacing the cognate full-length segment 1 RNA in progeny virions, while interfering with the expression of genome segment 1, its cognate RNA, and genome RNAs 2 and 3, but not genome RNA 6, a representative of the non-polymerase genes. Conclusions Our data contradict the dogma that a DI RNA only interferes with expression from its cognate full-length segment. There is reciprocity as cloned segment 2 and 3 DI RNAs inhibited expression of RNAs from a segment 1 target. These data demonstrate an unexpected complexity in the mechanism of interference by this cloned therapeutic DI RNA.
Collapse
Affiliation(s)
- Bo Meng
- Present Address: Department of Medicine, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Kirsten Bentley
- Present Address: Biomedical Sciences Research Complex, North Haugh, University of St. Andrews, St Andrews, KY16 9ST, UK
| | - Anthony C Marriott
- Present Address: Public Health England, Porton Down, Salisbury, SP4 0JG, UK
| | - Paul D Scott
- Present Address: Public Health England Birmingham Microbiology, Department of Pathology, Heart of England NHS Foundation Trust, Heartlands Hospital, Bordesley Green East, Salisbury, B9 5SS, UK
| | - Nigel J Dimmock
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Andrew J Easton
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
| |
Collapse
|
24
|
Hara K, Kashiwagi T, Hamada N, Watanabe H. Basic amino acids in the N-terminal half of the PB2 subunit of influenza virus RNA polymerase are involved in both transcription and replication. J Gen Virol 2017; 98:900-905. [DOI: 10.1099/jgv.0.000750] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Koyu Hara
- Department of Infection Control and Prevention, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Takahito Kashiwagi
- Department of Infection Control and Prevention, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Nobuyuki Hamada
- Department of Infection Control and Prevention, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Hiroshi Watanabe
- Department of Infection Control and Prevention, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| |
Collapse
|
25
|
Farmer LJ, Clark MP, Boyd MJ, Perola E, Jones SM, Tsai A, Jacobs MD, Bandarage UK, Ledeboer MW, Wang T, Deng H, Ledford B, Gu W, Duffy JP, Bethiel RS, Shannon D, Byrn RA, Leeman JR, Rijnbrand R, Bennett HB, O’Brien C, Memmott C, Nti-Addae K, Bennani YL, Charifson PS. Discovery of Novel, Orally Bioavailable β-Amino Acid Azaindole Inhibitors of Influenza PB2. ACS Med Chem Lett 2017; 8:256-260. [PMID: 28197322 DOI: 10.1021/acsmedchemlett.6b00486] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/20/2017] [Indexed: 01/25/2023] Open
Abstract
In our efforts to develop novel small-molecule inhibitors for the treatment of influenza, we utilized molecular modeling and the X-ray crystal structure of the PB2 subunit of the influenza polymerase to optimize a series of acyclic β-amino acid inhibitors, highlighted by compound 4. Compound 4 showed good oral exposure in both rat and mouse. More importantly, it showed strong potency versus multiple influenza-A strains, including pandemic 2009 H1N1 and avian H5N1 strains and showed a strong efficacy profile in a mouse influenza model even when treatment was initiated 48 h after infection. Compound 4 offers good oral bioavailability with great potential for the treatment of both pandemic and seasonal influenza.
Collapse
Affiliation(s)
- Luc J. Farmer
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Michael P. Clark
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Michael J. Boyd
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Emanuele Perola
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Steven M. Jones
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Alice Tsai
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Marc D. Jacobs
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Upul K. Bandarage
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Mark W. Ledeboer
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Tiansheng Wang
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Hongbo Deng
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Brian Ledford
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Wenxin Gu
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - John P. Duffy
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Randy S. Bethiel
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Dean Shannon
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Randal A. Byrn
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Joshua R. Leeman
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Rene Rijnbrand
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Hamilton B. Bennett
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Colleen O’Brien
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Christine Memmott
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Kwame Nti-Addae
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Youssef L. Bennani
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Paul S. Charifson
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, Massachusetts 02210, United States
| |
Collapse
|
26
|
Hengrung N, El Omari K, Serna Martin I, Vreede FT, Cusack S, Rambo RP, Vonrhein C, Bricogne G, Stuart DI, Grimes JM, Fodor E. Crystal structure of the RNA-dependent RNA polymerase from influenza C virus. Nature 2015; 527:114-7. [PMID: 26503046 PMCID: PMC4783868 DOI: 10.1038/nature15525] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 08/25/2015] [Indexed: 12/17/2022]
Abstract
Negative-sense RNA viruses, such as influenza, encode large, multidomain RNA-dependent RNA polymerases that can both transcribe and replicate the viral RNA genome. In influenza virus, the polymerase (FluPol) is composed of three polypeptides: PB1, PB2 and PA/P3. PB1 houses the polymerase active site, whereas PB2 and PA/P3 contain, respectively, cap-binding and endonuclease domains required for transcription initiation by cap-snatching. Replication occurs through de novo initiation and involves a complementary RNA intermediate. Currently available structures of the influenza A and B virus polymerases include promoter RNA (the 5' and 3' termini of viral genome segments), showing FluPol in transcription pre-initiation states. Here we report the structure of apo-FluPol from an influenza C virus, solved by X-ray crystallography to 3.9 Å, revealing a new 'closed' conformation. The apo-FluPol forms a compact particle with PB1 at its centre, capped on one face by PB2 and clamped between the two globular domains of P3. Notably, this structure is radically different from those of promoter-bound FluPols. The endonuclease domain of P3 and the domains within the carboxy-terminal two-thirds of PB2 are completely rearranged. The cap-binding site is occluded by PB2, resulting in a conformation that is incompatible with transcription initiation. Thus, our structure captures FluPol in a closed, transcription pre-activation state. This reveals the conformation of newly made apo-FluPol in an infected cell, but may also apply to FluPol in the context of a non-transcribing ribonucleoprotein complex. Comparison of the apo-FluPol structure with those of promoter-bound FluPols allows us to propose a mechanism for FluPol activation. Our study demonstrates the remarkable flexibility of influenza virus RNA polymerase, and aids our understanding of the mechanisms controlling transcription and genome replication.
Collapse
Affiliation(s)
- Narin Hengrung
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Kamel El Omari
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Itziar Serna Martin
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Frank T Vreede
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation and University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Robert P Rambo
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Clemens Vonrhein
- Global Phasing Ltd, Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - Gérard Bricogne
- Global Phasing Ltd, Sheraton House, Castle Park, Cambridge CB3 0AX, UK
| | - David I Stuart
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Jonathan M Grimes
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| |
Collapse
|
27
|
Skalickova S, Heger Z, Krejcova L, Pekarik V, Bastl K, Janda J, Kostolansky F, Vareckova E, Zitka O, Adam V, Kizek R. Perspective of Use of Antiviral Peptides against Influenza Virus. Viruses 2015; 7:5428-42. [PMID: 26492266 PMCID: PMC4632391 DOI: 10.3390/v7102883] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/22/2015] [Accepted: 09/30/2015] [Indexed: 01/13/2023] Open
Abstract
The threat of a worldwide influenza pandemic has greatly increased over the past decade with the emergence of highly virulent avian influenza strains. The increased frequency of drug-resistant influenza strains against currently available antiviral drugs requires urgent development of new strategies for antiviral therapy, too. The research in the field of therapeutic peptides began to develop extensively in the second half of the 20(th) century. Since then, the mechanisms of action for several peptides and their antiviral prospect received large attention due to the global threat posed by viruses. Here, we discussed the therapeutic properties of peptides used in influenza treatment. Peptides with antiviral activity against influenza can be divided into three main groups. First, entry blocker peptides such as a Flupep that interact with influenza hemagglutinin, block its binding to host cells and prevent viral fusion. Second, several peptides display virucidal activity, disrupting viral envelopes, e.g., Melittin. Finally, a third set of peptides interacts with the viral polymerase complex and act as viral replication inhibitors such as PB1 derived peptides. Here, we present a review of the current literature describing the antiviral activity, mechanism and future therapeutic potential of these influenza antiviral peptides.
Collapse
Affiliation(s)
- Sylvie Skalickova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
| | - Zbynek Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, Brno CZ-616 00, Czech Republic.
| | - Ludmila Krejcova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
| | - Vladimir Pekarik
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
| | - Karel Bastl
- Wool and Knitting Research Institute, Brno, Sujanovo namesti 3, Brno CZ-602 00, Czech Republic.
| | - Jozef Janda
- Laboratory of Tumour Biology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Libechov CZ-277 21, Czech Republic.
| | - Frantisek Kostolansky
- Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovak Republic.
| | - Eva Vareckova
- Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovak Republic.
| | - Ondrej Zitka
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, Brno CZ-616 00, Czech Republic.
| | - Vojtech Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, Brno CZ-616 00, Czech Republic.
| | - Rene Kizek
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-613 00, Czech Republic.
- Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, Brno CZ-616 00, Czech Republic.
| |
Collapse
|
28
|
Wu NC, Olson CA, Du Y, Le S, Tran K, Remenyi R, Gong D, Al-Mawsawi LQ, Qi H, Wu TT, Sun R. Functional Constraint Profiling of a Viral Protein Reveals Discordance of Evolutionary Conservation and Functionality. PLoS Genet 2015; 11:e1005310. [PMID: 26132554 PMCID: PMC4489113 DOI: 10.1371/journal.pgen.1005310] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/28/2015] [Indexed: 12/31/2022] Open
Abstract
Viruses often encode proteins with multiple functions due to their compact genomes. Existing approaches to identify functional residues largely rely on sequence conservation analysis. Inferring functional residues from sequence conservation can produce false positives, in which the conserved residues are functionally silent, or false negatives, where functional residues are not identified since they are species-specific and therefore non-conserved. Furthermore, the tedious process of constructing and analyzing individual mutations limits the number of residues that can be examined in a single study. Here, we developed a systematic approach to identify the functional residues of a viral protein by coupling experimental fitness profiling with protein stability prediction using the influenza virus polymerase PA subunit as the target protein. We identified a significant number of functional residues that were influenza type-specific and were evolutionarily non-conserved among different influenza types. Our results indicate that type-specific functional residues are prevalent and may not otherwise be identified by sequence conservation analysis alone. More importantly, this technique can be adapted to any viral (and potentially non-viral) protein where structural information is available. The analysis of sequence conservation is a common approach to identify functional residues within a protein. However, not all functional residues are conserved as natural evolution and species diversification permit continuous innovation of protein functionality through the retention of advantageous mutations. Non-conserved functional residues, which are often species-specific, may not be identified by conventional analysis of sequence conservation despite being biologically important. Here we described a novel approach to identify functional residues within a protein by coupling a high-throughput experimental fitness profiling approach with computational protein modeling. Our methodology is independent of sequence conservation and is applicable to any protein where structural information is available. In this study, we systematically mapped the functional residues on the influenza A PA protein and revealed that non-conserved functional residues are prevalent. Our results not only have significant implication on how functionality evolves during natural evolution, but also highlight the caveats when applying conservation-based approaches to identify functional residues within a protein.
Collapse
Affiliation(s)
- Nicholas C. Wu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - C. Anders Olson
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Yushen Du
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Shuai Le
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Kevin Tran
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Roland Remenyi
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Danyang Gong
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Laith Q. Al-Mawsawi
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Hangfei Qi
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Ting-Ting Wu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
| | - Ren Sun
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America,
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, United States of America,
- AIDS Institute, University of California, Los Angeles, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
29
|
Boyd MJ, Bandarage UK, Bennett H, Byrn RR, Davies I, Gu W, Jacobs M, Ledeboer MW, Ledford B, Leeman JR, Perola E, Wang T, Bennani Y, Clark MP, Charifson PS. Isosteric replacements of the carboxylic acid of drug candidate VX-787: Effect of charge on antiviral potency and kinase activity of azaindole-based influenza PB2 inhibitors. Bioorg Med Chem Lett 2015; 25:1990-4. [PMID: 25827523 DOI: 10.1016/j.bmcl.2015.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/04/2015] [Accepted: 03/06/2015] [Indexed: 10/23/2022]
Abstract
VX-787 is a first in class, orally bioavailable compound that offers unparalleled potential for the treatment of pandemic and seasonal influenza. As a part of our routine SAR exploration, carboxylic acid isosteres of VX-787 were prepared and tested against influenza A. It was found that the negative charge is important for maintaining potency and selectivity relative to kinase targets. Neutral carboxylic acid replacements generally resulted in compounds that were significantly less potent and less selective relative to the charged species.
Collapse
Affiliation(s)
- Michael J Boyd
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA.
| | - Upul K Bandarage
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Hamilton Bennett
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Randal R Byrn
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Ioana Davies
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Wenxin Gu
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Marc Jacobs
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Mark W Ledeboer
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Brian Ledford
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Joshua R Leeman
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Emanuele Perola
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Tiansheng Wang
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Youssef Bennani
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Michael P Clark
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| | - Paul S Charifson
- Vertex Pharmaceuticals Inc., 50 Northern Avenue, Boston, MA, USA
| |
Collapse
|
30
|
Cryo-EM Structure of Influenza Virus RNA Polymerase Complex at 4.3 Å Resolution. Mol Cell 2015; 57:925-935. [DOI: 10.1016/j.molcel.2014.12.031] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/15/2014] [Accepted: 12/17/2014] [Indexed: 12/26/2022]
|
31
|
Identification of PB2 mutations responsible for the efficient replication of H5N1 influenza viruses in human lung epithelial cells. J Virol 2015; 89:3947-56. [PMID: 25609813 DOI: 10.1128/jvi.03328-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
UNLABELLED Highly pathogenic H5N1 avian influenza viruses have caused outbreaks among poultry worldwide, resulting in sporadic infections in humans with approximately 60% mortality. However, efficient transmission of H5N1 viruses among humans has yet to occur, suggesting that further adaptation of H5N1 viruses to humans is required for their efficient transmission among humans. The viral determinants for efficient replication in humans are currently poorly understood. Here, we report that the polymerase PB2 protein of an H5N1 influenza virus isolated from a human in Vietnam (A/Vietnam/UT36285/2010, virus 36285) increased the growth ability of an avian H5N1 virus (A/wild bird/Anhui/82/2005, virus Wb/AH82) in human lung epithelial A549 cells (however, the reassortant virus did not replicate more efficiently than human 36285 virus). Furthermore, we demonstrate that the amino acid residues at positions 249, 309, and 339 of the PB2 protein from this human isolate were responsible for its efficient replication in A549 cells. PB2 residues 249G and 339M, which are found in the human H5N1 virus, are rare in H5N1 viruses from both human and avian sources. Interestingly, PB2-249G is found in over 30% of human seasonal H3N2 viruses, which suggests that H5N1 viruses may replicate well in human cells when they acquire this mutation. Our data are of value to H5N1 virus surveillance. IMPORTANCE Highly pathogenic H5N1 avian influenza viruses must acquire mutations to overcome the species barrier between avian species and humans. When H5N1 viruses replicate in human respiratory cells, they can acquire amino acid mutations that allow them to adapt to humans through continuous selective pressure. Several amino acid mutations have been shown to be advantageous for virus adaptation to mammalian hosts. Here, we found that amino acid changes at positions 249, 309, and 339 of PB2 contribute to efficient replication of avian H5N1 viruses in human lung cells. These findings are beneficial for evaluating the pandemic risk of circulating avian viruses and for further functional analysis of PB2.
Collapse
|
32
|
Preclinical activity of VX-787, a first-in-class, orally bioavailable inhibitor of the influenza virus polymerase PB2 subunit. Antimicrob Agents Chemother 2014; 59:1569-82. [PMID: 25547360 DOI: 10.1128/aac.04623-14] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
VX-787 is a novel inhibitor of influenza virus replication that blocks the PB2 cap-snatching activity of the influenza viral polymerase complex. Viral genetics and X-ray crystallography studies provide support for the idea that VX-787 occupies the 7-methyl GTP (m(7)GTP) cap-binding site of PB2. VX-787 binds the cap-binding domain of the PB2 subunit with a KD (dissociation constant) of 24 nM as determined by isothermal titration calorimetry (ITC). The cell-based EC50 (the concentration of compound that ensures 50% cell viability of an uninfected control) for VX-787 is 1.6 nM in a cytopathic effect (CPE) assay, with a similar EC50 in a viral RNA replication assay. VX-787 is active against a diverse panel of influenza A virus strains, including H1N1pdm09 and H5N1 strains, as well as strains with reduced susceptibility to neuraminidase inhibitors (NAIs). VX-787 was highly efficacious in both prophylaxis and treatment models of mouse influenza and was superior to the neuraminidase inhibitor, oseltamivir, including in delayed-start-to-treat experiments, with 100% survival at up to 96 h postinfection and partial survival in groups where the initiation of therapy was delayed up to 120 h postinfection. At different doses, VX-787 showed a 1-log to >5-log reduction in viral load (relative to vehicle controls) in mouse lungs. Overall, these favorable findings validate the PB2 subunit of the viral polymerase as a drug target for influenza therapy and support the continued development of VX-787 as a novel antiviral agent for the treatment of influenza infection.
Collapse
|
33
|
Davis AM, Chabolla BJ, Newcomb LL. Emerging antiviral resistant strains of influenza A and the potential therapeutic targets within the viral ribonucleoprotein (vRNP) complex. Virol J 2014; 11:167. [PMID: 25228366 PMCID: PMC4180549 DOI: 10.1186/1743-422x-11-167] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/12/2014] [Indexed: 11/10/2022] Open
Abstract
Emerging antiviral resistant strains of influenza A virus are greatly limiting the therapies available to stop aggressive infections. Genome changes that confer resistance to the two classes of approved antivirals have been identified in circulating influenza A viruses. It is only a matter of time before the currently approved influenza A antivirals are rendered ineffective, emphasizing the need for additional influenza antiviral therapies. This review highlights the current state of antiviral resistance in circulating and highly pathogenic influenza A viruses and explores potential antiviral targets within the proteins of the influenza A virus ribonucleoprotein (vRNP) complex, drawing attention to the viral protein activities and interactions that play an indispensable role in the influenza life cycle. Investigation of small molecule inhibition, accelerated by the use of crystal structures of vRNP proteins, has provided important information about viral protein domains and interactions, and has revealed many promising antiviral drug candidates discussed in this review.
Collapse
Affiliation(s)
| | | | - Laura L Newcomb
- Department of Biology, California State University San Bernardino, 5500 University Parkway, San Bernardino, CA 92407, USA.
| |
Collapse
|
34
|
Deep sequencing reveals the eight facets of the influenza A/HongKong/1/1968 (H3N2) virus cap-snatching process. Sci Rep 2014; 4:6181. [PMID: 25154590 PMCID: PMC4143772 DOI: 10.1038/srep06181] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/31/2014] [Indexed: 11/08/2022] Open
Abstract
The influenza A virus RNA polymerase cleaves the 5′ end of host pre-mRNAs and uses the capped RNA fragments as primers for viral mRNA synthesis. We performed deep sequencing of the 5′ ends of viral mRNAs from all genome segments transcribed in both human (A549) and mouse (M-1) cells infected with the influenza A/HongKong/1/1968 (H3N2) virus. In addition to information on RNA motifs present, our results indicate that the host primers are divergent between the viral transcripts. We observed differences in length distributions, nucleotide motifs and the identity of the host primers between the viral mRNAs. Mapping the reads to known transcription start sites indicates that the virus targets the most abundant host mRNAs, which is likely caused by the higher expression of these genes. Our findings suggest negligible competition amongst RdRp:vRNA complexes for individual host mRNA templates during cap-snatching and provide a better understanding of the molecular mechanism governing the first step of transcription of this influenza strain.
Collapse
|
35
|
Goka EA, Vallely PJ, Mutton KJ, Klapper PE. Mutations associated with severity of the pandemic influenza A(H1N1)pdm09 in humans: a systematic review and meta-analysis of epidemiological evidence. Arch Virol 2014; 159:3167-83. [PMID: 25078388 DOI: 10.1007/s00705-014-2179-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 07/12/2014] [Indexed: 10/25/2022]
Abstract
Mutations in the haemagglutinin (HA), non-structural protein 1 (NS1) and polymerase basic protein 2 (PB2) of influenza viruses have been associated with virulence. This study investigated the association between mutations in these genes in influenza A(H1N1)pdm09 virus and the risk of severe or fatal disease. Searches were conducted on the MEDLINE, EMBASE and Web of Science electronic databases and the reference lists of published studies. The PRISMA and STROBE guidelines were followed in assessing the quality of studies and writing-up. Eighteen (18) studies, from all continents, were included in the systematic review (recruiting patients 0 - 77 years old). The mutation D222G was associated with a significant increase in severe disease (pooled RD: 11 %, 95 % CI: 3.0 % - 18.0 %, p = 0.004) and the risk of fatality (RD: 23 %, 95 % CI: 14.0 %-31.0 %, p = < 0.0001). No association was observed between the mutations HA-D222N, D222E, PB2-E627K and NS1-T123V and severe/fatal disease. The results suggest that no virus quasispecies bearing virulence-conferring mutations in the HA, PB2 and NS1 predominated. However issues of sampling bias, and bias due to uncontrolled confounders such as comorbidities, and viral and bacterial coinfection, should be born in mind. Influenza A viruses should continue to be monitored for the occurrence of virulence-conferring mutations in HA, PB2 and NS1. There are suggestions that respiratory virus coinfections also affect virus virulence. Studies investigating the role of genetic mutations on disease outcome should make efforts to also investigate the role of respiratory virus coinfections.
Collapse
Affiliation(s)
- E A Goka
- Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, 1st Floor Stopford building, Oxford Road, Manchester, M13 9PL, UK,
| | | | | | | |
Collapse
|
36
|
Clark MP, Ledeboer MW, Davies I, Byrn RA, Jones SM, Perola E, Tsai A, Jacobs M, Nti-Addae K, Bandarage UK, Boyd MJ, Bethiel RS, Court JJ, Deng H, Duffy JP, Dorsch WA, Farmer LJ, Gao H, Gu W, Jackson K, Jacobs DH, Kennedy JM, Ledford B, Liang J, Maltais F, Murcko M, Wang T, Wannamaker MW, Bennett HB, Leeman JR, McNeil C, Taylor WP, Memmott C, Jiang M, Rijnbrand R, Bral C, Germann U, Nezami A, Zhang Y, Salituro FG, Bennani YL, Charifson PS. Discovery of a Novel, First-in-Class, Orally Bioavailable Azaindole Inhibitor (VX-787) of Influenza PB2. J Med Chem 2014; 57:6668-78. [DOI: 10.1021/jm5007275] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael P. Clark
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Mark W. Ledeboer
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Ioana Davies
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Randal A. Byrn
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Steven M. Jones
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Emanuele Perola
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Alice Tsai
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Marc Jacobs
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Kwame Nti-Addae
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Upul K. Bandarage
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Michael J. Boyd
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Randy S. Bethiel
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - John J. Court
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Hongbo Deng
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - John P. Duffy
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Warren A. Dorsch
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Luc J. Farmer
- Vertex Pharmaceuticals (Canada) Inc., 275 Armand-Frappier, Laval, Quebec H7V 4A7, Canada
| | - Huai Gao
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Wenxin Gu
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Katrina Jackson
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Dylan H. Jacobs
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Joseph M. Kennedy
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Brian Ledford
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Jianglin Liang
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - François Maltais
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Mark Murcko
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Tiansheng Wang
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - M. Woods Wannamaker
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Hamilton B. Bennett
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Joshua R. Leeman
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Colleen McNeil
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - William P. Taylor
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Christine Memmott
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Min Jiang
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Rene Rijnbrand
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Christopher Bral
- Arrowhead Research Corporation, 465 Science Drive, Suite C, Madison, Wisconsin 53711, United States
| | - Ursula Germann
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Azin Nezami
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | - Yuegang Zhang
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| | | | - Youssef L. Bennani
- Vertex Pharmaceuticals (Canada) Inc., 275 Armand-Frappier, Laval, Quebec H7V 4A7, Canada
| | - Paul S. Charifson
- Vertex Pharmaceuticals Inc., 50 Northern Ave, Boston, Massachusetts 02210, United States
| |
Collapse
|
37
|
Abstract
The N terminus of arenavirus L protein contains an endonuclease presumably involved in "cap snatching." Here, we employed the Lassa virus replicon system to map other L protein sites that might be involved in this mechanism. Residues Phe-1979, Arg-2018, Phe-2071, Asp-2106, Trp-2173, Tyr-2179, Arg-2200, and Arg-2204 were important for viral mRNA synthesis but dispensable for genome replication. Thus, the C terminus of L protein is involved in the mRNA synthesis process, potentially by mediating cap binding.
Collapse
|
38
|
Briese T, Chowdhary R, Travassos da Rosa A, Hutchison SK, Popov V, Street C, Tesh RB, Lipkin WI. Upolu virus and Aransas Bay virus, two presumptive bunyaviruses, are novel members of the family Orthomyxoviridae. J Virol 2014; 88:5298-309. [PMID: 24574415 PMCID: PMC4019087 DOI: 10.1128/jvi.03391-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/21/2014] [Indexed: 01/23/2023] Open
Abstract
UNLABELLED Emerging and zoonotic pathogens pose continuing threats to human health and ongoing challenges to diagnostics. As nucleic acid tests are playing increasingly prominent roles in diagnostics, the genetic characterization of molecularly uncharacterized agents is expected to significantly enhance detection and surveillance capabilities. We report the identification of two previously unrecognized members of the family Orthomyxoviridae, which includes the influenza viruses and the tick-transmitted Thogoto and Dhori viruses. We provide morphological, serologic, and genetic evidence that Upolu virus (UPOV) from Australia and Aransas Bay virus (ABV) from North America, both previously considered potential bunyaviruses based on electron microscopy and physicochemical features, are orthomyxoviruses instead. Their genomes show up to 68% nucleotide sequence identity to Thogoto virus (segment 2; ∼74% at the amino acid level) and a more distant relationship to Dhori virus, the two prototype viruses of the recognized species of the genus Thogotovirus. Despite sequence similarity, the coding potentials of UPOV and ABV differed from that of Thogoto virus, instead being like that of Dhori virus. Our findings suggest that the tick-transmitted viruses UPOV and ABV represent geographically distinct viruses in the genus Thogotovirus of the family Orthomyxoviridae that do not fit in the two currently recognized species of this genus. IMPORTANCE Upolu virus (UPOV) and Aransas Bay virus (ABV) are shown to be orthomyxoviruses instead of bunyaviruses, as previously thought. Genetic characterization and adequate classification of agents are paramount in this molecular age to devise appropriate surveillance and diagnostics. Although more closely related to Thogoto virus by sequence, UPOV and ABV differ in their coding potentials by lacking a proposed pathogenicity factor. In this respect, they are similar to Dhori virus, which, despite the lack of a pathogenicity factor, can cause disease. These findings enable further studies into the evolution and pathogenicity of orthomyxoviruses.
Collapse
Affiliation(s)
- Thomas Briese
- Center for Infection and Immunity, Columbia University, New York, New York, USA
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Rashmi Chowdhary
- Center for Infection and Immunity, Columbia University, New York, New York, USA
| | | | | | - Vsevolod Popov
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Craig Street
- Center for Infection and Immunity, Columbia University, New York, New York, USA
| | - Robert B. Tesh
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - W. Ian Lipkin
- Center for Infection and Immunity, Columbia University, New York, New York, USA
- Department of Pathology and Neurology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| |
Collapse
|
39
|
Manzoor R, Kuroda K, Yoshida R, Tsuda Y, Fujikura D, Miyamoto H, Kajihara M, Kida H, Takada A. Heat shock protein 70 modulates influenza A virus polymerase activity. J Biol Chem 2014; 289:7599-614. [PMID: 24474693 PMCID: PMC3953273 DOI: 10.1074/jbc.m113.507798] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 01/25/2014] [Indexed: 01/03/2023] Open
Abstract
The role of heat shock protein 70 (Hsp70) in virus replication has been discussed for many viruses. The known suppressive role of Hsp70 in influenza virus replication is based on studies conducted in cells with various Hsp70 expression levels. In this study, we determined the role of Hsp70 in influenza virus replication in HeLa and HEK293T cells, which express Hsp70 constitutively. Co-immunoprecipitation and immunofluorescence studies revealed that Hsp70 interacted with PB2 or PB1 monomers and PB2/PB1 heterodimer but not with the PB1/PA heterodimer or PB2/PB1/PA heterotrimer and translocated into the nucleus with PB2 monomers or PB2/PB1 heterodimers. Knocking down Hsp70 resulted in reduced virus transcription and replication activities. Reporter gene assay, immunofluorescence assay, and Western blot analysis of nuclear and cytoplasmic fractions from infected cells demonstrated that the increase in viral polymerase activity during the heat shock phase was accompanied with an increase in Hsp70 and viral polymerases levels in the nuclei, where influenza virus replication takes place, whereas a reduction in viral polymerase activity was accompanied with an increase in cytoplasmic relocation of Hsp70 along with viral polymerases. Moreover, significantly higher levels of viral genomic RNA (vRNA) were observed during the heat shock phase than during the recovery phase. Overall, for the first time, these findings suggest that Hsp70 may act as a chaperone for influenza virus polymerase, and the modulatory effect of Hsp70 appears to be a sequel of shuttling of Hsp70 between nuclear and cytoplasmic compartments.
Collapse
Affiliation(s)
- Rashid Manzoor
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
| | - Kazumichi Kuroda
- the Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, 173-8610, Japan
| | - Reiko Yoshida
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
| | - Yoshimi Tsuda
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
| | - Daisuke Fujikura
- the Division of Infection and Immunity, Research Center for Zoonosis Control, Hokkaido University, Sapporo, 001-0020, Japan
| | - Hiroko Miyamoto
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
| | - Masahiro Kajihara
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
| | - Hiroshi Kida
- the Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan, and
| | - Ayato Takada
- From the Division of Global Epidemiology, Research Center for Zoonosis Control and
- the School of Veterinary Medicine, University of Zambia, P. O. Box 32379, Lusaka, Zambia
| |
Collapse
|
40
|
Dong H, Fink K, Züst R, Lim SP, Qin CF, Shi PY. Flavivirus RNA methylation. J Gen Virol 2014; 95:763-778. [PMID: 24486628 DOI: 10.1099/vir.0.062208-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The 5' end of eukaryotic mRNA contains the type-1 (m7GpppNm) or type-2 (m7GpppNmNm) cap structure. Many viruses have evolved various mechanisms to develop their own capping enzymes (e.g. flavivirus and coronavirus) or to 'steal' caps from host mRNAs (e.g. influenza virus). Other viruses have developed 'cap-mimicking' mechanisms by attaching a peptide to the 5' end of viral RNA (e.g. picornavirus and calicivirus) or by having a complex 5' RNA structure (internal ribosome entry site) for translation initiation (e.g. picornavirus, pestivirus and hepacivirus). Here we review the diverse viral RNA capping mechanisms. Using flavivirus as a model, we summarize how a single methyltransferase catalyses two distinct N-7 and 2'-O methylations of viral RNA cap in a sequential manner. For antiviral development, a structural feature unique to the flavivirus methyltransferase was successfully used to design selective inhibitors that block viral methyltransferase without affecting host methyltransferases. Functionally, capping is essential for prevention of triphosphate-triggered innate immune activation; N-7 methylation is critical for enhancement of viral translation; and 2'-O methylation is important for subversion of innate immune response during viral infection. Flaviviruses defective in 2'-O methyltransferase are replicative, but their viral RNAs lack 2'-O methylation and are recognized and eliminated by the host immune response. Such mutant viruses could be rationally designed as live attenuated vaccines. This concept has recently been proved with Japanese encephalitis virus and dengue virus. The findings obtained with flavivirus should be applicable to other RNA viruses.
Collapse
Affiliation(s)
- Hongping Dong
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, Singapore 138670, Singapore
| | - Katja Fink
- Singapore Immunology Network, Agency for Science, Technology and Research, 8A Biomedical Grove, Singapore 138648, Singapore
| | - Roland Züst
- Singapore Immunology Network, Agency for Science, Technology and Research, 8A Biomedical Grove, Singapore 138648, Singapore
| | - Siew Pheng Lim
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, Singapore 138670, Singapore
| | - Cheng-Feng Qin
- Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Pei-Yong Shi
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, Singapore 138670, Singapore
| |
Collapse
|
41
|
Binh NT, Wakai C, Kawaguchi A, Nagata K. Involvement of the N-terminal portion of influenza virus RNA polymerase subunit PB1 in nucleotide recognition. Biochem Biophys Res Commun 2013; 443:975-9. [PMID: 24361882 DOI: 10.1016/j.bbrc.2013.12.071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/14/2013] [Indexed: 02/07/2023]
Abstract
The influenza virus PB1 protein functions as a catalytic subunit of the viral RNA-dependent RNA polymerase and contains the highly conserved motifs of RNA-dependent RNA polymerases together with putative nucleotide-binding sites. PB1 also binds to viral genomic RNAs and its replicative intermediates through the promoter regions. The detail function and interplay between functional domains are not clarified although a part of structures and functions of PB1 have been clarified. In this study, we analyzed the function of PB1 subunit in the sense of nucleotide recognition using ribavirin, which is a nucleoside analog and inhibits viral RNA synthesis of many RNA viruses including influenza virus. We screened ribavirin-resistant PB1 mutants from randomly mutated PB1 cDNA library using a mini-replicon assay, and we identified a single mutation at the amino acid position 27 of PB1 as an important residue for the nucleotide recognition.
Collapse
Affiliation(s)
- Nguyen Trong Binh
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Chitose Wakai
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Atsushi Kawaguchi
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Kyosuke Nagata
- University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
| |
Collapse
|
42
|
Yan Z, Zhang L, Fu H, Wang Z, Lin J. Design of the influenza virus inhibitors targeting the PA endonuclease using 3D-QSAR modeling, side-chain hopping, and docking. Bioorg Med Chem Lett 2013; 24:539-47. [PMID: 24365156 DOI: 10.1016/j.bmcl.2013.12.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/02/2013] [Accepted: 12/06/2013] [Indexed: 11/26/2022]
Abstract
With the emergence of drug resistance and the structural determination of the PA N-terminal domain (PAN), influenza endonucleases have become an attractive target for antiviral therapies for influenza infection. Here, we combined 3D-QSAR with side-chain hopping and molecular docking to produce novel structures as endonuclease inhibitors. First, a new molecular library was generated with side-chain hopping on an existing template molecule, L-742001, using an in-house fragment library that targets bivalent-cation-binding proteins. Then, the best 3D-QSAR model (AAAHR.500), with q(2)=0.76 and r(2)=0.97 from phase modeling, was constructed from 23 endonuclease inhibitors and validated with 17 test compounds. The AAAHR.500 model was then used to select effective candidates from the new molecular library. Combining 3D-QSAR with docking using Glide and Autodock, 13 compounds were considered the most likely candidate inhibitors. Docking studies showed that the binding modes of these compounds were consistent with the crystal structures of known inhibitors. These compounds could serve as potential endonuclease inhibitors for further biological activity tests.
Collapse
Affiliation(s)
- Zhihui Yan
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China; High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biomedicine and Technology, Tianjin 300457, China
| | - Lijie Zhang
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China; High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biomedicine and Technology, Tianjin 300457, China
| | - Haiyang Fu
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China; High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biomedicine and Technology, Tianjin 300457, China
| | - Zhonghua Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China
| | - Jianping Lin
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China; High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biomedicine and Technology, Tianjin 300457, China.
| |
Collapse
|
43
|
Tsurumura T, Qiu H, Yoshida T, Tsumori Y, Hatakeyama D, Kuzuhara T, Tsuge H. Conformational polymorphism of m7GTP in crystal structure of the PB2 middle domain from human influenza A virus. PLoS One 2013; 8:e82020. [PMID: 24312396 PMCID: PMC3843726 DOI: 10.1371/journal.pone.0082020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 10/28/2013] [Indexed: 01/07/2023] Open
Abstract
Influenza pandemics with human-to-human transmission of the virus are of great public concern. It is now recognized that a number of factors are necessary for human transmission and virulence, including several key mutations within the PB2 subunit of RNA-dependent RNA polymerase. The structure of the middle domain in PB2 has been revealed with or without m(7)GTP, thus the middle domain is considered to be novel target for structure-based drug design. Here we report the crystal structure of the middle domain of H1N1 PB2 with or without m(7)GTP at 1.9 Å and 2.0 Å resolution, respectively, which has two mutations (P453H, I471T) to increase electrostatic potential and solubility. Here we report the m(7)GTP has unique conformation differ from the reported structure. 7-methyl-guanine is fixed in the pocket, but particularly significant change is seen in ribose and triphosphate region: the buried 7-methyl-guanine indeed binds in the pocket forming by H357, F404, E361 and K376 but the triphosphate continues directly to the outer domain. The presented conformation of m(7)GTP may be a clue for the anti-influenza drug-design.
Collapse
Affiliation(s)
- Toshiharu Tsurumura
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, Japan
| | - Hao Qiu
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, Japan
| | - Toru Yoshida
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, Japan
| | - Yayoi Tsumori
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, Japan
| | - Dai Hatakeyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Takashi Kuzuhara
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Hideaki Tsuge
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, Japan
- * E-mail:
| |
Collapse
|
44
|
Abstract
The influenza A viruses cause yearly epidemics and occasional pandemics of respiratory disease, which constitute a serious health and economic burden. Their genome consists of eight single-stranded, negative-polarity RNAs that associate to the RNA polymerase and many nucleoprotein monomers to form ribonucleoprotein complexes (RNPs). Here, we focus on the organization of these RNPs, as well as on the structure and interactions of its constitutive elements and we discuss the mechanisms by which the RNPs transcribe and replicate the viral genome.
Collapse
|
45
|
Ngai KLK, Chan MCW, Chan PKS. Replication and transcription activities of ribonucleoprotein complexes reconstituted from avian H5N1, H1N1pdm09 and H3N2 influenza A viruses. PLoS One 2013; 8:e65038. [PMID: 23750226 PMCID: PMC3672204 DOI: 10.1371/journal.pone.0065038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 04/22/2013] [Indexed: 01/14/2023] Open
Abstract
Avian influenza viruses pose a serious pandemic threat to humans. Better knowledge on cross-species adaptation is important. This study examined the replication and transcription efficiency of ribonucleoprotein complexes reconstituted by plasmid co-transfection between H5N1, H1N1pdm09 and H3N2 influenza A viruses, and to identify mutations in the RNA polymerase subunit that affect human adaptation. Viral RNA polymerase subunits PB1, PB2, PA and NP derived from influenza viruses were co-expressed with pPolI-vNP-Luc in human cells, and with its function evaluated by luciferase reporter assay. A quantitative RT-PCR was used to measure vRNA, cRNA, and mRNA levels for assessing the replication and transcription efficiency. Mutations in polymerase subunit were created to identify signature of increased human adaptability. H5N1 ribonucleoprotein complexes incorporated with PB2 derived from H1N1pdm09 and H3N2 viruses increased the polymerase activity in human cells. Furthermore, single amino acid substitutions at PB2 of H5N1 could affect polymerase activity in a temperature-dependent manner. By using a highly sensitive quantitative reverse transcription-polymerase chain reaction, an obvious enhancement in replication and transcription activities of ribonucleoproteins was observed by the introduction of lysine at residue 627 in the H5N1 PB2 subunit. Although less strongly in polymerase activity, E158G mutation appeared to alter the accumulation of H5N1 RNA levels in a temperature-dependent manner, suggesting a temperature-dependent mechanism in regulating transcription and replication exists. H5N1 viruses can adapt to humans either by acquisition of PB2 from circulating human-adapted viruses through reassortment, or by mutations at critical sites in PB2. This information may help to predict the pandemic potential of newly emerged influenza strains, and provide a scientific basis for stepping up surveillance measures and vaccine production.
Collapse
MESH Headings
- Animals
- HEK293 Cells
- Humans
- Influenza A Virus, H1N1 Subtype/enzymology
- Influenza A Virus, H1N1 Subtype/genetics
- Influenza A Virus, H1N1 Subtype/physiology
- Influenza A Virus, H3N2 Subtype/enzymology
- Influenza A Virus, H3N2 Subtype/genetics
- Influenza A Virus, H3N2 Subtype/physiology
- Influenza A Virus, H5N1 Subtype/enzymology
- Influenza A Virus, H5N1 Subtype/genetics
- Influenza A Virus, H5N1 Subtype/physiology
- Influenza A virus/enzymology
- Influenza A virus/genetics
- Influenza A virus/physiology
- Mutation
- Pandemics
- RNA-Dependent RNA Polymerase/genetics
- Ribonucleoproteins/genetics
- Temperature
- Transcription, Genetic
- Viral Proteins/genetics
- Virus Replication
Collapse
Affiliation(s)
- Karry L. K. Ngai
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong Special Administration Region, People’s Republic of China
| | - Martin C. W. Chan
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong Special Administration Region, People’s Republic of China
| | - Paul K. S. Chan
- Department of Microbiology and Stanley Ho Centre for Emerging Infectious Diseases, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong Special Administration Region, People’s Republic of China
- * E-mail:
| |
Collapse
|
46
|
Cellular protein HAX1 interacts with the influenza A virus PA polymerase subunit and impedes its nuclear translocation. J Virol 2012; 87:110-23. [PMID: 23055567 DOI: 10.1128/jvi.00939-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Transcription and replication of the influenza A virus RNA genome occur in the nucleus through the viral RNA-dependent RNA polymerase consisting of PB1, PB2, and PA. Cellular factors that associate with the viral polymerase complex play important roles in these processes. To look for cellular factors that could associate with influenza A virus PA protein, we have carried out a yeast two-hybrid screen using a HeLa cell cDNA library. We identified six cellular proteins that may interact with PA. We focused our study on one of the new PA-interacting proteins, HAX1, a protein with antiapoptotic function. By using glutathione S-transferase pulldown and coimmunoprecipitation assays, we demonstrate that HAX1 specifically interacts with PA in vitro and in vivo and that HAX1 interacts with the nuclear localization signal domain of PA. Nuclear accumulation of PA was increased in HAX1-knockdown cells, and this phenotype could be reversed by reexpression of HAX1, indicating that HAX1 can impede nuclear transport of PA. As a consequence, knockdown of HAX1 resulted in a significant increase in virus yield and polymerase activity in a minigenome assay, and this phenotype could be reversed by reexpression of HAX1, indicating that HAX1 can inhibit influenza A virus propagation. Together, these results not only provide insight into the mechanism underlying nuclear transport of PA but also identify an intrinsic host factor that restricts influenza A virus infection.
Collapse
|
47
|
Nakazono Y, Hara K, Kashiwagi T, Hamada N, Watanabe H. The RNA polymerase PB2 subunit of influenza A/HongKong/156/1997 (H5N1) restricts the replication of reassortant ribonucleoprotein complexes [corrected]. PLoS One 2012; 7:e32634. [PMID: 22389716 PMCID: PMC3289661 DOI: 10.1371/journal.pone.0032634] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 01/28/2012] [Indexed: 11/18/2022] Open
Abstract
Background Genetic reassortment plays a critical role in the generation of pandemic strains of influenza virus. The influenza virus RNA polymerase, composed of PB1, PB2 and PA subunits, has been suggested to influence the efficiency of genetic reassortment. However, the role of the RNA polymerase in the genetic reassortment is not well understood. Methodology/Principal Findings Here, we reconstituted reassortant ribonucleoprotein (RNP) complexes, and demonstrated that the PB2 subunit of A/HongKong/156/1997 (H5N1) [HK PB2] dramatically reduced the synthesis of mRNA, cRNA and vRNA when introduced into the polymerase of other influenza strains of H1N1 or H3N2. The HK PB2 had no significant effect on the assembly of the polymerase trimeric complex, or on promoter binding activity or replication initiation activity in vitro. However, the HK PB2 was found to remarkably impair the accumulation of RNP. This impaired accumulation and activity of RNP was fully restored when four amino acids at position 108, 508, 524 and 627 of the HK PB2 were mutated. Conclusions/Significance Overall, we suggest that the PB2 subunit of influenza polymerase might play an important role for the replication of reassortant ribonucleoprotein complexes.
Collapse
Affiliation(s)
- Yoko Nakazono
- Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan
| | - Koyu Hara
- Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan
- * E-mail:
| | - Takahito Kashiwagi
- Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan
| | - Nobuyuki Hamada
- Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan
| | - Hiroshi Watanabe
- Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan
| |
Collapse
|
48
|
Polymerase activity of hybrid ribonucleoprotein complexes generated from reassortment between 2009 pandemic H1N1 and seasonal H3N2 influenza A viruses. Virol J 2011; 8:528. [PMID: 22152041 PMCID: PMC3267801 DOI: 10.1186/1743-422x-8-528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 12/12/2011] [Indexed: 11/24/2022] Open
Abstract
Background A novel influenza virus (2009 pdmH1N1) was identified in early 2009 and progressed to a pandemic in mid-2009. This study compared the polymerase activity of recombinant viral ribonucleoprotein (vRNP) complexes derived from 2009 pdmH1N1 and the co-circulating seasonal H3N2, and their possible reassortants. Results The 2009 pdmH1N1 vRNP showed a lower level of polymerase activity at 33°C compared to 37°C, a property remenisence of avian viruses. The 2009 pdmH1N1 vRNP was found to be more cold-sensitive than the WSN or H3N2 vRNP. Substituion of 2009 pdmH1N1 vRNP with H3N2-derived-subunits, and vice versa, still retained a substantial level of polymerase activity, which is probably compartable with survival. When the 2009 pdmH1N1 vRNP was substituted with H3N2 PA, a significant increase in activity was observed; whereas when H3N2 vRNP was substituted with 2009 pdmH1N1 PA, a significant decrease in activity occurred. Although, the polymerase basic protein 2 (PB2) of 2009 pdmH1N1 was originated from an avian virus, substitution of this subunit with H3N2 PB2 did not change its polymerase activity in human cells. Conclusions In conclusion, our data suggest that hybrid vRNPs resulted from reassortment between 2009 pdmH1N1 and H3N2 viruses could still retain a substantial level of polymerase activity. Substituion of the subunit PA confers the most prominent effect on polymerase activity. Further studies to explore the determinants for polymerase activity of influenza viruses in associate with other factors that limit host specificity are warrant.
Collapse
|
49
|
Molecular mechanisms of transcription and replication of the influenza A virus genome. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11515-011-1151-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
50
|
Seyer R, Hrincius ER, Ritzel D, Abt M, Mellmann A, Marjuki H, Kühn J, Wolff T, Ludwig S, Ehrhardt C. Synergistic adaptive mutations in the hemagglutinin and polymerase acidic protein lead to increased virulence of pandemic 2009 H1N1 influenza A virus in mice. J Infect Dis 2011; 205:262-71. [PMID: 22102733 DOI: 10.1093/infdis/jir716] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Influenza impressively reflects the paradigm of a viral disease in which continued evolution of the virus is of paramount importance for annual epidemics and occasional pandemics in humans. Because of the continuous threat of novel influenza outbreaks, it is essential to gather further knowledge about viral pathogenicity determinants. Here, we explored the adaptive potential of the influenza A virus subtype H1N1 variant isolate A/Hamburg/04/09 (HH/04) by sequential passaging in mice lungs. Three passages in mice lungs were sufficient to dramatically enhance pathogenicity of HH/04. Sequence analysis identified 4 nonsynonymous mutations in the third passage virus. Using reverse genetics, 3 synergistically acting mutations were defined as pathogenicity determinants, comprising 2 mutations in the hemagglutinin (HA[D222G] and HA[K163E]), whereby the HA(D222G) mutation was shown to determine receptor binding specificity and the polymerase acidic (PA) protein F35L mutation increasing polymerase activity. In conclusion, synergistic action of all 3 mutations results in a mice lethal pandemic H1N1 virus.
Collapse
Affiliation(s)
- Roman Seyer
- Institute of Molecular Virology, ZMBE, Muenster, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|