Viral RNA-binding ability conferred by SUMOylation at PB1 K612 of influenza A virus is essential for viral pathogenesis and transmission

Posttranslational modifications, such as SUMOylation, play specific roles in the life cycle of invading pathogens. However, the effect of SUMOylation on the adaptation, pathogenesis, and transmission of influenza A virus (IAV) remains largely unknown. Here, we found that a conserved lysine residue at position 612 (K612) of the polymerase basic protein 1 (PB1) of IAV is a bona fide SUMOylation site. SUMOylation of PB1 at K612 had no effect on the stability or cellular localization of PB1, but was critical for viral ribonucleoprotein (vRNP) complex activity and virus replication in vitro. When tested in vivo, we found that the virulence of SUMOylation-defective PB1/K612R mutant IAVs was highly attenuated in mice. Moreover, the airborne transmission of a 2009 pandemic H1N1 PB1/K612R mutant virus was impaired in ferrets, resulting in reversion to wild-type PB1 K612. Mechanistically, SUMOylation at K612 was essential for PB1 to act as the enzymatic core of the viral polymerase by preserving its ability to bind viral RNA. Our study reveals an essential role for PB1 K612 SUMOylation in the pathogenesis and transmission of IAVs, which can be targeted for the design of anti-influenza therapies.

Download Full-text

Mutational Analysis of Influenza A Virus Nucleoprotein: Identification of Mutations That Affect RNA Replication

Journal of Virology ◽

10.1128/jvi.73.2.1186-1194.1999 ◽

1999 ◽

Vol 73 (2) ◽

pp. 1186-1194 ◽

Cited By ~ 57

Author(s):

Ignacio Mena ◽

Enrique Jambrina ◽

Carmen Albo ◽

Beatriz Perales ◽

Juan Ortín ◽

...

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Rna Binding ◽

Mutational Analysis ◽

Intracellular Localization ◽

Single Amino Acid ◽

Temperature Sensitive ◽

Virus Mutant

ABSTRACT The influenza A virus nucleoprotein (NP) is a multifunctional polypeptide which plays a pivotal role in virus replication. To get information on the domains and specific residues involved in the different NP activities, we describe here the preparation and characterization of 20 influenza A virus mutant NPs. The mutations, mostly single-amino-acid substitutions, were introduced in a cDNA copy of the A/Victoria/3/75 NP gene and, in most cases, affected residues located in regions that were highly conserved across the NPs of influenza A, B, and C viruses. The mutant NPs were characterized (i) in vivo (cell culture) by analyzing their intracellular localization and their functionality in replication, transcription, and expression of model RNA templates; and (ii) in vitro by analyzing their RNA-binding and sedimentation properties. The results obtained allowed us to identify both a mutant protein that accumulated in the cytoplasm and mutations that altered the functionality and/or the oligomerization state of the NP polypeptide. Among the mutations that reduced the NP capability to express chloramphenicol acetyltransferase protein from a model viral RNA (vRNA) template, some displayed a temperature-sensitive phenotype. Interestingly, four mutant NPs, which showed a reduced functionality in synthesizing cRNA molecules from a vRNA template, were fully competent to reconstitute complementary ribonucleoproteins (cRNPs) capable of synthesizing vRNAs, which in turn yielded mRNA molecules. Based on the phenotype of these mutants and on previously published observations, it is proposed that these mutant NPs have a reduced capability to interact with the polymerase complex and that this NP-polymerase interaction is responsible for making vRNPs switch from mRNA to cRNA synthesis.

Download Full-text

CNOT4-Mediated Ubiquitination of Influenza A Virus Nucleoprotein Promotes Viral RNA Replication

mBio ◽

10.1128/mbio.00597-17 ◽

2017 ◽

Vol 8 (3) ◽

Cited By ~ 19

Author(s):

Yu-Chen Lin ◽

King-Song Jeng ◽

Michael M. C. Lai

Keyword(s):

Influenza Virus ◽

Influenza A Virus ◽

Ubiquitin Ligase ◽

Influenza A ◽

Rna Binding ◽

Rna Replication ◽

Viral Rna ◽

Mass Spectrometry Analysis ◽

Positive Role

ABSTRACT Influenza A virus (IAV) RNA segments are individually packaged with viral nucleoprotein (NP) and RNA polymerases to form a viral ribonucleoprotein (vRNP) complex. We previously reported that NP is a monoubiquitinated protein which can be deubiquitinated by a cellular ubiquitin protease, USP11. In this study, we identified an E3 ubiquitin ligase, CNOT4 (Ccr4-Not transcription complex subunit 4), which can ubiquitinate NP. We found that the levels of viral RNA, protein, viral particles, and RNA polymerase activity in CNOT4 knockdown cells were lower than those in the control cells upon IAV infection. Conversely, overexpression of CNOT4 rescued viral RNP activity. In addition, CNOT4 interacted with the NP in the cell. An in vitro ubiquitination assay also showed that NP could be ubiquitinated by in vitro -translated CNOT4, but ubiquitination did not affect the protein stability of NP. Significantly, CNOT4 increased NP ubiquitination, whereas USP11 decreased it. Mass spectrometry analysis of ubiquitinated NP revealed multiple ubiquitination sites on the various lysine residues of NP. Three of these, K184, K227, and K273, are located on the RNA-binding groove of NP. Mutations of these sites to arginine reduced viral RNA replication. These results indicate that CNOT4 is a ubiquitin ligase of NP, and ubiquitination of NP plays a positive role in viral RNA replication. IMPORTANCE Influenza virus, particularly influenza A virus, causes severe and frequent outbreaks among human and avian species. Finding potential target sites for antiviral agents is of utmost importance from the public health point of view. We previously found that viral nucleoprotein (NP) is ubiquitinated, and ubiquitination enhances viral RNA replication. In this study, we found a cellular ubiquitin ligase, CNOT4, capable of ubiquitinating NP. The ubiquitination sites are scattered on the surface of the NP molecule, which is critical for RNA replication. CNOT4 and a ubiquitin protease, USP11, together regulate the extent of NP ubiquitination and thereby the efficiency of RNA replication. This study thus identifies a potential antiviral target site and reveals a novel posttranslational mechanism for regulating viral replication. This represents a novel finding in the literature of influenza virus research.

Download Full-text

Interaction of the Influenza A Virus Nucleocapsid Protein with the Viral RNA Polymerase Potentiates Unprimed Viral RNA Replication

Journal of Virology ◽

10.1128/jvi.02293-07 ◽

2008 ◽

Vol 83 (1) ◽

pp. 29-36 ◽

Cited By ~ 61

Author(s):

Laura L. Newcomb ◽

Rei-Lin Kuo ◽

Qiaozhen Ye ◽

Yunyun Jiang ◽

Yizhi Jane Tao ◽

...

Keyword(s):

Influenza A Virus ◽

Nucleocapsid Protein ◽

Influenza A ◽

Rna Binding ◽

Direct Interaction ◽

Rna Replication ◽

Binding Activity ◽

Viral Rna ◽

Viral Polymerase

ABSTRACT The influenza A virus polymerase transcribes and replicates the eight virion RNA (vRNA) segments. Transcription is initiated with capped RNA primers excised from cellular pre-mRNAs by the intrinsic endonuclease of the viral polymerase. Viral RNA replication occurs in two steps: first a full-length copy of vRNA is made, termed cRNA, and then this cRNA is copied to produce vRNA. The synthesis of cRNAs and vRNAs is initiated without a primer, in contrast to the initiation of viral mRNA synthesis, and requires the viral nucleocapsid protein (NP). The mechanism of unprimed viral RNA replication is poorly understood. To elucidate this mechanism, we used purified recombinant influenza virus polymerase complexes and NP to establish an in vitro system that catalyzes the unprimed synthesis of cRNA and vRNA using 50-nucleotide-long RNA templates. The purified viral polymerase and NP are sufficient for catalyzing this RNA synthesis without a primer, suggesting that host cell factors are not required. We used this purified in vitro replication system to demonstrate that the RNA-binding activity of NP is not required for the unprimed synthesis of cRNA and vRNA. This result rules out two models that postulate that the RNA-binding activity of NP mediates the switch from capped RNA-primed transcription to unprimed viral RNA replication. Because we showed that NP lacking RNA-binding activity binds directly to the viral polymerase, it is likely that a direct interaction between NP and the viral polymerase results in a modification of the polymerase in favor of unprimed initiation.

Download Full-text

Antiviral activity of Ladania067, an extract from wild black currant leaves against influenza A virus in vitro and in vivo

Frontiers in Microbiology ◽

10.3389/fmicb.2014.00171 ◽

2014 ◽

Vol 5 ◽

Cited By ~ 12

Author(s):

Emanuel Haasbach ◽

Carmen Hartmayer ◽

Alice Hettler ◽

Alicja Sarnecka ◽

Ulrich Wulle ◽

...

Keyword(s):

Antiviral Activity ◽

Influenza A Virus ◽

Influenza A ◽

Black Currant

Download Full-text

Exacerbation of Influenza A Virus Disease Severity by Respiratory Syncytial Virus Co-Infection in a Mouse Model

Viruses ◽

10.3390/v13081630 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1630 ◽

Cited By ~ 1

Author(s):

Junu A. George ◽

Shaikha H. AlShamsi ◽

Maryam H. Alhammadi ◽

Ahmed R. Alsuwaidi

Keyword(s):

T Cells ◽

Respiratory Syncytial Virus ◽

Influenza A Virus ◽

Influenza A ◽

Immune Cell ◽

Virus Disease ◽

Viral Loads ◽

Syncytial Virus

Influenza A virus (IAV) and respiratory syncytial virus (RSV) are leading causes of childhood infections. RSV and influenza are competitive in vitro. In this study, the in vivo effects of RSV and IAV co-infection were investigated. Mice were intranasally inoculated with RSV, with IAV, or with both viruses (RSV+IAV and IAV+RSV) administered sequentially, 24 h apart. On days 3 and 7 post-infection, lung tissues were processed for viral loads and immune cell populations. Lung functions were also evaluated. Mortality was observed only in the IAV+RSV group (50% of mice did not survive beyond 7 days). On day 3, the viral loads in single-infected and co-infected mice were not significantly different. However, on day 7, the IAV titer was much higher in the IAV+RSV group, and the RSV viral load was reduced. CD4 T cells were reduced in all groups on day 7 except in single-infected mice. CD8 T cells were higher in all experimental groups except the RSV-alone group. Increased airway resistance and reduced thoracic compliance were demonstrated in both co-infected groups. This model indicates that, among all the infection types we studied, infection with IAV followed by RSV is associated with the highest IAV viral loads and the most morbidity and mortality.

Download Full-text

The combination of ribavirin and ozeltamivir effectively inhibits reproduction of influenza a virus resistant to rimantadine (Amantadine) in vitro and in vivo

Doklady Biochemistry and Biophysics ◽

10.1134/s1607672914020100 ◽

2014 ◽

Vol 455 (1) ◽

pp. 80-83 ◽

Cited By ~ 3

Author(s):

P. G. Deryabin ◽

G. A. Galegov ◽

I. D. Konstantinova ◽

I. S. Muzyka ◽

A. I. Miroshnikov ◽

...

Keyword(s):

Influenza A Virus ◽

Influenza A

Download Full-text

In vitro and in vivo mechanism of immunomodulatory and antiviral activity of Edible Bird's Nest (EBN) against influenza A virus (IAV) infection

Journal of Ethnopharmacology ◽

10.1016/j.jep.2016.03.020 ◽

2016 ◽

Vol 185 ◽

pp. 327-340 ◽

Cited By ~ 15

Author(s):

Amin Haghani ◽

Parvaneh Mehrbod ◽

Nikoo Safi ◽

Nur Ain Aminuddin ◽

Azadeh Bahadoran ◽

...

Keyword(s):

Antiviral Activity ◽

Influenza A Virus ◽

Influenza A ◽

Edible Bird’S Nest

Download Full-text

Inhibitory Activity of Honeysuckle Extracts against Influenza A Virus In Vitro and In Vivo

Virologica Sinica ◽

10.1007/s12250-020-00302-6 ◽

2020 ◽

Author(s):

Mengwei Li ◽

Yuxu Wang ◽

Jing Jin ◽

Jie Dou ◽

Qinglong Guo ◽

...

Keyword(s):

Influenza A Virus ◽

Inhibitory Activity ◽

Influenza A

Download Full-text

Influenza A Virus Inhibits RSV Infection via a Two-Wave Expression of IFIT Proteins

Viruses ◽

10.3390/v12101171 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1171

Author(s):

Yaron Drori ◽

Jasmine Jacob-Hirsch ◽

Rakefet Pando ◽

Aharona Glatman-Freedman ◽

Nehemya Friedman ◽

...

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Influenza Viruses ◽

Mass Spectrometry Analysis ◽

Influenza A Viruses ◽

Rsv Infection ◽

Syncytial Virus ◽

Mouse Lungs

Influenza viruses and respiratory syncytial virus (RSV) are respiratory viruses that primarily circulate worldwide during the autumn and winter seasons. Seasonal surveillance has shown that RSV infection generally precedes influenza. However, in the last four winter seasons (2016–2020) an overlap of the morbidity peaks of both viruses was observed in Israel, and was paralleled by significantly lower RSV infection rates. To investigate whether the influenza A virus inhibits RSV, human cervical carcinoma (HEp2) cells or mice were co-infected with influenza A and RSV. Influenza A inhibited RSV growth, both in vitro and in vivo. Mass spectrometry analysis of mouse lungs infected with influenza A identified a two-wave pattern of protein expression upregulation, which included members of the interferon-induced protein with the tetratricopeptide (IFITs) family. Interestingly, in the second wave, influenza A viruses were no longer detectable in mouse lungs. In addition, knockdown and overexpression of IFITs in HEp2 cells affected RSV multiplicity. In conclusion, influenza A infection inhibits RSV infectivity via upregulation of IFIT proteins in a two-wave modality. Understanding the immune system involvement in the interaction between influenza A and RSV viruses will contribute to the development of future treatment strategies against these viruses.

Download Full-text

Human Immunodeficiency Virus Type 1 Vif Protein Is an Integral Component of an mRNP Complex of Viral RNA and Could Be Involved in the Viral RNA Folding and Packaging Process

Journal of Virology ◽

10.1128/jvi.74.18.8252-8261.2000 ◽

2000 ◽

Vol 74 (18) ◽

pp. 8252-8261 ◽

Cited By ~ 81

Author(s):

Hui Zhang ◽

Roger J. Pomerantz ◽

Geethanjali Dornadula ◽

Yong Sun

Keyword(s):

Human Immunodeficiency Virus ◽

Rna Binding ◽

Viral Rna ◽

Immunodeficiency Virus ◽

Mrnp Complex ◽

Rna Interaction ◽

Vif Protein ◽

Hiv 1

ABSTRACT Virion infectivity factor (Vif) is a protein encoded by human immunodeficiency virus types 1 and 2 (HIV-1 and -2) and simian immunodeficiency virus, plus other lentiviruses, and is essential for viral replication either in vivo or in culture for nonpermissive cells such as peripheral blood lymphoid cells, macrophages, and H9 T cells. Defects in the vif gene affect virion morphology and reverse transcription but not the expression of viral components. It has been shown that Vif colocalizes with Gag in cells and Vif binds to the NCp7 domain of Gag in vitro. However, it seems that Vif is not specifically packaged into virions. The molecular mechanism(s) for Vif remains unknown. In this report, we demonstrate that HIV-1 Vif is an RNA-binding protein and specifically binds to HIV-1 genomic RNA in vitro. Further, Vif binds to HIV-1 RNA in the cytoplasm of virus-producing cells to form a 40S mRNP complex. Coimmunoprecipitation and in vivo UV cross-linking assays indicated that Vif directly interact with HIV-1 RNA in the virus-producing cells. Vif-RNA binding could be displaced by Gag-RNA binding, suggesting that Vif protein in the mRNP complex may mediate viral RNA interaction with HIV-1 Gag precursors. Furthermore, we have demonstrated that these Vif mutants that lose the RNA binding activity in vitro do not supportvif-deficient HIV-1 replication in H9 T cells, suggesting that the RNA binding capacity of Vif is important for its function. Further studies regarding Vif-RNA interaction in virus-producing cells will be important for studying the function of Vif in the HIV-1 life cycle.

Download Full-text