scholarly journals The Nucleolar Protein LYAR Facilitates Ribonucleoprotein Assembly of Influenza A Virus

2018 ◽  
Vol 92 (23) ◽  
Author(s):  
Cha Yang ◽  
Xiaokun Liu ◽  
Qingxia Gao ◽  
Tailang Cheng ◽  
Rong Xiao ◽  
...  
Keyword(s):  
Cell Growth ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Rna Synthesis ◽  
Nucleolar Protein ◽  
Host Factors ◽  
Viral Rna ◽  
A Cell ◽  
Transcription And Replication

ABSTRACTInfluenza A viral ribonucleoprotein (vRNP) is responsible for transcription and replication of the viral genome in infected cells and depends on host factors for its functions. Identification of the host factors interacting with vRNP not only improves understanding of virus-host interactions but also provides insights into novel mechanisms of viral pathogenicity and the development of new antiviral strategies. Here, we have identified 80 host factors that copurified with vRNP using affinity purification followed by mass spectrometry. LYAR, a cell growth-regulating nucleolar protein, has been shown to be important for influenza A virus replication. During influenza A virus infection, LYAR expression is increased and partly translocates from the nucleolus to the nucleoplasm and cytoplasm. Furthermore, LYAR interacts with RNP subunits, resulting in enhancing viral RNP assembly, thereby facilitating viral RNA synthesis. Taken together, our studies identify a novel vRNP binding host partner important for influenza A virus replication and further reveal the mechanism of LYAR regulating influenza A viral RNA synthesis by facilitating viral RNP assembly.IMPORTANCEInfluenza A virus (IAV) must utilize the host cell machinery to replicate, but many of the mechanisms of IAV-host interaction remain poorly understood. Improved understanding of interactions between host factors and vRNP not only increases our basic knowledge of the molecular mechanisms of virus replication and pathogenicity but also provides insights into possible novel antiviral targets that are necessary due to the widespread emergence of drug-resistant IAV strains. Here, we have identified LYAR, a cell growth-regulating nucleolar protein, which interacts with viral RNP components and is important for efficient replication of IAVs and whose role in the IAV life cycle has never been reported. In addition, we further reveal the role of LYAR in viral RNA synthesis. Our results extend and improve current knowledge on the mechanisms of IAV transcription and replication.

scholarly journals Model Suggesting that Replication of Influenza Virus Is Regulated by Stabilization of Replicative Intermediates

2004 ◽  
Vol 78 (17) ◽  
pp. 9568-9572 ◽  
Author(s):  
Frank T. Vreede ◽  
Tanis E. Jung ◽  
George G. Brownlee
Keyword(s):  
Rna Polymerase ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Viral Rna ◽  
Mrna Transcription ◽  
Rna Dependent Rna Polymerase ◽  
Replicative Intermediates ◽  
Negative Sense ◽  
Transcription And Replication

ABSTRACT The RNA-dependent RNA polymerase of influenza A virus is responsible for both transcription and replication of negative-sense viral RNA. It is thought that a “switching” mechanism regulates the transition between these activities. We demonstrate that, in the presence of preexisting viral RNA polymerase and nucleoprotein (NP), influenza A virus synthesizes both mRNA (transcription) and cRNA (replication) early in infection. We suggest that there may be no switch regulating the initiation of RNA synthesis and present a model suggesting that nascent cRNA is degraded by host cell nucleases unless it is stabilized by newly synthesized viral RNA polymerase and NP.

A small molecule multi-kinase inhibitor reduces influenza A virus replication by restricting viral RNA synthesis

2013 ◽  
Vol 100 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Luis Martinez-Gil ◽  
Judith G. Alamares-Sapuay ◽  
M.V. Ramana Reddy ◽  
Peter H. Goff ◽  
E. Premkumar Reddy ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Virus Replication ◽  
Small Molecule ◽  
Influenza A ◽  
Rna Synthesis ◽  
Kinase Inhibitor ◽  
Viral Rna

scholarly journals A Nucleolar Protein, Ribosomal RNA Processing 1 Homolog B (RRP1B), Enhances the Recruitment of Cellular mRNA in Influenza Virus Transcription

2015 ◽  
Vol 89 (22) ◽  
pp. 11245-11255 ◽  
Author(s):  
Wen-Chi Su ◽  
Shih-Feng Hsu ◽  
Yi-Yuan Lee ◽  
King-Song Jeng ◽  
Michael M. C. Lai
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Ribosomal Rna ◽  
Rna Processing ◽  
Influenza A ◽  
Host Factors ◽  
Viral Rna ◽  
Rna Dependent Rna Polymerase ◽  
Virus Transcription ◽  
Ribosomal Rna Processing

ABSTRACTInfluenza A virus (IAV) undergoes RNA transcription by a unique capped-mRNA-dependent transcription, which is carried out by the viral RNA-dependent RNA polymerase (RdRp), consisting of the viral PA, PB1, and PB2 proteins. However, how the viral RdRp utilizes cellular factors for virus transcription is not clear. Previously, we conducted a genome-wide pooled short hairpin RNA (shRNA) screen to identify host factors important for influenza A virus replication. Ribosomal RNA processing 1 homolog B (RRP1B) was identified as one of the candidates. RRP1B is a nucleolar protein involved in ribosomal biogenesis. Upon IAV infection, part of RRP1B was translocated from the nucleolus to the nucleoplasm, where viral RNA synthesis likely takes place. The depletion of RRP1B significantly reduced IAV mRNA transcription in a minireplicon assay and in virus-infected cells. Furthermore, we showed that RRP1B interacted with PB1 and PB2 of the RdRp and formed a coimmunoprecipitable complex with RdRp. The depletion of RRP1B reduced the amount of capped mRNA in the RdRp complex. Taken together, these findings indicate that RRP1B is a host factor essential for IAV transcription and provide a target for new antivirals.IMPORTANCEInfluenza virus is an important human pathogen that causes significant morbidity and mortality and threatens the human population with epidemics and pandemics every year. Due to the high mutation rate of the virus, antiviral drugs targeting viral proteins might ultimately lose their effectiveness. An alternative strategy that explores the genetic stability of host factors indispensable for influenza virus replication would thus be desirable. Here, we characterized the rRNA processing 1 homolog B (RRP1B) protein as an important cellular factor for influenza A virus transcription. We showed that silencing RRP1B hampered viral RNA-dependent RNA polymerase (RdRp) activity, which is responsible for virus transcription and replication. Furthermore, we reported that RRP1B is crucial for RdRp binding to cellular capped mRNA, which is a critical step of virus transcription. Our study not only provides a deeper understanding of influenza virus-host interplay, but also suggests a potential target for antiviral drug development.

scholarly journals Viral and Host Factors Required for Avian H5N1 Influenza A Virus Replication in Mammalian Cells

Viruses ◽  
2013 ◽  
Vol 5 (6) ◽  
pp. 1431-1446 ◽  
Author(s):  
Hong Zhang ◽  
Benjamin Hale ◽  
Ke Xu ◽  
Bing Sun
Keyword(s):  
Influenza A Virus ◽  
Virus Replication ◽  
Mammalian Cells ◽  
Influenza A ◽  
Host Factors ◽  
H5n1 Influenza

scholarly journals Mathematical Model for the Intracellular Kinetics of Influenza a Virus Replication in Vitro

2021 ◽  
Author(s):  
Diana Schwendener Forkel
Keyword(s):  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Infection Process ◽  
Treatment Modalities ◽  
Viral Production ◽  
A Cell ◽  
Basic Biology ◽  
Kinetics Of

In the last twenty years, mathematical modelling (MM) has been notably used to capture the infection kinetics of many infectious diseases as it allows insights into the basic biology, infection kinetics, and the mechanisms and efficacy of treatment modalities. MMs of influenza A virus (IAV) infection usually represent the process of virus replication within a cell as a ‘black box’ term for viral production. The simplification is appropriate when we are not interested in the microscopic details of infection. Recently though, MMs have begun to account for the kinetics of intracellular IAV replication. Herein, we examine the MM by Heldt et al., which is able to capture kinetics of IAV infection. It however, does so by adjusting parameters of the MM to various events in the infection process. We developed a robust, yet concise, MM for the intracellular kinetics of influenza A virus infection in vitro with a consistent set of parameters. We use attachment, fusion and RNA data gathered from literature sources to validate our simplified MM and match known infection kinetics consistent throughout infection.

scholarly journals Type-IInterferon-Inducible SERTAD3 Inhibits Influenza A Virus Replication by Blocking the Assembly of Viral RNA Polymerase Complex

Cell Reports ◽  
2020 ◽  
Vol 33 (5) ◽  
pp. 108342
Author(s):  
Nina Sun ◽  
Chunfeng Li ◽  
Xiao-Feng Li ◽  
Yong-Qiang Deng ◽  
Tao Jiang ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Viral Rna ◽  
Polymerase Complex

scholarly journals Influenza A Virus Panhandle Structure Is Directly Involved in RIG-I Activation and Interferon Induction

2015 ◽  
Vol 89 (11) ◽  
pp. 6067-6079 ◽  
Author(s):  
GuanQun Liu ◽  
Hong-Su Park ◽  
Hyun-Mi Pyo ◽  
Qiang Liu ◽  
Yan Zhou
Keyword(s):  
Viral Replication ◽  
Influenza A Virus ◽  
Promoter Region ◽  
Influenza A ◽  
Rna Synthesis ◽  
Nucleotide Composition ◽  
Viral Rna ◽  
Viral Transcription ◽  
Wild Type ◽  
Viral Promoter

ABSTRACTRetinoic acid-inducible gene I (RIG-I) is an important innate immune sensor that recognizes viral RNA in the cytoplasm. Its nonself recognition largely depends on the unique RNA structures imposed by viral RNA. The panhandle structure residing in the influenza A virus (IAV) genome, whose primary function is to serve as the viral promoter for transcription and replication, has been proposed to be a RIG-I agonist. However, this has never been proved experimentally. Here, we employed multiple approaches to determine if the IAV panhandle structure is directly involved in RIG-I activation and type I interferon (IFN) induction. First, in porcine alveolar macrophages, we demonstrated that the viral genomic coding region is dispensable for RIG-I-dependent IFN induction. Second, usingin vitro-synthesized hairpin RNA, we showed that the IAV panhandle structure could directly bind to RIG-I and stimulate IFN production. Furthermore, we investigated the contributions of the wobble base pairs, mismatch, and unpaired nucleotides within the wild-type panhandle structure to RIG-I activation. Elimination of these destabilizing elements within the panhandle structure promoted RIG-I activation and IFN induction. Given the function of the panhandle structure as the viral promoter, we further monitored the promoter activity of these panhandle variants and found that viral replication was moderately affected, whereas viral transcription was impaired dramatically. In all, our results indicate that the IAV panhandle promoter region adopts a nucleotide composition that is optimal for balanced viral RNA synthesis and suboptimal for RIG-I activation.IMPORTANCEThe IAV genomic panhandle structure has been proposed to be an RIG-I agonist due to its partial complementarity; however, this has not been experimentally confirmed. Here, we provide direct evidence that the IAV panhandle structure is competent in, and sufficient for, RIG-I activation and IFN induction. By constructing panhandle variants with increased complementarity, we demonstrated that the wild-type panhandle structure could be modified to enhance RIG-I activation and IFN induction. These panhandle variants posed moderate influence on viral replication but dramatic impairment of viral transcription. These results indicate that the IAV panhandle promoter region adopts a nucleotide composition to achieve optimal balance of viral RNA synthesis and suboptimal RIG-I activation. Our results highlight the multifunctional role of the IAV panhandle promoter region in the virus life cycle and offer novel insights into the development of antiviral agents aiming to boost RIG-I signaling or virus attenuation by manipulating this conserved region.

scholarly journals A mechanism for prime-realignment during influenza A virus replication

2017 ◽  
Author(s):  
Judith Oymans ◽  
Aartjan J.W. te Velthuis
Keyword(s):  
Influenza Virus ◽  
Rna Polymerase ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
De Novo ◽  
Severe Disease ◽  
Viral Rna ◽  
Insight Into

AbstractThe influenza A virus genome consists of eight segments of single-stranded RNA. These segments are replicated and transcribed by a viral RNA-dependent RNA polymerase (RdRp) that is made up of the influenza virus proteins PB1, PB2 and PA. To copy the viral RNA (vRNA) genome segments and the complementary RNA (cRNA) segments, the replicative intermediate of viral replication, the RdRp must use two promoters and two differentde novoinitiation mechanisms. On the vRNA promoter, the RdRp initiates on the 3’ terminus, while on the cRNA promoter the RdRp initiates internally and subsequently realigns the nascent vRNA product to ensure that the template is copied in full. In particular the latter process, which is also used by other RNA viruses, is not understood. Here we provide mechanistic insight into prime-realignment during influenza virus replication and show that it is controlled by the priming loop and a helix-loop-helix motif of the PB1 subunit of the RdRp. Overall, these observations advance our understanding of how the influenza A virus initiates viral replication and amplifies the genome correctly.ImportanceInfluenza A viruses cause severe disease in humans and are considered a major threat to our economy and health. The viruses replicate and transcribe their genome using an enzyme called the RNA polymerases. To ensure that the genome is amplified faithfully and abundant viral mRNAs are made for viral protein synthesis, the RNA polymerase must work correctly. In this report, we provide insight into the mechanism that the RNA polymerase employs to ensure that the viral genome is copied correctly.

scholarly journals The host factor ANP32A is required for influenza A virus vRNA and cRNA synthesis

2021 ◽  
Author(s):  
Benjamin E. Nilsson-Payant ◽  
Benjamin R. tenOever ◽  
Aartjan J.W. te Velthuis
Keyword(s):  
Avian Influenza ◽  
Rna Polymerase ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Host Factor ◽  
Rna Polymerases ◽  
Viral Rna ◽  
Influenza A Viruses

Influenza A viruses are negative-sense RNA viruses that rely on their own viral replication machinery to replicate and transcribe their segmented single-stranded RNA genome. The viral ribonucleoprotein complexes in which viral RNA is replicated consist of a nucleoprotein scaffold around which the RNA genome is bound, and a heterotrimeric RNA-dependent RNA polymerase that catalyzes viral replication. The RNA polymerase copies the viral RNA (vRNA) via a replicative intermediate, called the complementary RNA (cRNA), and subsequently uses this cRNA to make more vRNA copies. To ensure that new cRNA and vRNA molecules are associated with ribonucleoproteins in which they can be amplified, the active RNA polymerase recruits a second polymerase to encapsidate the cRNA or vRNA. Host factor ANP32A has been shown to be essential for viral replication and to facilitate the formation of a dimer between viral RNA polymerases. Differences between mammalian and avian ANP32A proteins are sufficient to restrict viral replication. It has been proposed that ANP32A is only required for the synthesis of vRNA molecules from a cRNA, but not vice versa. However, this view does not match recent molecular evidence. Here we use minigenome assays, virus infections, and viral promoter mutations to demonstrate that ANP32A is essential for both vRNA and cRNA synthesis. Moreover, we show that ANP32 is not only needed for the actively replicating polymerase, but also for the polymerase that is encapsidating nascent viral RNA products. Overall, these results provide new insights into influenza A virus replication and host adaptation. IMPORTANCE Zoonotic avian influenza A viruses pose a constant threat to global health, and they have the potential to cause pandemics. Species variations in host factor ANP32A play a key role in supporting the activity of avian influenza A virus RNA polymerases in mammalian hosts. Here we show that ANP32A acts at two stages in the influenza A virus replication cycle, supporting recent structural experiments, in line with its essential role. Understanding how ANP32A supports viral RNA polymerase activity and how it supports avian polymerase function in mammalian hosts is important for understanding influenza A virus replication and the development of antiviral strategies against influenza A viruses.

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