scholarly journals mSphere of Influence: Resolution of the Structure of an Influenza Virus Polymerase Is a Game Changer

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Mathilde Richard
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Influenza Viruses ◽  
Viral Rna ◽  
Structural Insight ◽  
Rna Promoter ◽  
Insight Into ◽  
Virus Biology ◽  
Game Changer

ABSTRACT Mathilde Richard works in the field of virology, more specifically on the evolution and pathogenesis of influenza viruses. In this mSphere of Influence article, she reflects on how the two articles “Structure of Influenza A Polymerase Bound to the Viral RNA Promoter” by A. Pflug, D. Guilligay, S. Reich, and S. Cusack (Nature 516:355–360, 2014, https://doi.org/10.1038/nature14008) and “Structural Insight into Cap-Snatching and RNA Synthesis by Influenza Polymerase” by S. Reich, D. Guilligay, A. Pflug, H. Malet, I. Berger, et al. (Nature 516:361–366, 2014, https://doi.org/10.1038/nature14009) made an impact on her by providing new grounds to study the influenza virus polymerase and its role in virus biology and evolution.

scholarly journals The C-Terminal Tail of TRIM56 Dictates Antiviral Restriction of Influenza A and B Viruses by Impeding Viral RNA Synthesis

2016 ◽  
Vol 90 (9) ◽  
pp. 4369-4382 ◽  
Author(s):  
Baoming Liu ◽  
Nan L. Li ◽  
Yang Shen ◽  
Xiaoyong Bao ◽  
Thomas Fabrizio ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Rna Viruses ◽  
E3 Ligase ◽  
Influenza Viruses ◽  
Restriction Factor ◽  
Virus Activity ◽  
Tripartite Motif ◽  
Positive Strand Rna

ABSTRACTAccumulating data suggest that tripartite-motif-containing (TRIM) proteins participate in host responses to viral infections, either by acting as direct antiviral restriction factors or through regulating innate immune signaling of the host. Of >70 TRIMs, TRIM56 is a restriction factor of several positive-strand RNA viruses, including three members of the familyFlaviviridae(yellow fever virus, dengue virus, and bovine viral diarrhea virus) and a human coronavirus (OC43), and this ability invariably depends upon the E3 ligase activity of TRIM56. However, the impact of TRIM56 on negative-strand RNA viruses remains unclear. Here, we show that TRIM56 puts a check on replication of influenza A and B viruses in cell culture but does not inhibit Sendai virus or human metapneumovirus, two paramyxoviruses. Interestingly, the anti-influenza virus activity was independent of the E3 ligase activity, B-box, or coiled-coil domain. Rather, deletion of a 63-residue-long C-terminal-tail portion of TRIM56 abrogated the antiviral function. Moreover, expression of this short C-terminal segment curtailed the replication of influenza viruses as effectively as that of full-length TRIM56. Mechanistically, TRIM56 was found to specifically impede intracellular influenza virus RNA synthesis. Together, these data reveal a novel antiviral activity of TRIM56 against influenza A and B viruses and provide insights into the mechanism by which TRIM56 restricts these medically important orthomyxoviruses.IMPORTANCEOptions to treat influenza are limited, and drug-resistant influenza virus strains can emerge through minor genetic changes. Understanding novel virus-host interactions that alter influenza virus fitness may reveal new targets/approaches for therapeutic interventions. We show here that TRIM56, a tripartite-motif protein, is an intrinsic host restriction factor of influenza A and B viruses. Unlike its antiviral actions against positive-strand RNA viruses, the anti-influenza virus activity of TRIM56 was independent of the E3 ligase activity. Rather, expression of a short segment within the very C-terminal tail of TRIM56 inhibited the replication of influenza viruses as effectively as that of full-length TRIM56 by specifically targeting viral RNA synthesis. These data reveal the remarkable multifaceted activity of TRIM56, which has developed multiple domains to inhibit multiple viral families. They also raise the possibility of developing a broad-spectrum, TRIM56-based antiviral approach for addition to influenza prophylaxis and/or control strategies.

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 A Mechanism for Priming and Realignment during Influenza A Virus Replication

2017 ◽  
Vol 92 (3) ◽  
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 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 priming and 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 by using an enzyme called the RNA polymerases. To ensure that the genome is amplified faithfully and that 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 Acquisition of Avian-Origin PB1 Facilitates Viral RNA Synthesis by the 2009 Pandemic H1N1 Virus Polymerase

Viruses ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 266
Author(s):  
Fangzheng Wang ◽  
Guanqun Liu ◽  
Yao Lu ◽  
Magda Hlasny ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Influenza A ◽  
Rna Synthesis ◽  
H1n1 Virus ◽  
Influenza Viruses ◽  
Viral Rna ◽  
Host Switching ◽  
Pandemic H1n1 ◽  
Adaptive Mutations ◽  
Pandemic Virus ◽  
Avian Origin

The constant crosstalk between the large avian reservoir of influenza A viruses (IAV) and its mammalian hosts drives viral evolution and facilitates their host switching. Direct adaptation of an avian strain to human or reassortment between avian-origin gene segments with that of human strains are the two mechanisms for the emergence of pandemic viruses. While it was suggested that the 1918 pandemic virus is of avian origin, reassortment of 1918 human isolates and avian influenza viruses led to the generation of 1957 and 1968 pandemic viruses. Interestingly, the avian PB1 segment, which encodes the catalytic subunit of IAV polymerase, is present in the 1957 and 1968 pandemic viruses. The biological consequence and molecular basis of such gene exchange remain less well understood. Using the 2009 pandemic H1N1 virus as a model, whose polymerase contains a human-origin PB1 subunit, we demonstrate that the acquisition of an avian PB1 markedly enhances viral RNA synthesis. This enhancement is also effective in the absence of PB2 adaptive mutations, which are key determinants of host switching. Mechanistically, the avian-origin PB1 does not appear to affect polymerase assembly but imparts the reassorted pandemic polymerase-augmented viral primary transcription and replication. Moreover, compared to the parental pandemic polymerase, the reassorted polymerase displays comparable complementary RNA (cRNA)-stabilizing activity but is specifically enhanced in progeny viral RNA (vRNA) synthesis from cRNA in a trans-activating manner. Overall, our results provide the first insight into the mechanism via which avian-origin PB1 enhances viral RNA synthesis of the 2009 pandemic virus polymerase.

scholarly journals Inhibition of Influenza Virus Replication by Nitric Oxide

1999 ◽  
Vol 73 (10) ◽  
pp. 8880-8883 ◽  
Author(s):  
Guus F. Rimmelzwaan ◽  
Marianne M. J. W. Baars ◽  
Pim de Lijster ◽  
Ron A. M. Fouchier ◽  
Albert D. M. E. Osterhaus
Keyword(s):  
Nitric Oxide ◽  
Influenza Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Virus Production ◽  
Influenza Viruses ◽  
No Donor ◽  
Infected Cells ◽  
Influenza Virus Replication ◽  
Darby Canine Kidney

ABSTRACT Nitric oxide (NO) has been shown to contribute to the pathogenesis of influenza virus-induced pneumonia in mouse models. Here we show that replication of influenza A and B viruses in Mabin Darby canine kidney cells is severely impaired by the NO donor,S-nitroso-N-acetylpenicillamine. Reduction of productively infected cells and virus production proved to correlate with inhibition of viral RNA synthesis, indicating that NO affects an early step in the replication cycle of influenza viruses.

scholarly journals A Seven-Segmented Influenza A Virus Expressing the Influenza C Virus Glycoprotein HEF

2008 ◽  
Vol 82 (13) ◽  
pp. 6419-6426 ◽  
Author(s):  
Qinshan Gao ◽  
Edward W. A. Brydon ◽  
Peter Palese
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Reverse Genetics ◽  
Fluorescent Protein ◽  
Chimeric Protein ◽  
Influenza Viruses ◽  
Viral Rna ◽  
Surface Glycoprotein ◽  
Influenza C Virus ◽  
Major Surface

ABSTRACT Influenza viruses are classified into three types: A, B, and C. The genomes of A- and B-type influenza viruses consist of eight RNA segments, whereas influenza C viruses only have seven RNAs. Both A and B influenza viruses contain two major surface glycoproteins: the hemagglutinin (HA) and the neuraminidase (NA). Influenza C viruses have only one major surface glycoprotein, HEF (hemagglutinin-esterase fusion). By using reverse genetics, we generated two seven-segmented chimeric influenza viruses. Each possesses six RNA segments from influenza virus A/Puerto Rico/8/34 (PB2, PB1, PA, NP, M, and NS); the seventh RNA segment encodes either the influenza virus C/Johannesburg/1/66 HEF full-length protein or a chimeric protein HEF-Ecto, which consists of the HEF ectodomain and the HA transmembrane and cytoplasmic regions. To facilitate packaging of the heterologous segment, both the HEF and HEF-Ecto coding regions are flanked by HA packaging sequences. When introduced as an eighth segment with the NA packaging sequences, both viruses are able to stably express a green fluorescent protein (GFP) gene, indicating a potential use for these viruses as vaccine vectors to carry foreign antigens. Finally, we show that incorporation of a GFP RNA segment enhances the growth of seven-segmented viruses, indicating that efficient influenza A viral RNA packaging requires the presence of eight RNA segments. These results support a selective mechanism of viral RNA recruitment to the budding site.

scholarly journals Mapping inhibitory sites on the RNA polymerase of the 1918 pandemic influenza virus using nanobodies

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Jeremy R. Keown ◽  
Zihan Zhu ◽  
Loïc Carrique ◽  
Haitian Fan ◽  
Alexander P. Walker ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Rna Polymerase ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Structural Data ◽  
Influenza Viruses ◽  
Viral Rna ◽  
Influenza A Viruses ◽  
Seasonal Epidemics ◽  
1918 Influenza

AbstractInfluenza A viruses cause seasonal epidemics and global pandemics, representing a considerable burden to healthcare systems. Central to the replication cycle of influenza viruses is the viral RNA-dependent RNA polymerase which transcribes and replicates the viral RNA genome. The polymerase undergoes conformational rearrangements and interacts with viral and host proteins to perform these functions. Here we determine the structure of the 1918 influenza virus polymerase in transcriptase and replicase conformations using cryo-electron microscopy (cryo-EM). We then structurally and functionally characterise the binding of single-domain nanobodies to the polymerase of the 1918 pandemic influenza virus. Combining these functional and structural data we identify five sites on the polymerase which are sensitive to inhibition by nanobodies. We propose that the binding of nanobodies at these sites either prevents the polymerase from assuming particular functional conformations or interactions with viral or host factors. The polymerase is highly conserved across the influenza A subtypes, suggesting these sites as effective targets for potential influenza antiviral development.

scholarly journals Biochemical and Structural Evidence in Support of a Coherent Model for the Formation of the Double-Helical Influenza A Virus Ribonucleoprotein

mBio ◽  
2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Qiaozhen Ye ◽  
Tom S. Y. Guu ◽  
Douglas A. Mata ◽  
Rei-Lin Kuo ◽  
Bartram Smith ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Viral Rna ◽  
Helical Structures ◽  
Structural Element ◽  
X Ray Crystallography ◽  
Multiple Copies ◽  
Infected Cells

ABSTRACTInfluenza A virions contain eight ribonucleoproteins (RNPs), each comprised of a negative-strand viral RNA, the viral polymerase, and multiple nucleoproteins (NPs) that coat the viral RNA. NP oligomerization along the viral RNA is mediated largely by a 28-amino-acid tail loop. Influenza viral RNPs, which serve as the templates for viral RNA synthesis in the nuclei of infected cells, are not linear but rather are organized in hairpin-like double-helical structures. Here we present results that strongly support a coherent model for the assembly of the double-helical influenza virus RNP structure. First, we show that NP self-associates much more weakly in the absence of RNA than in its presence, indicating that oligomerization is very limited in the cytoplasm. We also show that once NP has oligomerized, it can dissociate in the absence of bound RNA, but only at a very slow rate, indicating that the NP scaffold remains intact when viral RNA dissociates from NPs to interact with the polymerase during viral RNA synthesis. In addition, we identify a previously unknown NP-NP interface that is likely responsible for organizing the double-helical viral RNP structure. This identification stemmed from our observation that NP lacking the oligomerization tail loop forms monomers and dimers. We determined the crystal structure of this NP dimer, which reveals this new NP-NP interface. Mutation of residues that disrupt this dimer interface does not affect oligomerization of NPs containing the tail loop but does inactivate the ability of NPs containing the tail loop to support viral RNA synthesis in minigenome assays.IMPORTANCEInfluenza A virus, the causative agent of human pandemics and annual epidemics, contains eight RNA gene segments. Each RNA segment assumes the form of a rod-shaped, double-helical ribonucleoprotein (RNP) that contains multiple copies of a viral protein, the nucleoprotein (NP), which coats the RNA segment along its entire length. Previous studies showed that NP molecules can polymerize via a structural element called the tail loop, but the RNP assembly process is poorly understood. Here we show that influenza virus RNPs are likely assembled from NP monomers, which polymerize through the tail loop only in the presence of viral RNA. Using X-ray crystallography, we identified an additional way that NP molecules interact with each other. We hypothesize that this new interaction is responsible for organizing linear, single-stranded influenza virus RNPs into double-helical structures. Our results thus provide a coherent model for the assembly of the double-helical influenza virus RNP structure.

scholarly journals Structure of Influenza A Virus Promoter and its Implications for Viral RNA Synthesis

2001 ◽  
Vol 1 ◽  
pp. 812-814 ◽  
Author(s):  
Sung-Hun Bae ◽  
Byong-Seok Choi
Keyword(s):  
Influenza Virus ◽  
Hong Kong ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rna Synthesis ◽  
Viral Rna ◽  
Influenza Outbreak ◽  
Spanish Influenza ◽  
Virus Promoter

Since the worst worldwide pandemic ever recorded — the 1918 Spanish influenza outbreak that killed more than 20 million people — we have achieved significant advances in understanding the influenza virus. However, the fear of such a pandemic remains strong. For example, in 1997, when a lethal influenza variant afflicted eight people in Hong Kong, contributing to the death of six, officials feared the next wave had begun. They managed to solve the problem quickly, however, by destroying all of the poultry in Hong Kong[1].

Sign in / Sign up

Export Citation Format

Share Document