scholarly journals Inhibition of Anti-viral Stress Granule Formation by infectious bronchitis virus endoribonuclease nsp15 Ensures Efficient Virus Replication

2020 ◽  
Author(s):  
Bo Gao ◽  
Xiaoqian Gong ◽  
Shouguo Fang ◽  
Wenlian Weng ◽  
Yingjie Sun ◽  
...  
Keyword(s):  
Virus Replication ◽  
Infectious Bronchitis Virus ◽  
Rna Virus ◽  
Animal Health ◽  
Stress Granules ◽  
Antiviral Response ◽  
Viral Dsrna ◽  
Granule Formation ◽  
Infectious Bronchitis ◽  
Eif2α Phosphorylation

AbstractCytoplasmic stress granules (SGs) are generally triggered by stress-induced translation arrest for storing mRNAs. Recently, it has been shown that SGs exert anti-viral functions due to their involvement in protein synthesis shut off and recruitment of innate immune signaling intermediates. The largest RNA virus, coronavirus, mutates frequently and circulates among animals, imposing great threat to public safety and animal health; however, the significance of SGs in coronavirus infections is largely unknown. Infectious bronchitis virus (IBV) is the first identified coronavirus in 1930s and has been prevalent in poultry farm for many years. In this study, we provide evidence that IBV overcomes the host antiviral response by inhibiting SGs formation via the virus-encoded endoribonuclease nsp15. By immunofluorescence analysis, we observed that IBV infection not only did not trigger SGs formation in approximately 80% of the infected cells, but also impaired the formation of SGs triggered by heat shock, sodium arsenite, or NaCl stimuli. We show that the intrinsic endoribonuclease activity of nsp15 is responsible for the inhibition of SGs formation. In fact, nsp15-defective recombinant IBV (rIBV-nsp15-H238A) greatly induced the formation of SGs, along with accumulation of dsRNA and activation of PKR, whereas wild type IBV failed to do so. Consequently, infection with rIBV-nsp15-H238A triggered transcription of IFN-β which in turn greatly affected recombinant virus replication. Further analysis showed that SGs function as antiviral hub, as demonstrated by the attenuated IRF3-IFN response and increased production of IBV in SG-defective cells. Additional evidence includes the aggregation of PRRs and signaling intermediates to the IBV-induced SGs. Collectively, our data demonstrate that the endoribonuclease nsp15 of IBV suppresses the formation of antiviral hub SGs by regulating the accumulation of viral dsRNA and by antagonizing the activation of PKR, eventually ensuring productive virus replication. We speculate that coronaviruses employ similar mechanisms to antagonize the host anti-viral SGs formation for efficient virus replication, as the endoribonuclease function of nsp15 is conserved in all coronaviruses.Author summaryIt has been reported that stress granules (SGs) are part of the host cell antiviral response. Not surprisingly, viruses in turn produce an array of antagonists to counteract such host response. Here, we show that IBV inhibits the formation of SGs through its endoribonuclease nsp15, by reducing the accumulation of viral dsRNA, evading the activation of PKR, and by subsequently inhibiting eIF2α phosphorylation and SGs formation. Nsp15 also inhibits SG formation independent of the eIF2α pathway, probably by targeting host mRNA. Depletion of SG scaffold proteins decreases IRF3-IFN response and increases the production of IBV. All coronaviruses encode a conserved endoribonuclease nsp15, and it will be important to determine whether also other (non-avian) coronaviruses limit the formation of anti-viral SGs in a similar manner.

scholarly journals Infectious bronchitis virus regulates cellular stress granule signaling

2019 ◽  
Author(s):  
Matthew J. Brownsword ◽  
Nicole Doyle ◽  
Michèle Brocard ◽  
Nicolas Locker ◽  
Helena J. Maier
Keyword(s):  
Stress Responses ◽  
Infectious Bronchitis Virus ◽  
Cellular Stress ◽  
Stress Granules ◽  
Stress Granule ◽  
Granule Formation ◽  
Translation Machinery ◽  
Infectious Bronchitis ◽  
Eif2α Phosphorylation ◽  
Cellular Translation

AbstractViruses must hijack cellular translation machinery to efficiently express viral genes. In many cases, this is impeded by cellular stress responses. These stress responses swiftly relocate and repurpose translation machinery, resulting in global inhibition of translation and the aggregation of stalled 48S mRNPs into cytoplasmic foci called stress granules. This results in translational silencing of all mRNAs excluding those beneficial for the cell to resolve the specific stress. For example, expression of antiviral factors is maintained during viral infection. Here we investigated stress granule regulation by Gammacoronavirus infectious bronchitis virus (IBV), which causes the economically important poultry disease, infectious bronchitis. Interestingly, we found that IBV is able to inhibit multiple cellular stress granule signaling pathways whilst at the same time IBV replication also results in induction of seemingly canonical stress granules in a proportion of infected cells. Moreover, IBV infection uncouples translational repression and stress granule formation and both processes are independent of eIF2α phosphorylation. These results provide novel insights into how IBV modulates cellular translation and antiviral stress signaling.

scholarly journals Inhibition of anti-viral stress granule formation by coronavirus endoribonuclease nsp15 ensures efficient virus replication

2021 ◽  
Vol 17 (2) ◽  
pp. e1008690 ◽  
Author(s):  
Bo Gao ◽  
Xiaoqian Gong ◽  
Shouguo Fang ◽  
Wenlian Weng ◽  
Huan Wang ◽  
...  
Keyword(s):  
Virus Replication ◽  
Animal Health ◽  
Viral Dsrna ◽  
Granule Formation ◽  
Translation Arrest ◽  
Infectious Bronchitis ◽  
Innate Immune Signaling ◽  
Chemically Induced ◽  
Infected Cells ◽  
Coronavirus Infection

Cytoplasmic stress granules (SGs) are generally triggered by stress-induced translation arrest for storing mRNAs. Recently, it has been shown that SGs exert anti-viral functions due to their involvement in protein synthesis shut off and recruitment of innate immune signaling intermediates. The largest RNA viruses, coronaviruses, impose great threat to public safety and animal health; however, the significance of SGs in coronavirus infection is largely unknown. Infectious Bronchitis Virus (IBV) is the first identified coronavirus in 1930s and has been prevalent in poultry farm for many years. In this study, we provided evidence that IBV overcomes the host antiviral response by inhibiting SGs formation via the virus-encoded endoribonuclease nsp15. By immunofluorescence analysis, we observed that IBV infection not only did not trigger SGs formation in approximately 80% of the infected cells, but also impaired the formation of SGs triggered by heat shock, sodium arsenite, or NaCl stimuli. We further demonstrated that the intrinsic endoribonuclease activity of nsp15 was responsible for the interference of SGs formation. In fact, nsp15-defective recombinant IBV (rIBV-nsp15-H238A) greatly induced the formation of SGs, along with accumulation of dsRNA and activation of PKR, whereas wild type IBV failed to do so. Consequently, infection with rIBV-nsp15-H238A strongly triggered transcription of IFN-β which in turn greatly affected rIBV-nsp15-H238A replication. Further analysis showed that SGs function as an antiviral hub, as demonstrated by the attenuated IRF3-IFN response and increased production of IBV in SG-defective cells. Additional evidence includes the aggregation of pattern recognition receptors (PRRs) and signaling intermediates to the IBV-induced SGs. Collectively, our data demonstrate that the endoribonuclease nsp15 of IBV interferes with the formation of antiviral hub SGs by regulating the accumulation of viral dsRNA and by antagonizing the activation of PKR, eventually ensuring productive virus replication. We further demonstrated that nsp15s from PEDV, TGEV, SARS-CoV, and SARS-CoV-2 harbor the conserved function to interfere with the formation of chemically-induced SGs. Thus, we speculate that coronaviruses employ similar nsp15-mediated mechanisms to antagonize the host anti-viral SGs formation to ensure efficient virus replication.

scholarly journals Infectious Bronchitis Virus Regulates Cellular Stress Granule Signaling

Viruses ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 536
Author(s):  
Matthew J. Brownsword ◽  
Nicole Doyle ◽  
Michèle Brocard ◽  
Nicolas Locker ◽  
Helena J. Maier
Keyword(s):  
Stress Responses ◽  
Infectious Bronchitis Virus ◽  
Cellular Stress ◽  
Stress Granules ◽  
Stress Granule ◽  
Granule Formation ◽  
Infectious Bronchitis ◽  
Eif2α Phosphorylation ◽  
Cellular Translation ◽  
Cellular Stress Responses

Viruses must hijack cellular translation machinery to express viral genes. In many cases, this is impeded by cellular stress responses. These stress responses result in the global inhibition of translation and the storage of stalled mRNAs, into RNA-protein aggregates called stress granules. This results in the translational silencing of the majority of mRNAs excluding those beneficial for the cell to resolve the specific stress. For example, the expression of antiviral factors is maintained during viral infection. Here we investigated stress granule regulation by Gammacoronavirus infectious bronchitis virus (IBV), which causes the economically important poultry disease, infectious bronchitis. Interestingly, we found that IBV is able to inhibit multiple cellular stress granule signaling pathways, whilst at the same time, IBV replication also results in the induction of seemingly canonical stress granules in a proportion of infected cells. Moreover, IBV infection uncouples translational repression and stress granule formation and both processes are independent of eIF2α phosphorylation. These results provide novel insights into how IBV modulates cellular translation and antiviral stress signaling.

scholarly journals Cell Cycle Perturbations Induced by Infection with the Coronavirus Infectious Bronchitis Virus and Their Effect on Virus Replication

2006 ◽  
Vol 80 (8) ◽  
pp. 4147-4156 ◽  
Author(s):  
Brian Dove ◽  
Gavin Brooks ◽  
Katrina Bicknell ◽  
Torsten Wurm ◽  
Julian A. Hiscox
Keyword(s):  
Cell Cycle ◽  
Virus Replication ◽  
Infectious Bronchitis Virus ◽  
Rna Virus ◽  
Positive Strand ◽  
Infectious Bronchitis ◽  
M Phase ◽  
Infected Cells ◽  
Positive Strand Rna ◽  
The Impact

ABSTRACT In eukaryotic cells, cell growth and division occur in a stepwise, orderly fashion described by a process known as the cell cycle. The relationship between positive-strand RNA viruses and the cell cycle and the concomitant effects on virus replication are not clearly understood. We have shown that infection of asynchronously replicating and synchronized replicating cells with the avian coronavirus infectious bronchitis virus (IBV), a positive-strand RNA virus, resulted in the accumulation of infected cells in the G2/M phase of the cell cycle. Analysis of various cell cycle-regulatory proteins and cellular morphology indicated that there was a down-regulation of cyclins D1 and D2 (G1 regulatory cyclins) and that a proportion of virus-infected cells underwent aberrant cytokinesis, in which the cells underwent nuclear, but not cytoplasmic, division. We assessed the impact of the perturbations on the cell cycle for virus-infected cells and found that IBV-infected G2/M-phase-synchronized cells exhibited increased viral protein production when released from the block when compared to cells synchronized in the G0 phase or asynchronously replicating cells. Our data suggested that IBV induces a G2/M phase arrest in infected cells to promote favorable conditions for viral replication.

scholarly journals Retinoic Acid Inducible Gene I and Protein Kinase R, but Not Stress Granules, Mediate the Proinflammatory Response to Yellow Fever Virus

2020 ◽  
Vol 94 (22) ◽  
Author(s):  
Guillaume Beauclair ◽  
Felix Streicher ◽  
Maxime Chazal ◽  
Daniela Bruni ◽  
Sarah Lesage ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Rna Virus ◽  
Stress Granules ◽  
Cytokine Response ◽  
Fever Virus ◽  
Stress Granule ◽  
Proinflammatory Response ◽  
Granule Formation ◽  
Proinflammatory Mediators

ABSTRACT Yellow fever virus (YFV) is an RNA virus primarily targeting the liver. Severe YF cases are responsible for hemorrhagic fever, plausibly precipitated by excessive proinflammatory cytokine response. Pathogen recognition receptors (PRRs), such as the cytoplasmic retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), and the viral RNA sensor protein kinase R (PKR), are known to initiate a proinflammatory response upon recognition of viral genomes. Here, we sought to reveal the main determinants responsible for the acute cytokine expression occurring in human hepatocytes following YFV infection. Using a RIG-I-defective human hepatoma cell line, we found that RIG-I largely contributes to cytokine secretion upon YFV infection. In infected RIG-I-proficient hepatoma cells, RIG-I was localized in stress granules. These granules are large aggregates of stalled translation preinitiation complexes known to concentrate RLRs and PKR and are so far recognized as hubs orchestrating RNA virus sensing. Stable knockdown of PKR in hepatoma cells revealed that PKR contributes to both stress granule formation and cytokine induction upon YFV infection. However, stress granule disruption did not affect the cytokine response to YFV infection, as assessed by small interfering RNA (siRNA)-knockdown-mediated inhibition of stress granule assembly. Finally, no viral RNA was detected in stress granules using a fluorescence in situ hybridization approach coupled with immunofluorescence. Our findings suggest that both RIG-I and PKR mediate proinflammatory cytokine induction in YFV-infected hepatocytes, in a stress granule-independent manner. Therefore, by showing the uncoupling of the cytokine response from the stress granule formation, our model challenges the current view in which stress granules are required for the mounting of the acute antiviral response. IMPORTANCE Yellow fever is a mosquito-borne acute hemorrhagic disease caused by yellow fever virus (YFV). The mechanisms responsible for its pathogenesis remain largely unknown, although increased inflammation has been linked to worsened outcome. YFV targets the liver, where it primarily infects hepatocytes. We found that two RNA-sensing proteins, RIG-I and PKR, participate in the induction of proinflammatory mediators in human hepatocytes infected with YFV. We show that YFV infection promotes the formation of cytoplasmic structures, termed stress granules, in a PKR- but not RIG-I-dependent manner. While stress granules were previously postulated to be essential platforms for immune activation, we found that they are not required for the production of proinflammatory mediators upon YFV infection. Collectively, our work uncovered molecular events triggered by the replication of YFV, which could prove instrumental in clarifying the pathogenesis of the disease, with possible repercussions for disease management.

scholarly journals Impacts of Coronavirus on Farm and Pet Animals

2020 ◽  
Author(s):  
Sachin Subedi ◽  
Sulove Koirala ◽  
Lilong Chai
Keyword(s):  
Infectious Bronchitis Virus ◽  
Vaccine Development ◽  
Rna Virus ◽  
Farm Animals ◽  
Effective Vaccine ◽  
Nasal Discharge ◽  
Infectious Bronchitis ◽  
Gastrointestinal Lesions ◽  
On Farm ◽  
The Impact

Coronaviruses are positive sense RNA virus belonging to the Coronaviridae family, which are further subdivided into four genera: Alpha, Beta, Gamma, and Delta Coronaviruses. Infectious bronchitis virus and SARS-CoV belong to Beta Coronaviridae family. Infectious bronchitis virus causes respiratory and nephritic signs that includes tracheal rales, urate crystals, lethargy and nasal discharge. In livestock and pets, the Coronavirus infection causes mostly gastrointestinal lesions, which may be prevented through vaccination and biosecurity. Recent infections of SARS-CoV-2 (also known as COVID-19) on farm and pet animals were summarized in this study. Besides, zoo animals were reported with infections in some countries/regions. Although the damage of COVID-19 has not been reported as serious as highly pathogenic avian influenza (HPAI) and African Swine Fever (ASF) on farm animals so far, the transmission mechanism of COVID-19 among group animals/farms and its long-term impacts are still not clear. The impact of Coronavirus on animals and potential prevention strategies, such as vaccine development and farm biosecurity measures, were discussed. Prior to the development of the effective vaccine, the biosecurity measures (e.g., conventional disinfection strategies and innovated technologies) may play roles in preventing potential spread of diseases/viruses.

scholarly journals Global distributions and strain diversity of avian infectious bronchitis virus: a review

2017 ◽  
Vol 18 (1) ◽  
pp. 70-83 ◽  
Author(s):  
Faruku Bande ◽  
Siti Suri Arshad ◽  
Abdul Rahman Omar ◽  
Mohd Hair-Bejo ◽  
Aliyu Mahmuda ◽  
...  
Keyword(s):  
Infectious Bronchitis Virus ◽  
Viral Infections ◽  
Current Knowledge ◽  
Rna Virus ◽  
Economic Loss ◽  
Poultry Industry ◽  
Great Ability ◽  
Global Food Security ◽  
Infectious Bronchitis ◽  
Strain Diversity

AbstractThe poultry industry faces challenge amidst global food security crisis. Infectious bronchitis is one of the most important viral infections that cause huge economic loss to the poultry industry worldwide. The causative agent, infectious bronchitis virus (IBV) is an RNA virus with great ability for mutation and recombination; thus, capable of generating new virus strains that are difficult to control. There are many IBV strains found worldwide, including the Massachusetts, 4/91, D274, and QX-like strains that can be grouped under the classic or variant serotypes. Currently, information on the epidemiology, strain diversity, and global distribution of IBV has not been comprehensively reported. This review is an update of current knowledge on the distribution, genetic relationship, and diversity of the IBV strains found worldwide.

scholarly journals Reverse Genetics System for the Avian Coronavirus Infectious Bronchitis Virus

2001 ◽  
Vol 75 (24) ◽  
pp. 12359-12369 ◽  
Author(s):  
Rosa Casais ◽  
Volker Thiel ◽  
Stuart G. Siddell ◽  
David Cavanagh ◽  
Paul Britton
Keyword(s):  
Molecular Biology ◽  
Rna Polymerase ◽  
Vaccinia Virus ◽  
Infectious Bronchitis Virus ◽  
Reverse Genetics ◽  
Rna Virus ◽  
Full Length ◽  
T7 Rna Polymerase ◽  
Infectious Bronchitis

ABSTRACT Major advances in the study of the molecular biology of RNA viruses have resulted from the ability to generate and manipulate full-length genomic cDNAs of the viral genomes with the subsequent synthesis of infectious RNA for the generation of recombinant viruses. Coronaviruses have the largest RNA virus genomes and, together with genetic instability of some cDNA sequences in Escherichia coli, this has hampered the generation of a reverse-genetics system for this group of viruses. In this report, we describe the assembly of a full-length cDNA from the positive-sense genomic RNA of the avian coronavirus, infectious bronchitis virus (IBV), an important poultry pathogen. The IBV genomic cDNA was assembled immediately downstream of a T7 RNA polymerase promoter by in vitro ligation and cloned directly into the vaccinia virus genome. Infectious IBV RNA was generated in situ after the transfection of restricted recombinant vaccinia virus DNA into primary chick kidney cells previously infected with a recombinant fowlpox virus expressing T7 RNA polymerase. Recombinant IBV, containing two marker mutations, was recovered from the transfected cells. These results describe a reverse-genetics system for studying the molecular biology of IBV and establish a paradigm for generating genetically defined vaccines for IBV.

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