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1.
Int J Mol Sci ; 23(19)2022 Oct 02.
Article in English | MEDLINE | ID: covidwho-2066136

ABSTRACT

Coronavirus nonstructural protein 3 (nsp3) is a multi-functional protein, playing a critical role in viral replication and in regulating host antiviral innate immunity. In this study, we demonstrate that nsp3 from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and avian coronavirus infectious bronchitis virus (IBV) directly interacts with melanoma differentiation-associated gene 5 (MDA5), rendering an inhibitory effect on the MDA5-mediated type I interferon (IFN) response. By the co-expression of MDA5 with wild-type and truncated nsp3 constructs, at least three interacting regions mapped to the papain-like protease (PLpro) domain and two other domains located at the N- and C-terminal regions were identified in SARS-CoV-2 nsp3. Furthermore, by introducing point mutations to the catalytic triad, the deubiquitylation activity of the PLpro domain from both SARS-CoV-2 and IBV nsp3 was shown to be responsible for the suppression of the MDA5-mediated type I IFN response. It was also demonstrated that both MDA5 and nsp3 were able to interact with ubiquitin and ubiquitinated proteins, contributing to the interaction between the two proteins. This study confirms the antagonistic role of nsp3 in the MDA5-mediated type I IFN signaling, highlighting the complex interaction between a multi-functional viral protein and the innate immune response.


Subject(s)
Coronavirus Infections , Infectious bronchitis virus , Interferon Type I , Interferon-Induced Helicase, IFIH1 , SARS-CoV-2 , Viral Nonstructural Proteins , COVID-19 , Coronavirus Infections/immunology , Humans , Infectious bronchitis virus/metabolism , Interferon Type I/immunology , Interferon-Induced Helicase, IFIH1/metabolism , SARS-CoV-2/metabolism , Ubiquitin/metabolism , Ubiquitinated Proteins , Viral Nonstructural Proteins/metabolism
2.
Viruses ; 14(8)2022 08 10.
Article in English | MEDLINE | ID: covidwho-2024287

ABSTRACT

Receptor interacting protein kinase 3 (RIPK3) is a vital serine/threonine kinase in regulating the programmed destruction of infected cells to defend against RNA viruses. Although the role of RIPK3 in viruses in mice is well characterized, it remains unclear where in nephropathogenic infectious bronchitis virus (NIBV) in chickens. Here, we use a self-prepared polyclonal antibody to clarify the abundance of RIPK3 in tissues and define the contributions of RIPK3 in tissue damage caused by NIBV infection in chickens. Western blot analyses showed that RIPK3 polyclonal antibody can specifically recognize RIPK3 in the vital tissues of Hy-Line brown chicks and RIPK3 protein is abundantly expressed in the liver and kidney. Moreover, NIBV significantly upregulated the expression levels of RIPK3 in the trachea and kidney of chicks in a time-dependent manner. In addition, the activation of necroptosis in response to NIBV infection was demonstrated by the coimmunoprecipitation (CoIP) experiments through RIPK3 in the necrosome, which phosphorylates its downstream mixed-spectrum kinase structural domain-like protein (MLKL). Our findings offered preliminary insights into the key role of RIPK3 protein in studying the underlying mechanism of organ failure caused by NIBV infection.


Subject(s)
Infectious bronchitis virus , Viruses , Animals , Chickens , Immunoassay , Infectious bronchitis virus/metabolism , Mice , Necroptosis , Receptor-Interacting Protein Serine-Threonine Kinases/genetics , Viruses/metabolism
3.
Front Cell Infect Microbiol ; 12: 865283, 2022.
Article in English | MEDLINE | ID: covidwho-1822357

ABSTRACT

Nephropathogenic infectious bronchitis virus (NIBV) is one of the most important viral pathogens in the world poultry industry. Here, we used RT-qPCR, WB and immunofluorescence to explore the interaction between NIBV and the host innate immune system of the kidney. Multiple virions were found in the kidney tissues of the disease group under electron microscopy, and pathological changes such as structural damage of renal tubules and bleeding were observed by HE staining. In addition, we found that the mRNA levels of TLR7, TRAF6, and IKKß were upregulated after NIBV infection. IRF7 mRNA levels decreased significantly at 5 dpi and increased significantly at 11 to 18 dpi. The NF-κB P65 mRNA level increased significantly at 5 to 18 dpi and decreased at 28 dpi. However, NIBV infection-induced NF-κB P65 protein levels were downregulated at multiple time points. Moreover, we demonstrated that the cytokine (IFN-γ, IL-8, and IL-6) mRNA and protein expression levels were increased significantly at multiple time points after NIBV infection. Furthermore, immunofluorescence analysis showed that NF-κB P65 and IFN-γ were mainly located in the nuclear or perinuclear region. The positive signal intensity of NF-κB P65 was significantly lower than that of the normal group at 1 to 5 dpi, and there was no significant change in the subsequent time period. The positive signal intensity of IFN-γ decreased significantly at 5 dpi, and increased significantly at 11 to 28 dpi. In conclusion, we found that NIBV promoted cytokine release through the TLR7/NF-κB signaling axis, thus causing kidney injury.


Subject(s)
Infectious bronchitis virus , Animals , Chickens , Cytokines/metabolism , Infectious bronchitis virus/metabolism , Kidney/pathology , NF-kappa B/metabolism , RNA, Messenger/metabolism , Toll-Like Receptor 7/genetics
4.
J Virol ; 96(5): e0208621, 2022 03 09.
Article in English | MEDLINE | ID: covidwho-1736026

ABSTRACT

Coronavirus infections induce the expression of multiple proinflammatory cytokines and chemokines. We have previously shown that in cells infected with gammacoronavirus infectious bronchitis virus (IBV), interleukin 6 (IL-6), and IL-8 were drastically upregulated, and the MAP kinase p38 and the integrated stress response pathways were implicated in this process. In this study, we report that coronavirus infection activates a negative regulatory loop that restricts the upregulation of a number of proinflammatory genes. As revealed by the initial transcriptomic and subsequent validation analyses, the anti-inflammatory adenine-uridine (AU)-rich element (ARE)-binding protein, zinc finger protein 36 (ZFP36), and its related family members were upregulated in cells infected with IBV and three other coronaviruses, alphacoronaviruses porcine epidemic diarrhea virus (PEDV), human coronavirus 229E (HCoV-229E), and betacoronavirus HCoV-OC43, respectively. Characterization of the functional roles of ZFP36 during IBV infection demonstrated that ZFP36 promoted the degradation of transcripts coding for IL-6, IL-8, dual-specificity phosphatase 1 (DUSP1), prostaglandin-endoperoxide synthase 2 (PTGS2) and TNF-α-induced protein 3 (TNFAIP3), through binding to AREs in these transcripts. Consistently, knockdown and inhibition of JNK and p38 kinase activities reduced the expression of ZFP36, as well as the expression of IL-6 and IL-8. On the contrary, overexpression of mitogen-activated protein kinase kinase 3 (MKK3) and MAPKAP kinase-2 (MK2), the upstream and downstream kinases of p38, respectively, increased the expression of ZFP36 and decreased the expression of IL-8. Taken together, this study reveals an important regulatory role of the MKK3-p38-MK2-ZFP36 axis in coronavirus infection-induced proinflammatory response. IMPORTANCE Excessive and uncontrolled induction and release of proinflammatory cytokines and chemokines, the so-called cytokine release syndrome (CRS), would cause life-threatening complications and multiple organ failure in severe coronavirus infections, including severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and COVID-19. This study reveals that coronavirus infection also induces the expression of ZFP36, an anti-inflammatory ARE-binding protein, promoting the degradation of ARE-containing transcripts coding for IL-6 and IL-8 as well as a number of other proteins related to inflammatory response. Furthermore, the p38 MAP kinase, its upstream kinase MKK3 and downstream kinase MK2 were shown to play a regulatory role in upregulation of ZFP36 during coronavirus infection cycles. This MKK3-p38-MK2-ZFP36 axis would constitute a potential therapeutic target for severe coronavirus infections.


Subject(s)
Coronavirus Infections/metabolism , Interleukin-6/metabolism , Interleukin-8/metabolism , Tristetraprolin/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism , Adenine/metabolism , Animals , Cell Line , Chlorocebus aethiops , Coronavirus Infections/genetics , Gene Expression Regulation , Humans , Infectious bronchitis virus/metabolism , Infectious bronchitis virus/pathogenicity , Interleukin-6/genetics , Interleukin-8/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Phosphorylation , Protein Serine-Threonine Kinases/metabolism , Transcriptional Activation , Up-Regulation , Uridine/metabolism , Vero Cells
5.
Viruses ; 13(12)2021 12 17.
Article in English | MEDLINE | ID: covidwho-1580424

ABSTRACT

Infectious bronchitis virus (IBV), a gammacoronavirus, is an economically important virus to the poultry industry, as well as a significant welfare issue for chickens. As for all positive strand RNA viruses, IBV infection causes rearrangements of the host cell intracellular membranes to form replication organelles. Replication organelle formation is a highly conserved and vital step in the viral life cycle. Here, we investigate the localization of viral RNA synthesis and the link with replication organelles in host cells. We have shown that sites of viral RNA synthesis and virus-related dsRNA are associated with one another and, significantly, that they are located within a membrane-bound compartment within the cell. We have also shown that some viral RNA produced early in infection remains within these membranes throughout infection, while a proportion is trafficked to the cytoplasm. Importantly, we demonstrate conservation across all four coronavirus genera, including SARS-CoV-2. Understanding more about the replication of these viruses is imperative in order to effectively find ways to control them.


Subject(s)
Coronavirus/metabolism , Intracellular Membranes/metabolism , RNA, Viral/biosynthesis , Animals , Cell Line , Coronavirus/classification , Coronavirus/growth & development , Cytoplasm/metabolism , Humans , Infectious bronchitis virus/growth & development , Infectious bronchitis virus/metabolism , RNA, Double-Stranded/metabolism , Viral Replication Compartments/metabolism
6.
Int J Mol Sci ; 22(11)2021 May 26.
Article in English | MEDLINE | ID: covidwho-1244042

ABSTRACT

Infection induces the production of proinflammatory cytokines and chemokines such as interleukin-8 (IL-8) and IL-6. Although they facilitate local antiviral immunity, their excessive release leads to life-threatening cytokine release syndrome, exemplified by the severe cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this study, we investigated the roles of the integrated stress response (ISR) and activator protein-1 (AP-1) family proteins in regulating coronavirus-induced IL-8 and IL-6 upregulation. The mRNA expression of IL-8 and IL-6 was significantly induced in cells infected with infectious bronchitis virus (IBV), a gammacoronavirus, and porcine epidemic diarrhea virus, an alphacoronavirus. Overexpression of a constitutively active phosphomimetic mutant of eukaryotic translation initiation factor 2α (eIF2α), chemical inhibition of its dephosphorylation, or overexpression of its upstream double-stranded RNA-dependent protein kinase (PKR) significantly enhanced IL-8 mRNA expression in IBV-infected cells. Overexpression of the AP-1 protein cJUN or its upstream kinase also increased the IBV-induced IL-8 mRNA expression, which was synergistically enhanced by overexpression of cFOS. Taken together, this study demonstrated the important regulatory roles of ISR and AP-1 proteins in IL-8 production during coronavirus infection, highlighting the complex interactions between cellular stress pathways and the innate immune response.


Subject(s)
Coronavirus Infections/metabolism , Endoplasmic Reticulum Stress/genetics , Eukaryotic Initiation Factor-2/metabolism , Interleukin-8/metabolism , Unfolded Protein Response/genetics , Alphacoronavirus/metabolism , Alphacoronavirus/pathogenicity , Animals , Cell Line , Chlorocebus aethiops , Coronavirus Infections/genetics , Gammacoronavirus/metabolism , Gammacoronavirus/pathogenicity , Gene Expression Regulation , Humans , Immunity, Innate , Infectious bronchitis virus/metabolism , Infectious bronchitis virus/pathogenicity , Interleukin-8/genetics , Phosphorylation , Porcine epidemic diarrhea virus/metabolism , Porcine epidemic diarrhea virus/pathogenicity , Proto-Oncogene Proteins c-fos/genetics , Proto-Oncogene Proteins c-fos/metabolism , Proto-Oncogene Proteins c-jun/genetics , Proto-Oncogene Proteins c-jun/metabolism , Signal Transduction/genetics , Transcription Factor AP-1/genetics , Transcription Factor AP-1/metabolism , Up-Regulation , Vero Cells , eIF-2 Kinase/genetics , eIF-2 Kinase/metabolism
7.
Viruses ; 12(10)2020 09 29.
Article in English | MEDLINE | ID: covidwho-906373

ABSTRACT

The Gammacoronavirus infectious bronchitis virus (IBV) causes a highly contagious and economically important respiratory disease in poultry. In the laboratory, most IBV strains are restricted to replication in ex vivo organ cultures or in ovo and do not replicate in cell culture, making the study of their basic virology difficult. Entry of IBV into cells is facilitated by the large glycoprotein on the surface of the virion, the spike (S) protein, comprised of S1 and S2 subunits. Previous research showed that the S2' cleavage site is responsible for the extended tropism of the IBV Beaudette strain. This study aims to investigate whether protease treatment can extend the tropism of other IBV strains. Here we demonstrate that the addition of exogenous trypsin during IBV propagation in cell culture results in significantly increased viral titres. Using a panel of IBV strains, exhibiting varied tropisms, the effects of spike cleavage on entry and replication were assessed by serial passage cell culture in the presence of trypsin. Replication could be maintained over serial passages, indicating that the addition of exogenous protease is sufficient to overcome the barrier to infection. Mutations were identified in both S1 and S2 subunits following serial passage in cell culture. This work provides a proof of concept that exogenous proteases can remove the barrier to IBV replication in otherwise non-permissive cells, providing a platform for further study of elusive field strains and enabling sustainable vaccine production in vitro.


Subject(s)
Coronavirus Infections/drug therapy , Coronavirus Infections/virology , Infectious bronchitis virus/drug effects , Infectious bronchitis virus/physiology , Trypsin/therapeutic use , Viral Tropism/drug effects , Animals , Cell Line , Chlorocebus aethiops , Gammacoronavirus/drug effects , Infectious bronchitis virus/metabolism , Kinetics , Serial Passage , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells , Viral Envelope Proteins/metabolism , Virion/drug effects , Virion/metabolism , Virus Replication/drug effects
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