scholarly journals Virus-Specific Responses of Heterosigma akashiwo to Infection

2006 ◽  
Vol 72 (12) ◽  
pp. 7829-7834 ◽  
Author(s):  
Janice E. Lawrence ◽  
Corina P. D. Brussaard ◽  
Curtis A. Suttle
Keyword(s):  
Viral Infection ◽  
Rna Virus ◽  
Geographic Area ◽  
Heterosigma Akashiwo ◽  
Dna Virus ◽  
Cellular Physiology ◽  
Sytox Green ◽  
Double Stranded Dna ◽  
Infected Cells

ABSTRACT We used flow cytometry to examine the process of cell death in the bloom-forming alga Heterosigma akashiwo during infection by a double-stranded DNA virus (OIs1) and a single-stranded RNA virus (H. akashiwo RNA virus [HaRNAV]). These viruses were isolated from the same geographic area and infect the same strain of H. akashiwo. By use of the live/dead stains fluorescein diacetate and SYTOX green as indicators of cellular physiology, cells infected with OIs1 showed signs of infection earlier than HaRNAV-infected cultures (6 to 17 h versus 23 to 29 h). Intracellular esterase activity was lost prior to increased membrane permeability during infection with OIs1, while the opposite was seen with HaRNAV-infected cultures. In addition, OIs1-infected cells accumulated in the cultures while HaRNAV-infected cells rapidly disintegrated. Progeny OIs1 viruses consisted of large and small morphotypes with estimated latent periods of 11 and 17 h, respectively, and about 1,100 and 16,000 viruses produced per cell, respectively. In contrast, HaRNAV produced about 21,000 viruses per cell and had a latent period of 29 h. This study reveals that the characteristics of viral infection in algae are virus dependent and therefore are variable among viruses infecting the same species. This is an important consideration for ecosystem modeling exercises; calculations based on in situ measurements of algal physiology must be sensitive to the diverse responses of algae to viral infection.

scholarly journals Rotavirus Antagonizes Cellular Antiviral Responses by Inhibiting the Nuclear Accumulation of STAT1, STAT2, and NF-κB

2009 ◽  
Vol 83 (10) ◽  
pp. 4942-4951 ◽  
Author(s):  
Gavan Holloway ◽  
Thanhmai T. Truong ◽  
Barbara S. Coulson
Keyword(s):  
Gene Expression ◽  
Viral Infection ◽  
Rna Virus ◽  
Host Responses ◽  
Nuclear Accumulation ◽  
Type I ◽  
Nonstructural Proteins ◽  
Necrosis Factor Alpha ◽  
Intracellular Expression ◽  
Infected Cells

ABSTRACT A vital arm of the innate immune response to viral infection is the induction and subsequent antiviral effects of interferon (IFN). Rotavirus reduces type I IFN induction in infected cells by the degradation of IFN regulatory factors. Here, we show that the monkey rotavirus RRV and human rotavirus Wa also block gene expression induced by type I and II IFNs through a mechanism allowing signal transducer and activator of transcription 1 (STAT1) and STAT2 activation but preventing their nuclear accumulation. In infected cells, this may allow rotavirus to block the antiviral actions of IFN produced early in infection or by activated immune cells. As the intracellular expression of rotavirus nonstructural proteins NSP1, NSP3, and NSP4 individually did not inhibit IFN-stimulated gene expression, their involvement in this process is unlikely. RRV and Wa rotaviruses also prevented the tumor necrosis factor alpha-stimulated nuclear accumulation of NF-κB and NF-κB-driven gene expression. In addition, NF-κB was activated by rotavirus infection, confirming earlier findings by others. As NF-κB is important for the induction of IFN and other cytokines during viral infection, this suggests that rotavirus prevents cellular transcription as a means to evade host responses. To our knowledge, this is the first report of the use of this strategy by a double-stranded RNA virus.

scholarly journals Sensitive visualization of SARS-CoV-2 RNA with CoronaFISH

2021 ◽  
Author(s):  
Elena Rensen ◽  
Stefano Pietropaoli ◽  
Christian Weber ◽  
Sylvie Souquere ◽  
Pierre Isnard ◽  
...  
Keyword(s):  
Human Tissue ◽  
Rna Virus ◽  
Viral Rna ◽  
Initial Application ◽  
Positive Sense ◽  
Therapeutic Molecules ◽  
Infected Cells ◽  
Detailed Protocol ◽  
Transcription And Replication

AbstractThe current COVID-19 pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The positive-sense single-stranded RNA virus contains a single linear RNA segment that serves as a template for transcription and replication, leading to the synthesis of positive and negative-stranded viral RNA (vRNA) in infected cells. Tools to visualize viral RNA directly in infected cells are critical to analyze its replication cycle, screen for therapeutic molecules or study infections in human tissue. Here, we report the design, validation and initial application of fluorescence in situ hybridization (FISH) probes to visualize positive or negative RNA of SARS-CoV-2 (CoronaFISH). We demonstrate sensitive visualization of vRNA in African green monkey and several human cell lines, in patient samples and human tissue. We further demonstrate the adaptation of CoronaFISH probes to electron microscopy (EM). We provide all required oligonucleotide sequences, source code to design the probes, and a detailed protocol. We hope that CoronaFISH will complement existing techniques for research on SARS-CoV-2 biology and COVID-19 pathophysiology, drug screening and diagnostics.

scholarly journals Visualizing Antigen-Specific and Infected Cells in Situ Predicts Outcomes in Early Viral Infection

Science ◽  
2009 ◽  
Vol 323 (5922) ◽  
pp. 1726-1729 ◽  
Author(s):  
Q. Li ◽  
P. J. Skinner ◽  
S.-J. Ha ◽  
L. Duan ◽  
T. L. Mattila ◽  
...  
Keyword(s):  
Viral Infection ◽  
Infected Cells

scholarly journals Innate immunity to RNA virus is regulated by temporal and reversible sumoylation of RIG-I and MDA5

2017 ◽  
Vol 214 (4) ◽  
pp. 973-989 ◽  
Author(s):  
Ming-Ming Hu ◽  
Chen-Yang Liao ◽  
Qing Yang ◽  
Xue-Qin Xie ◽  
Hong-Bing Shu
Keyword(s):  
Innate Immunity ◽  
Viral Infection ◽  
Rna Virus ◽  
Late Phase ◽  
Antiviral Response ◽  
Viral Rna ◽  
Before And After ◽  
Infected Cells ◽  
Sumo E3 Ligase ◽  
Innate Antiviral Response

Sensing of viral RNA by the cytosolic receptors RIG-I and melanoma differentiation-associated gene 5 (MDA5) leads to innate antiviral response. How RIG-I and MDA5 are dynamically regulated in innate antiviral response is not well understood. Here, we show that TRIM38 positively regulates MDA5- and RIG-I–mediated induction of downstream genes and acts as a SUMO E3 ligase for their dynamic sumoylation at K43/K865 and K96/K888, respectively, before and after viral infection. The sumoylation of MDA5 and RIG-I suppresses their K48-linked polyubiquitination and degradation in uninfected or early-infected cells. Sumoylation of the caspase recruitment domains of MDA5 and RIG-I is also required for their dephosphorylation by PP1 and activation upon viral infection. At the late phase of viral infection, both MDA5 and RIG-I are desumoylated by SENP2, resulting in their K48-linked polyubiquitination and degradation. These findings suggest that dynamic sumoylation and desumoylation of MDA5 and RIG-I modulate efficient innate immunity to RNA virus and its timely termination.

scholarly journals Differential distribution of single-stranded DNA, double-stranded DNA, and RNA in adenovirus-induced intranuclear regions of HeLa cells.

1995 ◽  
Vol 43 (8) ◽  
pp. 749-759 ◽  
Author(s):  
M Thiry ◽  
F Puvion-Dutilleul
Keyword(s):  
Hela Cells ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Storage Site ◽  
Differential Distribution ◽  
Single Stranded Dna ◽  
Dna And Rna ◽  
Double Stranded Dna ◽  
Infected Cells ◽  
Nuclear Structures

We investigated in great detail the fine spatial distribution of nucleic acids within adenovirus-infected HeLa cells by various immunogold labeling procedures. To detect DNA, we used the in situ terminal deoxynucleotidyl transferase-immunogold technique. In addition to the expected evident label over the condensed host chromatin and the structures containing viral double- and single-stranded DNA, label was consistently revealed over round fibrillar spots. By contrast, other virus-induced substructures, such as compact rings, crystalloids, clear amorphous inclusions, and electron-dense amorphous inclusions, displayed no significant label. Except for the viral single-stranded DNA accumulation sites, identical labeling pattern was obtained with the in situ nick-translation-immunogold method. We further labeled the sections with anti-RNA antibodies. Label was present not only over the cytoplasm and the intranuclear fibrillogranular network but also quite obviously over the compact rings and interchromatin granule clusters. None was seen over the other nuclear structures of infected cells, notably over the fibrillar spots. We suggest that these fibrillar spots might be involved in the formation of the viral, non-encapsidated, double-stranded DNA storage site.

scholarly journals The Pro-Inflammatory Chemokines CXCL9, CXCL10 and CXCL11 Are Upregulated Following SARS-CoV-2 Infection in an AKT-Dependent Manner

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1062
Author(s):  
Victoria Callahan ◽  
Seth Hawks ◽  
Matthew A. Crawford ◽  
Caitlin W. Lehman ◽  
Holly A. Morrison ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Virus ◽  
Pulmonary Complications ◽  
Lung Epithelial Cells ◽  
Dependent Manner ◽  
Akt Inhibitor ◽  
Inflammatory Chemokines ◽  
Inflammatory State ◽  
Infected Cells ◽  
Ifn Γ

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible RNA virus that is the causative agent of the Coronavirus disease 2019 (COVID-19) pandemic. Patients with severe COVID-19 may develop acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) and require mechanical ventilation. Key features of SARS-CoV-2 induced pulmonary complications include an overexpression of pro-inflammatory chemokines and cytokines that contribute to a ‘cytokine storm.’ In the current study an inflammatory state in Calu-3 human lung epithelial cells was characterized in which significantly elevated transcripts of the immunostimulatory chemokines CXCL9, CXCL10, and CXCL11 were present. Additionally, an increase in gene expression of the cytokines IL-6, TNFα, and IFN-γ was observed. The transcription of CXCL9, CXCL10, IL-6, and IFN-γ was also induced in the lungs of human transgenic angiotensin converting enzyme 2 (ACE2) mice infected with SARS-CoV-2. To elucidate cell signaling pathways responsible for chemokine upregulation in SARS-CoV-2 infected cells, small molecule inhibitors targeting key signaling kinases were used. The induction of CXCL9, CXCL10, and CXCL11 gene expression in response to SARS-CoV-2 infection was markedly reduced by treatment with the AKT inhibitor GSK690693. Samples from COVID-19 positive individuals also displayed marked increases in CXCL9, CXCL10, and CXCL11 transcripts as well as transcripts in the AKT pathway. The current study elucidates potential pathway specific targets for reducing the induction of chemokines that may be contributing to SARS-CoV-2 pathogenesis via hyperinflammation.

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