scholarly journals Human and Murine IFIT1 Proteins Do Not Restrict Infection of Negative-Sense RNA Viruses of the Orthomyxoviridae, Bunyaviridae, and Filoviridae Families

2015 ◽  
Vol 89 (18) ◽  
pp. 9465-9476 ◽  
Author(s):  
Amelia K. Pinto ◽  
Graham D. Williams ◽  
Kristy J. Szretter ◽  
James P. White ◽  
José Luiz Proença-Módena ◽  
...  
Keyword(s):  
Cell Culture ◽  
Antiviral Activity ◽  
Ebola Virus ◽  
Rna Viruses ◽  
Ectopic Expression ◽  
A549 Cells ◽  
Host Protein ◽  
Interferon Response ◽  
Restriction Factor ◽  
Negative Sense

ABSTRACTInterferon-induced protein with tetratricopeptide repeats 1 (IFIT1) is a host protein with reported cell-intrinsic antiviral activity against several RNA viruses. The proposed basis for the activity against negative-sense RNA viruses is the binding to exposed 5′-triphosphates (5′-ppp) on the genome of viral RNA. However, recent studies reported relatively low binding affinities of IFIT1 for 5′-ppp RNA, suggesting that IFIT1 may not interact efficiently with this moiety under physiological conditions. To evaluate the ability of IFIT1 to have an impact on negative-sense RNA viruses, we infectedIfit1−/−and wild-type control mice and primary cells with four negative-sense RNA viruses (influenza A virus [IAV], La Crosse virus [LACV], Oropouche virus [OROV], and Ebola virus) corresponding to three distinct families. Unexpectedly, a lack ofIfit1gene expression did not result in increased infection by any of these viruses in cell culture. Analogously, morbidity, mortality, and viral burdens in tissues were identical betweenIfit1−/−and control mice after infection with IAV, LACV, or OROV. Finally, deletion of the human IFIT1 protein in A549 cells did not affect IAV replication or infection, and reciprocally, ectopic expression of IFIT1 in HEK293T cells did not inhibit IAV infection. To explain the lack of antiviral activity against IAV, we measured the binding affinity of IFIT1 for RNA oligonucleotides resembling the 5′ ends of IAV gene segments. The affinity for 5′-ppp RNA was approximately 10-fold lower than that for non-2′-O-methylated (cap 0) RNA oligonucleotides. Based on this analysis, we conclude that IFIT1 is not a dominant restriction factor against negative-sense RNA viruses.IMPORTANCENegative-sense RNA viruses, including influenza virus and Ebola virus, have been responsible for some of the most deadly outbreaks in recent history. The host interferon response and induction of antiviral genes contribute to the control of infections by these viruses. IFIT1 is highly induced after virus infection and reportedly has antiviral activity against several RNA and DNA viruses. However, its role in restricting infection by negative-sense RNA viruses remains unclear. In this study, we evaluated the ability of IFIT1 to inhibit negative-sense RNA virus replication and pathogenesis bothin vitroandin vivo. Detailed cell culture and animal studies demonstrated that IFIT1 is not a dominant restriction factor against three different families of negative-sense RNA viruses.

DDX3 inhibitors show antiviral activity against positive-sense single-stranded RNA viruses but not against negative-sense single-stranded RNA viruses: The coxsackie B model

2020 ◽  
Vol 178 ◽  
pp. 104750 ◽  
Author(s):  
Paola Quaranta ◽  
Giulia Lottini ◽  
Giulia Chesi ◽  
Flavia Contrafatto ◽  
Roberta Russotto ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Rna Viruses ◽  
Positive Sense ◽  
Negative Sense ◽  
Coxsackie B

scholarly journals Sequence-Specific Modifications Enhance the Broad-Spectrum Antiviral Response Activated by RIG-I Agonists

2015 ◽  
Vol 89 (15) ◽  
pp. 8011-8025 ◽  
Author(s):  
Cindy Chiang ◽  
Vladimir Beljanski ◽  
Kevin Yin ◽  
David Olagnier ◽  
Fethia Ben Yebdri ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Inflammatory Responses ◽  
Rna Viruses ◽  
Rna Virus ◽  
A549 Cells ◽  
Antiviral Response ◽  
Interferon Response

ABSTRACTThe cytosolic RIG-I (retinoic acid-inducible gene I) receptor plays a pivotal role in the initiation of the immune response against RNA virus infection by recognizing short 5′-triphosphate (5′ppp)-containing viral RNA and activating the host antiviral innate response. In the present study, we generated novel 5′ppp RIG-I agonists of varieous lengths, structures, and sequences and evaluated the generation of the antiviral and inflammatory responses in human epithelial A549 cells, human innate immune primary cells, and murine models of influenza and chikungunya viral pathogenesis. A 99-nucleotide, uridine-rich hairpin 5′pppRNA termed M8 stimulated an extensive and robust interferon response compared to other modified 5′pppRNA structures, RIG-I aptamers, or poly(I·C). Interestingly, manipulation of the primary RNA sequence alone was sufficient to modulate antiviral activity and inflammatory response, in a manner dependent exclusively on RIG-I and independent of MDA5 and TLR3. Both prophylactic and therapeutic administration of M8 effectively inhibited influenza virus and dengue virus replicationin vitro. Furthermore, multiple strains of influenza virus that were resistant to oseltamivir, an FDA-approved therapeutic treatment for influenza, were highly sensitive to inhibition by M8. Finally, prophylactic M8 treatmentin vivoprolonged survival and reduced lung viral titers of mice challenged with influenza virus, as well as reducing chikungunya virus-associated foot swelling and viral load. Altogether, these results demonstrate that 5′pppRNA can be rationally designed to achieve a maximal RIG-I-mediated protective antiviral response against human-pathogenic RNA viruses.IMPORTANCEThe development of novel therapeutics to treat human-pathogenic RNA viral infections is an important goal to reduce spread of infection and to improve human health and safety. This study investigated the design of an RNA agonist with enhanced antiviral and inflammatory properties against influenza, dengue, and chikungunya viruses. A novel, sequence-dependent, uridine-rich RIG-I agonist generated a protective antiviral responsein vitroandin vivoand was effective at concentrations 100-fold lower than prototype sequences or other RNA agonists, highlighting the robust activity and potential clinical use of the 5′pppRNA against RNA virus infection. Altogether, the results identify a novel, sequence-specific RIG-I agonist as an attractive therapeutic candidate for the treatment of a broad range of RNA viruses, a pressing issue in which a need for new and more effective options persists.

scholarly journals Inhibition of arenavirus entry and replication by the cell-intrinsic restriction factor ZMPSTE24 is enhanced by IFITM antiviral activity

2021 ◽  
Author(s):  
Robert J Stott ◽  
Toshana L Foster
Keyword(s):  
Virus Infection ◽  
Antiviral Activity ◽  
Viral Entry ◽  
Transmembrane Protein ◽  
Membrane Integrity ◽  
A549 Cells ◽  
Cellular Membrane ◽  
Restriction Factor ◽  
Lassa Virus ◽  
Live Virus

In the absence of effective vaccines and treatments, annual outbreaks of severe human haemorrhagic fever caused by arenaviruses, such as Lassa virus, continue to pose a significant human health threat. Understanding the balance of cellular factors that inhibit or promote arenavirus infection may have important implications for the development of effective antiviral strategies. Here, we identified the cell-intrinsic zinc transmembrane metalloprotease, ZMPSTE24, as a restriction factor against arenaviruses. Notably, CRISPR-Cas9-mediated knockout of ZMPSTE24 in human alveolar epithelial A549 cells increased arenavirus glycoprotein-mediated viral entry in pseudoparticle assays and live virus infection models. As a barrier to viral entry and replication, ZMPSTE24 may act as a downstream effector of interferon-induced transmembrane protein (IFITM) antiviral function; though through a yet poorly understood mechanism. Overexpression of IFITM1, IFITM2 and IFITM3 proteins did not restrict the entry of pseudoparticles carrying arenavirus envelope glycoproteins and live virus infection, yet depletion of IFITM protein expression enhanced virus entry and replication. Furthermore, gain-of-function studies revealed that IFITMs augment the antiviral activity of ZMPSTE24 against arenaviruses, suggesting a cooperative effect of viral restriction. We show that ZMPSTE24 and IFITMs affect the kinetics of cellular endocytosis, suggesting that perturbation of membrane structure and stability is likely the mechanism of ZMPSTE24-mediated restriction and cooperative ZMPSTE24-IFITM antiviral activity. Collectively, our findings define the role of ZMPSTE24 host restriction activity in the early stages of arenavirus infection. Moreover, we provide insight into the importance of cellular membrane integrity for productive fusion of arenaviruses and highlight a novel avenue for therapeutic development.

scholarly journals Reduced Nucleoprotein availability impairs negative-sense RNA virus replication and promotes host recognition

2021 ◽  
Author(s):  
Benjamin E. Nilsson-Payant ◽  
Daniel Blanco-Melo ◽  
Skyler Uhl ◽  
Beatriz Escudero-Pérez ◽  
Silke Olschewski ◽  
...  
Keyword(s):  
Host Response ◽  
Measles Virus ◽  
Influenza A ◽  
Ebola Virus ◽  
Rna Viruses ◽  
Viral Rna ◽  
Genome Replication ◽  
Replication Machinery ◽  
Molecular Patterns ◽  
Negative Sense

Negative-sense RNA viruses (NSVs) rely on prepackaged viral RNA-dependent RNA polymerases (RdRp) to replicate and transcribe their viral genomes. Their replication machinery consists of an RdRp bound to viral RNA which is wound around a nucleoprotein (NP) scaffold, forming a viral ribonucleoprotein complex. NSV NP is known to regulate transcription and replication of genomic RNA, however its role in maintaining and protecting the viral genetic material is unknown. Here, we exploited host microRNA expression to target NP of influenza A virus and Sendai virus to ascertain how this would impact genomic levels and the host response to infection. We find that in addition to inducing a drastic decrease in genome replication, the antiviral host response in the absence of NP is dramatically enhanced. Additionally, our data shows that insufficient levels of NP prevent the replication machinery of these NSVs to process full-length genomes, resulting in aberrant replication products which form pathogen-associated molecular patterns in the process. These dynamics facilitate immune recognition by cellular pattern recognition receptors leading to a strong host antiviral response. Moreover, we observe that the consequences of limiting NP levels are universal amongst NSVs including Ebola virus, Lassa virus and Measles virus. Overall, these results provide new insights into viral genome replication of negative-sense RNA viruses and highlight novel avenues towards developing effective antiviral strategies, adjuvants, and/or live-attenuated vaccines. IMPORTANCE Negative-sense RNA viruses comprise some of the most important known human pathogens, including influenza A virus, measles virus and Ebola virus. These viruses possess RNA genomes that are unreadable to the host as they require specific viral RNA dependent RNA polymerases in conjunction with other viral proteins such as nucleoprotein to be replicated and transcribed. As this process generates a significant amount of pathogen-associated molecular patterns, this phylum of viruses can result in a robust induction of the intrinsic host cellular response. To circumvent these defenses, these viruses form tightly regulated ribonucleoprotein replication complexes in order to protect their genomes from detection and to prevent excessive aberrant replication. Here we demonstrate the balance that negative-sense RNA viruses must achieve to both replicate efficiently and to avoid induction of the host defenses.

scholarly journals Deletion of Cytoplasmic Double-Stranded RNA Sensors Does Not Uncover Viral Small Interfering RNA Production in Human Cells

mSphere ◽  
2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Susan Schuster ◽  
Lotte E. Tholen ◽  
Gijs J. Overheul ◽  
Frank J. M. van Kuppeveld ◽  
Ronald P. van Rij
Keyword(s):  
Rna Interference ◽  
Antiviral Activity ◽  
Mammalian Cells ◽  
Rna Viruses ◽  
Antiviral Immunity ◽  
Antiviral Effect ◽  
Interferon Response ◽  
Rnai Pathway ◽  
Differentiated Cells ◽  
Positive Sense

ABSTRACT The contribution of the RNA interference (RNAi) pathway in antiviral immunity in vertebrates has been widely debated. It has been proposed that RNAi possesses antiviral activity in mammalian systems but that its antiviral effect is masked by the potent antiviral interferon response in differentiated mammalian cells. In this study, we show that inactivation of the interferon response is not sufficient to uncover antiviral activity of RNAi in human epithelial cells infected with three wild-type positive-sense RNA viruses. Antiviral immunity in insects and plants is mediated by the RNA interference (RNAi) pathway in which viral long double-stranded RNA (dsRNA) is processed into small interfering RNAs (siRNAs) by Dicer enzymes. Although this pathway is evolutionarily conserved, its involvement in antiviral defense in mammals is the subject of debate. In vertebrates, recognition of viral RNA induces a sophisticated type I interferon (IFN)-based immune response, and it has been proposed that this response masks or inhibits antiviral RNAi. To test this hypothesis, we analyzed viral small RNA production in differentiated cells deficient in the cytoplasmic RNA sensors RIG-I and MDA5. We did not detect 22-nucleotide (nt) viral siRNAs upon infection with three different positive-sense RNA viruses. Our data suggest that the depletion of cytoplasmic RIG-I-like sensors is not sufficient to uncover viral siRNAs in differentiated cells. IMPORTANCE The contribution of the RNA interference (RNAi) pathway in antiviral immunity in vertebrates has been widely debated. It has been proposed that RNAi possesses antiviral activity in mammalian systems but that its antiviral effect is masked by the potent antiviral interferon response in differentiated mammalian cells. In this study, we show that inactivation of the interferon response is not sufficient to uncover antiviral activity of RNAi in human epithelial cells infected with three wild-type positive-sense RNA viruses.

scholarly journals Analysis of viral RNA-host protein interactomes enables rapid antiviral drug discovery

2021 ◽  
Author(s):  
Shaojun Zhang ◽  
Wenze Huang ◽  
Lili Ren ◽  
Xiaohui Ju ◽  
Mingli Gong ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Ebola Virus ◽  
Rna Viruses ◽  
Antiviral Drug ◽  
Antiviral Agent ◽  
Viral Rna ◽  
Host Protein ◽  
Host Responses ◽  
Interaction Patterns ◽  
Global Public Health

RNA viruses including SARS-CoV-2, Ebola virus (EBOV), and Zika virus (ZIKV) constitute a major threat to global public health and society. The interactions between viral genomes and host proteins are essential in the life cycle of RNA viruses and thus provide targets for drug development. However, viral RNA-host protein interactions have remained poorly characterized. Here we applied ChIRP-MS to profile the interactomes of human proteins and the RNA genomes of SARS-CoV-2, EBOV, and ZIKV in infected cells. Integrated interactome analyses revealed interaction patterns that reflect both common and virus-specific host responses, and enabled rapid drug screening to target the vulnerable host factors. We identified Enasidenib as a SARS-CoV-2 specific antiviral agent, and Trifluoperazine and Cepharanthine as broad spectrum antivirals against all three RNA viruses.

scholarly journals Efficient incorporation and template-dependent polymerase inhibition are major determinants for the broad-spectrum antiviral activity of remdesivir

2021 ◽  
Author(s):  
Matthias Götte ◽  
Calvin J. Gordon ◽  
Hery W. Lee ◽  
Egor P. Tchesnokov ◽  
Jason K. Perry ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Broad Spectrum ◽  
Rna Viruses ◽  
Cyano Group ◽  
Nipah Virus ◽  
Antiviral Agent ◽  
Hemorrhagic Fever ◽  
Inhibitory Effects ◽  
Hemorrhagic Fever Virus ◽  
Negative Sense

Remdesivir (RDV) is a direct antiviral agent that is approved in several countries for the treatment of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RDV exhibits broad-spectrum antiviral activity against positive-sense RNA viruses, e.g., SARS-CoV-2 and hepatitis C virus (HCV) and non-segmented negative-sense RNA viruses, e.g., Nipah virus (NiV), while several segmented negative-sense RNA viruses such as influenza (Flu) virus or Crimean-Congo hemorrhagic fever virus (CCHFV) are not sensitive to the drug. The reasons for this apparent pattern are unknown. Here, we expressed and purified representative RNA-dependent RNA polymerases (RdRp) and studied three biochemical parameters that have been associated with the inhibitory effects of RDV-triphosphate (TP): (i) selective incorporation of the nucleotide substrate RDV-TP, (ii) the effect of the incorporated RDV-monophosphate (MP) on primer extension, and (iii) the effect of RDV-MP in the template during incorporation of the complementary UTP. The results of this study revealed a strong correlation between antiviral effects and efficient incorporation of RDV-TP. Delayed chain-termination is heterogeneous and usually inefficient at higher NTP concentrations. In contrast, template-dependent inhibition of UTP incorporation opposite the embedded RDV-MP is seen with all polymerases. Molecular modeling suggests a steric conflict between the 1′-cyano group of RDV-MP and conserved residues of RdRp motif F. We conclude that future efforts in the development of nucleotide analogues with a broader spectrum of antiviral activities should focus on improving rates of incorporation while capitalizing on the inhibitory effects of a bulky 1′-modification.

scholarly journals VP35 Knockdown Inhibits Ebola Virus Amplification and Protects against Lethal Infection in Mice

2006 ◽  
Vol 50 (3) ◽  
pp. 984-993 ◽  
Author(s):  
Sven Enterlein ◽  
Kelly L. Warfield ◽  
Dana L. Swenson ◽  
David A. Stein ◽  
Jeffery L. Smith ◽  
...  
Keyword(s):  
Cell Culture ◽  
Ebola Virus ◽  
Rna Viruses ◽  
Marburg Virus ◽  
Lethal Infection ◽  
Dependent Inhibition ◽  
Dna Analogs ◽  
Ebov Infection ◽  
Dose Dependent Inhibition ◽  
Positive Strand Rna

ABSTRACT Phosphorodiamidate morpholino oligomers (PMO) are a class of uncharged single-stranded DNA analogs modified such that each subunit includes a phosphorodiamidate linkage and morpholine ring. PMO antisense agents have been reported to effectively interfere with the replication of several positive-strand RNA viruses in cell culture. The filoviruses, Marburg virus and Ebola virus (EBOV), are negative-strand RNA viruses that cause up to 90% lethality in human outbreaks. There is currently no commercially available vaccine or efficacious therapeutic for any filovirus. In this study, PMO conjugated to arginine-rich cell-penetrating peptide (P-PMO) and nonconjugated PMO were assayed for the ability to inhibit EBOV infection in cell culture and in a mouse model of lethal EBOV infection. A 22-mer P-PMO designed to base pair with the translation start site region of EBOV VP35 positive-sense RNA generated sequence-specific and time- and dose-dependent inhibition of EBOV amplification in cell culture. The same oligomer provided complete protection to mice when administered before or after an otherwise lethal infection of EBOV. A corresponding nonconjugated PMO, as well as nonconjugated truncated versions of 16 and 19 base residues, provided length-dependent protection to mice when administered prophylactically. Together, these data suggest that antisense PMO and P-PMO have the potential to control EBOV infection and are promising therapeutic candidates.

scholarly journals Generation of a Sleeping Beauty Transposon-Based Cellular System for Rapid and Sensitive Screening for Compounds and Cellular Factors Limiting SARS-CoV-2 Replication

2021 ◽  
Vol 12 ◽  
Author(s):  
Marek Widera ◽  
Alexander Wilhelm ◽  
Tuna Toptan ◽  
Johanna M. Raffel ◽  
Eric Kowarz ◽  
...  
Keyword(s):  
Cell Culture ◽  
Transfection Efficiency ◽  
Signal To Noise Ratio ◽  
A549 Cells ◽  
Constitutive Expression ◽  
Sleeping Beauty ◽  
Interferon Response ◽  
Infection Model ◽  
Proliferation Capacity ◽  
Extensive Evaluation

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the acute respiratory disease COVID-19, which has become a global concern due to its rapid spread. The common methods to monitor and quantitate SARS-CoV-2 infectivity in cell culture are so far time-consuming and labor-intensive. Using the Sleeping Beauty transposase system, we generated a robust and versatile cellular infection model that allows SARS-CoV-2 infection experiments compatible for high-throughput and live cell imaging. The model is based on lung derived A549 cells, which show a profound interferon response and convenient cell culture characteristics. ACE2 and TMPRSS2 were introduced for constitutive expression (A549-AT). Subclones with varying levels of ACE2/TMPRSS2 were screened for optimal SARS-CoV-2 susceptibility. Furthermore, extensive evaluation demonstrated that SARS-CoV-2 infected A549-AT cells were distinguishable from mock-infected cells and already showed approximately 12 h post infection a clear signal to noise ratio in terms of cell roughness, fluorescence and a profound visible cytopathic effect. Moreover, due to the high transfection efficiency and proliferation capacity, Sleeping Beauty transposase-based overexpression cell lines with a second inducible fluorescence reporter cassette (eGFP) can be generated in a very short time, enabling the investigation of host and restriction factors in a doxycycline-inducible manner. Thus, the novel model cell line allows rapid and sensitive monitoring of SARS-CoV-2 infection and the screening for host factors essential for viral replication.

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