scholarly journals ISG15 Arg151 and the ISG15-Conjugating Enzyme UbE1L Are Important for Innate Immune Control of Sindbis Virus

2008 ◽  
Vol 83 (4) ◽  
pp. 1602-1610 ◽  
Author(s):  
Nadia V. Giannakopoulos ◽  
Elena Arutyunova ◽  
Caroline Lai ◽  
Deborah J. Lenschow ◽  
Arthur L. Haas ◽  
...  
Keyword(s):  
Virus Infection ◽  
Survival Benefit ◽  
Sindbis Virus ◽  
Innate Immune ◽  
Protein Conjugates ◽  
Antiviral Effects ◽  
Antiviral Function ◽  
Alpha Beta

ABSTRACT Interferon (IFN)-stimulated gene 15 (ISG15) is a ubiquitin-like molecule that conjugates to target proteins via a C-terminal LRLRGG motif and has antiviral function in vivo. We used structural modeling to predict human ISG15 (hISG15) residues important for interacting with its E1 enzyme, UbE1L. Kinetic analysis revealed that mutation of arginine 153 to alanine (R153A) ablated hISG15-hUbE1L binding and transthiolation of UbcH8. Mutation of other predicted UbE1L-interacting residues had minimal effects on the transfer of ISG15 from UbE1L to UbcH8. The capacity of hISG15 R153A to form protein conjugates in 293T cells was markedly diminished. Mutation of the homologous residue in mouse ISG15 (mISG15), arginine 151, to alanine (R151A) also attenuated protein ISGylation following transfection into 293T cells. We assessed the role of ISG15-UbE1L interactions in control of virus infection by constructing double subgenomic Sindbis viruses that expressed the mISG15 R151A mutant. While expression of mISG15 protected alpha/beta-IFN-receptor-deficient (IFN-αβR−/−) mice from lethality following Sindbis virus infection, expression of mISG15 R151A conferred no survival benefit. The R151A mutation also attenuated ISG15's ability to decrease Sindbis virus replication in IFN-αβR−/− mice or prolong survival of ISG15−/− mice. The importance of UbE1L was confirmed by demonstrating that mice lacking this ISG15 E1 enzyme were highly susceptible to Sindbis virus infection. Together, these data support a role for protein conjugation in the antiviral effects of ISG15.

scholarly journals Efficient Dicer processing of virus-derived double-stranded RNAs and its modulation by RIG-I-like receptor LGP2

2021 ◽  
Vol 17 (8) ◽  
pp. e1009790
Author(s):  
Yuqiang Zhang ◽  
Yan Xu ◽  
Yunpeng Dai ◽  
Zhe Li ◽  
Jiaxing Wang ◽  
...  
Keyword(s):  
Virus Infection ◽  
Sindbis Virus ◽  
De Novo ◽  
Somatic Cells ◽  
Interferon Response ◽  
Small Interfering Rnas ◽  
Rnai Suppressor ◽  
Antiviral Function

The interferon-regulated antiviral responses are essential for the induction of both innate and adaptive immunity in mammals. Production of virus-derived small-interfering RNAs (vsiRNAs) to restrict virus infection by RNA interference (RNAi) is a recently identified mammalian immune response to several RNA viruses, which cause important human diseases such as influenza and Zika virus. However, little is known about Dicer processing of viral double-stranded RNA replicative intermediates (dsRNA-vRIs) in mammalian somatic cells. Here we show that infected somatic cells produced more influenza vsiRNAs than cellular microRNAs when both were produced by human Dicer expressed de novo, indicating that dsRNA-vRIs are not poor Dicer substrates as previously proposed according to in vitro Dicer processing of synthetic long dsRNA. We report the first evidence both for canonical vsiRNA production during wild-type Nodamura virus infection and direct vsiRNA sequestration by its RNAi suppressor protein B2 in two strains of suckling mice. Moreover, Sindbis virus (SINV) accumulation in vivo was decreased by prior production of SINV-targeting vsiRNAs triggered by infection and increased by heterologous expression of B2 in cis from SINV genome, indicating an antiviral function for the induced RNAi response. These findings reveal that unlike artificial long dsRNA, dsRNA-vRIs made during authentic infection of mature somatic cells are efficiently processed by Dicer into vsiRNAs to direct antiviral RNAi. Interestingly, Dicer processing of dsRNA-vRIs into vsiRNAs was inhibited by LGP2 (laboratory of genetics and physiology 2), which was encoded by an interferon-stimulated gene (ISG) shown recently to inhibit Dicer processing of artificial long dsRNA in cell culture. Our work thus further suggests negative modulation of antiviral RNAi by a known ISG from the interferon response.

Flagellin induces innate immune genes in bronchial epithelial cells in vivo: Role of TET2

2021 ◽  
Author(s):  
Wanhai Qin ◽  
Xanthe Brands ◽  
Cornelis Veer ◽  
Alex F. Vos ◽  
Brendon P. Scicluna ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Bronchial Epithelial Cells ◽  
Innate Immune ◽  
Bronchial Epithelial ◽  
Immune Genes ◽  
Innate Immune Genes

scholarly journals ADAR1 function affects HPV replication and is associated to recurrent human papillomavirus-induced dysplasia in HIV coinfected individuals

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Maria Pujantell ◽  
Roger Badia ◽  
Iván Galván-Femenía ◽  
Edurne Garcia-Vidal ◽  
Rafael de Cid ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Immune Activation ◽  
Hpv Infection ◽  
Innate Immune ◽  
Type I ◽  
Innate Immune Activation ◽  
Enhanced Expression

AbstractInfection by human papillomavirus (HPV) alters the microenvironment of keratinocytes as a mechanism to evade the immune system. A-to-I editing by ADAR1 has been reported to regulate innate immunity in response to viral infections. Here, we evaluated the role of ADAR1 in HPV infection in vitro and in vivo. Innate immune activation was characterized in human keratinocyte cell lines constitutively infected or not with HPV. ADAR1 knockdown induced an innate immune response through enhanced expression of RIG-I-like receptors (RLR) signaling cascade, over-production of type-I IFNs and pro-inflammatory cytokines. ADAR1 knockdown enhanced expression of HPV proteins, a process dependent on innate immune function as no A-to-I editing could be identified in HPV transcripts. A genetic association study was performed in a cohort of HPV/HIV infected individuals followed for a median of 6 years (range 0.1–24). We identified the low frequency haplotype AACCAT significantly associated with recurrent HPV dysplasia, suggesting a role of ADAR1 in the outcome of HPV infection in HIV+ individuals. In summary, our results suggest that ADAR1-mediated innate immune activation may influence HPV disease outcome, therefore indicating that modification of innate immune effectors regulated by ADAR1 could be a therapeutic strategy against HPV infection.

scholarly journals JNK pathway restricts DENV, ZIKV and CHIKV infection by activating complement and apoptosis in mosquito salivary glands

2020 ◽  
Author(s):  
Avisha Chowdhury ◽  
Cassandra M. Modahl ◽  
Siok Thing Tan ◽  
Benjamin Wong Wei Xiang ◽  
Dorothée Missé ◽  
...  
Keyword(s):  
Immune Response ◽  
Virus Infection ◽  
Salivary Glands ◽  
Antiviral Effect ◽  
Negative Regulator ◽  
Chikv Infection ◽  
Jnk Pathway ◽  
Antiviral Effects ◽  
Antiviral Function ◽  
Arbovirus Infection

AbstractArbovirus infection of Aedes aegypti salivary glands (SGs) determines transmission. However, there is a dearth of knowledge on SG immunity. Here, we characterized SG immune response to dengue, Zika and chikungunya viruses using high-throughput transcriptomics. The three viruses regulate components of Toll, IMD and JNK pathways. However, silencing of Toll and IMD components showed variable effects on SG infection by each virus. In contrast, regulation of JNK pathway produced consistent responses. Virus infection increased with depletion of component Kayak and decreased with depletion of negative regulator Puckered. Virus-induced JNK pathway regulates complement and apoptosis in SGs via TEP20 and Dronc, respectively. Individual and co-silencing of these genes demonstrate their antiviral effects and that both may function together. Co-silencing either TEP20 or Dronc with Puckered annihilates JNK pathway antiviral effect. We identified and characterized the broad antiviral function of JNK pathway in SGs, expanding the immune arsenal that blocks arbovirus transmission.

scholarly journals Interferon-Stimulated Genes as Enhancers of Antiviral Innate Immune Signaling

2017 ◽  
Vol 10 (2) ◽  
pp. 85-93 ◽  
Author(s):  
Keaton M. Crosse ◽  
Ebony A. Monson ◽  
Michael R. Beard ◽  
Karla J. Helbig
Keyword(s):  
Immune Response ◽  
Viral Infection ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Regulatory Factor ◽  
Interferon Stimulated Genes ◽  
Innate Immune Signaling ◽  
Recent Advancement ◽  
Antiviral Function

The ability of a host to curb a viral infection is heavily reliant on the effectiveness of an initial antiviral innate immune response, resulting in the upregulation of interferon (IFN) and, subsequently, IFN-stimulated genes (ISGs). ISGs serve to mount an antiviral state within a host cell, and although the specific antiviral function of a number of ISGs has been characterized, the function of many of these ISGs remains to be determined. Recent research has uncovered a novel role for a handful of ISGs, some of them directly induced by IFN regulatory factor 3 in the absence of IFN itself. These ISGs, most with potent antiviral activity, are also able to augment varying arms of the innate immune response to viral infection, thereby strengthening this response. This new understanding of the role of ISGs may, in turn, help the recent advancement of novel therapeutics aiming to augment innate signaling pathways in an attempt to control viral infection and pathogenesis.

scholarly journals The ORF61 Protein Encoded by Simian Varicella Virus and Varicella-Zoster Virus Inhibits NF-κB Signaling by Interfering with IκBα Degradation

2015 ◽  
Vol 89 (17) ◽  
pp. 8687-8700 ◽  
Author(s):  
Travis Whitmer ◽  
Daniel Malouli ◽  
Luke S. Uebelhoer ◽  
Victor R. DeFilippis ◽  
Klaus Früh ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Varicella Zoster Virus ◽  
Primary Infection ◽  
Rhesus Macaques ◽  
Innate Immune ◽  
Simian Varicella Virus ◽  
Varicella Zoster ◽  
Varicella Virus

ABSTRACTVaricella-zoster virus (VZV) causes chickenpox upon primary infection and establishes latency in ganglia. Reactivation from latency causes herpes zoster, which may be complicated by postherpetic neuralgia. Innate immunity mediated by interferon and proinflammatory cytokines represents the first line of immune defense upon infection and reactivation. VZV is known to interfere with multiple innate immune signaling pathways, including the central transcription factor NF-κB. However, the role of these inhibitory mechanismsin vivois unknown. Simian varicella virus (SVV) infection of rhesus macaques recapitulates key aspects of VZV pathogenesis, and this model thus permits examination of the role of immune evasion mechanismsin vivo. Here, we compare SVV and VZV with respect to interference with NF-κB activation. We demonstrate that both viruses prevent ubiquitination of the NF-κB inhibitor IκBα, whereas SVV additionally prevents IκBα phosphorylation. We show that the ORF61 proteins of VZV and SVV are sufficient to prevent IκBα ubiquitination upon ectopic expression. We further demonstrate that SVV ORF61 interacts with β-TrCP, a subunit of the SCF ubiquitin ligase complex that mediates the degradation of IκBα. This interaction seems to inactivate SCF-mediated protein degradation in general, since the unrelated β-TrCP target Snail is also stabilized by ORF61. In addition to ORF61, SVV seems to encode additional inhibitors of the NF-κB pathway, since SVV with ORF61 deleted still prevented IκBα phosphorylation and degradation. Taken together, our data demonstrate that SVV interferes with tumor necrosis factor alpha (TNF-α)-induced NF-κB activation at multiple levels, which is consistent with the importance of these countermechanisms for varicella virus infection.IMPORTANCEThe role of innate immunity during the establishment of primary infection, latency, and reactivation by varicella-zoster virus (VZV) is incompletely understood. Since infection of rhesus macaques by simian varicella virus (SVV) is used as an animal model of VZV infection, we characterized the molecular mechanism by which SVV interferes with innate immune activation. Specifically, we studied how SVV prevents activation of the transcription factor NF-κB, a central factor in eliciting proinflammatory responses. The identification of molecular mechanisms that counteract innate immunity might ultimately lead to better vaccines and treatments for VZV, since overcoming these mechanisms, either by small-molecule inhibition or by genetic modification of vaccine strains, is expected to reduce the pathogenic potential of VZV. Moreover, using SVV infection of rhesus macaques, it will be possible to study how increasing the vulnerability of varicella viruses to innate immunity will impact viral pathogenesis.

scholarly journals Control of Sindbis Virus Infection by Antibody in Interferon-Deficient Mice

2000 ◽  
Vol 74 (8) ◽  
pp. 3905-3908 ◽  
Author(s):  
Andrew P. Byrnes ◽  
Joan E. Durbin ◽  
Diane E. Griffin
Keyword(s):  
Virus Infection ◽  
Sindbis Virus ◽  
Gamma Interferon ◽  
Unknown Mechanism ◽  
Beta Interferon ◽  
Alpha Beta ◽  
Deficient Mice

ABSTRACT Antibodies clear Sindbis virus from infected animals through an unknown mechanism. To determine whether interferon-induced pathways are required for this clearance, we examined mice which are unable to respond to alpha/beta interferon or gamma interferon. Although extremely susceptible to infection, such mice survived and completely cleared virus if antibodies against Sindbis virus were given.

scholarly journals The Mga Regulon but Not Deoxyribonuclease Sda1 of Invasive M1T1 Group A Streptococcus Contributes toIn VivoSelection of CovRS Mutations and Resistance to Innate Immune Killing Mechanisms

2015 ◽  
Vol 83 (11) ◽  
pp. 4293-4303 ◽  
Author(s):  
Guanghui Liu ◽  
Wenchao Feng ◽  
Dengfeng Li ◽  
Mengyao Liu ◽  
Daniel C. Nelson ◽  
...  
Keyword(s):  
Group A Streptococcus ◽  
Regulatory System ◽  
Innate Immune ◽  
M Protein ◽  
Content Type ◽  
Group A ◽  
Innate Immune Evasion ◽  
Selection Of

ABSTRACTInvasive M1T1 group AStreptococcus(GAS) can have a mutation in the regulatory system CovRS, and this mutation can render strains hypervirulent. Interestingly, via mechanisms that are not well understood, the host innate immune system's neutrophils select spontaneous M1T1 GAS CovRS hypervirulent mutants, thereby enhancing the pathogen's ability to evade immune killing. It has been reported that the DNase Sda1 is critical for the resistance of M1T1 strain 5448 to killing in human blood and provides pressure forin vivoselection of CovRS mutations. We reexamined the role of Sda1 in the selection of CovRS mutations and in GAS innate immune evasion. Deletion ofsda1or all DNase genes in M1T1 strain MGAS2221 did not alter emergence of CovRS mutants during murine infection. Deletion ofsda1in strain 5448 resulted in Δsda1mutants with (5448 Δsda1M+strain) and without (5448 Δsda1M−strain) M protein production. The 5448 Δsda1M+strain accumulated CovRS mutationsin vivoand resisted killing in the bloodstream, whereas the 5448 Δsda1M−strain lostin vivoselection of CovRS mutations and was sensitive to killing. The deletion ofemmand a spontaneous Mga mutation in MGAS2221 reduced and preventedin vivoselection for CovRS mutants, respectively. Thus, in contrast to previous reports, Sda1 is not critical forin vivoselection of invasive M1T1 CovRS mutants and GAS resistance to innate immune killing mechanisms. In contrast, M protein and other Mga-regulated proteins contribute to thein vivoselection of M1T1 GAS CovRS mutants. These findings advance the understanding of the progression of invasive M1T1 GAS infections.

scholarly journals Multiepitope Dendrimeric Antigen-Silica Particle Composites as Nano-Based Platforms for Specific Recognition of IgEs

2021 ◽  
Vol 12 ◽  
Author(s):  
Violeta Gil-Ocaña ◽  
Isabel M. Jimenez ◽  
Cristobalina Mayorga ◽  
Inmaculada Doña ◽  
Jose Antonio Céspedes ◽  
...  
Keyword(s):  
Silica Particle ◽  
Drug Hypersensitivity ◽  
Specific Ige ◽  
Design And Synthesis ◽  
Protein Conjugates ◽  
Drug Hypersensitivity Reactions ◽  
Homogeneous Composition

β-lactam antibiotics (BLs) are the drugs most frequently involved in drug hypersensitivity reactions. However, current in vitro diagnostic tests have limited sensitivity, partly due to a poor understanding of in vivo drug–protein conjugates that both induce the reactions and are immunologically recognized. Dendrimeric Antigen-Silica particle composites (DeAn@SiO2), consisting on nanoparticles decorated with BL-DeAns are promising candidates for improving the in vitro clinical diagnostic practice. In this nano-inspired system biology, the synthetic dendrimer plays the role of the natural carrier protein, emulating its haptenation by drugs and amplifying the multivalence. Herein, we present the design and synthesis of new multivalent mono- and bi-epitope DeAn@SiO2, using amoxicillin and/or benzylpenicillin allergenic determinants as ligands. The homogeneous composition of nanoparticles provides high reproducibility and quality, which is critical for in vitro applications. The suitable functionalization of nanoparticles allows the anchoring of DeAn, minimizing the nonspecific interactions and facilitating the effective exposure to specific IgE; while the larger interaction area increments the likelihood of capturing specific IgE. This achievement is particularly important for improving sensitivity of current immunoassays since IgE levels in BL allergic patients are very low. Our data suggest that these new nano-based platforms provide a suitable tool for testing IgE recognition to more than one BL simultaneously. Immunochemical studies evidence that mono and bi-epitope DeAn@SiO2 composites could potentially allow the diagnosis of patients allergic to any of these drugs with a single test. These organic–inorganic hybrid materials represent the basis for the development of a single screening for BL-allergies.

scholarly journals Single-cell transcriptional profiling of splenic fibroblasts reveals subset-specific innate immune signatures in homeostasis and during viral infection

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Joern Pezoldt ◽  
Carolin Wiechers ◽  
Florian Erhard ◽  
Ulfert Rand ◽  
Tanja Bulat ◽  
...  
Keyword(s):  
Virus Infection ◽  
Single Cell ◽  
Transcriptional Profiling ◽  
Innate Immune ◽  
Fibroblastic Cell ◽  
Immune Signatures ◽  
Healthy State ◽  
Cell Diversity ◽  
Red Pulp

AbstractOur understanding of the composition and functions of splenic stromal cells remains incomplete. Here, based on analysis of over 20,000 single cell transcriptomes of splenic fibroblasts, we characterized the phenotypic and functional heterogeneity of these cells in healthy state and during virus infection. We describe eleven transcriptionally distinct fibroblastic cell clusters, reassuring known subsets and revealing yet unascertained heterogeneity amongst fibroblasts occupying diverse splenic niches. We further identify striking differences in innate immune signatures of distinct stromal compartments in vivo. Compared to other fibroblasts and to endothelial cells, Ly6C+ fibroblasts of the red pulp were selectively endowed with enhanced interferon-stimulated gene expression in homeostasis, upon systemic interferon stimulation and during virus infection in vivo. Collectively, we provide an updated map of fibroblastic cell diversity in the spleen that suggests a specialized innate immune function for splenic red pulp fibroblasts.

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