Zebrafish as an animal model for the antiviral RNA interference pathway
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ABSTRACT:
ORGANISM(S): Danio rerio
PROVIDER: GSE160475 | GEO | 2023/10/30
REPOSITORIES: GEO
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Project description:Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes severe clinical symptoms and mortality in humans. Haemaphysalis longicornis tick has been identified as the competent vector for SFTSV transmission. Although antiviral RNA interference (RNAi) in insects has been well documented, the degree to which RNAi contributes to antiviral defense in ticks is still largely elusive. In this study, utilizing arthropod-borne RNA viruses, including SFTSV, we find abundant virus-derived small interfering RNAs (vsiRNAs) are induced in H. longicornis after infection through either microinjection or natural blood-feeding. Furthermore, we identify a Dicer2-like homolog, the core protein of antiviral RNAi pathway, in H. longicornis and knocking down this gene exacerbated virus amplification. To counteract this antiviral RNAi of ticks, viruses have evolved suppressors of RNAi (VSRs). Here, we show that reduced viral replication inversely correlated with the accumulation of vsiRNAs in ticks after infection with recombinant sindbis virus (SINV) expressing heterologous VSR proteins. Elucidating the antiviral RNAi pathway of ticks by model arthropod-borne RNA viruses in vivo is critical to understanding the virus-host interaction, providing a feasible intervention strategy to control tick-borne arbovirus transmission.
2024-01-16 | GSE165139 | GEO
Project description:RNA interference (RNAi) functions as an antiviral immune response in plants and invertebrates, whereas mammalian RNAi response has been found so far only in undifferentiated cells and in differentiated cells inactive in interferon (IFN) system or in infections with viruses disabling viral suppressors of RNAi (VSRs), thereby leading to question the physiological importance of the RNAi pathway in mammals. Here, we identified that wild-type Semliki Forest virus (SFV), a prototypic alphavirus, triggered the Dicer-dependent production of abundant viral (v)siRNAs in different mammalian somatic cells in the presence of VSR. These vsiRNAs were produced from viral dsRNA replicative intermediates, almost exclusively located at the 5’ termini of the viral genome, and loaded into AGO, and they were fully active in slicing cognate viral RNAs. Besides, Sindbis virus, another alphavirus, also induced vsiRNA generation in mammalian somatic cells. AGO2 deficiency increased SFV and SINV replication, while enoxacin, a known RNAi enhancer that functions at post steps of siRNA production, efficiently reduced viral replication. The nucleotide sequence at the 5’ termini of SFV and SINV genome is conserved among the Old World alphaviruses, and mutating the conserved sequences resulted in the recombinant SFV being deficient in vsiRNA production and irresponsive to antiviral RNAi. SFV infection also enabled the production of abundant vsiRNAs and antiviral RNAi in IFN-competent adult mice, and importantly, enhanced RNAi by enoxacin protected adult mice from lethal SFV challenge and reduced the virus-induced neuropathogenesis in the central neuron system. Overall, our findings provide evidence that mammalian antiviral RNAi is active in differentiated cells and adult mice with intact IFN response even in the presence of VSR and present a therapeutic strategy against alphaviruses that include many important emerging and reemerging human pathogens.
2022-10-04 | GSE214453 | GEO
Project description:The function and mechanism of the interferon-regulated antiviral responses have been extensively characterized. Recent studies have demonstrated induction of antiviral RNA interference (RNAi) in somatic cells against several mammalian RNA viruses rendered incapable of RNAi suppression. However, little is known about Dicer-mediated production of virus-derived small-interfering RNAs (vsiRNAs) in these cells active in the type I interferon response. Here we show that the dsRNA precursors of influenza vsiRNAs were processed more efficiently than cellular precursor microRNA hairpins by wild-type human Dicer expressed de novo in Dicer-knockout somatic cells. We found that infection of two strains of suckling mice with wild-type Nodamura virus (NoV) was associated with production of silencing-active vsiRNAs and direct sequestration of duplex vsiRNAs by its RNAi suppressor protein B2. Our findings from in vivo infection with Sindbis virus recombinants expressing NoV B2 or carrying a vsiRNA-targeted insert provide evidence for an antiviral function of the induced RNAi response. Interestingly, NoV infection induces expression of RIG-I-like receptor LGP2 to inhibit vsiRNA biogenesis and promote virulent infection in suckling mice. Our findings together reveal efficient Dicer processing of vsiRNA precursors in interferon-competent somatic cells and suckling mice in contrast to synthetic long dsRNA examined previously by in vitro dicing.
2021-07-28 | GSE155146 | GEO
Project description:Small RNAs play a critical role in host-pathogen interaction. In insects, for instance, small RNA-mediated silencing or RNA interference (RNAi) represents the main antiviral defense system. However, the antiviral role of RNAi has not been clearly proven in higher vertebrates. On the contrary, it is well established that the cell response relies on the recognition of viral RNAs by host pattern recognition receptors (PRR) to trigger the activation of the interferon pathway. Based on this evidence, we wished to contribute to this research field by identifying and characterizing small non-coding RNAs produced in mammalian cells upon RNA virus infection. We focused on Sindbis virus (SINV), the prototypical arbovirus, which by definition, is able to infect both vertebrate hosts and invertebrate vectors and triggers the interferon pathway or RNAi, respectively. Taking advantage of large scale sequencing, we cloned and sequenced small RNAs from both mock and SINV-infected mammalian cells (HEK 293 and VERO). We identified a novel population of viral small RNAs (vsRNAs) that accumulate as 20 to 30 nt species during infection. We assessed that this viral small RNA population is modified in 3'end and derived from the activation of the cellular antiviral endoribonuclease RNaseL. Altogether our results indicate a potential role for the SINV-derived small RNAs in the host defense mechanism.
2013-11-19 | E-GEOD-48831 | biostudies-arrayexpress
Project description:Tick-borne diseases (TBDs) are the most common illnesses transmitted by ticks, and the annual number of reported TBD cases continues to increase. The Asian longhorned tick, a vector associated with at least 30 human pathogens, is native to eastern Asia and recently reached the USA as an emerging disease threat. Newly identified tick-transmitted pathogens continue to be reported, raising concerns about how TBDs occur. Interestingly, tick can harbor pathogens without being affected themselves. For viral infections, ticks have their own immune systems that protect them from infection. Meanwhile, tick-borne viruses have evolved to avoid these defenses as they establish themselves within the vector. Here, we show in detail that infecting longhorned ticks with distinct arthropod-borne RNA viruses through two approaches natural blood feeding and injection, all induce the production of vsiRNAs. Dicer2-like homolog plays a role in regulating antiviral RNAi responses as knocking down of this gene enhanced viral replication. Furthermore, we demonstrate that tick antiviral RNAi responses are inhibited through expression heterologous VSR proteins in recombinant SINV. We identify both the virus and tick factors are critical components to understanding TBDs. Importantly, our study introduces a novel, in vivo virus-vector-mouse model system for exploring TBDs in the future.
2021-11-22 | GSE159277 | GEO
Project description:Small RNAs play a critical role in host-pathogen interaction. In insects, for instance, small RNA-mediated silencing or RNA interference (RNAi) represents the main antiviral defense system. However, the antiviral role of RNAi has not been clearly proven in higher vertebrates. On the contrary, it is well established that the cell response relies on the recognition of viral RNAs by host pattern recognition receptors (PRR) to trigger the activation of the interferon pathway. Based on this evidence, we wished to contribute to this research field by identifying and characterizing small non-coding RNAs produced in mammalian cells upon RNA virus infection. We focused on Sindbis virus (SINV), the prototypical arbovirus, which by definition, is able to infect both vertebrate hosts and invertebrate vectors and triggers the interferon pathway or RNAi, respectively.
2013-11-19 | GSE48831 | GEO
Project description:In Drosophila, the siRNA pathway is initiated when exogenous or endogenous double stranded RNA (dsRNA) is processed into siRNAs by Dicer-2 (Dcr-2) and a dsRNA-binding protein (dsRBP) cofactor called Loquacious (Loqs). The siRNAs are then loaded onto Argonaute-2 (Ago2) protein by the action of Dcr-2 with another dsRBP cofactor called R2D2. Loaded Ago2 executes the destruction of target RNAs that have sequence complementarity to the siRNA. Dcr-2, R2D2, and Ago2 have also been shown to be required for innate antiviral defense in Drosophila. However, the biogenesis of virus-derived siRNAs (vsiRNAs) and their targets in virus-infected cells remain unclear. Here, we analyzed the antiviral response in Drosophila by monitoring the replication of different RNA viruses and deep sequencing of small RNAs in infected animals. We show that vsiRNAs are generated by Dcr-2 processing of dsRNA formed during viral genome replication and transcription. These vsiRNAs then directly target viral transcripts but not genomes, to inhibit viral replication. The biogenesis of vsiRNAs was virtually independent of Loqs and R2D2. R2D2, however, was essential for sorting and loading of vsiRNAs onto Ago2 and effective silencing of viral RNA expression. Loqs was completely dispensable for silencing of viruses in contrast to its role in silencing of endogenous targets. Our results suggest the existence of a specific siRNA pathway triggered by viral infection independent of conserved dsRBP cofactors and separate from the endogenous pathway. Inhibition of virus replication resulting from direct injection of viral RNA into Drosophila embryos was also not dependent on Loqs, suggesting the distinction of the two pathways is not related to the mode of entry but recognition of intrinsic features of viral RNA or its mode of replication. We speculate that this unique framework might be necessary for a prompt and efficient antiviral response We analyzed the small RNA reponse to viral infection by deep sequencing of small RNA libraries from wild type and RNAi mutant adult flies infected with Sindbis birus and Vesicular Stomatatis virus.
2012-03-16 | E-GEOD-36449 | biostudies-arrayexpress
Project description:Mosquito-borne flaviviruses maintain life cycles in mammals and mosquitoes. RNA interference (RNAi) has been demonstrated as an anti-flavivirus mechanism in mosquitoes; however, whether and how flavivirus induces and antagonizes RNAi-mediated antiviral immunity in mammals remains unknown. Here we showed that NS2A of Dengue virus-2 (DENV2) act as a viral suppressor of RNAi (VSR). When NS2A-mediated RNAi suppression was disabled, the resulting mutant DENV2 induced Dicer-dependent production of abundant DENV2-derived siRNAs in differentiated mammalian cells. Importantly, VSR-disabled DENV2 showed severe replication defects in mosquito and mammalian cells, and mice, which were rescued by the deficiency of RNAi. Moreover, NS2As of multiple flaviviruses act as VSRs in vitro and during viral infection in both organisms. Overall, our findings demonstrate that antiviral RNAi can be induced by flavivirus, while flavivirus uses NS2A as bona fide VSR to evade RNAi in mammals and mosquitoes, highlighting the importance of RNAi in flaviviral vector-host life cycles.
2020-02-24 | GSE133284 | GEO
Project description:RNA interference (RNAi) is an antiviral immunity conserved in diverse eukaryotes including mammals, while viruses encodes viral suppressors of RNAi (VSRs) as countermeasures. However, the physiological impact of RNAi on viral infection in mammals has not been fully assessed, and it also remains unknown whether antiviral RNAi can be therapeutically exploited. Here, we show that peptides designed to target enterovirus A71 (EV-A71)-encoded protein 3A, a well-characterized VSR, triggered an effective antiviral response. These VSR-targeting peptides, particularly ER-DRI, abrogated the VSR function of 3A, which enabled EV-A71-derived siRNA production and unlocked RNAi response that potently inhibited EV-A71 infection in mammals. ER-DRI treatment elicited a strong in vivo antiviral RNAi response that protected mice against lethal EV-A71 challenge. It also potently inhibited another enterovirus, Coxsackievirus-A16, dependently of RNAi. Our findings demonstrate that antiviral RNAi does have a physiologically important impact in mammals and targeting VSRs is a promising strategy for antiviral therapies.
2021-07-31 | GSE179496 | GEO
Project description:RNA silencing has an important role mediating sequence-specific virus resistance. Here, we analyzed in detail the interference of Cucumber Mosaic Virus (CMV) with the RNA silencing machinery of Arabidopsis thaliana. We detected that CMV infection induced the production of viral small interfering RNAs (vsiRNAs) that account for a significant part of the sRNome affecting the levels of other sRNA classes. Furthermore, we analyzed the incorporation of vsiRNAs into the main ARGONAUTE (AGO) proteins with a described antiviral role and the viral RNA silencing suppressor (VRS) 2b, by combining protein immunoprecipitation with sRNA high-throughput sequencing. vsiRNAs accumulated to high levels in AGO2, followed by AGO1, AGO5 and AGO7. Interestingly, vsiRNAs represented a significant percentage of AGO-loaded sRNAs and displaced other endogenous sRNAs. As a countermeasure, the VSR 2b loaded vsiRNAs and mRNA-derived siRNAs, which affected the expression of the genes they derived from. Additionally, we analyzed how vsiRNAs incorporated into the endogenous RNA silencing pathways by exploring their target mRNAs using parallel analysis of RNA end (PARE) sequencing. This strategy allowed us to identify 61 genes with degradome data supporting their vsiRNA-mediated cleavage. This work exemplifies the complex relationship of RNA viruses with the endogenous RNA silencing machinery and the multiple aspects of virus resistance and virulence that this interaction induces.
2021-12-01 | GSE169677 | GEO