RNA Interference Targets Arbovirus Replication in Culicoides Cells

Schnettler, Esther; Ratinier, Maxime; Watson, Michael; Shaw, Andrew; McFarlane, Melanie; Varela, Mariana; Elliott, Richard M.; Palmarini, Massimo; Kohl, Alain

doi:10.1128/jvi.02848-12

Cited by 81 publications

(119 citation statements)

References 79 publications

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“…Dicer-2 may act upon the genome of the virus itself-as in the case of dsRNA viruses-and/or on viral replication and transcription intermediates, although structured, single-stranded RNA (ssRNA) may also be utilized (4). Interestingly, several deepsequencing data have revealed that approximately 18-to 30-nt viral small RNAs (vsRNAs) of infected insects are not evenly distributed along the genomes but map preferentially in distinct genomic areas (hot spots) versus genomic stretches with unmapped or less-mapped vsRNAs (cold spots) (4)(5)(6)(7)(8)(9)(10)(11)(12)(13). The origin of these profiles, as well as the hypothetical functional distinction between vsRNAs deriving from hot or cold spots, remains substantially elusive, although hot spots near the end of the genome have been attributed to structured regulatory viral regions (14) and an RNAi decoy-like mechanism driven by abundant vsRNAs has been proposed by another group (15).…”

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confidence: 99%

Viral Small-RNA Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection

Zografidis

Nieuwerburgh

Κολλιοπούλου

et al. 2015

J Virol

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The lepidopteran innate immune response against RNA viruses remains poorly understood, while in other insects several studies have highlighted an essential role for the exo-RNAi pathway in combating viral infection. Here, by using deep-sequencing technology for viral small-RNA (vsRNA) assessment, we provide evidence that exo-RNAi is operative in the silkworm Bombyx mori against both persistent and pathogenic infection of B. mori cytoplasmic polyhedrosis virus (BmCPV) which is characterized by a segmented double-stranded RNA (dsRNA) genome. Further, we show that Dicer-2 predominantly targets viral dsRNA and produces 20-nucleotide (nt) vsRNAs, whereas an additional pathway is responsive to viral mRNA derived from segment 10. Importantly, vsRNA distributions, which define specific hot and cold spot profiles for each viral segment, to a considerable degree overlap between Dicer-2-related (19 to 21 nt) and Dicer-2-unrelated vsRNAs, suggesting a common origin for these profiles. We found a degenerate motif significantly enriched at the cut sites of vsRNAs of various lengths which link an unknown RNase to the origins of vsRNAs biogenesis and distribution. Accordingly, the indicated RNase activity may be an important early factor for the host's antiviral defense in Lepidoptera. Central to the defense of insects against RNA viruses is the triggering of the so-called exogenous RNA interference pathway (exo-RNAi), by which viral double-stranded RNA (dsRNA) is cleaved intracellularly into viral small interfering RNAs (siRNAs) that in turn silence homologous transcripts (1). It is established that Dicer-2, a cytoplasmic RNase III class enzyme, recognizes and cuts successively the dsRNA template to produce small interfering RNA duplexes of ϳ21 nucleotides (nt) characterized by a signature of 2-nt 3=-hydroxyl overhangs (2). These duplexes are subsequently incorporated into the effector complex RISC (RNA-induced silencing complex) via interactions with Argonaute-2, which, upon discarding one of the two strands (passenger strand), is followed by selection and cleavage of viral sequences bearing perfect complementarity to the remaining strand (guide strand) (1, 3). Dicer-2 may act upon the genome of the virus itself-as in the case of dsRNA viruses-and/or on viral replication and transcription intermediates, although structured, single-stranded RNA (ssRNA) may also be utilized (4). Interestingly, several deepsequencing data have revealed that approximately 18-to 30-nt viral small RNAs (vsRNAs) of infected insects are not evenly distributed along the genomes but map preferentially in distinct genomic areas (hot spots) versus genomic stretches with unmapped or less-mapped vsRNAs (cold spots) (4-13). The origin of these profiles, as well as the hypothetical functional distinction between vsRNAs deriving from hot or cold spots, remains substantially elusive, although hot spots near the end of the genome have been attributed to structured regulatory viral regions (14) and an RNAi decoy-like mechanism driven by abundant vsRNAs ...

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mentioning

confidence: 99%

Viral Small-RNA Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection

Zografidis

Nieuwerburgh

Κολλιοπούλου

et al. 2015

J Virol

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“…The different replication strategies of these viruses may require different control mechanisms. The recent discovery of putative new antiviral responses such as melanisation and, particularly, the implication of piRNAs in mosquito antiviral immunity against a variety of arboviruses (CHIKV, SFV, SINV, DENV, LACV, RVFV, SBV and BTV) [45,68,82,102,103,123], show how complex the arthropod immune system is and how far there is still to go in understanding it. One of the questions that will surely be addressed in the future is how virus-derived piRNAs are generated and whether it is possible to use the knowledge gained to benefit vector control strategies.…”

Section: Discussionmentioning

confidence: 99%

“…In cells derived from Culicoides biting midges, viRNAs with PIWI signature have been observed after infection with bluetongue virus (BTV) and Schmallenberg virus (SBV) [103], suggesting this newly-discovered antiviral mechanism is not only a mosquito-specific response. Future work on other vector species including ticks will elucidate whether this mechanism has evolved in specific groups of dipteran vector species or is also an antiviral response in other arthropods.…”

Section: Mirnasmentioning

confidence: 99%

“…Despite the current lack of a published genome, RNAi has recently been shown to target replication of BTV and SBV in Culicoides cells in a manner similar to other arbovirus vectors [103]. RNAi has also been identified as an antiviral mechanism in tick cells [36,37] and has been used as a tool for knockdown of gene expression in tick and tick-borne disease research for over a decade [11,29], but the detailed mechanisms are still not well understood.…”

Section: Mirnasmentioning

confidence: 99%

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Antiviral responses of arthropod vectors: an update on recent advances

et al. 2014

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Arthropod vectors, such as mosquitoes, ticks, biting midges and sand flies, transmit many viruses that can cause outbreaks of disease in humans and animals around the world. Arthropod vector species are invading new areas due to globalisation and environmental changes, and contact between exotic animal species, humans and arthropod vectors is increasing, bringing with it the regular emergence of new arboviruses. For future strategies to control arbovirus transmission, it is important to improve our understanding of virus-vector interactions. In the last decade knowledge of arthropod antiviral immunity has increased rapidly. RNAi has been proposed as the most important antiviral response in mosquitoes and it is likely to be the most important antiviral response in all arthropods. However, other newly-discovered antiviral strategies such as melanisation and the link between RNAi and the JAK/STAT pathway via the cytokine Vago have been characterised in the last few years. This review aims to summarise the most important and most recent advances made in arthropod antiviral immunity.

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“…This mode of replication raises an interesting question: do dsRNA viruses escape from dsRNA-mediated antiviral responses, including RNA silencing? Some studies have detected vsRNAs, which are a hallmark of RNA silencing, from dsRNA viruses in insects using next-generation sequencing (NGS), including reoviruses (20)(21)(22), a totivirus (23), and entomobirnaviruses (24,25). These data suggested that encapsidated dsRNA viruses are also a target of RNA silencing.…”

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confidence: 95%

Differential Inductions of RNA Silencing among Encapsidated Double-Stranded RNA Mycoviruses in the White Root Rot Fungus Rosellinia necatrix

Yaegashi

Shimizu

Ito

et al. 2016

J Virol

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RNA silencing acts as a defense mechanism against virus infection in a wide variety of organisms. Here, we investigated inductions of RNA silencing against encapsidated double-stranded RNA (dsRNA) fungal viruses (mycoviruses), including a partitivirus (RnPV1), a quadrivirus (RnQV1), a victorivirus (RnVV1), a mycoreovirus (RnMyRV3), and a megabirnavirus (RnMBV1) in the phytopathogenic fungus Rosellinia necatrix. Expression profiling of RNA silencing-related genes revealed that a dicer-like gene, an Argonaute-like gene, and two RNA-dependent RNA polymerase genes were upregulated by RnMyRV3 or RnMBV1 infection but not by other virus infections or by constitutive expression of dsRNA in R. necatrix. Massive analysis of viral small RNAs (vsRNAs) from the five mycoviruses showed that 19-to 22-nucleotide (nt) vsRNAs were predominant; however, their ability to form duplexes with 3= overhangs and the 5= nucleotide preferences of vsRNAs differed among the five mycoviruses. The abundances of 19-to 22-nt vsRNAs from RnPV1, RnQV1, RnVV1, RnMyRV3, and RnMBV1 were 6.8%, 1.2%, 0.3%, 13.0%, and 24.9%, respectively. Importantly, the vsRNA abundances and accumulation levels of viral RNA were not always correlated, and the origins of the vsRNAs were distinguishable among the five mycoviruses. These data corroborated diverse interactions between encapsidated dsRNA mycoviruses and RNA silencing. Moreover, a green fluorescent protein (GFP)-based sensor assay in R. necatrix revealed that RnMBV1 infection induced silencing of the target sensor gene (GFP gene and the partial RnMBV1 sequence), suggesting that vsRNAs from RnMBV1 activated the RNA-induced silencing complex. Overall, this study provides insights into RNA silencing against encapsidated dsRNA mycoviruses. IMPORTANCEEncapsidated dsRNA fungal viruses (mycoviruses) are believed to replicate inside their virions; therefore, there is a question of whether they induce RNA silencing. Here, we investigated inductions of RNA silencing against encapsidated dsRNA mycoviruses (a partitivirus, a quadrivirus, a victorivirus, a mycoreovirus, and a megabirnavirus) in Rosellinia necatrix. We revealed upregulation of RNA silencing-related genes in R. necatrix infected with a mycoreovirus or a megabirnavirus but not with other viruses, which was consistent with the relatively high abundances of vsRNAs from the two mycoviruses. We also showed common and different molecular features and origins of the vsRNAs from the five mycoviruses. Furthermore, we demonstrated the activation of RNA-induced silencing complex by mycoviruses in R. necatrix. Taken together, our data provide insights into an RNA silencing pathway against encapsidated dsRNA mycoviruses which is differentially induced among encapsidated dsRNA mycoviruses; that is, diverse replication strategies exist among encapsidated dsRNA mycoviruses. RNA silencing is a sequence-specific RNA degradation mechanism that is widely conserved among eukaryotic organisms, including animals, plants, and fungi (1-4). This mechanism is triggered by th...

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RNA Interference Targets Arbovirus Replication in Culicoides Cells

Cited by 81 publications

References 79 publications

Viral Small-RNA Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection

Viral Small-RNA Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection

Antiviral responses of arthropod vectors: an update on recent advances

Differential Inductions of RNA Silencing among Encapsidated Double-Stranded RNA Mycoviruses in the White Root Rot Fungus Rosellinia necatrix

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