Inhibition of Viruses by RNA Interference

Virology Division, Kimron Veterinary institute, 12, 50250, Beit-Dagan, Israel.
Virus Genes (Impact Factor: 1.58). 07/2006; 32(3):299-306. DOI: 10.1007/s11262-005-6914-0
Source: PubMed


RNA-mediated interference (RNAi) is a recently discovered process by which dsRNA is able to silence specific gene functions. Although initially described in plants, nematodes and Drosophila, the process is currently considered to be an evolutionarily conserved process that is present in the entire eukaryotic kingdom in which its original function was as a defense mechanism against viruses and foreign nucleic acids. Similarly to the silencing of genes by RNAi, viral functions can be also silenced by the same mechanism, through the introduction of specific dsRNA molecules into cells, where they are targeted to essential genes or directly to the viral genome in case RNA viruses, thus arresting viral replication. Since the pioneering work of Elbashir and coworkers, who identified RNAi activity in mammalian cells, many publications have described the inhibition of viruses belonging to most if not all viral families, by targeting and silencing diverse viral genes as well as cell genes that are essential for virus replication. Moreover, virus expression vectors were developed and used as vehicles with which to deliver siRNAs into cells. This review will describe the use of RNAi to inhibit virus replication directly, as well as through the silencing of the appropriate cell functions.

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    • "However, RNAi molecules can activate off-target antiviral cytokines which cause undesirable effects [10]. This phenomenon , explored as immunostimulatory RNAi (isRNAi), as perceived in plants [11] and Drosophila [12], which are using this as an antiviral defence mechanism naturally. Offtarget effects of RNAi are unwanted but antiviral therapeutics may be benefited greatly from isRNAi, towards prevention of viral replication. "
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    ABSTRACT: The first influenza pandemic of 21ST century was attributed to a novel quadruple reassortant H1N1 virus that emerged in 2009. Currently available therapies for influenza have drug-resistant. Therefore, there is a need to develop new generation immunotherapeutic antiviral strategy. This study described the efficacy of a novel bifunctional immunostimulatory siRNAs against H1N1pdm swine flu virus by targeting the Nucleocapsid (NP) gene. Small interfering RNAs (siRNA) targeting conserved region of NP were screened for antiviral efficacy in human lung epithelial cells (A549). Further, a bifunctional siRNA was synthesized by combining immunostimulatory sequence (5'- UGUGU-3') with NP specific siRNA. This immunostimulatory siRNA (NP-1-is) revealed strong antiviral effect through reduction in mRNA copies (99.58%), reduction in virus associated cell apoptosis and inhibition of nucleocapsid protein in western blot. This immunostimulatory siRNA was found more effective than nontagged siRNA. Further studies including dose dependent and time course kinetics revealed that the NP-1-is siRNA is more effective at 20-80 nM with significant protection upto hpi. Besides, the qRT-PCR and western blot analysis confirmed higher antiviral response of immunostimulatory siRNA was due to upregulation of TLR-7 MyD88, IRF-7 and IFN-α. This study paves the way for broad-spectrum RNAi-based therapeutics using immunostimulatory motif towards improved antiviral effect. Hence this approach will be useful to confront the sudden emergence of pandemic strains.
    Current Gene Therapy 08/2015; 15(5). DOI:10.2174/1566523215666150812120547 · 2.54 Impact Factor
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    • "Up to today no specific therapeutic options are available for flaviviral infections and an effective therapy for TBEV infection would be highly desirable [13]. Results from in vitro and in vivo studies indicate that therapeutics based on RNA interference (RNAi) could be effective against viral infections, and small interfering RNA (siRNA) molecules are promising candidates for future clinical applications [14], [15], [16], [17]. Indeed, several RNAi-based antiviral drugs are currently being tested in clinical trials [18], [19], [20], [21]. "
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    ABSTRACT: Tick-borne encephalitis virus is the causative agent of tick-borne encephalitis, a potentially fatal neurological infection. Tick-borne encephalitis virus belongs to the family of flaviviruses and is transmitted by infected ticks. Despite the availability of vaccines, approximately 2000-3000 cases of tick-borne encephalitis occur annually in Europe for which no curative therapy is available. The antiviral effects of RNA mediated interference by small interfering RNA (siRNA) was evaluated in cell culture and organotypic hippocampal cultures. Langat virus, a flavivirus highly related to Tick-borne encephalitis virus exhibits low pathogenicity for humans but retains neurovirulence for rodents. Langat virus was used for the establishment of an in vitro model of tick-borne encephalitis. We analyzed the efficacy of 19 siRNA sequences targeting different regions of the Langat genome to inhibit virus replication in the two in vitro systems. The most efficient suppression of virus replication was achieved by siRNA sequences targeting structural genes and the 3' untranslated region. When siRNA was administered to HeLa cells before the infection with Langat virus, a 96.5% reduction of viral RNA and more than 98% reduction of infectious virus particles was observed on day 6 post infection, while treatment after infection decreased the viral replication by more than 98%. In organotypic hippocampal cultures the replication of Langat virus was reduced by 99.7% by siRNA sequence D3. Organotypic hippocampal cultures represent a suitable in vitro model to investigate neuronal infection mechanisms and treatment strategies in a preserved three-dimensional tissue architecture. Our results demonstrate that siRNA is an efficient approach to limit Langat virus replication in vitro.
    PLoS ONE 09/2012; 7(9):e44703. DOI:10.1371/journal.pone.0044703 · 3.23 Impact Factor
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    • "their genomes against transposons or viruses (Baulcombe 2005; Rosso et al. 2003; Stram and Kuznietzowa 2006; Vaucheret 2006). RNAi is triggered by double-stranded RNAs (dsRNAs), which are processed into small-interfering RNAs (siRNAs) by DICER enzymes (Vazquez 2006). "
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    ABSTRACT: RNA interference (RNAi) mechanism targets viral RNA for degradation. To test whether RNAi gene products contributed to viral RNA recombination, a series of Arabidopsis thaliana RNAi-defective mutants were infected with Brome mosaic virus (BMV) RNAs that have been engineered to support crossovers within the RNA3 segment. Single-cross RNA3-RNA1, RNA3-RNA2, and RNA3-RNA3 recombinants accumulated in both the wild-type (wt) and all knock-out lines at comparable frequencies. However, a reduced accumulation of novel 3' mosaic RNA3 recombinants was observed in ago1, dcl2, dcl4, and rdr6 lines but not in wt Col-0 or the dcl3 line. A BMV replicase mutant accumulated a low level of RNA3-RNA1 single-cross recombinants in Col-0 plants while, in a dcl2 dcl4 double mutant, the formation of both RNA3-RNA1 and mosaic recombinants was at a low level. A control infection in the cpr5-2 mutant, a more susceptible BMV Arabidopsis host, generated similar-to-Col-0 profiles of both single-cross and mosaic recombinants, indicating that recombinant profiles were, to some extent, independent of a viral replication rate. Also, the relative growth experiments revealed similar selection pressure for recombinants among the host lines. Thus, the altered recombinant RNA profiles have originated at the level of recombinant formation rather than because of altered selection. In conclusion, the viral replicase and the host RNAi gene products contribute in distinct ways to BMV RNA recombination. Our studies reveal that the antiviral RNAi mechanisms are utilized by plant RNA viruses to increase their variability, reminiscent of phenomena previously demonstrated in fungi.
    Molecular Plant-Microbe Interactions 09/2011; 25(1):97-106. DOI:10.1094/MPMI-05-11-0137 · 3.94 Impact Factor
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