Expression of Duplex shRNAs through a Lentiviral Vector against Cellular and Viral Genes Inflicts Sustained Inhibition of Hepatitis C Virus Replication
TL;DR: A lentiviral vector-based delivery system is a “single-shot” therapeutic strategy that can express duplex shRNA for long-term synergistic inhibition of HCV and qualify as a promising therapeutic approach for sustained inhibition ofHCV replication.
Abstract: Background: The RNAi-based transient therapeutic approach has been well explored for its potential against the hepatitis V virus (HCV). However, to achieve a sustained virological response, a consistent presence of siRNA is needed and it can be achieved by constitutively expressing shRNAs. In this context, the lentiviral vector has emerged as an attractive tool for shRNA delivery against HCV. Methods: We monitored HCV inhibition after single and multiple rounds of siRNA treatments against La autoantigen and HCV-NS5B in Huh-7.5 cells infected with the FL-J6/JFH chimeric HCV strain. A bicistronic self-inactivating third-generation lentiviral vector expressing shRNA under U6 and H1 promoters was constructed. To ascertain the long-term HCV inhibition, cells were transduced with lentiviral vectors and HCV inhibition was monitored by RT-PCR and Western blotting at regular intervals. Results: We observed transient antiviral activity after a single round of siRNA treatment, and consecutive rounds of treatments with siRNA demonstrated a sustained HCV inhibition. Delivery of duplex shRNA expressing lentiviral vectors provided constant expression of shRNA leading to synergistic and sustained HCV inhibition. Conclusion: A lentiviral vector-based delivery system is a “single-shot” therapeutic strategy. It can express duplex shRNA for long-term synergistic inhibition of HCV and qualify as a promising therapeutic approach for sustained inhibition of HCV replication.
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Dissertation•
01 Jan 2012
22 citations
TL;DR: RNAi effectors (e.g., siRNA, shRNA, and miRNA) can efficiently trigger the silencing of specific genes, and its genomic alteration functions allowed to pursue clinical trials in distinct areas, including infectious diseases, neurodegenerative disorders, and cancer as discussed by the authors.
Abstract: RNAi effectors (e.g., siRNA, shRNA, and miRNA) can efficiently trigger the silencing of specific genes, and its genomic alteration functions allowed to pursue clinical trials in distinct areas, including infectious diseases, neurodegenerative disorders, and cancer. Moreover, regarding cancer immunotherapy, RNAi therapeutics showed potential immunomodulatory ability by downregulating suppressive receptors such as PD-1 and CTLA-4, which restrict immune cell function and present challenges in cancer immunotherapy. Therefore, compared with extracellular targeting by antibodies, RNAi-mediated, cell-intrinsic disruption of inhibitory pathways in immune cells can promote an increased antitumor immune response. Along with nonviral vectors, DNA-based RNAi strategies might be a more promising method for immunomodulation to silence multiple inhibitory pathways in T cells than immune checkpoint blockade antibodies. Thus, in this review, we discuss diverse RNAi implementation strategies, with recent viral and non-viral mediated RNAi synergism to immunotherapy that augments the antitumor immunity. Finally, we provide the current progress of RNAi in clinical pipeline.
9 citations
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TL;DR: Results showed that the antiviral effect is influenced by different factors, including the promoter used to express the RNAi molecules and the selected cassette combination, which contribute to gain further insights in the design of RNAi-based gene therapy approaches against HIV-1 for clinical application.
Abstract: Gene therapy holds considerable promise for the functional cure of HIV-1 infection and, in this context, RNA interference (RNAi)-based approaches represent powerful strategies. Stable expression of small interfering RNAs (siRNAs) targeting HIV genes or cellular cofactors has the potential to render HIV-1 susceptible cells resistant to infection. To inhibit different steps of virus life cycle, self-inactivating lentiviral vectors expressing multiple siRNAs targeting the CCR5 cellular gene as well as vif and tat/rev viral transcripts, under the control of different RNA polymerase III promoters (U6, 7SK, H1) were developed. The use of a single RNA polymerase III promoter driving the expression of a sequence giving rise to three siRNAs directed against the selected targets (e-shRNA) was also investigated. Luciferase assay and inhibition of HIV-1 replication in human Jurkat T-cell line were adopted to select the best combination of promoter/siRNA. The efficacy of selected developed combinatorial vectors in interfering with viral replication was evaluated in human primary CD4+ T lymphocytes. We identified two effective anti-HIV combinatorial vectors that conferred protection against R5- and X4- tropic viruses. Overall, our results showed that the antiviral effect is influenced by different factors, including the promoter used to express the RNAi molecules and the selected cassette combination. These findings contribute to gain further insights in the design of RNAi-based gene therapy approaches against HIV-1 for clinical application.
20 citations
TL;DR: The results suggest that an approach based on the combination of cellular and viral siRNAs can be used as an effective alternative for hepatitis C viral suppression.
Abstract: Hepatitis C (HCV) is a viral disease affecting millions of people worldwide, and persistent HCV infection can lead to progressive liver disease with the development of liver cirrhosis and hepatocellular carcinoma. During treatment for hepatitis C, the occurrence of viral resistance is common. To reduce the occurrence of resistance, new viral treatments should target both viral and cellular factors. Many interactions occur between viral and host proteins during the HCV replication cycle and might be used for the development of new therapies against hepatitis C. Heat shock protein 90 (Hsp90) plays a role in the folding of cellular and viral proteins and also interacts with HCV proteins. In the present study, we knocked down the expression of the Hsp90 gene and inhibited viral replication using siRNA molecules. Reducing the expression of Hsp90 successfully decreased HCV replication. All siRNA molecules specific to the viral genome showed the efficient inhibition of viral replication, particularly siRNA targeted to the 5′UTR region. The combination of siRNAs targeting the viral genome and Hsp90 mRNA also successfully reduced HCV replication and reduced the occurrence of viral resistance. Moreover, these results suggest that an approach based on the combination of cellular and viral siRNAs can be used as an effective alternative for hepatitis C viral suppression.
17 citations
TL;DR: It is demonstrated that the antigenomic strand of HCV is not a viable RNAi target during HCV replication, providing new insights into HCV biology and have important implications for the design of more effective and safer antiviral RNAi strategies seeking to target HCV and other viruses with similar replicative strategies.
Abstract: Hepatitis C Virus (HCV) and other plus-strand RNA viruses typically require the generation of a small number of negative genomes (20–100× lower than the positive genomes) for replication, making the less-abundant antigenome an attractive target for RNA interference(RNAi)-based therapy. Because of the complementarity of duplex short hairpin RNA/small interfering RNA (shRNA/siRNAs) with both genomic and anti-genomic viral RNA strands, and the potential of both shRNA strands to become part of the targeting complexes, preclinical RNAi studies cannot distinguish which viral strand is actually targeted in infected cells. Here, we addressed the question whether the negative HCV genome was bioaccessible to RNAi. We first screened for the most active shRNA molecules against the most conserved regions in the HCV genome, which were then used to generate asymmetric anti-HCV shRNAs that produce biologically active RNAi specifically directed against the genomic or antigenomic HCV sequences. Using this simple but powerful and effective method to screen for shRNA strand selectivity, we demonstrate that the antigenomic strand of HCV is not a viable RNAi target during HCV replication. These findings provide new insights into HCV biology and have important implications for the design of more effective and safer antiviral RNAi strategies seeking to target HCV and other viruses with similar replicative strategies.
17 citations
TL;DR: The data both support antiviral activity consistent with an RNA interference mechanism and demonstrate the potential of PF-05095808 as a therapeutic agent for chronic HCV infection.
Abstract: PF-05095808 is a novel biological agent for chronic hepatitis C virus (HCV) therapy. It comprises a recombinant adeno-associated virus (AAV) DNA vector packaged into an AAV serotype 8 capsid. The vector directs expression of three short hairpin RNAs (shRNAs) targeted to conserved regions of the HCV genome. These shRNAs are processed by the host cell into the small interfering RNAs which mediate sequence-specific cleavage of target regions. For small-molecule inhibitors the key screens needed to assess in vitro activity are well defined; we developed new assays to assess this RNA interference agent and so to understand its therapeutic potential. Following administration of PF-05095808 or corresponding synthetic shRNAs, sequence-specific antiviral activity was observed in HCV replicon and infectious virus systems. To quantify the numbers of shRNA molecules required for antiviral activity in vitro and potentially also in vivo, a universal quantitative PCR (qPCR) assay was developed. The number of shRNA molecules needed to drive antiviral activity proved to be independent of the vector delivery system used for PF-05095808 administration. The emergence of resistant variants at the target site of one shRNA was characterized. A novel RNA cleavage assay was developed to confirm the spectrum of activity of PF-05095808 against common HCV clinical isolates. In summary, our data both support antiviral activity consistent with an RNA interference mechanism and demonstrate the potential of PF-05095808 as a therapeutic agent for chronic HCV infection.
15 citations
TL;DR: Results indicate that the NS5B-siRNAs used in this study can specifically inhibit HCV-RNA replication and protein expression compared to control cells and thereby becomes a powerful strategy to combat hepatitis C virus.
12 citations