Antisense oligonucleotide inhibition of hepatitis C virus genotype 4 replication in HepG2 cells

Exploring the Impact of Different Inflammatory Cytokines on Hepatitis C Virus Infection

Hepatitis C virus (HCV) infection is a global health concern affecting millions worldwide. Chronic HCV infection often leads to liver inflammation and can progress to cirrhosis and hepatocellular carcinoma. Inflammatory cytokines are crucial in modulating the immune response during HCV infection. This review aims to investigate the impact of different inflammatory cytokines on HCV infection and associated immune responses. This review was conducted to identify relevant studies on the interplay between inflammatory cytokines and HCV infection. The analysis focused on the effects of key inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 (IL-1), and interferon-gamma (IFN-γ), on HCV replication, immune cell activation, and liver inflammation. The findings reveal that these inflammatory cytokines can significantly influence HCV infection and the subsequent immune response. TNF-α, IL-6, and IL-1 have been shown to enhance HCV replication, while IFN-γ exerts antiviral effects by inhibiting viral replication and promoting immune cell-mediated clearance of infected hepatocytes. Moreover, these cytokines contribute to the recruitment and activation of immune cells, such as natural killer cells, T cells, and macrophages, which play critical roles in controlling HCV infection. Understanding the precise mechanisms by which inflammatory cytokines impact HCV infection is crucial for developing more targeted therapeutic strategies. Modulating the levels or activity of specific cytokines may provide opportunities to attenuate HCV replication, reduce liver inflammation, and improve treatment outcomes. In conclusion, this review highlights the significance of inflammatory cytokines in influencing HCV infection and associated immune responses.

Consensus small interfering RNA targeted to stem-loops II and III of IRES structure of 5' UTR effectively inhibits virus replication and translation of HCV sub-genotype 4a isolates from Saudi Arabia

Being the most conserved region of all hepatitis C virus (HCV) genotypes and sub-genotypes, the 5′ untranslated region (5′ UTR) of HCV genome signifies it’s importance as a potential target for anti-mRNA based treatment strategies like RNA interference. The advent and approval of first small interference RNA (siRNA) -based treatment of hereditary transthyretin-mediated amyloidosis for clinical use has raised the hopes to test this approach against highly susceptible viruses like HCV. We investigated the antiviral potential of consensus siRNAs targeted to stem-loops (SLs) II and III nucleotide motifs of internal ribosome entry site (IRES) structure within 5′ UTR of HCV sub-genotype 4a isolates from the Saudi population. siRNA inhibitory effects on viral replication and translation of full-length HCV genome were determined in a competent, persistent, and reproducible Huh-7 cell culture system maintained for one month. Maximal inhibition of RNA transcript levels of HCV-IRES clones and silencing of viral replication and translation of full-length virus genome was demonstrated by siRNAs targeted to SL-III nucleotide motifs of IRES in Huh-7 cells. siRNA Usi-169 decreased 5′ UTR RNA transcript levels of HCV-IRES clones up to 75% (P < 0.001) at 24 h post-transfection and 80% (P < 0.001) at 48 h treatment in Huh-7 cells. 5′ UTR-tagged GFP protein expression was significantly decreased from 70 to 80% in Huh-7 cells co-transfected with constructed vectors (i.e. pCR3.1/GFP/5′ UTR) and siRNA Usi-169 at 24 h and 48 h time-span. Viral replication was inhibited by more than 90% (P < 0.001) and HCV core (C) and hypervariable envelope glycoproteins (E1 and E2) expression was also significantly degraded by intracytoplasmic siRNA Usi-169 activity in persistent Huh-7 cell culture system. The findings unveil that siRNAs targeted to 5′ UTR-IRES of HCV sub-genotype 4a Saudi isolates show potent silencing of HCV replication and blocking of viral translation in a persistent in-vitro Huh-7 tissue culture system. Furthermore, we also elucidated that siRNA silencing of viral mRNA not only inhibits viral replication but also blocks viral translation. The results suggest that siRNA potent antiviral activity should be considered as an effective anti-mRNA based treatment strategies for further in-vivo investigations against less studied and harder-to-treat HCV sub-genotype 4a isolates in Saudi Arabia.

Mice Antibody Response to Conserved Nonadjuvanted Multiple Antigenic Peptides Derived from E1/E2 Regions of Hepatitis C Virus

Synthetic peptides are one of the hepatitis C virus (HCV)-specific small molecules that have antiviral activity and represent a target for HCV vaccine. This study aims to determine the lowest concentration of adjuvanted and non-adjuvanted (multiple antigenic peptide [MAP]) form of three conserved HCV envelope peptides that can induce murine immunogenic responses and evaluate the neutralization capacities of the generated antibodies (Abs) against HCV in cultured Huh7.5 cells. In this study, three HCV synthetic peptides, E1 peptide (a.a 315-323) and E2 peptides (a.a 412-419 and a.a 516-531) were synthesized. Female Balb/c mice were immunized with different concentration of either adjuvanted linear peptides or nonadjuvanted MAP peptides to determine the lowest dose that generates Ab responses enough to confer viral neutralization in vitro. The humoral responses targeting these peptides in immunized mice sera were measured by enzyme-linked immunosorbent assay (ELISA). Viral neutralization capacities of the generated mice Abs were assessed using Huh7.5 cells infected with the HCVcc infectious system (J6/JFH-1). The results of this study showed that the MAPs induce higher Ab titers than adjuvanted linear peptides after 4 weeks of immunization (p = 0.003). The viral neutralization experiments showed that the immunized mice sera contain anti E1/E2 Abs that blocked HCVcc (J6/JFH-1) entry into Huh7.5 cells. In conclusion, the three HCV envelope MAP peptides are more immunogenic and produce higher neutralizing Abs than linear peptides; therefore, they can be essential components for HCV vaccine.

In Silico Design and Experimental Validation of siRNAs Targeting Conserved Regions of Multiple Hepatitis C Virus Genotypes

RNA interference (RNAi) is a post-transcriptional gene silencing mechanism that mediates the sequence-specific degradation of targeted RNA and thus provides a tremendous opportunity for development of oligonucleotide-based drugs. Here, we report on the design and validation of small interfering RNAs (siRNAs) targeting highly conserved regions of the hepatitis C virus (HCV) genome. To aim for therapeutic applications by optimizing the RNAi efficacy and reducing potential side effects, we considered different factors such as target RNA variations, thermodynamics and accessibility of the siRNA and target RNA, and off-target effects. This aim was achieved using an in silico design and selection protocol complemented by an automated MysiRNA-Designer pipeline. The protocol included the design and filtration of siRNAs targeting highly conserved and accessible regions within the HCV internal ribosome entry site, and adjacent core sequences of the viral genome with high-ranking efficacy scores. Off-target analysis excluded siRNAs with potential binding to human mRNAs. Under this strict selection process, two siRNAs (HCV353 and HCV258) were selected based on their predicted high specificity and potency. These siRNAs were tested for antiviral efficacy in HCV genotype 1 and 2 replicon cell lines. Both in silico-designed siRNAs efficiently inhibited HCV RNA replication, even at low concentrations and for short exposure times (24h); they also exceeded the antiviral potencies of reference siRNAs targeting HCV. Furthermore, HCV353 and HCV258 siRNAs also inhibited replication of patient-derived HCV genotype 4 isolates in infected Huh-7 cells. Prolonged treatment of HCV replicon cells with HCV353 did not result in the appearance of escape mutant viruses. Taken together, these results reveal the accuracy and strength of our integrated siRNA design and selection protocols. These protocols could be used to design highly potent and specific RNAi-based therapeutic oligonucleotide interventions.

Impact of OAS1 Exon 7 rs10774671 Genetic Variation on Liver Fibrosis Progression in Egyptian HCV Genotype 4 Patients

The aim of this study was to assess the impact of genetic variants of oligoadenylate synthetase 1 (OAS1) single-nucleotide polymorphism (SNP) rs10774671 at the exon 7 splice acceptor site on liver fibrosis progression and hepatitis C virus (HCV) outcome in Egyptian HCV genotype 4 patients. In this study, 195 subjects were enrolled; 60 controls and 135 chronic HCV genotype 4 patients with different fibrosis grades. All subjects were genotyped for OAS1 SNP rs10774671 polymorphism by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. There was an increasing trend of liver fibrosis progression as 52.9% GG, 73.6% GA, and 83.3% AA genotypes were detected in late fibrosis patients (p = 0.025). The AA genotype was higher in the late fibrosis group than in the early fibrosis group (83.3% vs. 16.7%) (p = 0.001). The A allele was significantly affecting the liver fibrosis progression rate, more than the G allele (p = 0.001). The multivariate analysis showed that the OAS1 GA and AA genotypes were independent factors associated with liver progression (p = 0.009, odds ratio [OR] 3.467, 95% confidence interval [CI] 1.273-7.584). In addition, the A allele was associated with liver fibrosis progression (p = 0.014, OR 2.525, 95% CI 1.157-4.545). The polymorphism at OAS1 exon 7 rs3741981 might be a potential genetic marker and can be useful in the assessment of liver fibrosis progression and disease outcome in HCV-infected patients.

Gene therapies for hepatitis C virus

Hepatitis C virus (HCV) is a leading cause of chronic hepatitis and infects approximately three to four million people per year, about 170 million infected people in total, making it one of the major global health problems. In a minority of cases HCV is cleared spontaneously, but in most of the infected individuals infection progresses to a chronic state associated with high risk to develop liver cirrhosis, hepatocellular cancer, or liver failure. The treatment of HCV infection has evolved over the years. Interferon (IFN)-α in combination with ribavirin has been used for decades as standard therapy. More recently, a new standard-of-care treatment has been approved based on a triple combination with either HCV protease inhibitor telaprevir or boceprevir. In addition, various options for all-oral, IFN-free regimens are currently being evaluated. Despite substantial improvement of sustained virological response rates, some intrinsic limitations of these new direct-acting antivirals, including serious side effects, the risk of resistance development and high cost, urge the development of alternative or additional therapeutic strategies. Gene therapy represents a feasible alternative treatment. Small RNA technology, including RNA interference (RNAi) techniques and antisense approaches, is one of the potentially promising ways to investigate viral and host cell factors that are involved in HCV infection and replication. With this, newly developed gene therapy regimens will be provided to treat HCV. In this chapter, a comprehensive overview guides you through the current developments and applications of RNAi and microRNA-based gene therapy strategies in HCV treatment.

In vitro inhibition of hepatitis C virus by antisense oligonucleotides in PBMC compared to hepatoma cells

AIM

To assess the efficiency of phosphorothioate antisense oligodeoxynucleotide 1 (S-ODN1) on HCV translation inhibition in PBMC compared to hepatoma cells in vitro for the first time.

MATERIALS AND METHODS

The study included 34 treatment naive HCV patients. IRES domain III and IV sequence variations were tested in 45 clones from 9 HCV patients. PBMC of HCV positive patients were subjected to S-ODN in vitro. Concomitantly HepG2 cells infected by the same patient's serum were also treated with S-ODN1 for 24 and 48 hours. Cellular RNA was tested for HCV plus and minus strands by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Sequence variations were seen in HCV IRES domain III only while domain IV was conserved among all the tested patient's clones. S-ODN1 successfully inhibited HCV translation in HepG2 cells, while in PBMC inhibition was partial.

CONCLUSION

HCV IRES domain IV is more conserved than domain IIId in genotype 4 HCV patients. S-ODN against HCV IRES domain IV was not efficient to inhibit HCV translation in PBMC under the study conditions. Further studies testing other S-ODN targeting other HCV IRES domains in PBMC should be done.

Single nucleotide polymorphism at exon 7 splice acceptor site of OAS1 gene determines response of hepatitis C virus patients to interferon therapy

BACKGROUND AND AIM

Response to interferon therapy and disease progression in hepatitis C virus (HCV) infected patients differs among individuals, suggesting a possibility of a contribution of host genetic factors. 2'-5'-oligoadenylate synthetase 1 (OAS1), an important component of the innate immune system with a proven antiviral function, may therefore have a relationship with the response to interferon therapy and clinical course of HCV disease. Our aim was to determine the frequency of single nucleotide polymorphism (SNP) at exon 7 splice acceptor site (SAS) of the OAS1 gene in relation to the interferon response and status of HCV infection.

METHODS

A 203 bp fragment containing exon 7 SAS was amplified in 70 HCV chronic patients and 50 healthy controls. SNP was examined using restriction fragment length polymorphism (RFLP) genotyping method. Correlations of SNP genotypes with response to interferon and clinical status of patients were statistically analyzed.

RESULTS

There was an increasing trend of response from AA to AG to GG genotypes (P = 0.007). Genotype AA was associated with non-response to interferon and higher degree of liver fibrosis (P = 0.05). Multivariate analysis showed this SNP as independent and a significant determinant of the outcome of interferon therapy (odds ratio 4.913 [95% confidence interval 1.365-8.2], P = 0.006).

CONCLUSIONS

This is the first study to show a significant association between the functional SNP at exon 7 SAS of OAS1 gene and the viral response to interferon in chronic HCV patients. Patients with AA genotype were associated with progressive HCV disease and viral resistance to interferon therapy. This OAS SNP is a potential bio-marker to predict IFN response in chronic hepatitis C patients.

Human cytomegalovirus infection inhibits response of chronic hepatitis-C-virus-infected patients to interferon-based therapy

BACKGROUND AND AIM

Cytomegalovirus (CMV) is a ubiquitous pathogen that infects the majority of humans. Co-infection of CMV and hepatitis C virus (HCV) may deteriorate the prognosis of HCV-infected patients. This study was conducted to examine the role of CMV reactivation in determining the response rate to treatment with interferon and ribavirin therapy in chronic HCV patients.

METHODS

Viral loads and genotyping were assessed using reverse transcription polymerase chain reaction and Innolipa systems, respectively. Reactivation of CMV in HCV patients who were all positive for CMV immunoglobulin G antibodies was tested by amplification of the gB1 gene using the end-point dilution quantitative-nested polymerase chain reaction method.

RESULTS

CMV DNA was detected in 89.7% of non-responders and in 34.6% of sustained virological responders. Patients with reactivated CMV had significantly higher fibrosis scores (72.7%) than those with undetectable CMV DNA (23.8%, P=0.002). Patients with positive CMV had higher rates of non-response and relapse (79.5%) than those with negative CMV DNA (19%). Chronic HCV patients with latent CMV had higher rates of response (81%) to treatment than those with reactivated CMV (20.5%, P<0.001). Therefore, HCV patients with reactivated CMV and advanced fibrosis were least likely to achieve a sustained virological response following interferon therapy. This possibility is reduced to 50% of its original value in patients with reactivated CMV without fibrosis.

CONCLUSIONS

Besides the staging of liver fibrosis, CMV co-infection should be considered as an extremely important factor when designing predictive models for HCV response to interferon treatment.

Consensus siRNA for inhibition of HCV genotype-4 replication

Background

HCV is circulating as a heterogeneous group of quasispecies. It has been addressed that siRNA can inhibit HCV replication in-vitro using HCV clone and/or replicon which have only one genotype. The current study was conducted to assess whether siRNA can inhibit different HCV genotypes with many quasispecies and to assess whether consensus siRNA have the same effect as regular siRNA.

Methods

We generated two chemically synthesized consensus siRNAs (Z3 and Z5) which cover most known HCV genotype sequences and quasispecies using Ambium system. Highly positive HCV patient's serum with nine quasispecies was transfected in-vitro to Huh-7 cell line which supports HCV genotype-4 replication. siRNA (Z3&Z5) were transfected according to Qiagen Porta-lipid technique and subsequently cultured for eight days. HCV replication was monitored by RT-PCR for detection of plus and minus strands. Real-time PCR was used for quantification of HCV, whereas detection of the viral core protein was performed by western blot.

Results

HCV RNA levels decreased 18-fold (P = 0.001) and 25-fold (P = 0.0005) in cells transfected with Z3 and Z5, respectively, on Day 2 post transfection and continued for Day 3 by Z3 and Day 7 by Z5. Reduction of core protein expression was reported at Day 2 post Z3 siRNA transfection and at Day 1 post Z5 siRNA, which was persistent for Day 4 for the former and for Day 6 for the latter.

Conclusion

Consensus siRNA could be used as a new molecular target therapy to effectively inhibit HCV replication in the presence of more than one HCV quasispecies.

New therapeutic opportunities for Hepatitis C based on small RNA

Hepatitis C virus (HCV) infection is one of the major causes of chronic liver disease, including cirrhosis and liver cancer and is therefore, the most common indication for liver transplantation. Conventional antiviral drugs such as pegylated interferon-alpha, taken in combination with ribavirin, represent a milestone in the therapy of this disease. However, due to different viral and host factors, clinical success can be achieved only in approximately half of patients, making urgent the requirement of exploiting alternative approaches for HCV therapy. Fortunately, recent advances in the understanding of HCV viral replication and host cell interactions have opened new possibilities for therapeutic intervention. The most recent technologies, such as small interference RNA mediated gene-silencing, anti-sense oligonucleotides (ASO), or viral vector based gene delivery systems, have paved the way to develop novel therapeutic modalities for HCV. In this review, we outline the application of these technologies in the context of HCV therapy. In particular, we will focus on the newly defined role of cellular microRNA (miR-122) in viral replication and discuss its potential for HCV molecular therapy.

Effect of combined antisense oligodeoxynucleotides directed against the human papillomavirus type 16 on cervical carcinoma cells

BACKGROUND

Cervical cancer is highly associated with human papillomavirus (HPV) E6 and E7 gene expression. We have previously reported two antisense oligodeoxynucleotides (AS-ODNs) directed against adjacent targets within the HPV-16 E6/E7 mRNA (419 and 434), each able to downregulate HPV-16 E6/E7 mRNA in vitro and in vivo and to specifically inhibit tumor cell growth in culture and animal models.

METHODS

Towards potential clinical application and improved in vivo performance, we analyzed the effect of the combined treatment of 419-434 AS-ODNs on the anchorage independent growth (AIG) of HPV-16-positive cervical carcinoma cell lines.

RESULTS

We found similar responses between combined 419-434 and individual AS-ODNs treatments in RNaseH assays, cell uptake, and in vivo degradation of HPV-16 E6/E7 transcripts. Moreover, the combined use of 419-434 AS-ODNs resulted in additive AIG inhibition of CaSki and SiHa cells, similar to that obtained with equivalent doses of the individual AS-ODNs.

CONCLUSIONS

By using a combined treatment, it may be possible to overcome the potential mutations frequently reported within HPV-16 genome, thus improving the potential application of 419 and 434 AS-ODNs as a therapeutic alternative for cervical cancer.