HepG2 cells support viral replication and gene expression of hepatitis C virus genotype 4 in vitro

Development of latent Interferon alpha 2b as a safe therapeutic for treatment of Hepatitis C virus infection

Interferon therapy for the treatment of hepatitis C virus infection has very limited clinical application due to short serum half-life and side effects of therapy in systemic route of administration. In the present study, we have focused to improve the interferon therapy by overcoming the limitation of side effects. We hypothesized that latent interferon alpha 2b (IFNα2b) produced by fusion of Latency associated protein (LAP) domain of TGFβ and IFNα2b having HCV NS3 protease cleavage site as linker that will be activated only at target site (liver) by viral protease (HCV NS3 protease) present on the surface of infected cells. The fusion proteins were expressed in pichia pastoris as homodimer and cleaved by recombinant HCV NS3 protease in vitro into two fragments corresponding to the IFNα-2b and LAP respectively. The latency of chimeric proteins and biological activity after treatment with HCV NS3 protease was assessed by cytopathic effect inhibition assay in A594 cells infected with encephalomyocarditis virus (EMCV) and reduction in HCV viral load in Huh7 cells. The HCV NS3 protease was present on the surface of HCV replicating Huh7 cells in amount that activated half of the effective concentration (EC₅₀) of latent IFNα2b fusion protein. As free circulating HCV NS3 protease was not detected in sera from chronic HCV patients and in vitro cleavage of intact latent IFNα2b fusion protein was not observed with peripheral blood mononuclear cells (PBMCs) isolated from chronic HCV patients, thus there are less likely chances of activation and off target binding of latent IFNα2b to show side effects during systemic route of administration. Therefore, most of the side effects of interferon can be overwhelmed at the cost of 50% reduced biological activity. Thus, the use of latent IFNα2b can be considered again as an option for treatment of HCV infection in combination with direct acting antivirals rather than alone with improved safety profile.

Advances in the role of HCV nonstructural protein 5a (NS5A) of 3a genotype in inducing insulin resistance by possible phosphorylation of AKT/PKB

HCV genes interfere with host cellular genes and play crucial role in pathogenesis. The mechanism under which HCV genes induce insulin resistance is not much clear. This study is aimed to examine the role of HCV NS5A in inducing insulin resistance by examining its affect in the phosphorylation level of AKT/PKB. In the present study, HepG2 cells were transfected with HCV NS5A and after 24 hours of transfection, protein was extracted from cells that were pre induced with insulin at three different time intervals i.e. 1hour, 2 hours and 3hours. Dot Blot analysis was performed to study the phosphorylation level of AKT. Results showed that there is clear upregulation of serine 473 phosphorylation level of AKT in NS5A transfected cells as compared with control (without NS5A). In conclusion, upregulation of serine 473 phosphorylation by NS5A of HCV genotype 3a suggests that this gene impairs the normal insulin AKT/PKB signaling pathway that leads towards insulin resistance and Type 2 diabetes mellitus. Therefore, HCV non-structural protein NS5A should be considered as promising candidate to be studied in detail for HCV induced insulin resistance and should be regarded as a therapeutically important target for the prevention of chronic liver diseases.

Hepatitis c virus genotype 4 replication in the hepatocellular carcinoma cell line HepG2/C3A

BACKGROUND/AIMS

The lack of a reliable cell culture system allowing persistent in vitro hepatitis C virus (HCV) propagation is still restraining the search for novel antiviral strategies. HepG2 cells transfection with HCV allows for viral replication. However, the replication is weak presumably because of HepG2 lack of miRNA-122, which is essential for viral replication. Other agents such as polyethylene glycol (PEG) and dimethyl sulfoxide (DMSO) have been shown to increase the efficiency of infection with other viruses. This study included comparison of HCV genotype 4 5'UTR and core RNA levels and HCV core protein expression at different time intervals in the absence or presence of PEG and/or DMSO postinfection.

MATERIALS AND METHODS

We used serum with native HCV particles in infecting HepG2 cells in vitro. HCV replication was assessed by reverse transcriptase polymerase chain reaction for detection of HCV RNA and immunofluorescence and flow cytometry for detection of HCV core protein.

RESULTS

HCV 5'UTR and core RNA expression was evident at different time intervals after viral infection, especially after cells were treated with PEG. HCV core protein was also evident at different time intervals using both immunofluorescence and flow cytometry. PEG, not DMSO, has increased the HCV core protein expression in the treated cells, similar to its effect on viral RNA expression.

CONCLUSIONS

These expression profiles suggest that the current model of cultured HepG2 cells allows the study of HCV genotype 4 replication and different stages of the viral life cycle.

Screening the anti infectivity potentials of native N- and C-lobes derived from the camel lactoferrin against hepatitis C virus

BACKGROUND

Hepatitis C virus (HCV) infection represents a worldwide health threat that still needs efficient protective vaccine and/or effective drug. The traditional medicine, such as camel milk, is heavily used by the large sector of HCV patients to control the infection due to the high cost of the available standard therapy. Camel milk contains lactoferrin, which plays an important and multifunctional role in innate immunity and specific host defense against microbial infection. Continuing the analysis of the effectiveness of camel lactoferrin against HCV, the current study aimed to separate and purify the native N- and C-lobes from the proteolytically cleaved camel lactoferrin (cLF) and to compare their in vitro activities against the HCV infection in Huh7.5 cells in order to determine the most active domain.

METHODS

Lactoferrin and its digested N- and C-lobes were purified by Mono S 5/50 GL column and Superdex 200 5/150 column. The purified proteins were assessed through three venues: 1. To inhibit intracellular replication, HCV infected cells were treated with the proteins at different concentrations and time intervals; 2. The proteins were directly incubated with the viral particles (neutralization) and then such neutralized viruses were used to infect cells; 3. The cells were protected with proteins before exposure to the virus. The antiviral potentials of the cLf and its lobes were determined using three techniques: 1. RT-nested PCR, 2. Real-time PCR, and 3. Flow cytometry.

RESULTS

N- and C-lobes were purified in two consecutive steps; using Mono-S and Superdex 200 columns. The molecular mass of N- and C-lobes was about 40 kDa. cLF and its lobes could prevent HCV entry into Huh 7.5 cells with activity reached 100% through direct interaction with the virus. The inhibition of intracellular viral replication by N-lobe is 2-fold and 3-fold more effective than that of the cLF and C-lobe, respectively.

CONCLUSION

Generated native N- and C-lobes from camel lactoferrin demonstrated a range of noticeably different potentials against HCV cellular infectivity. The anti-HCV activities were sorted as N-lobe > cLf > C-lobe.

Inhibitory effect of kaolin minerals compound against hepatitis C virus in Huh-7 cell lines

Background

Hepatitis C virus (HCV) is estimated to infect 200 million individuals in the globe, including approximately 10 million in Pakistan causing both acute and chronic hepatitis. The standard treatment against HCV is pegylated interferon therapy in combination with a nucleoside analogue ribavirin. In addition, several herbal extracts and phytochemicals derivatives are used traditionally in the treatment of liver diseases as well as HCV infection. The present study determines the inhibitory effect of kaolin minerals compound against hepatitis C virus in Huh-7 cell lines.

Methods

Huh-7 cell lines were used for the in vitro HCV replication by using HCV positive sera from different patients with known HCV genotypes and viral titer/load. Total RNA was extracted from these infected cells and was quantified by real-time polymerase chain reaction (Real-time PCR). The viral titer was compared with the control samples to determine the anti-HCV activity of kaolin derived compounds. Kaolin is a group of clay minerals, with the chemical composition Al₂ Si₂O₅ (OH)₄.

Results

The results showed promising effectiveness of local kaolin derived anti-HCV compounds by causing 28% to 77% decrease in the HCV titer, when applied to infected Huh-7 cell lines. This study provides the basis for future work on these compounds especially to determine the specific pathway and mechanism for inhibitory action in the replicon systems of viral hepatitis.

Conclusions

Kaolin mineral derivatives show promising inhibitory effects against HCV genotypes 3a and 1a infection, which suggests its possible use as complementary and alternative medicine for HCV viral infection.

Effectiveness of human, camel, bovine and sheep lactoferrin on the hepatitis C virus cellular infectivity: comparison study

Purpose

The prevalence of HCV infection has increased during recent years and the incidence reach 3% of the world's population, and in some countries like Egypt, may around 20%. The developments of effective and preventive agents are critical to control the current public health burden imposed by HCV infection. Lactoferrin in general and camel lactoferrin specifically has been shown to have a compatitive anti-viral activity against hepatitis C virus (HCV). The purpose of this study was to examine and compare the anti-infectivity of native human, camel, bovine and sheep lactoferrin on continuous of HCV infection in HepG2 cells.

Material and methods

Used Lfs were purified by Mono S 5/50 GL column and Superdex 200 5/150 column. The purified Lfs were evaluated in two ways; 1. the pre-infected cells were treated with the Lfs to inhibit intracellular replication at different concentrations and time intervals, 2. Lfs were directly incubated with the virus molecules then used to cells infection. The antiviral activity of the Lfs were determined using three techniques; 1. RT-nested PCR, 2. Real-time PCR and 3. Flowcytometric.

Results

Human, camel, bovine and sheep lactoferrin could prevent the HCV entry into HepG2 cells by direct interaction with the virus instead of causing significant changes in the target cells. They were also able to inhibit virus amplification in HCV infected HepG2 cells. The highest anti-infectivity was demonstrated by the camel lactoferrin.

Conclusion

cLf has inhibitory effect on HCV (genotype 4a) higher than human, bovine and sheep lactoferrin.

Very-low-density lipoprotein (VLDL)-producing and hepatitis C virus-replicating HepG2 cells secrete no more lipoviroparticles than VLDL-deficient Huh7.5 cells

In the plasma samples of hepatitis C virus (HCV)-infected patients, lipoviroparticles (LVPs), defined as (very-) low-density viral particles immunoprecipitated with anti-β-lipoproteins antibodies are observed. This HCV-lipoprotein association has major implications with respect to our understanding of HCV assembly, secretion, and entry. However, cell culture-grown HCV (HCVcc) virions produced in Huh7 cells, which are deficient for very-low-density lipoprotein (VLDL) secretion, are only associated with and dependent on apolipoprotein E (apoE), not apolipoprotein B (apoB), for assembly and infectivity. In contrast to Huh7, HepG2 cells can be stimulated to produce VLDL by both oleic acid treatment and inhibition of the MEK/extracellular signal-regulated kinase (ERK) pathway but are not permissive for persistent HCV replication. Here, we developed a new HCV cell culture model to study the interaction between HCV and lipoproteins, based on engineered HepG2 cells stably replicating a blasticidin-tagged HCV JFH1 strain (JB). Control Huh7.5-JB as well as HepG2-JB cell lines persistently replicated viral RNA and expressed viral proteins with a subcellular colocalization of double-stranded RNA (dsRNA), core, gpE2, and NS5A compatible with virion assembly. The intracellular RNA replication level was increased in HepG2-JB cells upon dimethyl sulfoxide (DMSO) treatment, MEK/ERK inhibition, and NS5A overexpression to a level similar to that observed in Huh7.5-JB cells. Both cell culture systems produced infectious virions, which were surprisingly biophysically and biochemically similar. They floated at similar densities on gradients, contained mainly apoE but not apoB, and were not neutralized by anti-apoB antibodies. This suggests that there is no correlation between the ability of cells to simultaneously replicate HCV as well as secrete VLDL and their capacity to produce LVPs.

Anti-infectivity of camel polyclonal antibodies against hepatitis C virus in Huh7.5 hepatoma

Purpose

To extend the study of the camel milk proteins which have antiviral activity against HCV, camel naïve polyclonal IgGs, α-lactalbumin were purified from camel milk and their anti-HCV effect was examined using PBMCs and Huh7.5 cell-lines. They were compared with the activity of human polyclonal IgGs and camel lactoferrin and casein.

Material and methods

Three types of experiments were performed on PBMCs and HuH7.5 cell. HCV was directly incubated with the purified proteins and then mixed with both cell types, or the proteins were incubated with the cells and then exposed to HCV, or the HCV pre-infected cells were treated with the proteins to inhibit intracellular replication. The proteins were added to cells or virus at different concentrations and time intervals.

Results

Pretreated PBMCs and Huh7.5 cells with milk proteins were not protected when exposed to HCV infection. The direct interaction between HCV and camel IgGs and camel lactoferrin (cLf) led to a complete inhibition of HCV entry into cells, while casein, α-lactalbumin and human IgGs failed to inhibit HCV entry at any tested concentration. Camel IgGs showed ability to recognize HCV peptides with a significant titer (12 × 10³) in comparison with human IgGs which failed to do it. Camel lactoferrin was capable of inhibiting the intracellular HCV replication at concentrations of 0.25-1.25 mg/ml.

Conclusion

Camel milk naïve polyclonal IgGs isolated from camel milk could inhibit the HCV infectivity and demonstrated strong signal against its synthetic peptides. Lactoferrin inhibit the HCV infectivity started from 0.25 mg/ml. However, α-lactalbumin, human IgGs and casein failed to demonstrate any activity against HCV infectivity.

Development of persistent HCV genotype 3a infection cell culture model in huh-7 cell

Background

Hepatitis C virus (HCV) is one of the major health concerns globally, with genotype 3a as the most prevalent in Pakistan. Lack of efficient HCV genotype 3a small animal models as well as genomic replicons has hampered the complete understanding of its life cycle, pathogenesis and therapeutic options. In this study we aimed to develop a persistent HCV genotype 3a infectious cell culture model.

Methods

We inoculated Huh-7 cells with HCV genotype 3a serum. Cells and media supernatant were collected at different time periods up to 40^th day post infection. Culture media supernatant was also collected to find out its ability to infect naive Huh-7 cells.

Results

HCV replication was confirmed at both RNA and protein level through Real Time RCR and western blot using HCV core as marker. In order to validate the persistence of our model for HCV genotype 3a replication we inhibited the HCV replication through core specific siRNAs. The HCV RNA was detected intracellularly from the day one post infection up till 40^th day, while HCV core protein was detected from the second day up to 40^th day consistently. In culture media supernatant HCV RNA was also actively detected conferring its ability to infect the naive Huh-7 cells. Furthermore, core specific siRNA showed significant inhibition at 24^th hour post transfection both at RNA and protein level with progressive increase in the expression of core gene after 3^rd day. It clearly depicts that the Huh-7 successfully retained the HCV replication after degradation of siRNA.

Conclusion

Finally, we report that our persistent infection cell culture model consistently replicate HCV genotype 3a for more than 1 month.

Inhibition of HCV 3a genotype entry through host CD81 and HCV E2 antibodies

Background

HCV causes acute and chronic hepatitis which can eventually lead to permanent liver damage hepatocellular carcinoma and death. HCV glycoproteins play an important role in HCV entry by binding with CD81 receptors. Hence inhibition of virus at entry step is an important target to identify antiviral drugs against HCV.

Methods and result

The present study elaborated the role of CD81 and HCV glycoprotein E2 in HCV entry using retroviral pseudo-particles of 3a local genotype. Our results demonstrated that HCV specific antibody E2 and host antibody CD81 showed dose- dependent inhibition of HCV entry. HCV E2 antibody showed 50% reduction at a concentration of 1.5 ± 1 μg while CD81 exhibited 50% reduction at a concentration of 0.8 ± 1 μg. In addition, data obtained with HCVpp were also confirmed with the infection of whole virus of HCV genotype 3a in liver cells.

Conclusion

Our data suggest that HCV specific E2 and host CD81 antibodies reduce HCVpp entry and full length viral particle and combination of host and HCV specific antibodies showed synergistic effect in reducing the viral titer.

HCV entry receptors as potential targets for siRNA-based inhibition of HCV

Background

Hepatitis C virus (HCV) is a major health concern with almost 3% of the world's population (350 million individuals) and 10% of the Pakistani population chronically infected with this viral pathogen. The current therapy of interferon-α and ribavirin against HCV has limited efficiency, so alternative options are desperately needed. RNA interference (RNAi), which results in a sequence-specific degradation of HCV RNA has potential as a powerful alternative molecular therapeutic approach. Concerning viral entry, the HCV structural gene E2 is mainly involved in virus attachment to the host cell surface receptors i.e., CD81 tetraspanin, scavenger receptor class B type 1 (SR-B1), low density lipoprotein receptor (LDLR) and claudin1 (CLDN1).

Results

In this report, we studied the relationship of the HCV receptors CD81, LDL, CLDN1 and SR-B1to HCV infection. The potential of siRNAs to inhibit HCV-3a replication in serum-infected Huh-7 cells was demonstrated by treatment with siRNAs against HCV receptors, which resulted in a significant decrease in HCV viral copy number.

Conclusions

Our data clearly demonstrate that the RNAi-mediated silencing of HCV receptors is among the first of its type for the development of an effective siRNA-based therapeutic option against HCV-3a. These findings will shed further light on the possible role of receptors in inhibition of HCV-3a viral titre through siRNA mediated silencing.

Examination of the activity of camel milk casein against hepatitis C virus (genotype-4a) and its apoptotic potential in hepatoma and hela cell lines

BACKGROUND

Hepatitis C is a global health concern that represents a major cause of liver disease and socioeconomic burden. Currently, there is no vaccine that protects against this infection or drug that treats it effectively. The current treatment for hepatitis C virus (HCV) infection does not produce a sustained virologic response. Therefore,discovery and identification of a new drug for HCV treatment is a high priority.Camel milk is a traditional medicine that could improve the control of HCV.

OBJECTIVES

To assess the potential effect of casein purified from camel milk on HCV cellular infectivity in a tissue culture model.

MATERIALS AND METHODS

Casein was purified from defatted camel milk to electrophoretic homogeneity. PBMCs and HepG2 and HeLa cell lines were used. Three kinds of experiments were conducted. HCV was directly interacted with casein and then mixed with different cell types, casein was incubated with the cells and then exposed to HCV, and the HCV pre-infected cells were treated with casein at different concentrations and time intervals. Non-infected cells were used to assess cytotoxicity and the apoptosis effect of casein.

RESULTS

Direct interaction of casein (with or without α-lactalbumin) with neither the virus nor the cells prevented HCV cell entry. However, casein with α-lactalbumin induced a cytotoxic effect in HepG2 and HeLa cell lines but not in human naïve leukocytes. At all concentrations tested, casein with α-lactalbumin could induce apoptosis in both infected and non-infected HepG2 cells.

CONCLUSIONS

Camel milk casein (with or without α-lactalbumin) did not demonstrate any anti-HCV activity. However, the cellular apoptotic cascade was initiated in HepG2 and HeLa cells treated with casein (with α-lactalbumin) but not in naïve leukocytes.

Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

Anti HCV vaccine is not currently available and the present antiviral therapies fail to cure approximately half of the treated HCV patients. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 and test their neutralizing activities in a step towards developing therapeutic and/or prophylactic immunogens against HCV infection. Antibodies were generated by vaccination of goats with synthetic peptides derived from HCV E2. Viral neutralizing capacity of the generated anti E2 antibodies was tested using in vitro assays. Goats immunized with E2 synthetic peptides termed p412 [a.a 412-419], p430 [a.a 430-447] and p517 [a.a 517-531] generated high titers of antibody responses 2 to 4.5 fold higher than comparable titers of antibodies to the same epitopes in chronic HCV patients. In post infection experiments of native HCV into cultured Huh7.5 cells anti p412 and anti p 517 were proven to be neutralizing to HCV genotype 4a from patients' sera (87.5% and 75% respectively). On the contrary anti p430 exhibited weak viral neutralization capacity on the same samples (31.25%). Furthermore Ab mixes containing anti p430 exhibited reduced viral neutralization properties. From these experiments one could predict that neutralization by Abs towards different E2-epitopes varies considerably and success in the enrichment of neutralization epitope-specific antibodies may be accompanied by favorable results in combating HCV infection. Also, E2 conserved peptides p517 and p412 represent potential components of a candidate peptide vaccine against HCV infection.

Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

Anti HCV vaccine is not currently available and the present antiviral therapies fail to cure approximately half of the treated HCV patients. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 and test their neutralizing activities in a step towards developing therapeutic and/or prophylactic immunogens against HCV infection. Antibodies were generated by vaccination of goats with synthetic peptides derived from HCV E2. Viral neutralizing capacity of the generated anti E2 antibodies was tested using in vitro assays. Goats immunized with E2 synthetic peptides termed p412 [a.a 412-419], p430 [a.a 430-447] and p517 [a.a 517-531] generated high titers of antibody responses 2 to 4.5 fold higher than comparable titers of antibodies to the same epitopes in chronic HCV patients. In post infection experiments of native HCV into cultured Huh7.5 cells anti p412 and anti p 517 were proven to be neutralizing to HCV genotype 4a from patients' sera (87.5% and 75% respectively). On the contrary anti p430 exhibited weak viral neutralization capacity on the same samples (31.25%). Furthermore Ab mixes containing anti p430 exhibited reduced viral neutralization properties. From these experiments one could predict that neutralization by Abs towards different E2-epitopes varies considerably and success in the enrichment of neutralization epitope-specific antibodies may be accompanied by favorable results in combating HCV infection. Also, E2 conserved peptides p517 and p412 represent potential components of a candidate peptide vaccine against HCV infection.

Characterization of chronic HCV infection-induced apoptosis

Background

To understand the complex and largely not well-understood apoptotic pathway and immune system evasion mechanisms in hepatitis C virus (HCV)-associated hepatocellular carcinoma (HCC) and HCV associated chronic hepatitis (CH), we studied the expression patterns of a number of pro-apoptotic and anti-apoptotic genes (Fas, FasL, Bcl-2, Bcl-xL and Bak) in HepG2 cell line harboring HCV- genotype-4 replication. For confirmation, we also assessed the expression levels of the same group of genes in clinical samples obtained from 35 HCC and 34 CH patients.

Methods

Viral replication was assessed in the tissue culture medium by RT-PCR, quantitative Real-Time PCR (qRT-PCR); detection of HCV core protein by western blot and inhibition of HCV replication with siRNA. The expression level of Fas, FasL, Bcl-2, Bcl-xL and Bak was assessed by immunohistochemistry and RT-PCR whereas caspases 3, 8 and 9 were assessed by colorimetric assay kits up to 135 days post infection.

Results

There was a consistent increase in apoptotic activity for the first 4 weeks post-CV infection followed by a consistent decrease up to the end of the experiment. The concordance between the changes in the expression levels of Fas, FasL, Bcl-2, Bcl-xL and Bak in vitro and in situ was statistically significant (p < 0.05). Fas was highly expressed at early stages of infection in cell lines and in normal control liver tissues followed by a dramatic reduction post-HCV infection and an increase in the expression level of FasL post HCV infection. The effect of HCV infection on other apoptotic proteins started very early post-infection, suggesting that hepatitis C modulating apoptosis by modulating intracellular pro-apoptotic signals.

Conclusions

Chronic HCV infection differently modulates the apoptotic machinery during the course of infection, where the virus induces apoptosis early in the course of infection, and as the disease progresses apoptosis is modulated. This study could open a new opportunity for understanding the various signaling of apoptosis and in the developing a targeted therapy to inhibit viral persistence and HCC development.

Glycyrrhizin as antiviral agent against Hepatitis C Virus

BACKGROUND

Hepatitis C virus is a major cause of chronic liver diseases which can lead to permanent liver damage, hepatocellular carcinoma and death. The presently available treatment with interferon plus ribavirin, has limited benefits due to adverse side effects such as anemia, depression, fatigue, and "flu-like" symptoms. Herbal plants have been used for centuries against different diseases including viral diseases and have become a major source of new compounds to treat bacterial and viral diseases.

MATERIAL

The present study was design to study the antiviral effect of Glycyrrhizin (GL) against HCV. For this purpose, HCV infected liver cells were treated with GL at non toxic doses and HCV titer was measured by Quantitative real time RT-PCR.

RESULTS AND DISCUSSION

Our results demonstrated that GL inhibit HCV titer in a dose dependent manner and resulted in 50% reduction of HCV at a concentration of 14 ± 2 μg. Comparative studies were made with interferon alpha to investigate synergistic effects, if any, between antiviral compound and interferon alpha 2a. Our data showed that GL exhibited synergistic effect when combined with interferon. Moreover, these results were verified by transiently transfecting the liver cells with HCV 3a core plasmid. The results proved that GL dose dependently inhibit the expression of HCV 3a core gene both at mRNA and protein levels while the GAPDH remained constant.

CONCLUSION

Our results suggest that GL inhibit HCV full length viral particles and HCV core gene expression or function in a dose dependent manner and had synergistic effect with interferon. In future, GL along with interferon will be better option to treat HCV infection.

Glycyrrhizin as antiviral agent against Hepatitis C Virus

Background

Hepatitis C virus is a major cause of chronic liver diseases which can lead to permanent liver damage, hepatocellular carcinoma and death. The presently available treatment with interferon plus ribavirin, has limited benefits due to adverse side effects such as anemia, depression, fatigue, and "flu-like" symptoms. Herbal plants have been used for centuries against different diseases including viral diseases and have become a major source of new compounds to treat bacterial and viral diseases.

Material

The present study was design to study the antiviral effect of Glycyrrhizin (GL) against HCV. For this purpose, HCV infected liver cells were treated with GL at non toxic doses and HCV titer was measured by Quantitative real time RT-PCR.

Results and Discussion

Our results demonstrated that GL inhibit HCV titer in a dose dependent manner and resulted in 50% reduction of HCV at a concentration of 14 ± 2 μg. Comparative studies were made with interferon alpha to investigate synergistic effects, if any, between antiviral compound and interferon alpha 2a. Our data showed that GL exhibited synergistic effect when combined with interferon. Moreover, these results were verified by transiently transfecting the liver cells with HCV 3a core plasmid. The results proved that GL dose dependently inhibit the expression of HCV 3a core gene both at mRNA and protein levels while the GAPDH remained constant.

Conclusion

Our results suggest that GL inhibit HCV full length viral particles and HCV core gene expression or function in a dose dependent manner and had synergistic effect with interferon. In future, GL along with interferon will be better option to treat HCV infection.

Effect of combined siRNA of HCV E2 gene and HCV receptors against HCV

Background/Aim

Hepatitis C virus (HCV) is a major threat as almost 3% of the world's population (350 million individual) and 10% of the Pakistani population is chronically infected with this virus. RNA interference (RNAi), a sequence-specific degradation process of RNA, has potential to be used as a powerful alternative molecular therapeutic approach in spite of the current therapy of interferon-α and ribavirin against HCV which has limited efficiency. HCV structural gene E2 is mainly involved in viral cell entry via attachment with the host cell surface receptors i.e., CD81 tetraspanin, low density lipoprotein receptor (LDLR), scavenger receptor class B type 1 (SR-B1), and Claudin1 (CLDN1). Considering the importance of HCV E2 gene and cellular receptors in virus infection and silencing effects of RNAi, the current study was designed to target the cellular and viral factors as new therapeutic options in limiting HCV infection.

Results

In this study the potential of siRNAs to inhibit HCV-3a replication in serum-infected Huh-7 cells was investigated by combined treatment of siRNAs against the HCV E2 gene and HCV cellular receptors (CD81 and LDLR), which resulted in a significant decrease in HCV viral copy number.

Conclusion

From the current study it is concluded that the combined RNAi-mediated silencing of HCV E2 and HCV receptors is important for the development of effective siRNA-based therapeutic option against HCV-3a.

Down-regulation of IRES containing 5'UTR of HCV genotype 3a using siRNAs

Background

Hepatitis C virus (HCV) is a major causative agent of liver associated diseases leading to the development of hepatocellular carcinoma (HCC) all over the world and genotype-3a responsible for most of the cases in Pakistan. Due to the limited efficiency of current chemotherapy of interferon-α (IFN-α) and ribavirin against HCV infection alternative options are desperately needed out of which the recently discovered RNAi represent a powerful silencing approach for molecular therapeutics through a sequence-specific RNA degradation process to silence virus infection or replication. HCV translation is mediated by a highly conserved internal ribosome entry site (IRES) within the 5'UTR region making it a relevant target for new drug development.

Materials and methods

The present study was proposed to assess and explore the possibility of HCV silencing using siRNA targeting 5'UTR. For this analysis full length HCV 5'UTR of HCV-3a (pCR3.1/5'UTR) was tagged with GFP protein for in vitro analysis in Huh-7 cells. siRNA targeting 5'UTR were designed, and tested against constructed vector in Huh-7 cell line both at RNA and Protein levels. Furthermore, the effect of these siRNAs was confirmed in HCV-3a serum infected Huh-7 cell line.

Results

The expression of 5'UTR-GFP was dramatically reduced both at mRNA and protein levels as compared with Mock transfected and control siRNAs treated cells using siRNAs against IRES of HCV-3a genotype. The potential of siRNAs specificity to inhibit HCV-3a replication in serum-infected Huh-7 cells was also investigated; upon treatment with siRNAs a significant decrease in HCV viral copy number and protein expression was observed.

Conclusions

Overall, the present work of siRNAs against HCV 5'UTR inhibits HCV-3a expression and represents effective future therapeutic opportunities against HCV-3a genotype.

Inhibition of full length hepatitis C virus particles of 1a genotype through small interference RNA

Background

Hepatitis C virus (HCV), a member of the Flaviviridae family of viruses, is a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Currently, the only treatment available consists of a combination of Pegylated interferon alpha (INF-α) and ribavirin, but only half of the patients treated show a sufficient antiviral response. Thus there is a great need for the development of new treatments for HCV infections. RNA interference (RNAi) represents a new promising approach to develop effective antiviral drugs and has been extremely effective against HCV infection.

Results

This study was design to assess or explore the silencing effect of small interference RNAs (siRNAs) against full length HCV particles of genotype 1a. In the present study six 21-bp siRNAs were designed against different regions of HCV structural genes (Core, E1 and E2). Selected siRNAs were labeled as Csi 301, Csi 29, E1si 52, E1si 192, E2si 86 and E2si 493. Our results demonstrated that siRNAs directed against HCV core gene showed 70% reduction in viral titer in HCV infected liver cells. Moreover, siRNAs against E1 and E2 envelop genes showed a dramatic reduction in HCV viral RNA, E2si 86 exhibited 93% inhibition, while E1si 192, E2si 493 and E1si 52 showed 87%, 80%, and 66% inhibition respectively. No significant inhibition was detected in cells transfected with the negative control siRNA.

Conclusion

Our results suggested that siRNAs targeted against HCV structural genes efficiently silence full length HCV particles and provide an effective therapeutic option against HCV infection.

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.

Role of HCV Core gene of genotype 1a and 3a and host gene Cox-2 in HCV-induced pathogenesis

Background

Hepatitis C virus (HCV) Core protein is thought to trigger activation of multiple signaling pathways and play a significant role in the alteration of cellular gene expression responsible for HCV pathogenesis leading to hepatocellular carcinoma (HCC). However, the exact molecular mechanism of HCV genome specific pathogenesis remains unclear. We examined the in vitro effects of HCV Core protein of HCV genotype 3a and 1a on the cellular genes involved in oxidative stress and angiogenesis. We also studied the ability of HCV Core and Cox-2 siRNA either alone or in combination to inhibit viral replication and cell proliferation in HCV serum infected Huh-7 cells.

Results

Over expression of Core gene of HCV 3a genotype showed stronger effect in regulating RNA and protein levels of Cox-2, iNOS, VEGF, p-Akt as compared to HCV-1a Core in hepatocellular carcinoma cell line Huh-7 accompanied by enhanced PGE2 release and cell proliferation. We also observed higher expression levels of above genes in HCV 3a patient's blood and biopsy samples. Interestingly, the Core and Cox-2-specific siRNAs down regulated the Core 3a-enhanced expression of Cox-2, iNOS, VEGF, p-Akt. Furthermore, the combined siRNA treatment also showed a dramatic reduction in viral titer and expression of these genes in HCV serum-infected Huh-7 cells. Taken together, these results demonstrated a differential response by HCV 3a genotype in HCV-induced pathogenesis, which may be due to Core and host factor Cox-2 individually or in combination.

Conclusions

Collectively, these studies not only suggest a genotype-specific interaction between key players of HCV pathogenesis but also may represent combined viral and host gene silencing as a potential therapeutic strategy.

Post-transcriptional inhibition of hepatitis C virus replication through small interference RNA

Background

Hepatitis C Virus (HCV) infection is a major health problem throughout world that causes acute and chronic infection which resulted in liver fibrosis, hepatocellular carcinoma and death. The only therapy currently available for HCV infection is the combination of pegylated interferon alpha (PEG-IFN α) and ribavirin. This therapy can effectively clear the virus infection in only 50% of infected individuals. Hence, there is a dire need to develop antiviral agents against HCV.

Results

This study was design to examine the ability of exogenous small interfering RNAs (siRNAs) to block the replication of HCV in human liver cells. In the present study six 21-bp siRNAs were designed against different regions of HCV non-structural genes (NS2, NS3 serine protease/helicase, NS4Band NS5B RNA dependent RNA polymerase). siRNAs were labeled as NS2si241, NS3si-229, NS3si-858, NS4Bsi-166, NS5Bsi-241 and NS5Bsi-1064. We found that siRNAs against HCV NS2- NS5B efficiently inhibit HCV replication in Huh-7 cells. Our results demonstrated that siRNAs directed against HCV NS3 (NS3si-229 and NS3si-858) showed 58% and 88% reduction in viral titer respectively. Moreover, NS4Bsi-166 and NS5Bsi-1064 exhibited a dramatic reduction in HCV viral RNA and resulted in greater than 90% inhibition at a 20 μM concentration, while NS2si-241 showed 27% reduction in viral titer. No significant inhibition was detected in cells transfected with the negative control siRNA.

Conclusion

Our results suggest that siRNAs targeting against HCV non-structural genes (NS2-NS5B) efficiently inhibit HCV replication and combination of these siRNAs of different targets and interferon will be better option to treat HCV infection throughout the world.

Inhibition of core gene of HCV 3a genotype using synthetic and vector derived siRNAs

Background

Hepatitis C virus (HCV) is a major causative agent of liver associated diseases throughout the world, with genotype 3a responsible for most of the cases in Pakistan. Due to the limited efficiency of current therapy, RNA interference (RNAi) a novel regulatory and powerful silencing approach for molecular therapeutics through a sequence-specific RNA degradation process represents an alternative option.

Results

The current study was purposed to assess and explore the possibility of RNAi to silence the HCV-3a Core gene expression, which play complex role in regulation of cell growth and host genes expression essential for infectivity and disease progression. To identify the potent siRNA target sites, 5 small interfering RNAs (siRNAs) against Core gene were designed and in vitro transcribed after consensus sequence analysis of different HCV-3a isolates. Antiviral effects of siRNAs showed upto 80% inhibition of Core gene expression by different siRNAs into Huh-7 cells as compared with Mock transfected and control siRNAs treated cells. For long lasting effect of siRNAs, vector based short hairpin siRNAs (shRNAs) were designed and tested against HCV-3a Core which resulted in a similar pattern of inhibition on RNA and protein expression of HCV Core as synthetic siRNAs. Furthermore, the efficacy of cell culture tested siRNA and shRNA, were evaluated for inhibition of HCV replication in HCV infected serum inoculated Huh-7 cells and a significant decrease in HCV viral copy number was observed.

Conclusions

Our results support the possibility of using consensus siRNA and shRNA-based molecular therapy as a promising strategy in effective inhibition of HCV-3a genotype.

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.