Interferon-alpha-2b plus ribavirin: a review of its use in the management of chronic hepatitis C

Superior antiviral activity of IFNβ in genital HSV-1 infection

Type I interferons (IFNs) present the first line of defense against viral infections, providing antiviral, immunomodulatory and antiproliferative effects. The type I IFN family contains 12 IFNα subtypes and IFNβ, and although they share the same receptor, they are classified as non-redundant, capable to induce a variety of different IFN-stimulated genes. However, the biological impact of individual subtypes remains controversial. Recent data propose a subtype-specificity of type I IFNs revealing unique effector functions for different viruses and thus expanding the implications for IFNα-based antiviral immunotherapies. Despite extensive research, drug-resistant infections with herpes simplex virus type 1 (HSV-1), which is the common agent of recurrent orogenital lesions, are still lacking a protective or curing therapeutic. However, due to the risk of generalized infections in immunocompromised hosts as well as the increasing incidence of resistance to conventional antiherpetic agents, HSV infections raise major health concerns. Based on their pleiotropic effector functions, the application of type I IFNs represents a promising approach to inhibit HSV-1 replication, to improve host immunity and to further elucidate their qualitative differences. Here, selective IFNα subtypes and IFNβ were evaluated for their therapeutic potential in genital HSV-1 infections. Respective in vivo studies in mice revealed subtype-specific differences in the reduction of local viral loads. IFNβ had the strongest antiviral efficacy against genital HSV-1 infection in mice, whereas IFNα1, IFNα4, and IFNα11 had no impact on viral loads. Based on flow cytometric analyses of underlying immune responses at local and peripheral sites, these differences could be further assigned to specific modulations of the antiviral immunity early during HSV-1 infection. IFNβ led to enhanced systemic cytokine secretion and elevated cytotoxic responses, which negatively correlated with viral loads in the vaginal tract. These data provide further insights into the diversity of type I IFN effector functions and their impact on the immunological control of HSV-1 infections.

Searching for plant-derived antivirals against dengue virus and Zika virus

Background

The worldwide epidemics of diseases as dengue and Zika have triggered an intense effort to repurpose drugs and search for novel antivirals to treat patients as no approved drugs for these diseases are currently available. Our aim was to screen plant-derived extracts to identify and isolate compounds with antiviral properties against dengue virus (DENV) and Zika virus (ZIKV).

Methods

Seven thousand plant extracts were screened in vitro for their antiviral properties against DENV-2 and ZIKV by their viral cytopathic effect reduction followed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, previously validated for this purpose. Selected extracts were submitted to bioactivity-guided fractionation using high- and ultrahigh-pressure liquid chromatography. In parallel, high-resolution mass spectrometric data (MSn) were collected from each fraction, allowing compounds into the active fractions to be tracked in subsequent fractionation procedures. The virucidal activity of extracts and compounds was assessed by using the plaque reduction assay. EC₅₀ and CC₅₀ were determined by dose response experiments, and the ratio (EC₅₀/CC₅₀) was used as a selectivity index (SI) to measure the antiviral vs. cytotoxic activity. Purified compounds were used in nuclear magnetic resonance spectroscopy to identify their chemical structures. Two compounds were associated in different proportions and submitted to bioassays against both viruses to investigate possible synergy. In silico prediction of the pharmacokinetic and toxicity (ADMET) properties of the antiviral compounds were calculated using the pkCSM platform.

Results

We detected antiviral activity against DENV-2 and ZIKV in 21 extracts obtained from 15 plant species. Hippeastrum (Amaryllidaceae) was the most represented genus, affording seven active extracts. Bioactivity-guided fractionation of several extracts led to the purification of lycorine, pretazettine, narciclasine, and narciclasine-4-O-β-D-xylopyranoside (NXP). Another 16 compounds were identified in active fractions. Association of lycorine and pretazettine did not improve their antiviral activity against DENV-2 and neither to ZIKV. ADMET prediction suggested that these four compounds may have a good metabolism and no mutagenic toxicity. Predicted oral absorption, distribution, and excretion parameters of lycorine and pretazettine indicate them as candidates to be tested in animal models.

Conclusions

Our results showed that plant extracts, especially those from the Hippeastrum genus, can be a valuable source of antiviral compounds against ZIKV and DENV-2. The majority of compounds identified have never been previously described for their activity against ZIKV and other viruses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01751-z.

A Journey From SARS-CoV-2 to COVID-19 and Beyond: A Comprehensive Insight of Epidemiology, Diagnosis, Pathogenesis, and Overview of the Progress into Its Therapeutic Management

The 2019 novel coronavirus (2019-nCoV), commonly known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or coronavirus disease 2019 (COVID-19), was first revealed in late 2019 in Wuhan city, Hubei province, China. It was subsequently spread globally and thereby declared as a pandemic by WHO in March 2020. The disease causes severe acute respiratory illness and is highly contagious due to the fast-onward transmission. As of the mid of November 2020, the disease has affected 220 countries with more than 16 million active cases and 1.3 million deaths worldwide. Males, pregnant women, the elderly, immunosuppressed patients, and those with underlying medical conditions are more vulnerable to the disease than the general healthy population. Unfortunately, no definite treatment is available. Although remdesivir as an antiviral had been approved for use in those above 12 years of age and 40 kg weight group, it has been observed to be ineffective in large-scale SOLIDARITY trials by WHO. Moreover, dexamethasone has been found to increase the recovery rate of ventilated patients; oxygen and inhaled nitric oxide as a vasodilator have been given emergency expanded access. In addition, more than 57 clinical trials are being conducted for the development of the vaccines on various platforms. Two vaccines were found to be significantly promising in phase III results. It is concluded that till the approval of a specific treatment or development of a vaccine against this deadly disease, the preventive measures should be followed strictly to reduce the spread of the disease.

The Changed Proportion of CD45RA+/CD45RO+ T Cells in Chronic Hepatitis C Patients During Pegylated Interferon-α with Ribavirin Therapy

Infection with the hepatitis C virus (HCV) may progress toward chronic hepatitis, liver cirrhosis, and liver cancer. A therapy for patients with chronic HCV infection is the combination of pegylated interferon-α with ribavirin, which increases the rate of sustained virological response (SVR) to 56%. However, a practical biomarker to predict SVR is lacking. T cells expressing the CD45RA isoform are considered naive, and antigenic stimulation converts them to CD45RO⁺. CD45RO⁺ T cells exhibit immediate response and high lymphokine production, leading to the maintenance and upregulation of immune reactions. The aim of this study is to clarify the proportions of CD45RA⁺ and CD45RO⁺ T cells associated with rapid virological response and SVR. We collected blood samples from 32 HCV patients receiving the combined treatment. The samples were collected before, during 4th, 12th, and 24th therapy weeks, and 4th week posttherapy, and their T cell populations were analyzed using flow cytometry. Twenty-nine patients (90.6%) achieved SVR. There were significant declines in proportions of CD45RA⁺ cells during 4th, 12th, and 24th therapy weeks, and significant increases in proportions of CD45RO⁺ cells during 24th therapy week and 4th week posttherapy (P < 0.05). Patients undergoing hepatitis C therapy exhibited lowered CD45RA⁺ cell proportions and increased CD45RO⁺ cell proportions. This effect may be important in a patient's response to pegylated interferon-α with ribavirin therapy.

The role of HCV proteins on treatment outcomes

For many years, the standard of treatment for hepatitis C virus (HCV) infection was a combination of pegylated interferon alpha (Peg-IFN-α) and ribavirin for 24–48 weeks. This treatment regimen results in a sustained virologic response (SVR) rate in about 50 % of cases. The failure of IFN-α-based therapy to eliminate HCV is a result of multiple factors including a suboptimal treatment regimen, severity of HCV-related diseases, host factors and viral factors. In recent years, advances in HCV cell culture have contributed to a better understanding of the viral life cycle, which has led to the development of a number of direct-acting antiviral agents (DAAs) that target specific key components of viral replication, such as HCV NS3/4A, HCV NS5A, and HCV NS5B proteins. To date, several new drugs have been approved for the treatment of HCV infection. Application of DAAs with IFN-based or IFN-free regimens has increased the SVR rate up to >90 % and has allowed treatment duration to be shortened to 12–24 weeks. The impact of HCV proteins in response to IFN-based and IFN-free therapies has been described in many reports. This review summarizes and updates knowledge on molecular mechanisms of HCV proteins involved in anti-IFN activity as well as examining amino acid variations and mutations in several regions of HCV proteins associated with the response to IFN-based therapy and pattern of resistance associated amino acid variants (RAV) to antiviral agents.

Antiviral activity of virocidal peptide derived from NS5A against two different HCV genotypes: an in vitro study

This study aimed at assessment of the antiviral activity of an amphipathic α-helical peptide derived from the hepatitis C virus NS5A known as C5A virocidal peptide against different HCV genotypes. Two sources of HCV virus for in vitro study: HCV genotype 4 sera samples and JFH-1 infectious culture system genotype 2a were used. Several virocidal peptide concentrations were tested to determine the concentration that inhibits HCV propagation in Huh 7.5 cells according to three different prortocols (pre-infection, coinfection, and post infection). The capacity of the virocidal peptide to block HCV in Huh7.5 cells infected with different 10 individual serum samples was evaluated. In the pre-infection protocol, virocidal concentration (20, 50, and 75 μM) showed no viral RNA. In the co-infection protocol, virocidal concentrations (10, 20, 50, 75 μM) showed no viral RNA while in post-infection protocol, 75 μM was the only concentration that blocked the HCV activity. Results of Huh7.5 cell line transfected with HCV cc J6/JFH and treated with virocidal peptide revealed that only the higher virocidal concentration (75 μM) showed no amplification. The percentage of virocidal blocking in the 10 HCV individual serum samples was 60%. In conclusion, the C5A virocidal peptide has potent antiviral activity against HCV.

Current progress in antiviral strategies

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Antiviral agents function as either viral targets or host factors.

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Virus-targeting antivirals (VTAs) function through a direct (DVTAs) or an indirect (InDVTAs) method in the viral life cycle.

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Host-targeting antivirals (HTAs) include reagents that target the host proteins that are involved in the viral life cycle.

The prevalence of chronic viral infectious diseases, such as human immunodeficiency virus (HIV), hepatitis C virus (HCV), and influenza virus; the emergence and re-emergence of new viral infections, such as picornaviruses and coronaviruses; and, particularly, resistance to currently used antiviral drugs have led to increased demand for new antiviral strategies and reagents. Increased understanding of the molecular mechanisms of viral infection has provided great potential for the discovery of new antiviral agents that target viral proteins or host factors. Virus-targeting antivirals can function directly or indirectly to inhibit the biological functions of viral proteins, mostly enzymatic activities, or to block viral replication machinery. Host-targeting antivirals target the host proteins that are involved in the viral life cycle, regulating the function of the immune system or other cellular processes in host cells. Here we review key targets and considerations for the development of both antiviral strategies.

Benzohydroxamic acids as potent and selective anti-HCV agents

A diverse collection of 40 derivatives of benzohydroxamic acid (BHAs) of various structural groups were synthesized and tested against hepatitis C virus (HCV) in full-genome replicon assay. Some of these compounds demonstrated an exceptional activity, suppressing viral replication at sub-micromolar concentrations. The compounds were inactive against key viral enzymes NS3, and NS5B in vitro assays, suggesting host cell inhibition target(s). The testing results were consistent with metal coordination by the BHAs hydroxamic group in complex with a target(s). Remarkably, this class of compounds did not suppress poliomyelitis virus (PV) propagation in RD cells indicating a specific antiviral activity of BHAs against HCV.

Closing in on the target: sustained virologic response in hepatitis C virus genotype 1 infection response-guided therapy

Retrospective analyses of the boceprevir and telaprevir phase 3 trial data demonstrate the clinical relevance of detected but not quantifiable hepatitis C virus (HCV) genotype 1 RNA during treatment. These analyses illustrate the importance of using precise and standard terminology in reporting low-level HCV RNA results for consistent data collection across clinical trials, and to ensure optimal virologic response-guided treatment decision making in clinical practice. In the context of currently available quantitative HCV RNA assays, we clarify that unquantifiable HCV RNA should be classified as target detected or target not detected, as both have been shown to reflect clinically different qualitative HCV RNA levels during treatment. Additionally, use of terms such as "undetectable" or "below limit of detection" should be avoided as such terms are imprecise, not consistently defined, and often misinterpreted.

Hepatitis C viremia and genotype distribution among a sample of nonmedical prescription drug users exposed to HCV in rural Appalachia

Research has demonstrated that hepatitis C (HCV) genotype distribution varies geographically and demographically. This exploratory study examines HCV viremia, viral concentration, and genotype distribution among anti-HCV positive, rural Appalachian nonmedical prescription drug users. The study population was randomly selected from a pool of 200 anti-HCV positive participants in a longitudinal study. Those randomly chosen were representative of the overall pool in terms of demographics, drug use, and other risk behaviors. Participants were tested serologically for HCV RNA, viral concentration, and genotype, and interview-administered questionnaires examined behavioral and demographic characteristics. Of the 81 participants, 69% tested RNA positive, 59% of which had viral loads exceeding 800,000 IU/ml. Approximately 66% of the RNA positive sample had genotype 1a; types 2b (16%) and 3a (13%) were less common. RNA positive participants were not significantly different than RNA negative participants demographically or behaviorally. Likewise, with the exception of education, genotype 1 participants were not significantly different than those with genotype 2 or 3. The prevalence of active HCV infection highlights a need for prevention and treatment in this population. However, the predominance of genotype 1 may present challenges due to its association with decreased responsiveness to drug treatment, although the novel class of direct-acting antivirals such as telaprevir and boceprevir offer new hope in this regard. The prevalence of genotype 1 may also foreshadow heightened burden of hepatocellular carcinoma and elevated healthcare expenditures. More research is needed to characterize HCV infection and genotype in this population.

Ribavirin restores ESR1 gene expression and tamoxifen sensitivity in ESR1 negative breast cancer cell lines

Tumor growth is estrogen independent in approximately one-third of all breast cancers, which makes these patients unresponsive to hormonal treatment. This unresponsiveness to hormonal treatment may be explained through the absence of the estrogen receptor alpha (ESR1). The ESR1 gene re-expression through epigenetic modulators such as DNA methyltransferase inhibitors and/or histone deacetylase inhibitors restores tamoxifen sensitivity in ESR1 negative breast cancer cell lines and opens new treatment horizons in patients who were previously associated with a poor prognosis.In the study presented herein, we tested the ability of ribavirin, which shares some structural similarities with the DNA-methyltransferase inhibitor 5-azacytidine and which is widely known as an anti-viral agent in the treatment of hepatitis C, to restore ESR1 gene re-expression in ESR1 negative breast cancer cell lines.In our study we identified ribavirin to restore ESR1 gene re-expression alone and even more in combination with suberoylanilide hydroxamic acid (SAHA - up to 276 fold induction).Ribavirin and analogs could pave the way to novel translational research projects that aim to restore ESR1 gene re-expression and thus the susceptibility to tamoxifen-based endocrine treatment strategies.

Stability of recombinant bovine interferon-γ antiviral activity in the absence of stabilizing additives

The stability of recombinant bovine interferon-γ (rbIFN-γ) produced by a baculovirus expression system was investigated under different storage conditions: freezing-thawing and storage for 30 days at temperatures of -80, 4, 25, and 37°C. Antiviral activity was not significantly decreased by freeze-thawing at least five times. Furthermore, although not statistically different, antiviral activity gradually decreased as temperature increased. These findings suggest that rbIFN-γ possesses high thermal and freeze-thaw stability.

Structure-based library design in efficient discovery of novel inhibitors

Structure-based library design employs both structure-based drug design (SBDD) and combinatorial library design. Combinatorial library design concepts have evolved over the past decade, and this chapter covers several novel aspects of structure-based library design together with successful case studies in the anti-viral drug design HCV target area. Discussions include reagent selections, diversity library designs, virtual screening, scoring/ranking, and post-docking pose filtering, in addition to the considerations of chemistry synthesis. Validation criteria for a successful design include an X-ray co-crystal complex structure, in vitro biological data, and the number of compounds to be made, and these are addressed in this chapter as well.

Pegylated interferons for the treatment of chronic hepatitis C: pharmacological and clinical differences between peginterferon-alpha-2a and peginterferon-alpha-2b

Chronic infection with hepatitis C virus (HCV) is a major healthcare problem, affecting an estimated 170 million people worldwide. Interferon-alpha has formed the basis of treatment regimens since the identification of HCV, either alone or in conjunction with the nucleoside analogue ribavirin. The relatively recent introduction of pegylated forms of interferon-alpha, with greater stability and in vivo activity, has substantially improved sustained virological response (SVR) rates compared with unmodified interferon-alpha, with SVR rates of 35-66% when used in conjunction with ribavirin in randomized controlled trials. Two pegylated interferon (peginterferon)-alpha molecules are commercially available for the treatment of chronic hepatitis C, and these differ in the size and nature of the covalently attached polyethylene glycol (PEG) moiety, with resulting differences in pharmacokinetics and in dosing regimens. Peginterferon-alpha-2b has a linear 12 kDa PEG chain covalently attached primarily to histidine-34 of interferon-alpha-2b via an unstable urethane bond that is subject to hydrolysis once injected, releasing native interferon-alpha-2b. The branched, 40 kDa PEG chain of peginterferon-alpha-2a is covalently attached via stable amide bonds to lysine residues of interferon-alpha-2a, and circulates as an intact molecule. Consequently, peginterferon-alpha-2a has a very restricted volume of distribution, longer half-life and reduced clearance compared with native interferon-alpha-2a, and can be given once weekly independently of bodyweight. Peginterferon-alpha-2b has a shorter half-life in serum than peginterferon-alpha-2a and requires bodyweight-based dosing. The majority of head-to-head randomized controlled trials, including the large, randomized IDEAL (Individualized Dosing Efficacy versus Flat Dosing to Assess Optimal Pegylated Interferon Therapy) trial (n = 3070), demonstrated similar SVR rates for peginterferon-alpha-2a and peginterferon-alpha-2b (41% vs 39% in IDEAL), in combination with ribavirin; however, two randomized controlled trials (n = 431 and 320) demonstrated a statistically significant benefit for peginterferon-alpha-2a (66% vs 54%, and 69% vs 54%). Furthermore, two large retrospective studies and one prospective observational study in real-life settings have shown a significant benefit for peginterferon-alpha-2a versus peginterferon-alpha-2b, although SVR rates were generally lower than those seen in controlled trials. The use of interferon-alpha with or without ribavirin is frequently associated with a range of adverse effects, including influenza-like symptoms, haematological changes and neuropsychiatric disturbances, and this is true also of the peginterferons, with similar levels of adverse events, dose reduction and discontinuation from treatment. Peginterferon-alpha-2a and peginterferon-alpha-2b appear from comparative studies to be similarly tolerated, with few differences of clinical significance noted. Peginterferon plus ribavirin, as the standard of care for patients with chronic hepatitis C, may in the future form the basis of improved treatment regimens that include new, targeted anti-HCV agents to increase SVR rates even further.

Potential benefits of sequential inhibitor-mutagen treatments of RNA virus infections

Lethal mutagenesis is an antiviral strategy consisting of virus extinction associated with enhanced mutagenesis. The use of non-mutagenic antiviral inhibitors has faced the problem of selection of inhibitor-resistant virus mutants. Quasispecies dynamics predicts, and clinical results have confirmed, that combination therapy has an advantage over monotherapy to delay or prevent selection of inhibitor-escape mutants. Using ribavirin-mediated mutagenesis of foot-and-mouth disease virus (FMDV), here we show that, contrary to expectations, sequential administration of the antiviral inhibitor guanidine (GU) first, followed by ribavirin, is more effective than combination therapy with the two drugs, or than either drug used individually. Coelectroporation experiments suggest that limited inhibition of replication of interfering mutants by GU may contribute to the benefits of the sequential treatment. In lethal mutagenesis, a sequential inhibitor-mutagen treatment can be more effective than the corresponding combination treatment to drive a virus towards extinction. Such an advantage is also supported by a theoretical model for the evolution of a viral population under the action of increased mutagenesis in the presence of an inhibitor of viral replication. The model suggests that benefits of the sequential treatment are due to the involvement of a mutagenic agent, and to competition for susceptible cells exerted by the mutant spectrum. The results may impact lethal mutagenesis-based protocols, as well as current antiviral therapies involving ribavirin.

RNA viruses are associated with many important human and animal diseases such as AIDS, influenza, hemorrhagic fevers and several forms of hepatitis. RNA viruses mutate at very high rates and, therefore, can adapt easily to environmental changes. Viral mutants resistant to antiviral inhibitors are readily selected, resulting in treatment failure. The simultaneous administration of three or more inhibitors is a means to prevent or delay selection of resistant mutants. A new antiviral strategy termed lethal mutagenesis is presently under investigation. It consists of the administration of mutagenic agents to elevate the mutation rate of the virus above the maximum level compatible with virus infectivity, without mutagenizing the host cells. Since low amounts of virus are extinguished more easily, the combination of a mutagen and inhibitor was more efficient than a mutagen alone in driving virus to extinction. Here we show that foot-and-mouth disease virus replicating in cell culture can be extinguished more easily when the inhibitor guanidine is administered first, followed by the mutagenic agent ribavirin, than when both drugs are administered simultaneously. Interfering mutants that contribute to extinction were active in the presence of ribavirin but not in the presence of guanidine. This observation provides a mechanism for the advantage of the sequential versus the combination treatment. This unexpected effectiveness of a sequential treatment is supported by a theoretical model of virus evolution in the presence of the inhibitor and the mutagen. The results can have an application for future lethal mutagenesis protocols and for current antiviral treatments that involve the antiviral agent ribavirin when it acts as a mutagen.

A simple method to monitor serum concentrations of fluoxetine and its major metabolite for pharmacokinetic studies

A rapid, selective and sensitive isocratic reversed-phase HPLC assay coupled with MS/MS detection for simultaneous quantification of fluoxetine and its major active metabolite in serum samples has been developed. Analytes were extracted with a simple three step liquid-liquid procedure and chromatographic separation was achieved on a C18 column. Because of its sensitivity, this HPLC/MS/MS method is suitable both for routine therapeutic drug monitoring and for pharmacokinetic studies, due to its low limits of quantification.

New challenges for mathematical and statistical modeling of HIV and hepatitis C virus in injecting drug users

Injecting drug users are not only driving blood-borne transmission of HIV and hepatitis C virus but also likely drive sexual transmission of HIV in large parts of the world. Mathematical and statistical modeling can provide important insights in these epidemiological processes and on the potential impact of interventions but have been little used to date. This review aims to discuss the potential areas of application of modeling in the field of viral infections in injecting drug users. After reviewing key examples of published modeling work on HIV and hepatitis C virus in injecting drug users, we discuss recent developments in the epidemiology, diagnosis, treatment and prevention of these infections. In particular, new methods for the diagnosis of early HIV infection, new antivirals for a more effective treatment of HIV, hepatitis B and hepatitis C virus infections, new concepts in design and surveillance of interventions for drug users and increasing possibilities of molecular typing of pathogens are changing the questions and decisions for public health policy makers who deal with drug-related infectious diseases. Research including mathematical modeling is needed to understand the impact of new diagnostic tools, new treatment options and combined intervention strategies on the epidemiology of viral infections in injecting drug users. Methodological advances in mathematical modeling are required to adequately approach some of the ensuing research questions. Modeling has much to offer for solving urgent policy questions, but current levels of funding in modeling research are insufficient and need to be scaled up to make better use of these possibilities.

Immunostimulatory effects of three classes of CpG oligodeoxynucleotides on PBMC from HCV chronic carriers

Background

Chronic hepatitis C virus (HCV) infection results from weak or absent T cell responses. Pegylated-interferon-alpha (IFN-α) and ribavirin, the standard of care for chronic HCV, have numerous immune effects but are not potent T cell activators. A potent immune activator such as TLR9 agonist CpG oligodeoxynucleotide (CpG) may complement current treatment approaches.

Methods

Peripheral blood mononuclear cells (PBMC) obtained from HCV chronic carriers who failed previous treatment and from healthy donors were incubated in vitro with the three main CpG classes (A, B or C), recombinant IFN-α-2b (IntronA) and/or ribavirin. Proliferation and cytokine secretion (IFN-α, IL-10 and IP-10) were evaluated.

Results

CpG induced proliferation and cytokine secretion in patterns expected for each CpG class with similar group means for HCV and healthy donors. IntronA and ribavirin, alone or together, had no detectable effects. IntronA and C-Class CpG together induced more IFN-α than CpG alone in most subjects. IFN-α secretion was proportional to the number of plasmacytoid dendritic cells in PBMC from healthy donors but not HCV donors in whom responses were highly heterogeneous.

Conclusion

The strong immune stimulatory effect of CpG on PBMC isolated from treatment-failed HCV patients suggests possible utility alone or in combination with current HCV antiviral treatment.

Measurement of ribavirin and evaluation of its stability in human plasma by high-performance liquid chromatography with UV detection

A simple high-performance liquid chromatography method for the determination of the antiviral agent ribavirin in human plasma was developed and validated. The method involved solid-phase extraction on phenyl boronic acid cartridges, a reversed-phase liquid chromatography with a Waters Atlantis dC18 (150 mm x 3.9 mm, 5 microm) column and a mobile phase consisting of 10 mM potassium phosphate buffer (pH 4.0), and ultraviolet detection at 207 nm. This assay proved to be sensitive (lower limit of quantification of 0.05 microg/ml), linear (correlation coefficients >or=0.997), specific (no interference with various potentially co-administrated drugs), reproducible (both intra-day and inter-day coefficients of variation <or=4.3%), and accurate (deviations ranged from -5.6 to 2.2% and from -6.0 to 4.0% for intra-day and inter-day analysis, respectively). The method was applied to therapeutic monitoring of patients undergoing ribavirin treatment for hepatitis C and proved to be robust and reliable. Thus, this method provides a simple, sensitive, precise and reproducible assay for dosing ribavirin that can be readily adaptable to routine use by clinical laboratories with standard equipment. In addition, we evaluated the stability of ribavirin in plasma under various conditions, since no detailed study on thermal stability of ribavirin has been reported so far and discrepant data do exist on ribavirin stability upon conditions that clinical samples commonly experience. Ribavirin was stable in human plasma stored at room temperature for at least 24 h or at -20 degrees C for up to 1 month, after three freeze-thaw cycles, as well as in samples undergoing heat inactivation of infectious viruses for 60 min at 60 degrees C. The drug was also stable in processed samples stored at -20 degrees C for 3 days (as dried extracts) or at 20 degrees C for 4 days (as reconstituted samples).

Oral resiquimod in chronic HCV infection: safety and efficacy in 2 placebo-controlled, double-blind phase IIa studies

BACKGROUND/AIMS

To explore safety, pharmacokinetics, and pharmacodynamics of oral administration of resiquimod, a Toll-like receptor 7 and 8 agonist that induces endogenous interferon-alpha, in subjects with chronic hepatitis C virus infection.

METHODS

Two randomized, double-blind phase IIa studies of resiquimod administered two times per week for 4 weeks. Multicenter study (U.S.): 12 subjects received resiquimod 0.01 mg/kg and 4 received placebo. Single center study (France): 6 subjects received 0.01 mg/kg, 11 received 0.02 mg/kg and 6 received placebo.

RESULTS

Resiquimod 0.01 mg/kg was tolerated; two 0.2 mg/kg subjects discontinued treatment. More subjects reported severe grade adverse events at 0.02 mg/kg; events were consistent with systemic cytokine induction, including fever, headache, shivering, and lymphopenia. Mean maximum serum resiquimod concentrations were 3.82+/-1.47 and 7.55+/-4.17 ng/mL for 0.01 mg/kg and 0.02 mg/kg, respectively. At 0.02 mg/kg, two, three and one subjects had maximal reductions in viral levels of at least 1-, 2- and 3-logs, respectively; reductions were generally transient. Interferon-alpha levels appeared correlated with decreases in viral titer and lymphocyte counts, as well as increase in neutrophil counts.

CONCLUSIONS

Oral administration of resiquimod 0.02 mg/kg transiently reduced viral levels but was associated with adverse effects similar to interferon-alpha.

Treatment of hepatitis C virus infection

Acute and chronic hepatitis C virus (HCV) infection remains a serious health problem worldwide, however, there has been advancement in the treatment of HCV infection due to standard treatment using pegylated interferon and ribavirin. The literature indicates that therapy for HCV is becoming more individualized. In addition to considering genotype and viral RNA levels before treatment, achievement of an early virologic response (EVR) and a rapid virologic response (RVR) is now possible during therapy. Moreover, problem patients, such as non-responders, relapsers, HIV or HBV co-infected patients, patients with liver cirrhosis, and pre- or post-liver transplantation patients are an increasing fraction of the patients requiring treatment. This article reviews the literature regarding standard treatments and problem patients with acute and chronic HCV infection. It also includes discussion on contraindications and side effects of treatment with interferon and ribavirin, as well as new drug development.

Evaluation of the anti-hepatitis C virus effect of novel potent, selective, and orally bioavailable JNK and VEGFR kinase inhibitors

Screening of a focused library of TGF beta kinase inhibitors in the cellular HCV replicon model with luciferase read out yielded a number of low micromolar HCV inhibitors. Medicinal chemistry driven optimization resulted in the discovery of 4-[2-(5-bromo-2-fluoro-phenyl)pteridin-4-ylamino]-N-[3-(2- oxopyrrolidin-1-yl)propyl]nicotinamide 36 with a replicon EC(50) of 64nM, associated with a selective kinase inhibitory profile for human JNK kinases 2 and 3 as well as VEGFR-1, 2, and 3 kinases. Moreover, 36 showed an advantageous PK profile in mice. Experiments performed using different replicon constructs suggest that this series of kinase inhibitors might mediate their effect through the HCV non-structural protein 5A (NS5A).

T cell receptor excision circles (TRECs), CD4+, CD8+, and their CD45RO+, and CD45RA+, subpopulations in hepatitis C virus (HCV)-HIV-co-infected patients during treatment with interferon alpha plus ribavirin: analysis in a population on effective antiretroviral therapy

Interferon (IFN)-alpha induced CD4(+) T lymphopenia is a toxic effect of the treatment of chronic hepatitis C virus (HCV) in human immunodeficiency virus (HIV)-co-infected patients. To increase the knowledge about this secondary effect, we performed an analysis of the evolution of the T cell receptor excision circles (TRECs), CD4(+) and CD8(+) T cells and of their CD45RO(+) and CD45RA(+) subpopulations during the treatment of chronic hepatitis HCV with peginterferon alpha (pegIFN-alpha) + ribavirin. Twenty HCV/HIV-co-infected patients, with undetectable HIV load after highly active antiretroviral therapy (HAART), were treated with pegIFN-alpha + ribavirin. TRECs were determined using real-time polymerase chain reaction. CD4(+) and CD8(+) T cells and their CD45RO(+) and CD45RA(+) subpopulations were analysed by two-colour flow cytometry. Median baseline CD4(+) and CD8(+) T cells were 592 mm(3) and 874 mm(3), respectively. Median baseline CD45RO(+) subpopulation was 48% for CD4(+) T and 57% for CD8(+) T lymphocytes. A progressive decrease in both T cell populations, as well as of their CD45RO(+) and CD45RA(+) subpopulations, was detected, with a difference between the baseline and nadir levels approaching 50%. The evolution of T cell populations and TRECs was independent of the response to the treatment. T lymphocytes and their subpopulations returned to baseline levels at 24 weeks after the end of treatment, with the exception of the T CD4(+) CD45RA(+) subpopulation. The ratio of CD4(+) CD45RO(+)/CD4(+) CD45RA(+) increased from 0.89 (baseline) to 1.44 (24 weeks after the end of the therapy). TRECs/ml did not return to the basal values. In conclusion, a significant reduction of CD4(+) and CD8(+) T cells, and of their CD45RA(+) and CD45RO(+) subpopulations, in HIV/HCV co-infected patients treated with pegIFN-alpha was observed. Both subpopulations increased after the suppression of treatment, but the CD4(+) CD45RA subpopulation did not reach the basal levels as a consequence, at least in part, of a decrease in thymic production.

Role of erythrocytes as a reservoir for ribavirin and relationship with adverse reactions in the early phase of interferon combination therapy for chronic hepatitis C virus infections

We investigated the relationship between serum ribavirin concentrations and clearance, as well as therapeutic efficacy and adverse reactions, in 97 Japanese patients with chronic hepatitis C virus infections treated with a 6-month course of high-dose alpha2b interferon (6 million units/day) plus ribavirin (600 to 800 mg/day) combination therapy. This randomized trial showed that the saturation of ribavirin uptake after taking ribavirin capsules does not occur within a dose range of 600 to 800 mg/day, which is a standard dosage used clinically in Japan. Serum ribavirin concentrations and clearance did not correlate with sustained virological response rates. Fourteen patients discontinued therapy because of adverse reactions, and sustained virological response rates were significantly reduced by discontinuation of therapy, while dose reduction of ribavirin did not alter the therapeutic effects. Ribavirin concentrations after 1 week and ribavirin clearance were significantly correlated with discontinuation of ribavirin; however, a multiple-regression analysis revealed that only hemoglobin concentration, but not ribavirin clearance, was a significant factor for discontinuation of therapy (odds ratio, 0.514; 95% confidence interval, 0.311 to 0.85; P = 0.0095). It appears that peripheral erythrocytes may act as a reservoir for ribavirin and regulate serum ribavirin levels in the very early phase of treatment.

Antiviral activity of CHO-SS cell-derived human omega interferon and other human interferons against HCV RNA replicons and related viruses

The fully glycosylated human omega interferon produced from CHO-SS cells (glycosylated IFN-omega) has been shown to be well-tolerated in man and to induce a sustained virologic response in patients infected with hepatitis C virus (HCV). We examined the antiviral activity of glycosylated IFN-omega and various human IFNs (IFN-alpha, -beta, -gamma and non-glycosylated bacterial (Escherichia coli) recombinant IFN-omega (non-glycosylated IFN-omega)) against HCV RNA replicons and several viruses related to HCV. Since none of the IFNs displayed cytotoxicity we compared their activities based on the effective concentration of the IFN that inhibited virus growth by 50% (EC50). Glycosylated IFN-omega was found to be the most potent antiviral agent of all the IFNs tested against bovine viral diarrhea virus (BVDV), yellow fever virus and West Nile virus. With HCV RNA replicons, non-glycosylated IFN-omega was comparable in activity to IFN-alpha while glycosylated IFN-omega was markedly more potent, indicating that glycosylation has an important effect on its activity. Drug combination analysis of glycosylated IFN-omega+ribavirin (RBV) in BVDV showed a synergy of antiviral effects similar to IFN-alpha+RBV, as well as a unique antagonism of RBV cytotoxic effects by glycosylated IFN-omega. Transcription factor (TF) profiling indicated that IFN-alpha or glycosylated IFN-omega treatment upregulated the same 17 TFs. IFN-alpha and glycosylated IFN-omega also upregulated 9 and 40 additional unique TFs, respectively. The differences in the expression of these TFs were modest, but statistically significantly different for eight of the TFs that were upregulated exclusively by glycosylated IFN-omega. The activation of these additional TFs by glycosylated IFN-omega might contribute to its high potency.

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

BACKGROUND

Hepatitis C (HCV) viral infection is a serious medical problem in Egypt and it has a devastating impact on the Egyptian economy. It is estimated that over 15% of Egyptians are infected by the virus and thus finding a cure for this disease is of utmost importance. Current therapies for hepatitis C virus (HCV) genotype 4 with interferon/ribavirin have not been successful and thus the development of alternative therapy for this genotype is desperately needed.

RESULTS

Although previous studies utilizing viral subgenomic or full cDNA fragments linked to reporter genes transfected into adhered cells or in a cell free system showed promise, demonstration of efficient viral replication was lacking. Thus, we utilized HepG2 cells infected with native HCV RNA genomes in a replication competent system and used antisense phosphorothioate Oligonucleotides (S-ODN) against stem loop IIId and the AUG translation start site of the viral polyprotein precursor to monitor viral replication. We were able to show complete arrest of intracellular replication of HCV-4 at 1 uM S-ODN, thus providing a proof of concept for the potential antiviral activity of S-ODN on native genomic replication of HCV genotype 4.

CONCLUSION

We have successfully demonstrated that by using two S-ODNs [(S-ODN1 (nt 326-348) and S-ODN-2 (nt 264-282)], we were able to completely inhibit viral replication in culture, thus confirming earlier reports on subgenomic constructs and suggesting a potential therapeutic value in HCV type 4.

Peginterferon-alpha 2a for the treatment of hepatitis B infection

Chronic hepatitis B is one of the world's most common serious diseases with > 300 million patients worldwide. Currently recommended treatments include conventional interferon (IFN), lamivudine and adefovir. Recently, peginterferon-alpha2a (PEG-IFN-alpha2a, Pegasys; Hoffmann-La Roche & Co.) has been approved for use in patients with chronic hepatitis B in the US, the EU, Switzerland, Turkey and in several countries in the Asia-Pacific region. Several trials have been carried out using PEG-IFN-alpha2a (40 kDa) compared with conventional IFN, lamivudine monotherapy and a combination of PEG-IFN-alpha2a and lamivudine in patients with hepatitis Be antigen- (HBeAg) positive chronic hepatitis B, and patients with HBeAg-negative chronic hepatitis B. PEG-IFN-alpha2a was shown to be superior to conventional IFN in HBeAg-positive disease and to lamivudine in both HBeAg-positive and HBeAg-negative chronic hepatitis B. Although there was greater suppression of virus while on therapy, the combination of lamivudine and PEG-IFN-alpha2a did not enhance sustained response at the end of the 24-week follow-up period, compared with PEG-IFN monotherapy. In addition, approximately 3% of patients underwent hepatitis B surface antigen (HBsAg) seroconversion - the ultimate marker of therapeutic response, which is rarely seen following treatment with antiviral agents. The side effect profile was reasonable. PEG-IFN-alpha2a could become the treatment of choice in many patients with both HBeAg-positive and HBeAg-negative disease and, in those who fail to respond, consideration could then be given to the use of antiviral agents.

Dual-action mechanism of viramidine functioning as a prodrug and as a catabolic inhibitor for ribavirin

An investigational nucleoside analogue drug, viramidine, has recently emerged as a potentially safer alternative to ribavirin for the treatment of hepatitis C viral infection. We have reported that viramidine mainly functions as a prodrug of ribavirin that is enriched in the liver. This in vitro study further explores viramidine's activity against nucleoside phosphorylase, a host enzyme that is responsible for phosphorolysis of ribavirin in vivo. Our experiments show that viramidine inhibits ribavirin phosphorolysis with a K(i) of 2.5 microM. This result suggests that viramidine may act through a dual-action mechanism by serving as a prodrug of ribavirin and concomitantly as an inhibitor for nucleoside phosphorylase catabolism of ribavirin.

Hepatitis C virus

Hepatitis C virus is a common blood-borne pathogen that is now declining as a new infection in the population. However, women and men who were infected 2 to 3 decades ago are now developing liver damage. To prevent further damage, treatment with IFN and ribavirin is available. Because of adverse events, this treatment requires close supervision over 6 to 12 months, which is often provided by a clinic nurse in collaboration with the physician and pharmacist. Educational outreach to the public and health care providers may help identify patients earlier and promote screening of high-risk groups.

Effects of interferon, ribavirin, and iminosugar derivatives on cells persistently infected with noncytopathic bovine viral diarrhea virus

Persistent infection with hepatitis C virus (HCV) is a major cause of chronic hepatitis in humans. In chronic carriers, the viral infection induces liver damage that predisposes the patient for cirrhosis and can lead to hepatocellular carcinoma. Current chemotherapies are limited to alpha interferon (IFN-alpha) used either alone or in combination with ribavirin (RBV). In addition to its limited efficacy, this treatment is frequently poorly tolerated because of its side effects. The urgently needed development of new drugs is made difficult by the lack of an in vitro or in vivo infectivity model, and no cell line has been found so far to reliably and reproducibly support HCV infection. For this reason, the closely related pestivirus bovine viral diarrhea virus (BVDV) has sometimes been used as a surrogate in vitro infectivity model. In this study we used an MDBK cell line persistently infected with noncytopathic BVDV to assess the antiviral effect of IFN-alpha and RBV, the two drugs currently in clinical use against HCV. The same system was then used to evaluate the potential of two classes of iminosugar derivates to clear noncytopathic BVDV infection from MDBK cells. We show that treatment with long-alkyl-chain deoxynojirimycin derivatives, which are inhibitors of the endoplasmic reticulum (ER)-resident alpha-glucosidases, can greatly reduce the amount of secreted enveloped viral RNA. Long-alkyl-chain deoxygalactonojirimycin derivatives, which do not inhibit ER alpha-glucosidases, were less potent but still more effective in this system than IFN-alpha or ribavirin.

A comparison of hepatitis C treatment and outcomes at academic, private and Veterans' Affairs treatment centres

BACKGROUND

Currently, there is a lack of published data examining hepatitis C treatment practices in different care settings.

AIM

To provide data describing treatment practices for patients with hepatitis C virus infection in actual clinical practice, and to examine clinical outcomes in patients treated with interferon alpha-2b/ribavirin combination therapy in academically affiliated centres, private treatment centres and Veterans' Affairs treatment centres.

METHODS

This multi-centre, retrospective, cohort study of 231 patients examined hepatitis C virus treatment practices in patients receiving interferon alpha-2b from January 1997 to May 2001 and explored outcomes in academically affiliated, private and Veterans' Affairs centres.

RESULTS

Differences in treatment practice and use of diagnostic procedures were found. Genotype testing was under-utilized in non-academic sites (academic centres, 79.2%; private centres, 33.7%; Veterans' Affairs centres, 35.9%; P<0.001). Liver biopsies were performed less often in private sites (academic centres, 95.8%; private centres, 80.0%; Veterans' Affairs centres, 92.2%; P<0.01). End-of-treatment viral response (academic centres, 40.0%; private centres, 31.3%; Veterans' Affairs centres, 17.2%; P<0.05) was lower than that found in published trial data. Multivariate analysis revealed genotype 1 as the single significant predictor of treatment failure (P<0.01).

CONCLUSIONS

Outside of the academic setting, there is significantly less diagnostic work-up performed prior to the initiation of hepatitis C virus therapy. This suggests a need for a standardization of care across treatment settings.

Synthesis and antiviral evaluation of ribavirin congeners containing a hexitol moiety

Several ribavirin congeners containing a hexitol moiety were prepared via ring opening of two different epoxides with the methylcarboxylate ester of triazole and further elaboration. Unfortunately, none of the newly synthesized compounds displayed appreciable antiviral activity.

Synergistic in vitro interactions between alpha interferon and ribavirin against bovine viral diarrhea virus and yellow fever virus as surrogate models of hepatitis C virus replication

Monotherapy of hepatitis C virus infection with either alpha interferon or ribavirin alone is rather ineffective, while the use of the two antivirals together is much more efficacious. In vitro drug-drug combination analysis utilizing related members of the family Flaviviridae, bovine viral diarrhea virus and yellow fever virus, revealed significant direct synergistic interactions between these drugs' antiviral activities that might explain this clinical observation.

Comprehensive review of hepatitis C for psychiatrists: risks, screening, diagnosis, treatment, and interferon-based therapy complications

Hepatitis C is an RNA virus responsible for chronic infection in at least 4 million Americans. Patients are often unaware that they have contracted the virus until the appearance of long-term consequences of the infection, primarily cirrhosis and hepatocellular carcinoma. Many patients with hepatitis C have comorbid psychiatric and/or substance abuse disorders. Treatments for hepatitis C infection are based on interferon-alfa therapy and have shown increasing effectiveness in recent years; however, interferon-alfa therapy also poses significant risks for physical and neuropsychiatric side effects. Since psychiatrists often serve as primary caregivers for patients who are at higher risk for hepatitis C infection, knowledge about the diagnosis, prognosis, and treatment of this disease is needed. In the first half of this article, the authors review the epidemiology, transmission, pathophysiology and disease course of hepatitis C, as well as the neuropsychiatric complications of hepatitis C infection. They also discuss the incidence of comorbid psychiatric disorders in patients with hepatitis C infection and consider the impact of the infection on patients' quality of life. The authors then provide an overview of the clinical management of HCV infection, including screening procedures, decision-making about treatment, available treatments (interferon-alfa, pegylated interferon-alpha, combination therapy with interferon and ribavirin) and their side effects and potential drug-drug interactions, and prediction of treatment response. The authors then discuss management of the neuropsychiatric complications of treatment with interferon-alpha and ribavirin, including depression, mania and psychosis, and cognitive and neurological complications. The final section of the article focuses on special issues related to the treatment of hepatitis C infection in patients with substance abuse or dependence and/or other comorbid psychiatric illness.

Ribavirin derivatives with a hexitol moiety: synthesis and antiviral evaluation

Current standard therapy for the treatment of chronic infections with hepatitis C virus consists of combination therapy with (pegylated) interferon-alpha and ribavirin. 1,5-Anhydrohexitol nucleoside analogues are constrained congeners known to mimic the ribonucleoside conformation. Within this series some analogues are endowed with strong antiviral properties, particularly against herpesviruses. The six-membered anhydrohexitol ring was, therefore, combined with the triazolyl carboxamide moiety of ribavirin, thus providing a new series of ribavirin analogues. None of the newly synthesized compounds elicited any substantial antiviral activity, neither against herpes simplex virus type 1 and 2, nor against bovine viral diarrhoea virus (a surrogate for hepatitis C virus) or the yellow fever virus.

Peginterferon-alpha-2a (40kD) plus ribavirin: a review of its use in the management of chronic hepatitis C

Pegylation of interferon-alpha-2a is associated with improved sustained virological response rates in patients with chronic hepatitis C. Subsequently, combination therapy with peginterferon-alpha-2a (40kD) [Pegasys] and ribavirin (Copegus trade mark, Rebetol) was investigated to establish if the efficacy of peginterferon-alpha-2a (40kD) monotherapy could be further enhanced. Subcutaneous peginterferon-alpha-2a (40kD) was administered at a dosage of 180 micro g once weekly and oral ribavirin was usually administered at a dosage of 1000 or 1200 mg/day. In treatment-naive patients with chronic hepatitis C, the sustained virological response rate (assessed 24 weeks after the end of a 48-week treatment period) was significantly higher in peginterferon-alpha-2a (40kD) plus ribavirin recipients than in peginterferon-alpha-2a (40kD) plus placebo recipients or interferon-alpha-2b plus ribavirin recipients (56% vs 29% and 44%). Retrospective analysis revealed that peginterferon-alpha-2a (40kD) plus ribavirin recipients who did not achieve an early virological response were unlikely to achieve a sustained response. Treatment with peginterferon-alpha-2a (40kD) plus another antiviral agent (ribavirin, mycophenolate mofetil, amantadine, or ribavirin and amantadine) was beneficial in patients with chronic hepatitis C who had relapsed during or after, or had not responded to, treatment with interferon-alpha-2b plus ribavirin. In the relapse study, sustained virological response rates in recipients of peginterferon-alpha-2a (40kD) plus ribavirin were 45% with and 38% without amantadine. Peginterferon-alpha-2a (40kD) plus ribavirin appears beneficial in patients with chronic hepatitis C considered difficult to treat (e.g. patients infected with hepatitis C virus genotype 4, African-American patients, patients with advanced fibrosis or cirrhosis and patients co-infected with HIV). Flu-like symptoms and depression occurred significantly less frequently with peginterferon-alpha-2a (40kD) plus ribavirin than with interferon-alpha-2b plus ribavirin. Similar proportions of patients receiving peginterferon-alpha-2a (40kD) plus ribavirin, peginterferon-alpha-2a (40kD) plus placebo and interferon-alpha-2b plus ribavirin withdrew from treatment because of laboratory abnormalities or other adverse events. In conclusion, combination therapy comprising subcutaneous peginterferon-alpha-2a (40kD) and oral ribavirin is an important new treatment option for chronic hepatitis C. Peginterferon-alpha-2a (40kD) plus oral ribavirin is significantly more effective than peginterferon-alpha-2a (40kD) monotherapy or interferon-alpha-2b plus ribavirin at inducing a sustained virological response in treatment-naive patients with chronic hepatitis C. Preliminary data suggest that peginterferon-alpha-2a (40kD) plus ribavirin is also beneficial in treatment-experienced patients and in patients who have traditionally been considered difficult to treat. Combination therapy with peginterferon-alpha-2a (40kD) and oral ribavirin is poised to become a valuable first-line treatment option in chronic hepatitis C.

Hepatitis C therapeutics: current status and emerging strategies

Chronic infection with hepatitis C virus (HCV) is an emerging global epidemic. The development of effective HCV antiviral therapeutics continues to be a daunting challenge owing to the absence of adequate animal models and tissue-culture systems for analysis and propagation of the virus. Despite these obstacles, inhibitors of the replicative elements of HCV, immune modulators and non-specific hepatoprotective agents are being pursued and exciting progress has been made. Successful therapeutic intervention of HCV will probably require combination approaches and new approaches, including host drug discovery targets.