Effect of human leukocyte interferon on hepatitis B virus infection in patients with chronic active hepatitis

UBR7 E3 Ligase Suppresses Interferon-β Mediated Immune Signaling by Targeting Sp110 in Hepatitis B Virus-Induced Hepatocellular Carcinoma

A newly discovered E3 ubiquitin ligase, UBR7, plays a crucial role in histone H2BK120 monoubiquitination. Here, we report a novel function of UBR7 in promoting hepatitis B virus (HBV) pathogenesis, which further leads to HBV-induced hepatocellular carcinoma (HCC). Transcriptomics analysis from HCC patients revealed the deregulation of UBR7 in cancer. Remarkably, targeting UBR7, particularly its catalytic function, led to a significant decrease in viral copy numbers. We also identified the speckled family protein Sp110 as an important substrate of UBR7. Notably, Sp110 has been previously shown to be a resident of promyelocytic leukemia nuclear bodies (PML-NBs), where it remains SUMOylated, and during HBV infection, it undergoes deSUMOylation and exits the PML body. We observed that UBR7 ubiquitinates Sp110 at critical residues within its SAND domain. Sp110 ubiquitination downregulates genes in the type I interferon response pathway. Comparative analysis of RNA-Seq from the UBR7/Sp110 knockdown data set confirmed that the IFN-β signaling pathway gets deregulated in HCC cells in the presence of HBV. Single-cell RNA-Seq analysis of patient samples further confirmed the inverse correlation between the expression of Sp110/UBR7 and the inflammation score. Notably, silencing of UBR7 induces IRF7 phosphorylation, thereby augmenting interferon (IFN)-β and the downstream interferon-stimulated genes (ISGs). Further, wild-type but not the ubiquitination-defective mutant of Sp110 could be recruited to the type I interferon response pathway genes. Our study establishes a new function of UBR7 in non-histone protein ubiquitination, promoting viral persistence, and has important implications for the development of therapeutic strategies targeting HBV-induced HCC.

Phytochemical and biological studies of Panicum antidotale aerial parts ethanol extract supported by molecular docking study

Panicum antidotale has traditionally been used as a poultice to alleviate local inflammation and painful diseases. This study aimed to evaluate the anti-inflammatory, wound-healing, analgesic, and antipyretic potential of its ethanol extract (PAAPEE) in vivo for the first time. In vitro antioxidant assays of Panicum antidotale using a 2,2-diphenyl-1-picrylhydrazyl assay revealed that it showed IC50 of 62.50 ± 6.85 μg/mL in contrast to standard, ascorbic acid, that showed IC50 of 85.51 ± 0.38 μg/mL. Administration of PAAPEE at a dose of 500 mg/kg (PAAPEE-500) displayed 78.44% and 75.13% inhibition of paw edema in carrageenen and histamine-induced edema models. respectively, 6 h post-treatment compared to that of the untreated group. Furthermore, it showed 68.78% inhibition of Freund's complete adjuvant-induced edema 21 days after treatment. It reduced the animal's rectal temperature in the yeast-induced fever model to 99.45 during the fourth h post-treatment. It significantly inhibited abnormal writhing by 44% in the acetic acid-induced pain model. PAE-500 also showed enhancement in wound closure by 72.52% with respect to that of the untreated group on the 10th day post-treatment using the excision healing of wound model. Histopathological examination of skin samples confirmed this improvement, showing enhanced tissue architecture with minimal infiltration of inflammatory cells. High-performance liquid chromatography (HPLC) of PAAPEE revealed the presence of quercetin, gallic, p-coumaric, benzoic, chlorogenic, syringic, ferulic, cinnamic, and sinapic acids. Molecular docking of 5-lipoxygenase and glycogen synthase kinase-3 β protein indicated their potential interaction within the active sites of both enzymes. Thus, P. antidotale serves as an effective natural wound-healing, anti-inflammatory, analgesic, and antipyretic agent.

Past, present, and future of long-term treatment for hepatitis B virus

The estimated world prevalence of hepatitis B virus (HBV) infection is 316 million. HBV infection was identified in 1963 and nowadays is a major cause of cirrhosis and hepatocellular carcinoma (HCC) despite universal vaccination programs, and effective antiviral therapy. Long-term administration of nucleos(t)ide analogues (NA) has been the treatment of choice for chronic hepatitis B during the last decades. The NA has shown a good safety profile and high efficacy in controlling viral replication, improving histology, and decreasing the HCC incidence, decompensation, and mortality. However, the low probability of HBV surface antigen seroclearance made necessary an indefinite treatment. The knowledge, in recent years, about the different phases of the viral cycle, and the new insights into the role of the immune system have yielded an increase in new therapeutic approaches. Consequently, several clinical trials evaluating combinations of new drugs with different mechanisms of action are ongoing with promising results. This integrative literature review aims to assess the knowledge and major advances from the past of hepatitis B, the present of NA treatment and withdrawal, and the future perspectives with combined molecules to achieve a functional cure.

In vitro functional analysis of gRNA sites regulating assembly of hepatitis B virus

The roles of RNA sequence/structure motifs, Packaging Signals (PSs), for regulating assembly of an HBV genome transcript have been investigated in an efficient in vitro assay containing only core protein (Cp) and RNA. Variants of three conserved PSs, within the genome of a strain not used previously, preventing correct presentation of a Cp-recognition loop motif are differentially deleterious for assembly of nucleocapsid-like particles (NCPs). Cryo-electron microscopy reconstruction of the T = 4 NCPs formed with the wild-type gRNA transcript, reveal that the interior of the Cp shell is in contact with lower resolution density, potentially encompassing the arginine-rich protein domains and gRNA. Symmetry relaxation followed by asymmetric reconstruction reveal that such contacts are made at every symmetry axis. We infer from their regulation of assembly that some of these contacts would involve gRNA PSs, and confirmed this by X-ray RNA footprinting. Mutation of the ε stem-loop in the gRNA, where polymerase binds in vivo, produces a poor RNA assembly substrate with Cp alone, largely due to alterations in its conformation. The results show that RNA PSs regulate assembly of HBV genomic transcripts in vitro, and therefore may play similar roles in vivo, in concert with other molecular factors.

Exploring the Pivotal Immunomodulatory and Anti-Inflammatory Potentials of Glycyrrhizic and Glycyrrhetinic Acids

Licorice extract is a Chinese herbal medication most often used as a demulcent or elixir. The extract usually consists of many components but the key ingredients are glycyrrhizic (GL) and glycyrrhetinic acid (GA). GL and GA function as potent antioxidants, anti-inflammatory, antiviral, antitumor agents, and immuneregulators. GL and GA have potent activities against hepatitis A, B, and C viruses, human immunodeficiency virus type 1, vesicular stomatitis virus, herpes simplex virus, influenza A, severe acute respiratory syndrome-related coronavirus, respiratory syncytial virus, vaccinia virus, and arboviruses. Also, GA was observed to be of therapeutic valve in human enterovirus 71, which was recognized as the utmost regular virus responsible for hand, foot, and mouth disease. The anti-inflammatory mechanism of GL and GA is realized via cytokines like interferon-γ, tumor necrotizing factor-α, interleukin- (IL-) 1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, and IL-17. They also modulate anti-inflammatory mechanisms like intercellular cell adhesion molecule 1 and P-selectin, enzymes like inducible nitric oxide synthase (iNOS), and transcription factors such as nuclear factor-kappa B, signal transducer and activator of transcription- (STAT-) 3, and STAT-6. Furthermore, DCs treated with GL were capable of influencing T-cell differentiation toward Th1 subset. Moreover, GA is capable of blocking prostaglandin-E2 synthesis via blockade of cyclooxygenase- (COX-) 2 resulting in concurrent augmentation nitric oxide production through the enhancement of iNOS2 mRNA secretion in Leishmania-infected macrophages. GA is capable of inhibiting toll-like receptors as well as high-mobility group box 1.

Ropeginterferon alfa-2b every 2 weeks as a novel pegylated interferon for patients with chronic hepatitis B

Background

Ropeginterferon alfa-2b is a novel mono-pegylated interferon that has only one major form as opposed to 8–14 isomers of other on-market pegylated interferon, allowing injection every two or more weeks with higher tolerability. It received European Medicines Agency and Taiwan marketing authorization in 2019 and 2020, for treatment of polycythemia vera. This phase I/II study aimed to have preliminary evaluation of safety and efficacy in chronic hepatitis B.

Methods

Thirty-one HBeAg-positive and 31 HBeAg-negative were stratified by HBeAg status and randomized at 1:1:1 ratio to q2w ropeginterferon alfa-2b 350 μg (group 1), q2w 450 μg (group 2) or q1w PEG-IFN alfa-2a 180 μg (group 3). Each patient received 48-week treatment (TW48) and 24-week post-treatment follow-up (FW24).

Results

The baseline demographics were comparable among the three groups, except for mean HBeAg in HBeAg-positive patients (2.90, 2.23, 2.99 log₁₀ S/CO, respectively). Cumulative HBeAg seroconversion rate at follow-up period was 27.3% (3/11), 36.4% (4/11), and 11.1% (1/9) with time to HBeAg seroconversion starting from TW24, TW16, and TW48 in group 1, 2, and 3, respectively. The rate of HBV DNA < 2000 IU/mL and HBsAg levels < 1500 IU/mL at FW24 were comparable in all groups. Ropeginterferon alfa-2b (group 1 & 2) had numerically lower incidence of rash (9.5% and 4.5%) as compared to PEG-IFN alfa-2a (36.8%). Ropeginterferon alfa-2b 350 μg (group 1) had more ALT elevation (38.1%), however the rate was comparable in group 2 (9.1%) and group 3 (10.5%).

Conclusion

In this preliminary study, ropeginterferon alfa-2b, although in only half the number of injections, is as safe and effective as pegylated interferon alfa-2a for chronic hepatitis B.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s12072-020-10098-y) contains supplementary material, which is available to authorized users.

The pros and cons of interferons for oncolytic virotherapy

Interferons (IFN) are potent immune stimulators that play key roles in both innate and adaptive immune responses. They are considered the first line of defense against viral pathogens and can even be used as treatments to boost the immune system. While viruses are usually seen as a threat to the host, an emerging class of cancer therapeutics exploits the natural capacity of some viruses to directly infect and kill cancer cells. The cancer-specificity of these bio-therapeutics, called oncolytic viruses (OVs), often relies on defective IFN responses that are frequently observed in cancer cells, therefore increasing their vulnerability to viruses compared to healthy cells. To ensure the safety of the therapy, many OVs have been engineered to further activate the IFN response. As a consequence of this IFN over-stimulation, the virus is cleared faster by the immune system, which limits direct oncolysis. Importantly, the therapeutic activity of OVs also relies on their capacity to trigger anti-tumor immunity and IFNs are key players in this aspect. Here, we review the complex cancer-virus-anti-tumor immunity interplay and discuss the diverse functions of IFNs for each of these processes.

Targeting Host Innate and Adaptive Immunity to Achieve the Functional Cure of Chronic Hepatitis B

Despite the availability of an effective preventive vaccine for hepatitis B virus (HBV) for over 38 years, chronic HBV (CHB) infection remains a global health burden with around 257 million patients. The ideal treatment goal for CHB infection would be to achieve complete cure; however, current therapies such as peg-interferon and nucleos(t)ide analogs are unable to achieve the functional cure, the newly set target for HBV chronic infection. Considering the fact functional cure has been accepted as an endpoint in the treatment of chronic hepatitis B by scientific committee, the development of alternative therapeutic strategies is urgently needed to functionally cure CHB infection. A promising target for future therapeutic strategies is immune modulation to restore dysfunctional HBV-specific immunity. In this review, we provide an overview of the progress in alternative therapeutic strategies, including immune-based therapeutic approaches that enhance host innate and adaptive immunity to achieve and increase the functional cure from CHB infection.

Discovery of New Hepatitis B Virus Capsid Assembly Modulators by an Optimal High-Throughput Cell-Based Assay

In this article, a simple and effective high-throughput screening (HTS) assay was developed to identify anti-HBV compounds by using a HepAD38 luciferase reporter (HepAD38-luc) cell line that can effectively exclude the false positive hit compounds targeted on the tetracycline off (tet-off) regulation system. Through screening in-house chemical libraries, N-phenylpiperidine-3-carboxamide derivatives, represented by 1 and 2, were identified, while the other false positive hits (i.e., quinoxaline (3) and benzothiazin (4) derivatives) were simultaneously excluded. Compounds 1 and 2 exhibit strong inhibitory activity against HBV replication in both HepAD38 and HepG2.2.15 cells. Further studies revealed that 1 and 2 reduced extracellular HBV DNA, HBeAg, and intracellular HBV intermediates, including total DNA, RNA, and precore RNA of HBV. Size-exclusion chromatography (SEC) and electron microscopy (EM) investigations demonstrated that 1 and 2 remarkably induced the formation of morphologically intact capsids and accelerated the dynamics of capsid assembly, suggesting that both 1 and 2 were type I capsid assembly modulators (CAMs).

Shared and Distinct Functions of Type I and Type III Interferons

Type I interferons (IFNs) (IFN-α, IFN-β) and type III IFNs (IFN-λ) share many properties, including induction by viral infection, activation of shared signaling pathways, and transcriptional programs. However, recent discoveries have revealed context-specific functional differences. Here, we provide a comprehensive review of type I and type III IFN activities, highlighting shared and distinct features from molecular mechanisms through physiological responses. Beyond discussing canonical antiviral functions, we consider the adaptive immune priming, anti-tumor, and autoimmune functions of IFNs. We discuss a model wherein type III IFNs serve as a front-line defense that controls infection at epithelial barriers while minimizing damaging inflammatory responses, reserving the more potent type I IFN response for when local responses are insufficient. In this context, we discuss current therapeutic applications targeting these cytokine pathways and highlight gaps in understanding of the biology of type I and type III IFNs in health and disease.

Taming a beast: lessons from the domestication of hepatitis C virus

"What I cannot create, I do not understand." Richard Feynman may have championed reasoning from first principles in his famous blackboard missive, but he could just as well have been referring to the plight of a molecular virologist. What cannot be grown in a controlled laboratory setting, we cannot fully understand. The story of the laboratory domestication of hepatitis C virus (HCV) is now a classic example of virologists applying all manner of inventive skill to create cell-based models of infection in order to clarify prospective drug targets. In this review, we highlight key successes and failures that were instructive in achieving cell-based models for HCV studies and drug development. We also emphasize the lessons learned from the ∼40 year saga that may be applicable to viruses yet unknown and uncultured.

Evolutionary biology of human hepatitis viruses

Hepatitis viruses are major threats to human health. During the last decade, highly diverse viruses related to human hepatitis viruses were found in animals other than primates. Herein, we describe both surprising conservation and striking differences of the unique biological properties and infection patterns of human hepatitis viruses and their animal homologues, including transmission routes, liver tropism, oncogenesis, chronicity, pathogenesis and envelopment. We discuss the potential for translation of newly discovered hepatitis viruses into preclinical animal models for drug testing, studies on pathogenesis and vaccine development. Finally, we re-evaluate the evolutionary origins of human hepatitis viruses and discuss the past and present zoonotic potential of their animal homologues.

Quantitative systems pharmacology of interferon alpha administration: A multi-scale approach

The therapeutic effect of a drug is governed by its pharmacokinetics which determine the downstream pharmacodynamic response within the cellular network. A complete understanding of the drug-effect relationship therefore requires multi-scale models which integrate the properties of the different physiological scales. Computational modelling of these individual scales has been successfully established in the past. However, coupling of the scales remains challenging, although it will provide a unique possibility of mechanistic and holistic analyses of therapeutic outcomes for varied treatment scenarios. We present a methodology to combine whole-body physiologically-based pharmacokinetic (PBPK) models with mechanistic intracellular models of signal transduction in the liver for therapeutic proteins. To this end, we developed a whole-body distribution model of IFN-α in human and a detailed intracellular model of the JAK/STAT signalling cascade in hepatocytes and coupled them at the liver of the whole-body human model. This integrated model infers the time-resolved concentration of IFN-α arriving at the liver after intravenous injection while simultaneously estimates the effect of this dose on the intracellular signalling behaviour in the liver. In our multi-scale physiologically-based pharmacokinetic/pharmacodynamic (PBPK/PD) model, receptor saturation is seen at low doses, thus giving mechanistic insights into the pharmacodynamic (PD) response. This model suggests a fourfold lower intracellular response after administration of a typical IFN-α dose to an individual as compared to the experimentally observed responses in in vitro setups. In conclusion, this work highlights clear differences between the observed in vitro and in vivo drug effects and provides important suggestions for future model-based study design.

Liposomal vaccine formulations as prophylactic agents: design considerations for modern vaccines

Vaccinology is one of the most important cornerstones in modern medicine, providing better quality of life. The human immune system is composed of innate and adaptive immune processes that interplay when infection occurs. Innate immunity relies on pathogen-associated molecular patterns which are recognized by pathogen recognition receptors localized in antigen presenting cells. After antigen processing and presentation, CD4+ T cell polarization occurs, further leading to B cell and CD8+ activation and humoral and cell-mediated adaptive immune responses. Liposomes are being employed as vaccine technologies and their design is of importance to ensure proper immune responses. Physicochemical parameters like liposome size, charge, lamellarity and bilayer fluidity must be completely understood to ensure optimal vaccine stability and efficacy. Liposomal vaccines can be developed to target specific immune cell types for the induction of certain immune responses. In this review, we will present promising liposomal vaccine approaches for the treatment of important viral, bacterial, fungal and parasitic infections (including tuberculosis, TB). Cationic liposomes are the most studied liposome types due to their enhanced interaction with the negatively charged immune cells. Thus, a special section on the cationic lipid dimethyldioctadecylammonium and TB is also presented.

Hepatitis B Virus Immunopathology, Model Systems, and Current Therapies

Most people develop acute hepatitis B virus (HBV)-related hepatitis that is controlled by both humoral and cellular immune responses following acute infection. However, a number of individuals in HBV-endemic areas fail to resolve the infection and consequently become chronic carriers. While a vaccine is available and new antiviral drugs are being developed, elimination of persistently infected cells is still a major issue. Standard treatment in HBV infection includes IFN-α, nucleoside, or nucleotide analogs, which has direct antiviral activity and immune modulatory capacities. However, immunological control of the virus is often not durable. A robust T-cell response is associated with control of HBV infection and liver damage; however, HBV-specific T cells are deleted, dysfunctional, or become exhausted in chronic hepatitis patients. As a result, efforts to restore virus-specific T-cell immunity in chronic HBV patients using antiviral therapy, immunomodulatory cytokines, or therapeutic vaccination have had little success. Adoptive cell transfer of T cells with specificity for HBV antigen⁺ cells represents an approach aiming to ultimately eliminate residual hepatocytes carrying HBV covalently closed circular DNA (cccDNA). Here, we discuss recent findings describing HBV immunopathology, model systems, and current therapies.

Alpha-interferon treatment in hepatitis B

Pegylated interferon-α (PEG-IFN-α) is a first line option in the treatment of chronic hepatitis B. Compared with nucleos(t)ide analogues (NAs), therapy with PEG-IFN-α has the advantages of finite treatment duration and higher rates of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) seroconversion, but the disadvantage of greater adverse effects. Choosing PEG-IFN-α requires careful evaluation of the likelihood of achieving a sustained off-treatment response. Sustained off-treatment response with PEG-IFN-α can be predicted by baseline factors in HBeAg positive disease. These include genotype A or B, low viral load, high alanine aminotransferase (ALT), older age and female gender. On the other hand, no pre-treatment factors have been identified that can reliably predict response in HBeAg negative disease. Using on-treatment quantitative HBsAg levels, failure of a long term response can be identified with high negative predictive value (NPV). However, no combination of on treatment parameters have been identified so far that can precisely forecast successful treatment. Up until recently, there was little evidence supporting the use of combining PEG-IFN with NAs. The addition of PEG-IFN in patients who already have viral suppression with NAs therapy appears superior to continuing NAs alone in achieving a sustained response. Also, tenofovir disoproxil fumarate (TDF) in combination with PEG-IFN has been reported to enable significantly higher HBsAg loss than with either monotherapy alone. This occurred in both HBeAg positive and negative patients across all genotypes. In spite of recent developments, rates of HBsAg loss are still only in the order of 10% and so cure remains elusive. Further research is required to identify the optimal combination or sequential therapy regimen, and the subgroups with the highest rates of response so that they can be targeted.

Biological Therapies of Immunologic Diseases: Strategies for Immunologic Interventions

The immune system possesses a vast number of potential targets for therapeutic intervention. Although therapies for many pathways have been pursued, only few have yielded significant success. Hindrances in altering biologic pathways include the potential for unwanted downstream effects, ineffectiveness owing to biological redundancy, recognition of a therapeutic molecule as foreign by the body's innate immune system, and the risks of subsequent malignancy and/or autoimmunity. This article covers currently available biotherapeutic agent classes as well as potential direction for future therapy.

Evolution in Our Understanding of Hepatitis B Virus Virology and Immunology

Hepatitis B virus (HBV) infection is a major global health challenge. HBV can cause significant morbidity and mortality by establishing acute and chronic hepatitis. Approximately 250 million people worldwide are chronically infected, and more than 2 billion people have been exposed to HBV. Since the discovery of HBV, the advances in our understanding of HBV virology and immunology have translated into effective vaccines and therapies for HBV infection. Although current therapies successfully suppress viral replication but rarely succeed in viral eradication, recent discoveries in HBV virology and immunology provide exciting rationales for novel treatment strategies aiming at HBV cure.

Hepatitis B: Treatment for the 21st Century

Hepatitis B virus (HBV) infection constitutes a worldwide public health problem, causing both acute and chronic liver infections. Although a vaccine has been developed that is effective in preventing HBV infection, this is of no benefit to the estimated 350 million carriers of the virus. Chronic hepatitis B infection may lead to cirrhosis of the liver and hepatocellular carcinoma. Therefore, there is a clear need for antiviral therapy. Alpha interferon was the first therapeutic agent used against HBV infection. However, its lack of efficacy in many patients and significant adverse event profile has prompted the development of alternative therapies. Nucleoside analogues are currently being investigated as potential anti-HBV agents, with two compounds, famciclovir and lamivudine, undergoing Phase III clinical trials of long-term use. In preclinical studies using the Pekin duck model for hepatitis B, both compounds have been found to reduce the amount of serum duck HBV DNA to sub-detectable levels during therapy. However, once therapy was stopped, the virus returned to pretreatment levels, making long-term treatment necessary. In clinical studies in chronic hepatis B patients, treatment with these agents also resulted in a significant reduction of HBV DNA levels but, again, the return of HBV DNA after discontinuing treatment indicates the need for long-term therapy. The need for long-term treatment means that the virus may develop resistance to the antiviral agents. Resistance mutations to both famciclovir and lamivudine are now being reported after treatment of chronic HBV infection with these agents. Combination therapy may be a strategy to overcome the development of resistance. Therapeutic vaccines and new antiviral agents are also being developed.

Antiviral Effect of Interferon Therapy for Patients with Chronic Hepatitis C

Thirty-two patients with chronic hepatitis who were positive for hepatitis C virus (HCV) RNA by polymerase chain reaction and had antibody to HCV (anti-HCV), were enrolled in this study. Twenty of them were also positive for antibody to the GOR epitope (anti-GOR). Sixteen of the enrolled patients were treated with human lymphoblastoid interferon for six months. Treatment was initiated with 3 million units of interferon daily for 2 weeks, followed by 3 million units three times a week for 6 weeks and 1.5 million units three times a week for 16 weeks. The efficacy of therapy was assessed by comparison with the results in 16 untreated patients. Aminotransferase values, titre of anti-HCV and anti-GOR antibodies showed significant decreases throughout the therapy compared with baseline levels and the untreated patients. After a 3 month follow-up, nine treated patients (56.3%) had normal aminotransferase activities and six of them eliminated HCV RNA from their sera (37.5%). Three of these six patients became negative for both anti-HCV and anti-GOR antibodies (18.8%). None of the untreated control patients had normal aminotransferase activities or became negative for HCV markers. The present study suggests that human lymphoblastoid interferon can control the disease activity and eliminate hepatitis C virus from patients with chronic hepatitis C.

Hepatitis B: 50 years after the discovery of Australia antigen

It is an honour to be invited to recount the progress in our understanding and management of hepatitis B 50 years after the discovery of Australia antigen (Au Ag). During this half century, we have gone from identifying the causative agent--hepatitis B virus (HBV), understanding its biology and the disease it causes, to having vaccines that can prevent HBV infection and antiviral therapy that can suppress HBV replication and prevent progression of HBV-related liver disease. As a result of the progress, prevalence of HBV infection and morbidity and mortality from chronic HBV infection has declined.

Current and future directions for treating hepatitis B virus infection

Hepatitis B virus (HBV) persistently infects approximately 350 million people, and approximately 600000 liver-related deaths are observed per year worldwide. HBV infection is also one of the major risk factors for hepatocellular carcinoma (HCC). The persistence of serum hepatitis B e antigen (HBeAg) and high level of serum HBV DNA are thought to reflect a high HBV replication status in hepatocytes, causing cirrhosis, HCC and liver-related deaths. It has been reported that antiviral therapy, such as peginterferon and nucleos(t)ide analogues (NUCs), could suppress liver-related death by inhibiting the HBV DNA levels and inducing seroconversion from HBeAg to antibody to HBe antigen. Currently, peginterferon is widely used, but there are also several disadvantages in the use of peginterferon, such as various adverse events, the administration route and duration. It is difficult to predict the effects of treatment and interferon is contraindicated for the patients with advanced fibrosis of the liver and cirrhosis. With respect to NUCs, entecavir and tenofovir disoproxil fumarate are current the first-choice drugs. NUCs can be administered orally, and their anti-viral effects are stronger than that of peginterferon. However, because cessation of NUC administration leads to high levels of viral replication and causes severe hepatitis, they must be administered for a long time. On the other hand, the use of both interferon and NUCs cannot eliminate covalently closed circular DNA of HBV. In this review, we evaluate the natural course of chronic HBV infection and then provide an outline of these representative drugs, such as peginterferon, entecavir and tenofovir disoproxil fumarate.

Viral hepatitis: past and future of HBV and HDV

Viral hepatitis is a significant disease afflicting hundreds of millions of people. Hepatitis-causing viruses initiate significant morbidity and mortality by establishing both acute and chronic infections, and several of these viruses are specifically associated with the development of hepatocellular carcinoma (HCC). Consequently, intense research efforts are focused on increasing our understanding of virus biology and on improving antiviral therapy. Even though viral hepatitis can be caused by several viruses from a range of virus families, the discovery of components of the hepatitis B virus (HBV) became a catalyst for the development of diagnostic assays that differentiate between these viruses as well as strategies for novel methods of vaccine development. Improvements in both the treatment and prevention of viral hepatitis are advancing rapidly. However, HBV, along with the associated infection by the hepatitis D virus, is still among the most common pathogens afflicting humans.

Twenty-five years of type I interferon-based treatment: a critical analysis of its therapeutic use

The clinical exploitation of type I interferon (IFN) as an antiviral and antineoplastic agent is based on the properties originally attributed to this cytokine family, with schedules reflecting only their antiviral and antiproliferative activities. Nevertheless, type I IFN has emerged as a central activator of the innate immunity. As current schedules of treatment for chronic hepatitis C and for hematological and solid tumors, based on the continuous administration of recombinant type I IFN or pegylated formulations, disregard viral resistance, host genetic variants predicting treatment outcome and mechanisms of refractoriness, new administration schedules, the combination of type I IFN with new drugs and the increased monitoring of patients’ susceptibility to type I IFN are expected to provide a new life to this valuable cytokine.

The Molecular and Structural Basis of HBV-resistance to Nucleos(t)ide Analogs

Infection with hepatitis B virus (HBV) is a worldwide health problem. Chronic hepatitis B can lead to fibrosis, liver cirrhosis, and hepatocellular carcinoma (HCC). Management of the latter two conditions often requires liver transplantation. Treatment with conventional interferon or pegylated interferon alpha can clear the virus, but the rates are very low. The likelihood, however, of viral resistance to interferon is minimal. The main problems with this therapy are the frequency and severity of side effects. In contrast, nucleos(t)ide analogs (NAs) have significantly lower side effects, but require long term treatment as sustained virological response rates are extremely low. However, long term treatment with NAs increases the risk for the development of anti-viral drug resistance. Only by understanding the molecular basis of resistance and using agents with multiple sites of action can drugs be designed to optimally prevent the occurrence of HBV antiviral resistance.

Advances in and the future of treatments for hepatitis C

Enormous progress has been made in the understanding of the hepatitis C virus and the development of novel therapeutic agents since the identification of the virus 25 years ago. From initial interferon monotherapy providing only 6% viral clearance rate in the 1980s, pharmacotherapeutics has now entered an exciting new era with direct-acting antiviral agents demonstrating viral clearance rates of more than 70%. We are now at the beginning of an era where combinations of direct-acting antiviral agents may pave the way for interferon-free regimens, even improving the viral clearance rate to near 100%.

Medical virology of hepatitis B: how it began and where we are now

Infection with hepatitis B virus (HBV) may lead to acute or chronic hepatitis. HBV infections were previously much more frequent but there are still 240 million chronic HBV carriers today and ca. 620,000 die per year from the late sequelae liver cirrhosis or hepatocellular carcinoma. Hepatitis B was recognized as a disease in ancient times, but its etiologic agent was only recently identified. The first clue in unraveling this mystery was the discovery of an enigmatic serum protein named Australia antigen 50 years ago by Baruch Blumberg. Some years later this was recognized to be the HBV surface antigen (HBsAg). Detection of HBsAg allowed for the first time screening of inapparently infected blood donors for a dangerous pathogen. The need to diagnose clinically silent HBV infections was a strong driving force in the development of modern virus diagnostics. HBsAg was the first infection marker to be assayed with a highly sensitive radio immune assay. HBV itself was among the first viruses to be detected by assay of its DNA genome and IgM antibodies against the HBV core antigen were the first to be selectively detected by the anti-μ capture assay. The cloning and sequencing of the HBV genome in 1978 paved the way to understand the viral life cycle, and allowed development of efficient vaccines and drugs. Today’s hepatitis B vaccine was the first vaccine produced by gene technology. Among the problems that still remain today are the inability to achieve a complete cure of chronic HBV infections, the recognition of occult HBV infections, their potential reactivation and the incomplete protection against escape mutants and heterologous HBV genotypes by HBV vaccines.

IFN-α subtypes: distinct biological activities in anti-viral therapy

During most viral infections, the immediate host response is characterized by an induction of type I IFN. These cytokines have various biological activities, including anti-viral, anti-proliferative and immunomodulatory effects. After induction, they bind to their IFN-α/β receptor, which leads to downstream signalling resulting in the expression of numerous different IFN-stimulated genes. These genes encode anti-viral proteins that directly inhibit viral replication as well as modulate immune function. Thus, the induction of type I IFN is a very powerful tool for the host to fight virus infections. Many viruses evade this response by various strategies like the direct suppression of IFN induction or inhibition of the IFN signalling pathway. Therefore, the therapeutic application of exogenous type I IFN or molecules that induce strong IFN responses should be of great potential for future immunotherapies against viral infections. Type I IFN is currently used as a treatment in chronic hepatitis B and C virus infection, but as yet is not widely utilized for other viral infections. One reason for this restricted clinical use is that type I IFN belongs to a multigene family that includes 13 different IFN-α subtypes and IFN-β, whose individual anti-viral and immunomodulatory properties have so far not been investigated in detail to improve IFN therapy against viral infections in humans. In this review, we summarize the recent achievements in defining the distinct biological functions of type I IFN subtypes in cell culture and in animal models of viral infection as well as their clinical usage in chronic hepatitis virus infections.

Treatment of hepatitis C infections with interferon: a historical perspective

Interferons were first described in 1957, but it was not until 34 years after their discovery that sufficient quantities of it were available for treatment of hepatitis C virus (HCV) infections, Clinicians now have an excellent understanding of the basis for the effectiveness of interferon alpha (IFN-α) in the therapy of this disease. Treatment with IFN-α is more efficient when it complemented by the antiviral ribavirin and the IFN-α is conjugated with polyethylene glycol to form peginterferon. In the near future treatment of HCV with IFN-α may involve new anti-HCV agents that are currently under development.

Progress in the use of RNA interference as a therapy for chronic hepatitis B virus infection

Chronic infection with hepatitis B virus (HBV) occurs in approximately 6% of the world's population and carriers of the virus are at risk for hepatocellular carcinoma and cirrhosis. Current treatment regimens, which include interferon-α and nucleoside/nucleotide analogs, are only partially effective and new treatment methods remain an important objective. Harnessing the RNA interference (RNAi) pathway to achieve post-transcriptional silencing of rogue genetic elements is an exciting avenue for development of novel therapeutic strategies. The specific and potent suppression of HBV gene expression and replication is an attractive option as a novel and effective approach for the treatment of chronic HBV infection. However, despite significant and rapid progress, existing RNAi technologies require further refinement before clinical applications can be realized. Here, we review current efforts aimed at improving the efficiency of anti-HBV RNAi-based delivery systems, at limiting the toxicities associated with RNAi modalities and at preventing reactivation of viral replication. We discuss the progress towards clinical implementation of anti-HBV RNAi therapies.

When rheumatology meets hepatology: are anti-TNFs safe in hepatitis B virus carriers?

Over the past decades, more effective and less toxic biologicals have revolutionized rheumatology therapy in our battle against the autoimmune chronic inflammation of rheumatoid arthritis and spondyloarthropathy. But what about for patients who have previously had an infection of the liver? Prior hepatitis B virus infection clearly presents a challenge for clinicians. In a study by Charpin and colleagues of 21 patients whose hepatitis B virus serology suggested carrier status, anti-TNF treatment appeared to be safe during a limited follow-up period of 3 years. Studies are needed with longer follow-up, particularly in patients with low antibody titres (antiHBc). In the 3-year period, however, about 30% of the patients developed significant lowering of antibody titres, which may become relevant during long-term follow-up. Charpin and colleagues are the first to reveal promising data on the relative safety of anti-TNFs in a small series of hepatitis B carriers for up to 3 years.

Interferons as Therapy for Viral and Neoplastic Diseases: From Panacea to Pariah to Paragon

For more than 20 years after the excitement engendered by their discovery in 1957 as antiviral agents, there were no significant clinical uses of interferons; however, following their cloning they have been employed as effective treatment for several viral, autoimmune, and neoplastic diseases.

Trial with human leucocyte interferon and vidarabine in herpes simplex virus encephalitis: diagnostic and therapeutic problems

A combination therapy of human interferon, vidarabine, and dexamethasone was administered to six patients with proven (Patients I-III) or presumed (Patients IV-VI) herpes simplex virus encephalitis (HSVE). Interferon combined with dexamethasone was given to one patient with presumed HSVE (Patient VII). Leucopenia and elevated serum transaminase levels appeared in all patients and a diffuse bleeding in one of them. Patients II, III and IV died, 26, 43, and 209 days after the onset of encephalitis, respectively. Patients I, V, VI, and VII were left with moderate brain damage although their physical condition was good. HSV encephalitis presents diagnostic difficulties, complementary diagnostic methods are needed, and current therapeutic trials must be considered as preliminary.

Effect of long-term treatment with human leukocyte interferon on various laboratory parameters

Leukocyte interferon was given by i.m. injection as adjuvant therapy to 9 patients with osteosarcoma. The dose was 3 X 10(6) standard units daily for one month, and then 3 times a week for the next 17 months. Blood samples were drawn at intervals for a number of routine tests during the 18-month course of interferon administration and during the subsequent 18 months. On withdrawal of the interferon treatment, the mean Hb concentration rose significantly and the mean ESR fell significantly. There was no significant change in the leukocyte and platelet counts or in the alkaline phosphatase, alanine and aspartate aminotransferase or plasma protein levels.

Lamivudine monotherapy for chronic hepatitis B infection with acute exacerbation revisited

BACKGROUND

Acute exacerbation (AE) of chronic hepatitis B virus (HBV) infection in cancer chemotherapy patients and in organ transplant recipients receiving immunosuppressants may cause catastrophe and high mortality. Hence, immediate treatment with nucleoside analogues for such patients has become a consensus. Anti-HBV therapeutic trials in Asia have shown that AE of chronic hepatitis B (CH-B) may result in increased sustained remission (SR) rate with lamivudine monotherapy. Nonetheless, AE episodes in CH-B patients may evolve uneventfully and lead to spontaneous remission. Thus, the policy of immediate anti-HBV therapy for AE patients reaches an impasse. Once treatment is initiated, life long HBV suppression may be necessary.

OBJECTIVE

To determine whether lamivudine monotherapy during an AE of CH-B results in an increase in SR compared with no therapy.

METHODS

A cohort of 154 CH-B patients seropositive for hepatitis B e antigen with AE formed the study group. This included 102 cases receiving a nationwide therapeutic trial of 18-month lamivudine monotherapy that were compared with 52 cases with no therapy. All were observed for at least 30 months, which encompassed the 18-month on treatment period and a 12-month posttreatment follow-up.

RESULTS

No significant increase was observed in the SR rate in the lamivudine treatment group compared with the spontaneous remission rate in the untreated patients (P=0.782, Fisher's exact test).

CONCLUSION

AE does not increase the SR rate during 18-month lamivudine monotherapy. Immediate lamivudine therapy for AE patients is not justified as mandatory. The policy should be only applied to AE patients with impending liver failure.