Therapy Of Hepatitis B Virus Infection Research Articles

An HBV susceptibility variant of KNG1 modulates the therapeutic effects of interferons α and λ1 in HBV infection by promoting MAVS lysosomal degradation.

Hepatitis B virus (HBV) infection is one of the main causes of hepatocellular carcinoma (HCC). The relationship between HBV infection and the host genome as well as their underlying mechanisms remain largely unknown. In this study, we performed a whole-genome exon sequencing analysis of 300 sib-pairs of Chinese HBV-infected families with the goal of identifying variants and genes involved in HBV infection. A site-direct mutant plasmid was used to investigate the function of SNP rs76438938 in KNG1. The functional and mechanical studies of KNG1 were conducted with invitro liver cell lines and a hydrodynamic injection model invivo. The impact of KNG1 on HBV infection therapy was determined in hepatocytes treated with IFN-α/λ1. Our whole-exon association study of 300 families with hepatitis B infection found that SNP rs76438938 in KNG1 significantly increased the risk for HBV infection, and the rs76438938-T allele was found to promote HBV replication by increasing the stability of KNG1 mRNA. By competitively binding HSP90A with MAVS, KNG1 can inhibit the expression of types I and III IFNs by promoting MAVS lysosomal degradation. Such suppression of IFN expression and promotion of HBV replication by Kng1 were further demonstrated with an animal model invivo. Lastly, we showed that the rs76438938-C allele can improve the therapeutic effect of IFN-α and -λ1 in HBV infection. This study identified a SNP, rs76438938, in a newly discovered host gene, KNG1, for its involvement in HBV infection and treatment effect through modulating the cellular antiviral process. This study was supported in part by the Independent Task of State Key Laboratory for Diagnosis and Treatment of Infectious Diseases of the First Affiliated Hospital of Zhejiang University, the China Precision Medicine Initiative (2016YFC0906300), and the Research Center for Air Pollution and Health of Zhejiang University.

Defining the specificity and function of a human neutralizing antibody for Hepatitis B virus

Hepatitis B Virus (HBV) is a hepadnavirus that is the principal pathogen underlying viral liver disease in human populations. In this study, we describe the isolation and characterization of a fully human monoclonal antibody for HBV. This HuMab was isolated by a combinatorial screen of the memory B-cell repertoire from an acute/recovered HBV-infected patient. Lead candidate selection was based upon strong binding and neutralizing activity for live HBV. We provide a detailed biochemical/biophysical, and subclass characterization of its specificity and affinity against all of the principal HBV genotypes combined with a functional analysis of its in vitro activity. We also demonstrate its potential as a prophylaxis/therapy in vivo using human liver chimeric mouse models for HBV infection. These data have important implications for our understanding of natural human immunity to HBV and suggest that this potentially represents a new antibody-based anti-viral candidate for prophylaxis and/or therapy for HBV infection.

Communicable and noncommunicable liver disease in HIV

The aim of this study was to highlight the profound changes in the cause in chronic liver disease in HIV-infected individuals. Hepatitis C virus (HCV) has been transformed into a curable viral infection by highly effective treatments. This has resulted in elimination of chronic hepatitis C in HIV-coinfected individuals at least in resource-rich settings. Hepatitis B virus (HBV) has become a chronic infection, which is easily controlled by long-term therapy with HBV polymerase inhibitors. As a result, nonalcoholic steatohepatitis (NASH) has gained clinical importance. The obesity epidemic in the general population has also included people with HIV and weight gain has been associated with some newer antiretroviral drugs, such as HIV integrase inhibitors and tenofovir alafenamide fumarate. Medical treatment for obesity is a focus of intense research efforts, but currently, the only convincing therapeutic option in morbidly obese patients is bariatric surgery, which can also improve liver outcomes. The wider use of this approach has included HIV-infected individuals allowing to assess at least the safety aspects of bariatric surgery in this special population. The shift from communicable to noncommunicable liver disease is changing the clinical practice in HIV-infected individuals. Research activities are focusing more on treatment of NASH and obesity, although a curative therapy for HBV infection would have a great clinical impact.

MicroRNA-185 reduces the expression of hepatitis B virus surface antigen by targeting PRKCH in HepG2 2.2.15 cells

MicroRNAs (miRNAs) are single-stranded noncoding RNAs with 18 to 25 nucleotides and play critical roles in a wide spectrum of biological processes. We repored that miR-185 inhibited hepatitis B surface antigen (HBsAg) expression and hepatitis B virus (HBV) replication without affecting the proliferation of HepG2 2.2.15 cells, compared with the controls. We identified that protein kinase C eta (PRKCH) is a direct target gene of miR-185 that affects HBV replication and protein expression and that the miR-185 may suppress HBV replication. Our results provide more information for gene therapy in HBV infection. Keywords: miR-185; HBV; HBV surface antigen; viral replication; PRKCH.

Recent Progress on Neutralizing Antibodies against Hepatitis B Virus and its Implications.

Hepatitis B virus (HBV) infection remains a global health problem. As "cure" for chronic hepatitis B is of current priority, hepatitis B immunoglobulin (HBIG) has been utilized for several decades to provide post-exposure prophylaxis. In recent years, a number of monoclonal antibodies (mAbs) targeting HBV have been developed and demonstrated with high affinity, specificity, and neutralizing potency. HBV neutralizing antibodies may play a potentially significant role in the search for an HBV cure. In this review, we will summarize the recent progress in developing HBV-neutralizing antibodies, describing their characteristics and potential clinical applications. HBV neutralizing antibodies could be a promising alternative in the prevention and treatment of HBV infection. More importantly, global collaboration and coordinated approaches are thus needed to facilitate the development of novel therapies for HBV infection.

HBV Immune-Therapy: From Molecular Mechanisms to Clinical Applications.

Chronic hepatitis B virus (HBV) infection represents a worldwide public health concern with approximately 250 million people chronically infected and at risk of developing liver cirrhosis and hepatocellular carcinoma. Nucleos(t)ide analogues (NUC) are the most widely used therapies for HBV infection, but they often require long-lasting administration to avoid the risk of HBV reactivation at withdrawal. Therefore, there is an urgent need to develop novel treatments to shorten the duration of NUC therapy by accelerating virus control, and to complement the effect of available anti-viral therapies. In chronic HBV infection, virus-specific T cells are functionally defective, and this exhaustion state is a key determinant of virus persistence. Reconstitution of an efficient anti-viral T cell response may thus represent a rational strategy to treat chronic HBV patients. In this perspective, the enhancement of adaptive immune responses by a checkpoint inhibitor blockade, specific T cell vaccines, lymphocyte metabolism targeting, and autologous T cell engineering, including chimeric antigen receptor (CAR) and TCR-redirected T cells, constitutes a promising immune modulatory approach for a therapeutic restoration of protective immunity. The advances of the emerging immune-based therapies in the setting of the HBV research field will be outlined.

Characterization of MHC class II-restricted T-cell receptors for T-cell therapy of HBV infection

Background & Aim Hepatitis B virus (HBV) infection remains a severe health problem with current treatment options being unable to achieve viral clearance. Since virus eradication is known to be accompanied by a strong T-cell response in patients with resolved infection, adoptive T-cell therapy represents a promising therapeutic approach. We recently demonstrated that CD8+ T cells grafted with T-cell receptors (TCR) restricted by MHC class I have the potential to cure HBV infection in vitro and in vivo. Nevertheless, also CD4+ T cells are known to play an important role in resolving HBV infection and may therefore potentially benefit T-cell therapy. We thus identified, cloned and characterized MHC class II-restricted TCRs from HBV-specific CD4+ T cells. Methods, Results & Conclusion HBV peptides were used to stimulate PBMC from donors with cleared HBV infection. HBV-specific CD4+ T cells secreting TNF-α were sorted by flow cytometry and clonally expanded. Subsequently, variable sequences of TCR α- and β-chains were identified, codon-optimized and cloned into a retroviral vector with murine constant domains. After retroviral transduction, all TCRs were expressed on primary T cells and characterized in depth regarding their MHC restriction, specificity, binding affinity and functionality. A total of 23 TCRs specific for 7 different epitopes from HBV envelope, core or polymerase protein were generated. Through retroviral titration, TCR integration was limited to under 5 integrates per cell, as determined by qPCR. Transduction rates ranging from 65-85% were measured by flow cytometry, where strength of surface expression was found to be characteristic of the TCR rather than the number of integrates. Through co-culture with partially matched lymphoblastoid cell lines, 6 different MHC class II restrictions were identified, including HLA-DRB1*01, *07, *04 and *13 or HLA-DPB1*02 and *04. 17 TCRs recognized at least 3 HBV genotype variants and 12 TCRs had a high binding affinity with EC50 values in a low nanomolar range. Similarly, 12 TCRs were able to recognize endocytosed and intracellularly processed viral antigen. 20 TCRs were capable of activating CD8+ T cells, inducing granzyme B secretion in 75-100% of transduced T cells. Taken together, our set of 23 MHC class II-restricted TCRs recognizes epitopes derived from HBV core, surface and polymerase protein. These TCRs enabled both CD4+ and CD8+ T cells to detect antigen on MHC class II in a nanomolar range, resulting in antigen-specific T-cell activation.

Editorial: Recent Advances in HBV and HCV Immunology.

Viral hepatitis is a major public health problem. While a prophylactic vaccine is now available for hepatitis B virus (HBV), an estimated 240–350 million people worldwide are persistently infected with HBV (1–3). There is not yet an approved vaccine to prevent hepatitis C virus (HCV) infection, and between 130 and 200 million people are believed to be chronically infected worldwide (4–6). Untreated, HBV and HCV can each cause liver inflammation, fibrosis, and cirrhosis, and predispose patients to liver failure and hepatocellular carcinoma (2, 5). These infections are difficult and expensive to treat. Therapy for HBV infection may be lifelong, and a true cure with loss of HBV cccDNA from the liver is rarely achieved (2). IFNα-based therapy was the only option for chronic HCV infection until recently; these regimens were often poorly tolerated and frequently ineffective. An array of direct-acting antiviral drugs has greatly improved the outlook for HCV therapy since 2011 (7), but the expense of the new drugs may limit the number of people who benefit. We still do not understand the immunologic mechanisms leading to chronic HBV and HCV infection, how the immune system controls these viruses, and how the immune system contributes to disease pathogenesis. These topics must be understood in order to develop improved therapies and, at least in the case of HCV, an effective vaccine. Our goal in this Research Topic is to cover advancements toward this understanding. The immune response in the liver – where HBV and HCV each flourish – is incompletely understood. Many of our insights into the immune responses to HBV and HCV have come from studies of human peripheral blood, with limited comparisons to the cells in the liver. The liver is believed to constitute a tolerogenic environment as it receives portal venous blood rich in microbial products from the gut (8, 9). During persistent infection with either HCV or HBV, virus-specific T cells may decrease in number. The virus-specific T cells that can be found tend to have an exhausted phenotype including expression of inhibitory co-receptors, such as PD-1, CTLA-4, or Tim3 (10). Age at the time of exposure is an important predictor of the outcome of HBV infection: those infected in the perinatal period or early in childhood are likely to experience chronic infection, while those infected as adults often mount a successful immune response, with elimination of the template cccDNA from the liver (2). Antiviral immune responses wax and wane during chronic HBV infection. In this Topic, Schuch and colleagues review the roles of CD8+ T cells and natural killer cells in HBV infection (11). Sharma and colleagues present a study of Treg cells in HBV-associated hepatocellular carcinoma (12). Rajoriya and colleagues review the roles of γδ T cells in HBV or HCV infection as well as other conditions (13). HCV causes persistent infection in an estimated 50–85% of those exposed (14). Innate and adaptive immune responses can drive spontaneous clearance of HCV infection. In this Topic, Abdel-Hakeem and Shoukry review the role of the immune response in resolution of HCV infection (15). Sung and colleagues focus on the roles played by CD8+ T cells during acute HCV (16). Genome-wide association studies have highlighted a role for IFNλ in determining the outcome of HCV infection and IFNα-based antiviral therapy; this issue is reviewed by Laidlaw and Dustin (17). Cashman and colleagues discuss the roles of humoral immunity in acute and persistent HCV infection (18). Chronic HCV infection is also associated with extrahepatic disease; Sidharthan and colleagues present gene expression study showing a role for monocytes in HCV-associated mixed cryoglobulinemic vasculitis (19). Because of shared modes of transmission, up to 30% of individuals with HIV infection may also be infected with HCV; co-infected individuals have increased inflammation and accelerated liver damage (14). Cho and colleagues present a study of T cell phenotype, activation, and function in HCV–HIV co-infected patients, highlighting distinct changes in T cell function during co-infection – even when HIV is well controlled with highly active antiretroviral therapy (20).

Cyclin D2 plays a regulatory role in HBV replication

Hepatitis B virus (HBV) infection is the leading cause of liver diseases. However, the molecular mechanisms of HBV infection and carcinogenesis have not been fully elucidated. In this study, we found that cyclin D2 was upregualted in HBV-expressing cells and liver tissues of HBV-transgenic mice. Gene silencing of cyclin D2 inhibited HBV DNA replicative intermediates, 3.5kb mRNA, core protein level, as well as the secretions of HBsAg and HBeAg. On the contrary, overexpression of cyclin D2 promoted HBV replication. Furthermore, cyclin D2 regulated HBV replication by enhancing the activity of HBV core and Sp1 promoters by targeting transcription factor CREB2. Silencing of CREB2 abolished enhancement of HBV replication induced by cyclin D2. Together, our study has uncovered a positive role of cyclin D2 in HBV replication. It is conceivable that therapeutic application of cyclin D2 inhibitor in HBV infection therapy.

Bacteriophages and their applications in the diagnosis and treatment of hepatitis B virus infection.

Hepatitis B virus (HBV) infection is a major global health challenge leading to serious disorders such as cirrhosis and hepatocellular carcinoma. Currently, there exist various diagnostic and therapeutic approaches for HBV infection. However, prevalence and hazardous effects of chronic viral infection heighten the need to develop novel methodologies for the detection and treatment of this infection. Bacteriophages, viruses that specifically infect bacterial cells, with a long-established tradition in molecular biology and biotechnology have recently been introduced as novel tools for the prevention, diagnosis and treatment of HBV infection. Bacteriophages, due to tremendous genetic flexibility, represent potential to undergo a huge variety of surface modifications. This property has been the rationale behind introduction of phage display concept. This powerful approach, together with combinatorial chemistry, has shaped the concept of phage display libraries with diverse applications for the detection and therapy of HBV infection. This review aims to offer an insightful overview of the potential of bacteriophages in the development of helpful prophylactic (vaccine design), diagnostic and therapeutic strategies for HBV infection thereby providing new perspectives to the growing field of bacteriophage researches directing towards HBV infection.

Efficacy of Treatments for Patients with Chronic Liver Disease due to Coinfection with Hepatitis B and C Viruses

The hepatitis B virus (HBV) and the hepatitis C virus (HCV) are the leading causes of chronic liver disease. Patients with chronic liver disease who are co infected with both HBV and HCV develop cirrhosis and hepatocellular carcinoma (HCC) more rapidly than patients with monoinfection with HBV alone or HCV alone. However, standard-of-care recommendations have not been well established for patients with HBV/HCV co infection. In this study, a literature review was conducted on the efficacy of therapies for patients with HBV/HCV coinfection. Many papers reported that following combination therapy with interferon (IFN) plus ribavirin (RBV), there were no significant differences in the rate of achievement of a sustained virological response (SVR) to HCV between patients with HBV/HCV coinfection and patients with HCV monoinfection. However, the efficacy of these therapies for HBV infection in coinfected patients is complex. In patients with HBV/HCV coinfection characterized by a predominance of HCV, it is highly probable for serum hepatitis B surface antigen (HBsAg) titers to decrease or disappear during or after IFN/RBV combination therapy. On the other hand, reactivation of HBV due to the suspected inhibition of HCV replication is sometimes detected in coinfected patients during or after IFN/RBV combination therapy.

Ezetimibe blocks hepatitis B virus infection after virus uptake into hepatocytes

Current treatment of chronic hepatitis B virus (HBV) infection mainly targets viral replication in hepatocytes and leads to curing only in exceptional cases. Despite their potential to improve therapeutic success, no drugs interfering with early infection steps of the hepatotropic pathogen HBV are available to date. Recently, entry of the hepatitis C virus (HCV) has been shown to occur along hepatic cholesterol uptake pathways and ezetimibe, a drug which blocks this lipid transport, has been shown to inhibit HCV infection. We here investigated the effect of ezetimibe on HBV infection using differentiated HepaRG cells as a cell-culture infection model. Treatment with ezetimibe inhibited establishment of intrahepatic cccDNA and expression of viral replication markers when cells were infected with HBV virions, while we observed no effect when the HBV viral genome was transduced via an adenoviral vector. Our data suggest that modulating hepatic cholesterol uptake by ezetimibe inhibits early HBV infection and that ezetimibe sensitive lipid transport pathways represent new targets for antiviral therapy in HBV infection.

Therapy for HBV Infection in Hemodialysis Patients: Is it Possible?

Despite the use of preventive measures, particularly hepatitis B virus (HBV) vaccine, and recent advances in antiviral therapy, chronic HBV infection has still remained a public health concern among infected dialysis patients because it results in an increased risk of morbidity and mortality [1]. However, Alavian et al. have shown that the prevalence of HBV infection among hemodialysis (HD) patients in Iran declined to 2.4 - 2.6% in 2005 [2][3]. Furthermore, the clinical course and natural history of HBV infection are different in dialysis and nondialysis patients, and it may lead to a unique clinical problem in dialysis subjects. In addition, limited data are available on the optimal therapy of chronic HBV infection in dialysis patients. Therefore, in this article we discuss whether antiviral therapy is possible in infected dialysis patients with HBV.

Prophylaxis and therapy of HBV infection in 20 patients treated with disease modifying antirheumatic drugs or with biological agents for rheumatic diseases

To evaluate the safety and tolerability of lamivudine in patients with HBV infection needing immunosuppressive treatment for rheumatic diseases. Twenty patients with rheumatic diseases planned to receive immunosuppressive DMARDs or biological agents were screened for HBV markers. In all active carriers antiviral treatment was recommended. Inactive carriers (HBsAg positive, aminotrasferase and viremia persistently normal) were divided into two risk categories according to the type and the degree of immunosuppression, and antiviral prophylaxis was started only in patients of the high risk category. Antiviral treatment was recommended also in potential occult carriers (HBsAg negative, HBcAb positive) treated with rituximab. In twenty patients antiviral treatment was started: 1 was a potential occult carrier planned to receive rituximab; 9 were inactive carriers, in which prophylactic therapy was needed for a high risk of HBV reactivation (in 3, for the use of TNF blocking agents); 10 were treated for active viral replication. Prophylaxis and therapy were performed with lamivudine. In three patients adefovir was associated. Antiviral drugs were well tolerated. In all cases, immunosuppressive treatment was given for the planned duration of therapy, with good results on the rheumatic diseases. Median duration of antiviral treatment was 19 months (for a total of 386 month/person). No cases of viral reactivation were observed. Our experience demonstrates the feasibility of a prophylaxis and therapy of HBV infection in patients with rheumatic diseases. This approach reduces the risk of viral reactivation and allows the choice of the optimal immunosuppressive treatment in rheumatic patients.

New globally faces of hepatitis B and C in the world.

Worldwide, infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) have become a major cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) and the major global problems for public health in the world and Iran (1–3). HBV infection is the main cause of chronic liver disease in Iran (4) and the seroprevalence of HBV infection in Iran has been decreased during the last two decades (5). The main risk factor for HBV transmission was related to maternal-to-infantile transmission and the infantile vaccination with high coverage is the main cause for changes in epidemiology of HBV infection. But today, we have more risk factors for transmission in adulthood. The community contacts more in adolescence and the health policy makers should attend more for control of HBV infection. People awareness, risk factors modifications, harm reduction programmes in young addicted persons, vaccination against HBV in adults should be consider for control of HBV infection in future. We have less new cases, but we will have more cirrhotic cases and we need to consider the best therapy for prevention of HBV infection to end-stage phases. Therapy of HBV infection in which phase and which drugs are the debate. The goal of therapy in chronic hepatitis B (CHB) patients is sustained suppression of HBV viremia and decrease progression of liver disease to cirrhosis and HCC with the ultimate goal of improving survival. This can be pursued by maintaining constant inhibition of viral replication through a long term treatment with nucleos(t)ide analogs or by inducing, through the combined antiviral and immunomodulatory effects of interferon, a sustained immune response (6). Standard interferon is the oldest approved drug in therapy of HBV infection, but it has a limited response rate. Recently new published data have shown the better response with pegylated interferon in therapy of chronic HBV infection (7, 8). PEG-IFNα-2a has been licensed for the treatment of both HBeAg-positive and HBeAg-negative chronic HBV as a 48-week course, given by subcutaneous injection once weekly in a dosage of 180 mg. The main side effects of therapy with nucleos(t)ide analogs such as lamivudine, adefovir and entecavir, is emergence of resistance (9, 10). These events will decrease benefit of therapy with anti-viral agents. HBs Ag level in prediction of therapy response The main question was and is regarding how and when we can conclude the therapy in HBV infection is effective and we should continue or it is ineffective and we should discontinue it. During recent years serum HBsAg is hypothesized to be a marker for immunological response to therapy, independent of virological response as measured using HBV DNA levels, because of its correlation with intrahepatic HBV covalently closed circular (ccc) DNA, the main replicative template of HBV (11). HBsAg levels appear to differentiate patients in the inactive carrier state from those with active disease or from inactive carriers with a high probability of subsequent relapse. Furthermore, recent studies have shown that on- treatment HBsAg levels are predictive of a durable off-treatment response to peginterferon (PEG-IFN), and can accurately identify non-responders early during therapy, both in HBeAg-positive, and HBeAg-negative patients. Among those who underwent HBsAg loss within 6 years of follow-up, serum HBsAg levels were a better predictor than HBV DNA levels. Low serum levels of HBsAg, alone or in combination with HBV DNA levels, 1 year after HBeAg seroconversion can predict HBsAg loss in patients with HBV infection (12). Currently, multiple diagnostic assays are available for quantification of HBsAg. That we should use the validate method for diagnosis.

B7-DC-silenced dendritic cells induce stronger anti-HBV immunity in transgenic mice

Hepatitis B virus (HBV) is a noncytopathic DNA virus and is the pathogen of acute and chronic hepatitis. Interferon and nucleotide analogues such as lamivudine and adefovir are the current treatment strategies of HBV infection; however, it is still a serious disease. Therefore, the development of new therapeutic options against HBV is needed. In the present study, we have investigated whether the vectors carrying short hairpin RNA (shRNA) targeting the murine B7-DC gene could silence the expression of B7-DC and analyzed the function of gene-modified dendritic cells (DCs) by mixed lymphocyte reaction. The results demonstrated that two shRNA vectors efficiently suppressed the expression of B7-DC. The MLR assay showed that shRNA-B7-DC-transfected DCs induced markedly higher allogeneic lymphocyte proliferation than transfected DCs with the vector plasmid pAS and untreated DCs at all dilutions. The most efficient shRNA plasmid vector against B7-DC was then used to silence the expression of B7-DC on DCs, the gene-modified DCs were pulsed with HBV-specific peptides, and HBV transgenic mice were immunized. After three rounds of immunization, the splenocytes were stimulated in vitro and tested for cytotoxicitic T lymphocyte activity, while the sera were used to detect the level of HBsAg and HBV DNA. The data demonstrated that blockade of B7-DC on DCs augmented the cytolytic activity induced by immunization with peptide-pulsed DCs and significantly reduced the concentration of serum HBsAg and HBV DNA, suggesting that silencing of B7-DC is of potential value in DC-based therapy of HBV infection.

Hepatitis B virus preS2 gene-specific locked nucleic acid antisense oligonucleotides significantly inhibit hepatitis B virus replication and expression in HepG2 2.2.15 cells

AIM: To investigate the inhibitory effects of hepatitis B virus (HBV) preS2 gene-specific locked nucleic acid (LNA) antisense oligonucleotides on HBV replication and expression in HepG2 2.2.15 cells. METHODS: Three LNA antisense oligonucle-otides of different lengths that are complementary to the translation initiation region of the HBV preS2 gene were designed, synthesized and introduced into HepG2 2.2.15 cells by cationic liposome-mediated transfection. Hepatitis B surface antigen (HbsAg) and HBV DNA levels in cell supernatant were tested by time-resolved immunofluorescence assay (TRFIA) and fluorescent quantitative-polymerase chain reaction (FQ-PCR). The inhibitory effects of different antisense oligonucleotides on HBV DNA replication and expression were compared. The cell toxicity of LNA antisense oligonucleotides was evaluated by methyl thiazolyl tetrazolium (MTT) assay. RESULTS: On day 1 after transfection with LNA antisense oligonucleotides, the expression of HBsAg and the replication of HBV DNA were inhibited. On day 7, the reduced rates of HBsAg and HBV DNA levels were 45.79%, 52.92% and 67.21% as well as 35.15%, 40.69% and 52.16% in the non-modified antisense oligonucleotide group, all-phosphorothioate-modified antisense oligonucleotide group and LNA antisense oligo-nucleotide group, respectively. LNA antisense oligonucleotides showed the strongest inhibitory effects on viral activity and had no impact on cell metabolism. Compared with the control group, the reduced rates of HBsAg and HBV DNA levels achieved in each of the above groups were significantly higher (all P＜0.01). Moreover, the reduced rates of HBsAg and HBV DNA levels in the LNA antisense oligonucleotide group were significantly higher than those in other antisense oligonucleotide groups (all P＜0.05). CONCLUSION: LNA antisense oligonucleotides targeting the preS2 gene can effectively inhibit the replication and expression of HBV in vitro. The preS2 gene can be used as an effective target for gene therapy of HBV infection.

Special Considerations and Treatment of Patients with HBV-HIV Coinfection

Coinfection with HIV and hepatitis B virus (HBV) substantially alters the natural course of HBV infection as well as its management. Therapy for HBV infection in HIV-coinfected patients requires several factors to be taken into consideration, such as whether the antiviral activity of a particular agent is specific for HBV (that is, adefovir, entecavir, telbivudine and pegylated interferon) or for both viruses (that is, lamivudine, emtricitabine and tenofovir), whether the chosen drug has the potential for inducing drug resistance and cross-resistance, and whether use of the agent is associated with hepatotoxicity. For coinfected patients who do not require therapy for their HIV infection, clinicians should avoid prescribing monotherapy with agents that have activity against HIV (that is, tenofovir, entecavir, emtricitabine or lamivudine) so as not to compromise future HIV care. This review discusses the current status of treatment of hepatitis B in the setting of HIV infection. It describes emerging therapeutic strategies and addresses challenges in the treatment of coinfection.

Influence of Mutations in the Hepatitis B Virus Genome on Virus Replication and Drug Resistance - Implications for Novel Antiviral Strategies

Persistent infection with the hepatitis B virus (HBV) represents a major health problem worldwide with over 350 million patients at risk of developing liver cirrhosis or hepatocellular carcinoma. HBV is a small, partially double-stranded DNA virus with four overlapping genes and a unique life cycle, creating an intracellular pool of covalently closed circular DNA molecules for persistence and an RNA template for replication via reverse transcription. Mutations occur frequently, and particular selection pressures, both endogenous (host immune clearance) and exogenous (vaccines and antivirals), readily select escape mutants. For example, HBeAg-negative chronic HBV infection with either basal core promoter or precore mutations is predominant in many parts of the world. Therapy of HBV infection with the nucleoside analogue lamivudine frequently leads to the selection of drug-resistant strains with polymerase mutations. Treatment options for chronic HBV infection include at present either interferon-alpha or the oral nucleos(t)ide analogues lamivudine or adefovir. However, these drugs have drawbacks, including possible serious side effects and low response rates in HBeAg-negative patients in the case of interferon or recurrence of viremia after cessation of therapy and development of escape mutants after a long period of treatment with nucleoside inhibitors. Recent advances of in vitro and in vivo models allow to study new antiviral strategies, including novel nucleoside analogues, nucleocapsid inhibitors or small interfering RNA. This review summarises the impact of clinically relevant mutations in the HBV genome on viral replication and drug sensitivity, the current status of therapy and promising future perspectives on novel drug regimens.

RNA interference-mediated inhibition of Hepatitis B Virus replication

Persistent and recurrent infection of hepatitis B virus (HBV) represents one of the most common and severe viral infections of humans, and has caused a formidable health problem in the affected countries. Currently used antiviral drugs have a very limited success on controlling HBV replication and infection. RNA interference (RNAi), a process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of target mRNA in mammalian and plant cells, has recently been used to knockdown gene expression in various species. In this study, we sought to determine whether RNAi-mediated silencing of HBV viral gene expression could lead to the effective inhibition of HBV replication. We first developed RNAi vectors that expressed small interfering RNA (siRNA) and targeted the HBV core or surface gene sequence. Our results demonstrated that these specific siRNAs efficiently reduced the levels of corresponding viral RNAs and proteins, and thus suppressed viral replication. Treatment with siRNA gave the greatest reduction in the levels of HBsAg (92%) and in HBeAg (85%) respectively in the cultured cell medium. Our findings further demonstrated that the RNAi-mediated antiviral effect was sequence-specific and dose-dependent. Therefore, our findings strongly suggest that RNAi-mediated silencing of HBV viral genes could effectively inhibit the replication of HBV, hence RNAi-based strategy should be further explored as a more efficacious antiviral therapy of HBV infection.