Treatment of HBV/HCV coinfection

HIV Infection Predisposes to Increased Chances of HBV Infection: Current Understanding of the Mechanisms Favoring HBV Infection at Each Clinical Stage of HIV Infection

Human immunodeficiency virus (HIV) selectively targets and destroys the infection-fighting CD4+ T-lymphocytes of the human immune system, and has a life cycle that encompasses binding to certain cells, fusion to that cell, reverse transcription of its genome, integration of its genome into the host cell DNA, replication of the HIV genome, assembly of the HIV virion, and budding and subsequent release of free HIV virions. Once a host is infected with HIV, the host’s ability to competently orchestrate effective and efficient immune responses against various microorganisms, such as viral infections, is significantly disrupted. Without modern antiretroviral therapy (ART), HIV is likely to gradually destroy the cellular immune system, and thus the initial HIV infection will inexorably evolve into acquired immunodeficiency syndrome (AIDS). Generally, HIV infection in a patient has an acute phase, a chronic phase, and an AIDS phase. During these three clinical stages, patients are found with relatively specific levels of viral RNA, develop rather distinctive immune conditions, and display unique clinical manifestations. Convergent research evidence has shown that hepatitis B virus (HBV) co-infection, a common cause of chronic liver disease, is fairly common in HIV-infected individuals. HBV invasion of the liver can be facilitated by HIV infection at each clinical stage of the infection due to a number of contributing factors, including having identical transmission routes, immunological suppression, gut microbiota dysbiosis, poor vaccination immune response to hepatitis B immunization, and drug hepatotoxicity. However, there remains a paucity of research investigation which critically describes the influence of the different HIV clinical stages and their consequences which tend to favor HBV entrenchment in the liver. Herein, we review advances in the understanding of the mechanisms favoring HBV infection at each clinical stage of HIV infection, thus paving the way toward development of potential strategies to reduce the prevalence of HBV co-infection in the HIV-infected population.

HBV/HIV Coinfection: Impact on the Development and Clinical Treatment of Liver Diseases

Hepatitis B virus (HBV) infection is a common contributor to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Approximately 10% of people with human immunodeficiency virus (HIV) also have chronic HBV co-infection, owing to shared transmission routes. HIV/HBV coinfection accelerates the progression of chronic HBV to cirrhosis, end-stage liver disease, or hepatocellular carcinoma compared to chronic HBV mono-infection. HBV/HIV coinfection alters the natural history of hepatitis B and renders the antiviral treatment more complex. In this report, we conducted a critical review on the epidemiology, natural history, and pathogenesis of liver diseases related to HBV/HIV coinfection. We summarized the novel therapeutic options for these coinfected patients.

Hepatitis C Virus Infection: Host⁻Virus Interaction and Mechanisms of Viral Persistence

Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host-HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host-HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence.

Farnesoid X receptor agonist GW4064 indirectly inhibits HCV entry into cells via down-regulating scavenger receptor class B type I

Farnesoid X receptor (FXR) agonists play important regulatory roles in bile acid, lipid and glucose metabolism in vitro and in vivo. Thus, FXR agonists exhibit potential therapeutic effects on metabolism-related diseases that are associated with extrahepatic manifestations induced by hepatitis C virus (HCV) infection. This study investigated the effect and mechanism of FXR agonist GW4064 against HCV in vitro to explore the potential application of FXR agonists. Results showed that GW4064 and other FXR agonists have potent antiviral activity against HCV in Huh7.5 cells. GW4064 down-regulated the expression of scavenger receptor class B type I protein via FXR and thereby indirectly inhibited HCV entry into cells, leading to interruption of HCV life cycle. GW4064 also exhibited synergistic anti-HCV effect with known direct-acting antiviral agents (DAAs) used in the clinic and remained sensitive to DAA-resistant HCV mutations. Therefore, FXR agonists are also a kind of antiviral agent, and might be helpful in treatment of HCV-induced hepatic and extrahepatic manifestations.

An important role of SREBP-1 in HBV and HCV co-replication inhibition by PTEN

HBV HCV co-infection leads to more severe liver diseases including liver cancer than mono-infections. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor, inhibits sterol regulatory element binding protein-1 (SREBP-1). In this study, we characterized the effect of the PTEN - SREBP-1 pathway on HBV HCV co-replication in a cellular model. We found that HBV and HCV can co-replicate in Huh-7 cells with no interference. Overexpression of PTEN inhibits, whereas PTEN knockdown enhances, HBV replication as well as HBV and HCV co-replication. Knocking down SREBP-1 decreases HBV replication in an HBx-dependent manner. SREBP-1 knockdown also decreases HCV replication. PTEN knockdown is concomitant with increased nuclear SREBP-1 levels. PTEN and SREBP-1 double knockdown results in intermediate levels of HBV and HCV replication in mono- and co-replication scenarios. Taken together, we demonstrated, for the first time, that the PTEN - SREBP-1 pathway can regulate HBV HCV co-replication.

Rare clinically significant hepatic events and hepatitis B reactivation occur more frequently following rather than during direct-acting antiviral therapy for chronic hepatitis C: Data from a national US cohort

Recently, cases of hepatitis B virus reactivation (HBVr) with direct-acting antiviral therapy (DAAs) for HCV have been reported. However, few data exist from large, Western cohorts. The study objectives were to evaluate the incidence of alanine aminotransferase (ALT) flares, clinically significant hepatic events, and HBVr among a national cohort of US veterans with prior exposure to HBV (anti-HBc+) treated with DAAs. We used a national administrative database to identify patients treated with DAAs from January 2014 through November 2016 and obtained clinical and demographic as well as HBV and HCV treatment data. HBVr was defined as an at least 1-log increase in HBV DNA titre. Among 17 779 anti-HBc+ patients, 17 400 were HIV- and 379 were HIV+. Among the HIV- patients, 17 266 (99%) were HBsAg- prior to DAA therapy and 134 were HBsAg+. Among HIV-, HBsAg- patients, ALT elevations greater than 10 times the upper limit of normal (ULN; ≥300 IU/mL) were rare and occurred more frequently after treatment completion: 31 cases (<0.1%) during vs 85 (0.6%) following treatment. Clinically significant hepatic events defined as ALT increases >100 IU/L with total bilirubin >2.5 mg/dL occurred in 39 cases (0.3%), most often following DAA completion (n = 35 cases, 3/35 in setting of HCV relapse). Among 31 patients with post-DAA hepatic events without HCV relapse, 10 (32%) were confirmed unrelated to HBVr by HBsAg and/or HBV DNA testing, 1 (3%) confirmed due to HBVr, and 20 (65%) did not have documented HBV-related testing. One additional case of HBsAg- to + seroreversion was identified. Among HBsAg+ DAA recipients, 2/97 (2%), both with cirrhosis, experienced ALT elevations ≥300 IU/mL in the setting of HBVr. In conclusion, clinically significant hepatic events and HBVr were rare and much more likely among HBsAg-positive individuals. Anti-HBc + patients should be monitored for ALT flares and HBVr during and possibly for up to 6 months post-DAA therapy.

后DAA时代抗HCV治疗的现状及存在问题

近年来, 由于直接抗病毒药物(direct-acting antiviral agents, DAAs)具有高效、使用方便、不良反应小、疗程短、临床治愈率高的优点, 使其在临床的应用越来越广泛. 许多著名的制药公司对其研究不断, 其上市及更新的速度未减. 随着DAAs的广泛应用及指南更新, 抗丙型肝炎病毒(hepatitis C virus, HCV)的治疗已经步入全口服药物时期, 即已经步入后DAA时代. 但在使用DAAs抗HCV治疗过程中存在许多问题, 使用时需谨慎.

Prevalence and Determinants of Cryptosporidium Infection in an Underdeveloped Rural Region of Southwestern China

Few studies have focused on the epidemiology of Cryptosporidium in resource-challenged settings in China. We report a community-based cross-sectional study to investigate the prevalence of Cryptosporidium infection and its risk factors and associations with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) infections. The prevalence of Cryptosporidium infection was 12.6% (95% confidence interval = 11.0-14.3). Individuals living in households with ≥ 5 family members and raising domestic pigs tended to have a greater risk of Cryptosporidium infection. In addition, Cryptosporidium infection was significantly associated with HBV infection. There were no significant associations of Cryptosporidium infection with HIV viral load and HBV viral load. Further studies are needed to determine the association of Cryptosporidium infection with HBV infection.

The role of quantitative hepatitis B surface antigen revisited

In the past 10years, there has been a lot of enthusiasm surrounding the use of serum hepatitis B surface antigen (HBsAg) quantification to predict disease activity and monitor treatment response in chronic hepatitis B. The measurement of HBsAg levels have been standardized in IU/ml, and nowadays it is almost a mandatory measurement due to the development of new antiviral treatments aiming at HBsAg seroclearance, i.e., functional cure of hepatitis B. Recently, there has been an improved understanding of the molecular virology of HBsAg, and particularly the relative roles of covalently closed circular DNA and integrated hepatitis B virus (HBV) DNA. This has shed new light on the interpretation of HBsAg levels in different phases of chronic hepatitis B. HBsAg level can assist the differentiation of immune tolerance and immune clearance in hepatitis B e antigen (HBeAg)-positive patients, and it can predict inactive disease and spontaneous HBsAg seroclearance in HBeAg-negative patients. The determination of HBsAg level is pivotal to individualize pegylated interferon (PegIFN) treatment; it is the key investigation to decide early termination of PegIFN among non-responders. Among patients treated by nucleos(t)ide analogues, responders tend to have dramatic reduction of HBsAg to low levels, which may be followed by HBsAg seroclearance. With newer data on combination treatment of PegIFN and nucleos(t)ide analogues as well as emerging new antiviral agents, HBsAg quantification is expected to become increasingly important to monitor and guide antiviral therapy for chronic hepatitis B.

Management of chronic hepatitis B in patients from special populations

Here we review the management of chronic hepatitis B (CHB) in four special categories of patients: CHB in pregnancy, in patients on immunosuppressive treatments, in patients undergoing liver transplantation, and in patients coinfected with human immunodeficiency virus (HIV) or hepatitis C virus (HCV).

Complete replication of hepatitis B virus and hepatitis C virus in a newly developed hepatoma cell line

The absence of a robust cell culture system for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection has limited the analysis of the virus lifecycle and drug discovery. We have established a hepatoma cell line, HLCZ01, the first cell line, to the authors' knowledge, supporting the entire lifecycle of both HBV and HCV. HBV surface antigen (HBsAg)-positive particles can be observed in the supernatant and the lumen of the endoplasmic reticulum of the cells via electron microscopy. Interestingly, HBV and HCV clinical isolates propagate in HLCZ01 cells. Both viruses replicate in the cells without evidence of overt interference. HBV and HCV entry are blocked by antibodies against HBsAg and human CD81, respectively, and the replication of HBV and HCV is inhibited by antivirals. HLCZ01 cells mount an innate immune response to virus infection. The cell line provides a powerful tool for exploring the mechanisms of virus entry and replication and the interaction between host and virus, facilitating the development of novel antiviral agents and vaccines.

Anti-viral treatment and cancer control

Hepatitis B virus (HBV), hepatitis C virus (HCV), human papillomavirus (HPV), and Epstein-Barr virus (EBV) contribute to about 10-15 % global burden of human cancers. Conventional chemotherapy or molecular target therapies have been used to treat virus-associated cancers. However, a more proactive approach would be the use of antiviral treatment to suppress or eliminate viral infections to prevent the occurrence of cancer in the first place. Antiviral treatments against chronic HBV and HCV infections have achieved this goal, with significant reduction in the incidence of hepatocellular carcinoma in treated patients. Antiviral treatments for EBV, Kaposi's sarcoma-associated herpesvirus (KSHV), and human T-cell lymphotropic virus type 1 (HTLV-1) had limited success in treating refractory EBV-associated lymphoma and post-transplant lymphoproliferative disorder, KSHV-associated Kaposi's sarcoma in AIDS patients, and HTLV-1-associated acute, chronic, and smoldering subtypes of adult T-cell lymphoma, respectively. Therapeutic HPV vaccine and RNA-interference-based therapies for treating HPV-associated cervical cancers also showed some encouraging results. Taken together, antiviral therapies have yielded promising results in cancer prevention and treatment. More large-scale studies are necessary to confirm the efficacy of antiviral therapy. Further investigation for more effective and convenient antiviral regimens warrants more attention.

Prevention of hepatocellular carcinoma in chronic viral hepatitis B and C infection

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide, with the majority of cases associated with persistent infection from hepatitis B virus (HBV) or hepatitis C virus (HCV). Natural history studies have identified risk factors associated with HCC development among chronic HBV and HCV infection. High-risk infected individuals can now be identified by the usage of risk predictive scores. Vaccination plays a central role in the prevention of HBV-related HCC. Treatment of chronic HBV infection, especially by nucleoside analogue therapy, could also reduce the risk of HBV-related HCC. Concerning HCV infection, besides the advocation of universal precautions to reduce the rate of infection, pegylated interferon and ribavirin could also reduce the risk of HCV-related HCC among those achieving a sustained virologic response. Recently there has been mounting evidence on the role of chemopreventive agents in reducing HBV- and HCV-related HCC. The continued advances in the understanding of the molecular pathogenesis of HCC would hold promise in preventing this highly lethal cancer.

Synthetic anti-lipopolysaccharide peptides and hepatitis C virus infection

INTRODUCTION

Hepatitis C virus (HCV) infection is a leading cause of cirrhosis and hepatocellular carcinoma. Although antiviral therapy has been markedly improved by the licensing of direct-acting antivirals, safety, resistance, high costs and difficult-to-treat patients remain important challenges.

AREAS COVERED

This article focuses and comments on the recent development of synthetic anti-lipopolysaccharide peptides (SALPs) which bind to highly sulfated glycosaminoglycan/heparan sulfate (HS) on cell surface. HS serves as a primary docking site for several viruses to their respective host cells before the viruses interact with their cell surface receptor(s). In vitro studies have shown that SALPs inhibit entry of HCV without cell toxicity.

EXPERT OPINION

SALPs prevent viral infection in cell culture model systems. Treatment studies of established HCV infection in cell culture models as well as proof-of-concept and safety studies in animal models are needed to evaluate their potential for drug development. The mechanism of action of SALPs as entry inhibitors suggests a potential application for HCV-infected patients to prevent reinfection of the liver graft in liver transplantation. Potential limitations may include high doses to obtain an antiviral effect and a target which is widely expressed and has a key function in cell physiology.

Prevalence and associated clinical characteristics of hepatitis B, C, and HIV infections among injecting drug users in Korea

Injecting drug use is associated with an increased risk of blood-borne viral infections, such as hepatitis B and C viruses (HBV and HCV, respectively) and human immunodeficiency virus (HIV). However, their prevalence, virological characteristics, and associated factors are not clear among the injecting drug users in Korea. The aim of this study was to determine the prevalence of HBV, HCV, and HIV infection, as well as their virological and clinical characteristics of injecting drug users in South Korea. Between 2007 and 2010, 318 injecting drug users (89.3% male; mean ± age 41.9 ± 8.15 years) were participated. While HIV infection was not found, the seroprevalence of anti-HCV and HBV surface antigen (HBsAg) was 48.4% (n = 154) and 6.6% (n = 21), respectively. HBV/HCV co-infection was found in 4.1% (n = 13). Occult HBV infection was suggested in 5.0% (n = 16). Among the HCV genotypes, 1b (37.7%) and 2a/2c (35.7%) were mostly often detected. HCV RNA was detected in 98.1% (n = 151/154) and high-level viremia (HCV RNA level, ≥400,000 IU/ml) were observed in 59.6% (n = 90/151). In multiple logistic regression analysis, old age (OR 1.18 per year, 95% CI = 1.09-1.27) and ever-sharing injecting equipment (OR 4.17, 95% CI = 1.39-12.45) independently predicted HCV mono-infection. The prevalence of HBV and HCV infection were high but largely undiagnosed in the present sample of Korean injecting drug users. Strategic prevention, screening, and treatment are needed to reduce further transmission and morbidity.

Sequential immunological analysis of HBV/HCV co-infected patients during Peg-IFN/RBV therapy

BACKGROUND

The immunopathogenesis of dual chronic infection with hepatitis B virus and hepatitis C virus (HBV/HCV) remains unclear. The in vivo suppressive effects of each virus on the other have been reported. In this study we aimed to analyze the virological and immunological parameters of HBV/HCV coinfected patients during pegylated interferon/ribavirin (Peg-IFN/RBV) therapy.

METHODS

One patient with high HBV-DNA and high HCV-RNA titers (HBV-high/HCV-high) and 5 patients with low HBV-DNA and high HCV-RNA titers (HBV-low/HCV-high) were enrolled. Twenty patients monoinfected with HBV and 10 patients monoinfected with HCV were enrolled as control subjects.. In vitro cultures of Huh 7 cells with HBV/HCV dual infection were used to analyze the direct interaction of HBV/HCV.

RESULTS

Direct interaction of HBV clones and HCV could not be detected in the Huh-7 cells. In the HBV-high/HCV-high-patient, the HCV-RNA level gradually declined and HBV-DNA gradually increased during Peg-IFN/RBV therapy. Activated CD4- and CD8-positive T cells were increased at 1 month of Peg-IFN/RBV-therapy, but HBV-specific IFN-γ-secreting cells were not increased and HBV-specific interleukin (IL)-10 secreting cells were increased. The level of HBV- and HCV-specific IFN-γ-secreting cells in the HBV-high/HCV-high-patient was low in comparison to that in the HBV- or HCV-monoinfected patients. In the HBV-low/HCV-high-patient, HCV-RNA and HBV-DNA rapidly declined during Peg-IFN/RBV therapy. Activated CD4- and CD8-positive T cells were increased, and HBV- and HCV-specific IFN-γ-secreting cells were also increased during Peg-IFN/RBV-therapy.

CONCLUSION

The immunological responses of the HBV-high/HCV-high patient were low in comparison to the responses in HBV and HCV monoinfected patients. Moreover, the response of immune cells in the HBV-high/HCV-high patient during Peg-IFN/RBV therapy was insufficient to suppress HBV and HCV.

Natural history of acute and chronic hepatitis C

Hepatitis C virus (HCV) infection remains a major global health burden. Hepatitis C causes significant liver-related morbidity and mortality due to hepatic decompensation and development of hepatocellular carcinoma. In addition, extra-hepatic manifestations of hepatitis C are frequent. There is a very large interindividual variability in the natural history of both acute and chronic hepatitis C which can be explained in part by a combination of various host, viral and environmental factors. Successful antiviral treatment can prevent short- and long-term complications of HCV infection in many patients. Still, the relative contribution of distinct risk factors for disease progression in different phases of HCV infection needs to be better defined. Personalized treatment approaches for HCV infection should consider individual risk profiles to avoid both under- and over-treatment - which will remain important also in upcoming era of interferon-free treatment of hepatitis C.

Fighting against viral hepatitis: lessons from Taiwan

Viral hepatitis and its sequelae are important health problems worldwide, including Taiwan. For the last 40 years, Taiwan's scientists and health care providers have worked hard to control these sequelae, and the results have been excellent. The author, Ding-Shinn Chen, had a key role in planning and establishing the control program in Taiwan, and participated in the endeavors from the very beginning. In this perspective, he describes how he became interested in research as a medical student, his encounters with hepatitis B and C, how he and his colleagues started early detection of hepatocellular carcinoma (HCC), how he helped Taiwan's government create and implement the Viral Hepatitis Control Program, and how the effectiveness of the program in the decrease of hepatitis B carriage and HCC was monitored. He also discusses how he pioneered the use of interferon-α plus ribavirin to treat chronic hepatitis C. Hepatitis B viral load as a risk factor for HCC and cirrhosis in hepatitis B surface antigen carriers is reviewed briefly, as is the prevention of sequelae by antiviral therapies. Finally, Dr. Chen discusses unresolved issues that must be addressed and predicts the changes of the patterns of liver disease in Taiwan beyond the mid-21st century, which is in part affected by the fight against viral hepatitis that was initiated in the early 1980s.

CONCLUSION

Dr. Chen's perspective illustrates Taiwan's fight against viral hepatitis over the last 40 years. This experience can be shared by other countries in which the disease is equally prevalent.

Hepatitis B and C virus hepatocarcinogenesis: lessons learned and future challenges

Worldwide, hepatocellular carcinoma (HCC) is one of the most common cancers. It is thought that 80% of hepatocellular carcinomas are linked to chronic infections with the hepatitis B (HBV) or hepatitis C (HCV) viruses. Chronic HBV and HCV infections can alter hepatocyte physiology in similar ways and may utilize similar mechanisms to influence the development of HCC. There has been significant progress towards understanding the molecular biology of HBV and HCV and identifying the cellular signal transduction pathways that are altered by HBV and HCV infections. Although the precise molecular mechanisms that link HBV and HCV infections to the development of HCC are not entirely understood, there is considerable evidence that both inflammatory responses to infections with these viruses, and associated destruction and regeneration of hepatocytes, as well as activities of HBV- or HCV-encoded proteins, contribute to hepatocyte transformation. In this review, we summarize progress in defining mechanisms that may link HBV and HCV infections to the development of HCC, discuss the challenges of directly defining the processes that underlie HBV- and HCV-associated HCC, and describe areas that remain to be explored.

HBV therapy: guidelines and open issues

Therapy of chronic hepatitis B is currently based on two different strategies: (a) a finite course of treatment with pegylated interferon aimed to induce a sustained virological response that is maintained long-term after therapy withdrawal and (b) an indefinite treatment with oral anti-HBV nucleoside/nucleotide analogues (NUCs) aimed to achieve long-term complete suppression of HBV replication. The first strategy is typically used in patients with less advanced liver disease, with high ALT and no too high HBV-DNA and is particularly successful in the younger patients and in those infected with HBV genotype A or B. The suppressive strategy is instead typically adopted for patients with more advanced liver disease, and for those who have failed or cannot tolerate interferon therapy. Recently, following the implementation of third generation NUCs with high antiviral potency and barrier to resistance, the indication of oral therapy has gained credibility and indication, although most guidelines still recommend to start these drugs only in the presence of significant and progressive liver disease. This review summarises the recent Recommendations produced for the treatment of chronic HBV infection, with particular focus on the 2010 Italian Guidelines.