Molecular basis for persistent hepatitis B virus infection in the liver after clearance of serum hepatitis B surface antigen

Furanocoumarins promote proteasomal degradation of viral HBx protein and down-regulate cccDNA transcription and replication of hepatitis B virus

Nucleot(s)ide analogues, the current antiviral treatments against chronic hepatitis B (CHB) infection, are non-curative due to their inability to eliminate covalently closed circular DNA (cccDNA) from the infected hepatocytes. Preclinical studies have shown that coumarin derivatives can effectively reduce the HBV DNA replication. We evaluated the antiviral efficacy of thirty new coumarin derivatives in cell culture models for studying HBV. Furanocoumarins Fc-20 and Fc-31 suppressed the levels of pre-genomic RNA as well as cccDNA, and reduced the secretion of virions, HBsAg and HBeAg. The antiviral efficacies of Fc-20 and Fc31 improved further when used in combination with the hepatitis B antiviral drug Entecavir. There was a marked reduction in the intracellular HBx level in the presence of these furanocoumarins due to proteasomal degradation resulting in the down-regulation of HBx-dependent viral genes. Importantly, both Fc-20 and Fc-31 were non-cytotoxic to cells even at high concentrations. Further, our molecular docking studies confirmed a moderate to high affinity interaction between furanocoumarins and viral HBx via residues Ala3, Arg26 and Lys140. These data suggest that furanocoumarins could be developed as a new therapeutic for CHB infection.

Efficacy of Antiviral Prophylaxis up to 6 or 12 Months From Completion of Rituximab in Resolved Hepatitis B Patients: A Multicenter, Randomized Study

BACKGROUND

Rituximab occasionally induces reactivation of hepatitis B virus (HBV) in patients with resolved HBV, at times with fatal consequences. The optimal duration of prophylactic antiviral therapy in this situation is unclear. We aimed to investigate the difference in HBV reactivation according to the duration of prophylactic tenofovir disoproxil fumarate (TDF) in patients with resolved HBV and receiving rituximab.

METHODS

A multicenter, randomized, open-label, prospective study was conducted in hepatitis B surface antigen-negative and anti-HBc-positive non-Hodgkin's lymphoma patients treated with rituximab-based chemotherapy. A total of 90 patients were randomized and received prophylactic TDF from the initiation of rituximab until 6 months (the 6-month group) or 12 months (the 12-month group) after the completion of rituximab. The primary outcome was the difference in HBV reactivation and the secondary outcomes were the difference in hepatitis flare and adverse events between the two groups.

RESULTS

In an intention to treat (ITT) analysis, HBV reactivation occurred in 1 of 43 patients (2.3%; 95% confidence interval [CI], 0.41-12%) at a median of 13.3 months in the 6-month group and 2 of 41 patients (4.9%; 95% CI, 1.4-16%) at a median of 13.7 months in the 12-month group. In a per protocol (PP) analysis, HBV reactivation occurred in 1 of 18 patients (5.6%; 95% CI, 0.99-26%) at 13.3 months in the 6-month group and 1 of 13 patients (7.7%; 95% CI, 1.4-33%) at 9.7 months in the 12-month group. The cumulative incidence of HBV reactivation was not significantly different between the two groups in ITT and PP analyses (P = 0.502 and 0.795, respectively). The occurrence of adverse events was not significantly different between the two groups in ITT (9.3% in the 6-month group, 22.0% in the 12-month group, P = 0.193) and PP analyses (5.6% in the 6-month group, 7.7% in the 12-month group, P > 0.999).

CONCLUSION

Prophylactic TDF up to 6 months after completion of rituximab-based chemotherapy is sufficient in terms of the efficacy and safety of reducing HBV reactivation in patients with resolved HBV.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02585947.

Global burden of hepatitis B virus: current status, missed opportunities and a call for action

Chronic hepatitis B virus (HBV) infection affects about 296 million people worldwide and is the leading aetiology of cirrhosis and liver cancer globally. Major medical complications also include acute flares and extrahepatic manifestations. In addition, people living with HBV infection also experience stigma. HBV-related cirrhosis resulted in an estimated 331,000 deaths in 2019, and it is estimated that the number of deaths from HBV-related liver cancer in 2019 was 192,000, an increase from 156,000 in 2010. Meanwhile, HBV remains severely underdiagnosed and effective measures that can prevent infection and disease progression are underutilized. Birth dose coverage for HBV vaccines remains low, particularly in low-income countries or regions where HBV burden is high. Patients with HBV infection are inadequately evaluated and linked to care and are undertreated worldwide, even in high-income countries or regions. Despite the goal of the World Health Organization to eliminate viral hepatitis as a public health problem by 2030, the annual global deaths from HBV are projected to increase by 39% from 2015 to 2030 if the status quo remains. In this Review, we discuss the current status and future projections of the global burden of HBV infection. We also discuss gaps in the current care cascade and propose future directions.

Clinical implication of immune checkpoint inhibitor on the chronic hepatitis B virus infection

AIM

The risk of hepatitis B virus (HBV) reactivation with immune checkpoint inhibitors (ICIs) is an important issue that has not yet been fully investigated. ICI is also expected to have an antiviral effect on HBV due to its immune tolerance inhibitory effect. We herein investigated the risk of HBV reactivation and the antiviral effect of ICI administration.

METHODS

This study included 892 patients on ICIs between September 2014 and May 2021 at our hospital. The frequency of HBV reactivation and antiviral effects were investigated.

RESULTS

Among the 892 patients who underwent ICI, 27 were hepatitis B surface antigen (HBsAg) positive. HBV reactivation was evaluated in 24 cases, among which 4.1% (1/24) had HBV reactivation. Nucleic acid analog prophylaxis was not administered to patients with reactivation. In a study of 15 cases, the amount of HBsAg decreased from baseline; 2.18 ± 0.77 log to 48 weeks later; 1.61 ± 1.38 log (p = 0.17). Forty-eight weeks after the start of ICI, disappearance of HBsAg was observed in two out of 15 cases (13.3%), and one case each with and without nucleic acid analog.

CONCLUSION

In rare cases, HBsAg-positive patients may be reactivated by ICI administration. On the other hand, when ICI is administered, it is expected to have an antiviral effect on HBV due to its immune tolerance inhibitory effect, and future drug development is expected.

Prevalence of occult hepatitis B infection in liver biopsy sample of patients with nonviral liver disease

Aim: To determine the prevalence of occult hepatitis B (HBV) infection (OBI) in patients with nonviral liver disease. Materials & methods: This study included 83 HBsAg-negative patients followed up at a gastroenterohepatology clinic. The presence of HBV DNA was investigated by using an in-house nested-PCR method applied to liver parenchymal biopsy samples obtained from patients who underwent due nonviral chronic liver disease. Results: OBI was detected in 19 (22.9%) of the 83 cases, in 11 (44%) of 25 anti-HBc-positive patients, and 15 (31.9%) of 47 anti-HBc and/or anti-HBs antibodies-positive patients. Conclusion: There is a considerable prevalence of OBI among patients with nonviral chronic liver disease. Therefore, it is suggested that closely monitoring HBV can be useful to prevent or more effectively manage possible OBI-related complications among patients with nonviral chronic liver disease, especially those who are HBsAg seronegative or anti-HBV antibody seropositive.

Occult Hepatitis B Virus Infection: An Update

Occult hepatitis B virus (HBV) infection (OBI) refers to a condition in which replication-competent viral DNA is present in the liver (with detectable or undetectable HBV DNA in the serum) of individuals testing negative for the HBV surface antigen (HBsAg). In this peculiar phase of HBV infection, the covalently closed circular DNA (cccDNA) is in a low state of replication. Many advances have been made in clarifying the mechanisms involved in such a suppression of viral activity, which seems to be mainly related to the host's immune control and epigenetic factors. OBI is diffused worldwide, but its prevalence is highly variable among patient populations. This depends on different geographic areas, risk factors for parenteral infections, and assays used for HBsAg and HBV DNA detection. OBI has an impact in several clinical contexts: (a) it can be transmitted, causing a classic form of hepatitis B, through blood transfusion or liver transplantation; (b) it may reactivate in the case of immunosuppression, leading to the possible development of even fulminant hepatitis; (c) it may accelerate the progression of chronic liver disease due to different causes toward cirrhosis; (d) it maintains the pro-oncogenic properties of the "overt" infection, favoring the development of hepatocellular carcinoma.

Role of hepatitis B virus in development of hepatocellular carcinoma: Focus on covalently closed circular DNA

Chronic infection with hepatitis B virus (HBV) remains a major global health problem, especially in developing countries. It may lead to prolonged liver damage, fibrosis, cirrhosis, and hepatocellular carcinoma. Persistent chronic HBV infection is related to host immune response and the stability of the covalently closed circular DNA (cccDNA) in human hepatocytes. In addition to being essential for viral transcription and replication, cccDNA is also suspected to play a role in persistent HBV infections or hepatitis relapses since cccDNA is very stable in non-dividing human hepatocytes. Understanding the pathogenicity and oncogenicity of HBV components would be essential in the development of new diagnostic tools and treatment strategies. This review summarizes the role and molecular mechanisms of HBV cccDNA in hepatocyte transformation and hepatocarcinogenesis and current efforts to its detection and targeting.

Novel Neplanocin A Derivatives as Selective Inhibitors of Hepatitis B Virus with a Unique Mechanism of Action

Novel neplanocin A derivatives have been identified as potent and selective inhibitors of hepatitis B virus (HBV) replication in vitro. These include (1S,2R,5R)-5-(5-bromo-4-methyl-7H-pyrrolo[2,3-d]-pyrimidin-7-yl)-3-(hydroxymethyl)cyclopent-3-ene-1,2-diol (AR-II-04-26) and (1S,2R,5R)-5-(4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-(hydroxylmethyl)cyclopent-3-ene-1,2-diol (MK-III-02-03). The 50% effective concentrations of AR-II-04-26 and MK-III-02-03 were 0.77 ± 0.23 and 0.83 ± 0.36 μM in HepG2.2.15.7 cells, respectively. These compounds reduced intracellular HBV RNA levels in HepG2.2.15.7 cells and infected primary human hepatocytes. Accordingly, they could reduce HBs and HBe antigen production in the culture supernatants, which was not observed with clinically approved anti-HBV nucleosides and nucleotides (reverse transcriptase inhibitors). The neplanocin A derivatives also inhibited HBV RNA derived from cccDNA. In addition, unlike neplanocin A itself, the compounds did not inhibit S-adenosyl-l-homocysteine hydrolase activity. Thus, it appears that the mechanism of action of AR-II-04-26 and MK-III-02-03 differs from that of the clinically approved anti-HBV agents. Although their exact mechanism (target molecule) remains to be elucidated, the novel neplanocin A derivatives are considered promising candidate drugs for inhibition of HBV replication.

Phylogeographic Genetic Diversity in the White Sucker Hepatitis B Virus across the Great Lakes Region and Alberta, Canada

Hepatitis B viruses belong to a family of circular, double-stranded DNA viruses that infect a range of organisms, with host responses that vary from mild infection to chronic infection and cancer. The white sucker hepatitis B virus (WSHBV) was first described in the white sucker (Catostomus commersonii), a freshwater teleost, and belongs to the genus Parahepadnavirus. At present, the host range of WSHBV and its impact on fish health are unknown, and neither genetic diversity nor association with fish health have been studied in any parahepadnavirus. Given the relevance of genomic diversity to disease outcome for the orthohepadnaviruses, we sought to characterize genomic variation in WSHBV and determine how it is structured among watersheds. We identified WSHBV-positive white sucker inhabiting tributaries of Lake Michigan, Lake Superior, Lake Erie (USA), and Lake Athabasca (Canada). Copy number in plasma and in liver tissue was estimated via qPCR. Templates from 27 virus-positive fish were amplified and sequenced using a primer-specific, circular long-range amplification method coupled with amplicon sequencing on the Illumina MiSeq. Phylogenetic analysis of the WSHBV genome identified phylogeographical clustering reminiscent of that observed with human hepatitis B virus genotypes. Notably, most non-synonymous substitutions were found to cluster in the pre-S/spacer overlap region, which is relevant for both viral entry and replication. The observed predominance of p1/s3 mutations in this region is indicative of adaptive change in the polymerase open reading frame (ORF), while, at the same time, the surface ORF is under purifying selection. Although the levels of variation we observed do not meet the criteria used to define sub/genotypes of human and avian hepadnaviruses, we identified geographically associated genome variation in the pre-S and spacer domain sufficient to define five WSHBV haplotypes. This study of WSHBV genetic diversity should facilitate the development of molecular markers for future identification of genotypes and provide evidence in future investigations of possible differential disease outcomes.

Hepatitis B virus persistence and reactivation

Hepatitis B virus (HBV) infection causes chronic hepatitis and has long term complications. Individuals ever infected with HBV are at risk of viral reactivation under certain circumstances. This review summarizes studies on HBV persistence and reactivation with a focus on the definitions and mechanisms. Emphasis is placed on the interplay between HBV replication and host immunity as this interplay determines the patterns of persistence following viral acquisition. Chronic infections exhibit as overt persistence when a defective immune response fails to control the viral replication. The HBV genome persists despite an immune response in the form of covalently closed circular DNA (cccDNA) and integrated DNA, rendering an occult state of viral persistence in individuals whose infection appears to have been resolved. We have described HBV reactivation that occurs because of changes in the virus or the immune system. This review aims to raise the awareness of HBV reactivation and to understand how HBV persists, and discusses the risks of HBV reactivation in a variety of clinical settings.

Diverse Virus and Host-Dependent Mechanisms Influence the Systemic and Intrahepatic Immune Responses in the Woodchuck Model of Hepatitis B

Woodchuck infected with woodchuck hepatitis virus (WHV) represents the pathogenically nearest model of hepatitis B and associated hepatocellular carcinoma (HCC). This naturally occurring animal model also is highly valuable for development and preclinical evaluation of new anti-HBV agents and immunotherapies against chronic hepatitis (CH) B and HCC. Studies in this system uncovered a number of molecular and immunological processes which contribute or likely contribute to the immunopathogenesis of liver disease and modulation of the systemic and intrahepatic innate and adaptive immune responses during hepadnaviral infection. Among them, inhibition of presentation of the class I major histocompatibility complex on chronically infected hepatocytes and a role of WHV envelope proteins in this process, as well as augmented hepatocyte cytotoxicity mediated by constitutively expressed components of CD95 (Fas) ligand- and perforin-dependent pathways, capable of eliminating cells brought to contact with hepatocyte surface, including activated T lymphocytes, were uncovered. Other findings pointed to a role of autoimmune response against hepatocyte asialoglycoprotein receptor in augmenting severity of liver damage in hepadnaviral CH. It was also documented that WHV in the first few hours activates intrahepatic innate immunity that transiently decreases hepatic virus load. However, this activation is not translated in a timely manner to induction of virus-specific T cell response which appears to be hindered by defective activation of antigen presenting cells and presentation of viral epitopes to T cells. The early WHV infection also induces generalized polyclonal activation of T cells that precedes emergence of virus-specific T lymphocyte reactivity. The combination of these mechanisms hinder recognition of virus allowing its dissemination in the initial, asymptomatic stages of infection before adaptive cellular response became apparent. This review will highlight a range of diverse mechanisms uncovered in the woodchuck model which affect effectiveness of the anti-viral systemic and intrahepatic immune responses, and modify liver disease outcomes. Further exploration of these and other mechanisms, either already discovered or yet unknown, and their interactions should bring more comprehensive understanding of HBV pathogenesis and help to identify novel targets for therapeutic and preventive interventions. The woodchuck model is uniquely positioned to further contribute to these advances.

New Biomarkers of Chronic Hepatitis B

Chronic hepatitis B (CHB) infection leads to clinically heterogeneous disease outcomes. Different viral markers are utilized to monitor treatment effects and predict risk of complications in patients with CHB. Hepatitis B core-related antigen (HBcrAg) is a novel serum composite viral protein whose performance has been proven to be superior to that of existing viral markers. It showed good correlation with intrahepatic covalently closed-circular DNA. Its profile differs drastically in patients in different disease phases, and the level declines with antiviral therapies. HBcrAg may be helpful for predicting hepatocellular carcinoma development and hepatitis B virus (HBV) reactivation in immunosuppressed patients. Another emerging measurable serum marker, HBV RNA, exists in the form of pregenomic RNA-containing virions. Its profile differs between patients in different disease phases in a similar manner to that of HBcrAg. HBV RNA is present in serum at lower levels than HBV DNA in treatment-naïve patients by 1–2 logs. In contrast, its level is higher than HBV DNA in patients receiving nucleos(t)ide analogues (NAs). A significant decline in serum RNA was observed in patients receiving novel antiviral therapies, including core protein allosteric modulators and RIG-1/NOD2 agonists. Both HBcrAg and HBV RNA may be helpful for predicting off-therapy sustained virological control in patients who stop long-term NA treatment.

Update of the statements on biology and clinical impact of occult hepatitis B virus infection

In October 2018 a large number of international experts with complementary expertise came together in Taormina to participate in a workshop on occult hepatitis B virus infection (OBI). The objectives of the workshop were to review the existing knowledge on OBI, to identify issues that require further investigation, to highlight both existing controversies and newly emerging perspectives, and ultimately to update the statements previously agreed in 2008. This paper represents the output from the workshop.

A quantitative method for hepatitis B virus covalently closed circular DNA enables distinguishing direct acting antivirals from cytotoxic agents

Studying the biogenesis of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) and developing anti-HBV agents require analytical methods to quantify viral DNA levels inside host cells. The well-accepted Southern blotting method is only semi-quantitative, while the other widely used methods (based on qPCR) have been questioned as to their fidelity for cccDNA quantification. In addition, Southern blotting and qPCR results barely reflect the number of host cells present in an analytical sample. We here developed new techniques that substantially improve cccDNA detection and quantification, including a sample pretreatment method that i) exploits high temperature and exonuclease V (an ATP-dependent, bidirectional exonuclease) digestion to effectively increase the amplification efficiency of HBV cccDNA by removing rcDNA and denaturing the cccDNA template, and ii) a method that splits cell samples and uses separate extraction technologies to facilitate "host normalization" based on host genomic DNA signals. Our study introduces new analytical techniques that should be useful for the basic biology and translational studies of HBV.

Reactivation of Hepatitis B Virus Infection With Reverse Seroconversion Following Umbilical Cord Allogeneic Hematopoietic Cell Transplantation in a Hepatitis-B-Immune Patient: A Case Report

Hepatitis B virus (HBV) reactivation in patients with prior exposure to HBV and protective levels of hepatitis B surface antibody (HBsAb) is a rare phenomenon and is termed reverse seroconversion. We describe a case of reactivation of HBV infection following reverse seroconversion in a patient who underwent umbilical cord allogeneic hematopoietic cell transplantation (UHCT). The patient developed acute hepatitis with positive hepatitis B surface antigen (HBsAg) and HBV DNA in the context of prior strongly positive HBsAb. The patient was treated with oral tenofovir and liver function tests returned to normal 3 months later. Long-term monitoring for HBV reactivation should be considered in patients with prior exposure to HBV undergoing UHCT regardless of HBsAb status.

Safety of hepatitis B virus core antibody-positive grafts in liver transplantation: A single-center experience in China

BACKGROUND

Given the shortage of suitable liver grafts for liver transplantation, proper use of hepatitis B core antibody-positive livers might be a possible way to enlarge the donor pool and to save patients with end-stage liver diseases. However, the safety of hepatitis B virus core antibody positive (HBcAb⁺) donors has been controversial. Initial studies were mainly conducted overseas with relatively small numbers of HBcAb⁺ liver recipients, and there are few relevant reports in the population of mainland China. We hypothesized that the safety of HBcAb⁺ liver grafts is not suboptimal.

AIM

To evaluate the safety of using hepatitis B virus (HBV) core antibody-positive donors for liver transplantation in Chinese patients.

METHODS

We conducted a retrospective study enrolling 1071 patients who underwent liver transplantation consecutively from 2005 to 2016 at West China Hospital Liver Transplantation Center. Given the imbalance in several baseline variables, propensity score matching was used, and the outcomes of all recipients were reviewed in this study.

RESULTS

In the whole population, 230 patients received HBcAb⁺ and 841 patients received HBcAb negative (HBcAb^-) liver grafts. The 1-, 3- and 5-year survival rates in patients and grafts between the two groups were similar (patient survival: 85.8% vs 87.2%, 77.4% vs 81.1%, 72.4% vs 76.7%, log-rank test, P = 0.16; graft survival: 83.2% vs 83.6%, 73.8% vs 75.9%, 70.8% vs 74.4%, log-rank test, P = 0.19). After propensity score matching, 210 pairs of patients were generated. The corresponding 1-, 3- and 5-year patient and graft survival rates showed no significant differences. Further studies illustrated that the post-transplant major complication rates and liver function recovery after surgery were also similar. In addition, multivariate regression analysis in the original cohort and propensity score-matched Cox analysis demonstrated that receiving HBcAb⁺ liver grafts was not a significant risk factor for long-term survival. These findings were consistent in both HBV surface antigen-positive (HBsAg⁺) and HBsAg negative (HBsAg^-) patients.

Newly diagnosed HBV infection had a relatively higher incidence in HBsAg^- patients with HBcAb⁺ liver grafts (13.23%), in which HBV naive recipients suffered most (31.82%), although this difference did not affect patient and graft survival (P = 0.50 and P = 0.49, respectively). Recipients with a high HBV surface antibody (anti-HBs) titer (more than 100 IU/L) before transplantation and antiviral prophylaxis with nucleos(t)ide antiviral agents post-operation, such as nucleos(t)ide antiviral agents, had lower de novo HBV infection risks.

CONCLUSION

HBcAb⁺ liver grafts do not affect the long-term outcome of the recipients. Combined with proper postoperative antiviral prophylaxis, utilization of HBcAb⁺ grafts is rational and feasible.

Impact of previous hepatitis B infection on the clinical outcomes from chronic hepatitis C? A population-level analysis

Chronic coinfection with hepatitis C virus (HCV) and hepatitis B virus (HBV) is associated with adverse liver outcomes. The clinical impact of previous HBV infection on liver disease in HCV infection is unknown. We aimed at determining any association of previous HBV infection with liver outcomes using antibodies to the hepatitis B core antigen (HBcAb) positivity as a marker of exposure. The Scottish Hepatitis C Clinical Database containing data for all patients attending HCV clinics in participating health boards was linked to the HBV diagnostic registry and mortality data from Information Services Division, Scotland. Survival analyses with competing risks were constructed for time from the first appointment to decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver-related mortality. Records of 8513 chronic HCV patients were included in the analyses (87 HBcAb positive and HBV surface antigen [HBsAg] positive, 1577 HBcAb positive and HBsAg negative, and 6849 HBcAb negative). Multivariate cause-specific proportional hazards models showed previous HBV infection (HBcAb positive and HBsAg negative) significantly increased the risks of decompensated cirrhosis (hazard ratio [HR]: 1.29, 95% CI: 1.01-1.65) and HCC (HR: 1.64, 95% CI: 1.09-2.49), but not liver-related death (HR: 1.02, 95% CI: 0.80-1.30). This is the largest study to date showing an association between previous HBV infection and certain adverse liver outcomes in HCV infection. Our analyses add significantly to evidence which suggests that HBV infection adversely affects liver health despite apparent clearance. This has important implications for HBV vaccination policy and indications for prioritization of HCV therapy.

Flap endonuclease 1 is involved in cccDNA formation in the hepatitis B virus

Hepatitis B virus (HBV) is one of the major etiological pathogens for liver cirrhosis and hepatocellular carcinoma. Chronic HBV infection is a key factor in these severe liver diseases. During infection, HBV forms a nuclear viral episome in the form of covalently closed circular DNA (cccDNA). Current therapies are not able to efficiently eliminate cccDNA from infected hepatocytes. cccDNA is a master template for viral replication that is formed by the conversion of its precursor, relaxed circular DNA (rcDNA). However, the host factors critical for cccDNA formation remain to be determined. Here, we assessed whether one potential host factor, flap structure-specific endonuclease 1 (FEN1), is involved in cleavage of the flap-like structure in rcDNA. In a cell culture HBV model (Hep38.7-Tet), expression and activity of FEN1 were reduced by siRNA, shRNA, CRISPR/Cas9-mediated genome editing, and a FEN1 inhibitor. These reductions in FEN1 expression and activity did not affect nucleocapsid DNA (NC-DNA) production, but did reduce cccDNA levels in Hep38.7-Tet cells. Exogenous overexpression of wild-type FEN1 rescued the reduced cccDNA production in FEN1-depleted Hep38.7-Tet cells. Anti-FEN1 immunoprecipitation revealed the binding of FEN1 to HBV DNA. An in vitro FEN activity assay demonstrated cleavage of 5′-flap from a synthesized HBV DNA substrate. Furthermore, cccDNA was generated in vitro when purified rcDNA was incubated with recombinant FEN1, DNA polymerase, and DNA ligase. Importantly, FEN1 was required for the in vitro cccDNA formation assay. These results demonstrate that FEN1 is involved in HBV cccDNA formation in cell culture system, and that FEN1, DNA polymerase, and ligase activities are sufficient to convert rcDNA into cccDNA in vitro.

Hepatitis B virus (HBV) infection remains a worldwide health problem that affects more than 350 million people. HBV is one of the major etiological pathogens for liver cirrhosis and hepatocellular carcinoma. HBV covalently closed circular DNA (cccDNA) is a key viral intermediate for persistent infection. However, the molecular mechanism of cccDNA formation has not been clarified. Here, we found that the host factor flap-endonuclease 1 (FEN1) is pivotal in cccDNA formation. We developed a novel cccDNA formation assay by the incubation of purified viral DNA with recombinant FEN1, DNA polymerase, and DNA ligase. This study provides new insights into the molecular mechanisms of cccDNA formation and proposes FEN1 as a potential anti-HBV drug target.

Occult HBV infection in HCC and cirrhotic tissue of HBsAg-negative patients: a virological and clinical study

Aim

To evaluate the virological and clinical characteristics of occult HBV infection (OBI) in 68 consecutive HBsAg-negative patients with biopsy-proven cirrhosis and HCC.

Methods

HBV DNA was sought and sequenced in plasma, HCC tissue and non-HCC liver tissue by PCRs using primers for HBV core, surface and x regions. OBI was identified by the presence of HBV DNA in at least two different PCRs.

Results

OBI was detected in HCC tissue of 13 (20%) patients and in non-HCC liver tissue of 3 of these 13. OBI was detected in HCC tissue of 54.5% of 11 anti-HBs- negative/anti-HBc-positive patients, in 29.4% of 17 anti-HBs/anti-HBc-positive and in 5% of 40 anti-HBs/anti-HBc-negative (p < 0.0005). The 13 patients with OBI in HCC tissue more frequently than the 55 without showed Child-B or -C cirrhosis (53.9% vs. 5.5%, p < 0.0001) and BCLC-B or -C stages (46.1% vs. 1.8%, p < 0.0001). The pre-S1, pre-S2 and S region sequences in HCC tissue showed amino acid (AA) substitutions (F19L, P24L, S59F, T131I, Q129H) and deletions (in positions 4,8, 17 and 86) in the S region, AA substitutions (T40S, P124K, L54P, G76A, N222T and I273L) in pre-S1 region and AA substitutions in pre-S2 region (P41H and P66L). In the 3 patients showing OBI also in non-HCC liver tissue the S, pre-S1 and pre-S2 sequencing displayed patterns of mutations different.

Conclusions

The study showed a significant correlation between OBI and the severity of liver damage, several patterns of mutations in the S, pre-S1 and pre-S2 regions in HCC tissue, some at their first description.

Combinational use of hepatitis B viral antigens predicts responses to nucleos(t)ide analogue/peg-interferon sequential therapy

BACKGROUND

This prospective cohort study searched for factors associated with a response to nucleos(t)ide analogue/peg-interferon (NUC/peg-IFN) sequential therapy.

METHODS

A total of 95 patients with chronic hepatitis B being treated with NUCs were enrolled. Immediately following NUC cessation, peg-IFN was administered at 180 µg/dose weekly for 48 weeks.

RESULTS

Twenty-six patients (27%) were judged to be responders at 48 weeks after the completion of peg-IFN. Analysis of baseline factors revealed that hepatitis B surface antigen (HBsAg) <3.1 log IU/ml and HB core-related antigen (HBcrAg) <3.9 log U/ml were significant indicators of a treatment response. The levels of the markers decreased in both responders and non-responders during peg-IFN therapy but continued falling in responders only after halting peg-IFN. Lower HBsAg (<2.0 log IU/ml) and HBcrAg (<3.8 log U/ml) levels at the time of response judgment were also significantly associated with a favorable response. While lower HBcrAg at baseline was the sole predictor of decreased HBcrAg levels at judgment, lower HBsAg, lower HBcrAg, and the use of adefovir dipivoxil at baseline predicted decreased HBsAg levels at the study endpoint. The use of adefovir dipivoxil was also associated with higher serum IFN-λ3, which might have contributed to the reduction in patient HBsAg levels.

CONCLUSIONS

The combinational use of HBsAg and HBcrAg levels at baseline and their changes throughout sequential therapy may be useful for predicting a response to NUC/peg-IFN sequential therapy.

Identification of an Intermediate in Hepatitis B Virus Covalently Closed Circular (CCC) DNA Formation and Sensitive and Selective CCC DNA Detection

Hepatitis B virus (HBV) covalently closed circular (CCC) DNA functions as the only viral template capable of coding for all the viral RNA species and is thus essential to initiate and sustain viral replication. CCC DNA is converted, in a multistep and ill-understood process, from a relaxed circular (RC) DNA, in which neither of the two DNA strands is covalently closed. To detect putative intermediates during RC DNA to CCC DNA conversion, two 3' exonucleases, exonuclease I (Exo I) and Exo III, were used in combination to degrade all DNA strands with a free 3' end, which would nevertheless preserve closed circular DNA in either single-stranded (SS) or double-stranded (DS) form. Indeed, an RC DNA species with a covalently closed minus strand but an open plus strand (closed minus-strand RC DNA [cM-RC DNA]) was detected by this approach. Further analyses indicated that at least some of the plus strands in such a putative intermediate likely still retained the RNA primer that is attached to the 5' end of the plus strand in RC DNA, suggesting that minus-strand closing can occur before plus-strand processing. Furthermore, the same nuclease treatment proved to be useful for sensitive and specific detection of CCC DNA by removing all DNA species other than closed circular DNA. Application of these and similar approaches may allow the identification of additional intermediates during CCC DNA formation and facilitate specific and sensitive detection of CCC DNA, which should help elucidate the pathways of CCC DNA formation and the factors involved.IMPORTANCE The hepatitis B virus (HBV) covalently closed circular (CCC) DNA, by serving as the viral transcriptional template, is the molecular basis of viral persistence. CCC DNA is converted, in a multistep and ill-understood process, from relaxed circular (RC) DNA. Little is currently understood about the pathways or factors involved in CCC DNA formation. We have now detected a likely intermediate during the conversion of RC DNA to CCC DNA, thus providing important clues to the pathways of CCC DNA formation. Furthermore, the same experimental approach that led to the detection of the intermediate could also facilitate specific and sensitive detection of CCC DNA, which has remained challenging. This and similar approaches will help identify additional intermediates during CCC DNA formation and elucidate the pathways and factors involved.

Detection of HBV Covalently Closed Circular DNA

Chronic hepatitis B virus (HBV) infection affects approximately 240 million people worldwide and remains a serious public health concern because its complete cure is impossible with current treatments. Covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by present therapeutics and may result in persistence and relapse. Drug development targeting cccDNA formation and maintenance is hindered by the lack of efficient cccDNA models and reliable cccDNA detection methods. Southern blotting is regarded as the gold standard for quantitative cccDNA detection, but it is complicated and not suitable for high-throughput drug screening, so more sensitive and simple methods, including polymerase chain reaction (PCR)-based methods, Invader assays, in situ hybridization and surrogates, have been developed for cccDNA detection. However, most methods are not reliable enough, and there are no unified standards for these approaches. This review will summarize available methods for cccDNA detection. It is hoped that more robust methods for cccDNA monitoring will be developed and that standard operation procedures for routine cccDNA detection in scientific research and clinical monitoring will be established.

The Impact of Chemotherapy on Hepatitis B Antibody Titer in Patients with Hematological Malignancies

Objective:

To investigate the influence of chemotherapy (CT) on HBsAb titer in patients receiving CT due to hematological malignancy.

Materials and Methods:

The data of 75 patients who received CT with the diagnosis of various hematological malignancies and who had serum HBsAb levels measured prior to and after the cessation of CT were evaluated retrospectively.

Results:

The median age of the patients was 52 years (range: 16-78) with 49 (65%) males and 26 (35%) females. Median HBsAb titer decreased significantly after CT compared to the pre-CT median HBsAb titer [68 (range: 0-1000) vs. 100 (range: 6.2-1000)] (p=0.001). In subgroup analysis, median HBsAb titer decreased significantly after CT in acute leukemia patients [110 (range: 6.2-1000) vs. 67.8 (range: 0-1000)] (p=0.003) and in patients receiving intensive CT [97.2 (range: 6.2-1000) vs. 71 (range: 0-1000)] (p=0.036). The decrease in median HBsAb titer was significant in male patients (p<0.001). HBsAb became negative after CT in 9 patients who were HBcAb-negative and had lower pre-CT HBsAb levels.

Conclusion:

HBsAb decreased after CT, especially in acute leukemia and male patients, and in patients receiving intensive CT.

A comparison of PCR assays for beak and feather disease virus and high resolution melt (HRM) curve analysis of replicase associated protein and capsid genes

Beak and feather disease virus (BFDV) threatens a wide range of endangered psittacine birds worldwide. In this study, we assessed a novel PCR assay and genetic screening method using high-resolution melt (HRM) curve analysis for BFDV targeting the capsid (Cap) gene (HRM-Cap) alongside conventional PCR detection as well as a PCR method that targets a much smaller fragment of the virus genome in the replicase initiator protein (Rep) gene (HRM-Rep). Limits of detection, sensitivity, specificity and discriminatory power for differentiating BFDV sequences were compared. HRM-Cap had a high positive predictive value and could readily differentiate between a reference genotype and 17 other diverse BFDV genomes with more discriminatory power (genotype confidence percentage) than HRM-Rep. Melt curve profiles generated by HRM-Cap correlated with unique DNA sequence profiles for each individual test genome. The limit of detection of HRM-Cap was lower (2×10^-5ng/reaction or 48 viral copies) than that for both HRM-Rep and conventional BFDV PCR which had similar sensitivity (2×10^-6ng or 13 viral copies/reaction). However, when used in a diagnostic setting with 348 clinical samples there was strong agreement between HRM-Cap and conventional PCR (kappa=0.87, P<0.01, 98% specificity) and HRM-Cap demonstrated higher specificity (99.9%) than HRM-Rep (80.3%).

Hepatitis B Virus and DNA Stimulation Trigger a Rapid Innate Immune Response through NF-κB

Cell-intrinsic innate immunity provides a rapid first line of defense to thwart invading viral pathogens through the production of antiviral and inflammatory genes. However, the presence of many of these signaling pathways in the liver and their role in hepatitis B virus (HBV) pathogenesis is unknown. Recent identification of intracellular DNA-sensing pathways and involvement in numerous diverse disease processes including viral pathogenesis and carcinogenesis suggest a role for these processes in HBV infection. To characterize HBV-intrinsic innate immune responses and the role of DNA- and RNA-sensing pathways in the liver, we used in vivo and in vitro models including analysis of gene expression in liver biopsies from HBV-infected patients. In addition, mRNA and protein expression were measured in HBV-stimulated and DNA-treated hepatoma cell lines and primary human hepatocytes. In this article, we report that HBV and foreign DNA stimulation results in innate immune responses characterized by the production of inflammatory chemokines in hepatocytes. Analysis of liver biopsies from HBV-infected patients supported a correlation among hepatic expression of specific chemokines. In addition, HBV elicits a much broader range of gene expression alterations. The induction of chemokines, including CXCL10, is mediated by melanoma differentiation-associated gene 5 and NF-κB-dependent pathways after HBV stimulation. In conclusion, HBV-stimulated pathways predominantly activate an inflammatory response that would promote the development of hepatitis. Understanding the mechanism underlying these virus-host interactions may provide new strategies to trigger noncytopathic clearance of covalently closed circular DNA to ultimately cure patients with HBV infection.

Sodium taurocholate cotransporting polypeptide inhibition efficiently blocks hepatitis B virus spread in mice with a humanized liver

Sodium taurocholate cotransporting polypeptide (NTCP) is a recently discovered hepatitis B virus (HBV) receptor. In the present study, we used TK-NOG mice with a humanized liver to examine the impact of endogenous NTCP expression on HBV infection. Upon inoculation with HBV, these mice exhibited clear viremia in 2 weeks, and serum HBV DNA levels gradually increased. The frequency of HBsAg-positive hepatocytes in the liver was 5.1 ± 0.6% at 2 weeks and increased with increasing HBV DNA levels, reaching 92.9 ± 2.8% at 10 to 12 weeks. In vivo siRNA-mediated NTCP knockdown before and after HBV inoculation significantly suppressed the levels of HBV replication and the frequency of HBsAg-positive hepatocytes at 2 weeks, whereas NTCP knockdown 13 weeks after infection did not affect these parameters. Similar to the humanized mouse livers in the early phase of HBV infection, human liver samples from chronic hepatitis B patients, especially those treated with nucleos(t)ide analogues, contained a considerable number of hepatocytes that were negative for the anti-HBs antibody. In conclusion, NTCP inhibition prevents the spread of HBV-infected hepatocytes in mice with a humanized liver. NTCP-targeted therapy has potential for regulating HBV infection in patients with chronic hepatitis B.

Occult HBV infection in the oncohematological setting

INTRODUCTION

Occult hepatitis B infection (OBI), a virological condition characterized by a low release of Hepatitis B Virus (HBV) from liver cells and low HBV-DNA levels in serum and/or liver tissue of HBsAg-negative subjects, may reactivate in oncohematological patients undergoing immunosuppression by aggressive chemotherapy or hematopoietic stem cell transplantation. The entity of OBI reactivation varies from an increase in HBV replication without liver damage to an active HBV replication followed by liver cell necrosis, frequently severe and in some cases life threatening. Because of a possible severe outcome associated with OBI reactivation (hepatic failure or death due to the discontinuation of chemotherapy), prophylaxis with anti-HBV nucleot(s)ide analogues is recommended in relation to the foreseeable degree of immunosuppression.

MATERIALS AND METHODS

This review article focuses on the clinical impact of OBI in the oncohematological setting and is addressed to all health care workers having in care oncohematological patients or involved in the treatment of HBV infection and OBI prophylaxis.

CONCLUSION

International guidelines have indicated lamivudine prophylaxis in hematopoietic stem cell transplantation and when high-dose corticosteroids or anti-CD20 or anti-CD52 monoclonal antibodies are used. Entecavir or tenofovir should replace lamivudine for patients with advanced liver diseases for whom reactivation of OBI may be life threatening. When anti-CD20 or anti-CD52 sparing schedules or other non-aggressive chemotherapies are used, monitoring may be indicated, but very early treatment with highly effective antiviral drugs (entecavir or tenofovir) should be administered once a reactivation of OBI has occurred.

Effect of prior hepatitis B virus exposure on long-term risk of liver-related events after liver transplantation

OBJECTIVE

To characterize the risk of liver-related events and death in hepatitis B virus (HBV)-exposed liver transplantation (LT) recipients.

METHODS

Retrospective review was performed in all adults who underwent LT between January 1995 through December 2010 at the Johns Hopkins Hospital. Recipients with graft failure or death within 14 d of LT or missing HBV status were excluded, leaving 575 individuals for analysis. Patients were classified according to HBV exposure status: Unexposed, Resolved HBV, Chronic HBV, or hepatitis B core antibody (anti-HBc) seropositive liver donor.

RESULTS

Compared with HBV-unexposed patients, the relative hazard of combined liver-related events (rejection, cirrhosis, re-transplantation) and death after LT was not increased in patients with a baseline history of resolved HBV infection or chronic hepatitis B. Using anti-HBc seropositive donors also did not increase the risk of liver-related events, death, or composite events (all p ≥ 0.05). However, hepatitis C was associated with liver-related events [adjusted hazard ratio (aHR), 1.59; 95% confidence interval (CI), 1.00-2.52], and blacks had a higher risk of death (aHR, 1.50; 95% CI, 1.01-2.22).

CONCLUSION

LT of patients with prior HBV exposure or use of anti-HBc seropositive donors is not associated with increased risk of liver-related events or death.

Inferior graft survival of hepatitis B core positive grafts is not influenced by post-transplant hepatitis B infection in liver recipients--5-year single-center experience

Nonoptimal liver grafts, and among them organs from anti-HBc+ donors, are increasingly used for liver transplantation. In this retrospective study including 1065 adult liver transplantations performed between 1977 and 2012, we analyzed long-term patient and graft survival and occurrence of HBV infection. A total of 52 (5.1%) patients received an anti-HBc+ graft. The 10-year graft and patient survival of these recipients were 50.9% and 59.0% compared to 72.0% and 76.5% (P = 0.001; P = 0.004) of patients receiving anti-HBc- grafts, respectively. Cox regression model showed that high urgency allocation (P = 0.003), recipient age (P = 0.027), anti-HCV+ recipients (P = 0.005), and anti-HBc+ organs (P = 0.048) are associated with decreased graft survival. Thirteen of 52 (25.0%) patients receiving anti-HBc+ grafts developed post-transplant HBV infection within a mean of 2.8 years. In this study, antiviral prophylaxis did not have significant impact on HBV infection, but long-term survival (P = 0.008). Development of post-transplant HBV infection did not affect adjusted 10-year graft survival (100% vs. 100%; P = 1). Anti-HBc+ liver grafts can be transplanted with reasonable but inferior long-term patient and graft survival. The inferior graft survival is not, however, related with post-transplant HBV infection as long as early diagnosis and treatment take place.

Are current screening protocols for chronic hepatitis B virus infection adequate?

Chronic hepatitis B virus (HBV) infection screening usually includes only HBV surface antigen (HBsAg) testing; HBV core and surface antibody (anti-HBc, anti-HBs) assays, indicating resolved infection and immunity, are not routinely performed. Yet, serum HBV DNA is measurable in approximately 10% of HBsAg-negative/anti-HBc-positive cases, representing occult HBV infection (OBI). Patient blood samples from 2 Veterans Affairs medical center look-back investigations were screened for HBV infection using HBsAg enzyme immunoassays. Supplementary testing included anti-HBc and anti-HBs enzyme immunoassays. For anti-HBc-positive samples, HBV DNA testing was performed. Background OBI prevalence was further estimated at these 2 facilities based on HBV serology testing results from 1999-2012. Finally, a literature review was performed to determine OBI prevalence in the published literature. Of 1887 HBsAg-negative cohort patients, 98 (5.2%) were anti-HBc positive/anti-HBs negative; and 175 (9.3%), anti-HBc positive/anti-HBs positive. Six of 273 were HBV DNA positive, representing 0.3% of the total tested and 2.2% who were anti-HBc positive/anti-HBs negative or anti-HBc positive/anti-HBs positive. Among 32,229 general population veterans at these 2 sites who had any HBV testing, 4/108 (3.7%) were HBV DNA positive, none of whom were part of the cohort. In 129 publications with HBsAg-negative patients, 1817/1,209,426 (0.15%) had OBI. However, excluding blood bank studies with greater than 1000 patients, the OBI rate increased to 1800/17,893 (10%). OBI is not rare and has implications for transmission and disease detection. HBsAg testing alone is insufficient for detecting all chronic HBV infections. These findings may impact blood donation, patient HBV screening, follow-up protocols for patients assumed to have cleared the infection, and initiation of immunosuppression in patients with distant or undetected HBV.

T- and B-cell responses and previous exposure to hepatitis B virus in 'anti-HBc alone' patients

A serologic response to hepatitis B virus (HBV) defined as 'anti-HBc alone' is commonly observed, but its significance remains unclear. This study aimed to define the relationship between 'anti-HBc alone' serostatus and HBV infection, including HBV-specific T- and B-cell memory responses. We enrolled 31 'anti-HBc alone' patients. Total HBV DNA and cccDNA were tested by nested polymerase chain reaction (PCR) analysis in liver samples from 22 'anti-HBc alone' patients vs controls (chronic or resolved HBV infection), followed by HBsAg/HBcAg immunohistochemical (IHC) staining. IFN-γ secretion by HBV-specific T cells was compared in individuals who were 'anti-HBc alone' (n = 27), resolved HBV (n = 21), chronic HBV (n = 24) and 12 healthy controls using enzyme-linked immunospot (ELISpot) assays. An HBsAg-IgG B-cell ELISpot assay was performed in 'anti-HBc alone' patients before and after one dose of recombinant HBsAg vaccine. The majority (23/31, 74.2%) of the 'anti-HBc alone' individuals were co-infected with HCV. Infrequent intrahepatic total HBV DNA (2/22, 9.1%) and cccDNA (1/22, 4.5%) were detected in biopsies; HBsAg and HBcAg IHC staining was negative. HBV-specific T-cell responses were similar between 'anti-HBc alone' individuals and HBV resolvers. Circulating HBV-memory B-cell responses were detected in all 'anti-HBc alone' individuals, consistent with an HBsAg-specific memory pool. After one HBV vaccine dose, increased anti-HBs antibody levels were observed, accompanied by an expansion of HBsAg-specific memory B cells (P = 0.0226). 'Anti-HBc alone' individuals showed HBV-specific T-cell and memory B-cell responses typical of previous viral exposure and protective memory, suggesting a resolved infection.

Asymptomatic Hepadnaviral Persistence and Its Consequences in the Woodchuck Model of Occult Hepatitis B Virus Infection

Woodchuck hepatitis virus (WHV) is molecularly and pathogenically closely related to hepatitis B virus (HBV). Both viruses display tropism towards hepatocytes and cells of the immune system and cause similar liver pathology, where acute hepatitis can progress to chronic hepatitis and to hepatocellular carcinoma (HCC). Two forms of occult hepadnaviral persistence were identified in the woodchuck-WHV model: secondary occult infection (SOI) and primary occult infection (POI). SOI occurs after resolution of a serologically apparent infection with hepatitis or after subclinical serologically evident virus exposure. POI is caused by small amounts of virus and progresses without serological infection markers, but the virus genome and its replication are detectable in the immune system and with time in the liver. SOI can be accompanied by minimal hepatitis, while the hallmark of POI is normal liver morphology. Nonetheless, HCC develops in about 20% of animals with SOI or POI within 3 to 5 years. The virus persists throughout the lifespan in both SOI and POI at serum levels rarely greater than 100 copies/mL, causes hepatitis and HCC when concentrated and administered to virus-naïve woodchucks. SOI is accompanied by virus-specific T and B cell immune responses, while only virus-specific T cells are detected in POI. SOI coincides with protection against reinfection, while POI does not and hepatitis develops after challenge with liver pathogenic doses >1000 virions. Both SOI and POI are associated with virus DNA integration into the liver and the immune system genomes. Overall, SOI and POI are two distinct forms of silent hepadnaviral persistence that share common characteristics. Here, we review findings from the woodchuck model and discuss the relevant observations made in human occult HBV infection (OBI).

Hepatitis B virus reactivation associated with antirheumatic therapy: Risk and prophylaxis recommendations

Accompanying the increased use of biological and non-biological antirheumatic drugs, a greater number of cases of hepatitis B virus (HBV) reactivation have been reported in inactive hepatitis B surface antigen (HBsAg) carriers and also in HBsAg-negative patients who have resolved HBV infection. The prevalence of resolved infection varies in rheumatic disease patients, ranging from 7.3% to 66%. Through an electronic search of the PubMed database, we found that among 712 patients with resolved infection in 17 observational cohort studies, 12 experienced HBV reactivation (1.7%) during biological antirheumatic therapy. Reactivation rates were 2.4% for etanercept therapy, 0.6% for adalimumab, 0% for infliximab, 8.6% for tocilizumab, and 3.3% for rituximab. Regarding non-biological antirheumatic drugs, HBV reactivation was observed in 10 out of 327 patients with resolved infection from five cohort studies (3.2%). Most of these patients received steroids concomitantly. Outcomes were favorable in rheumatic disease patients. A number of recommendations have been established, but most of the supporting evidence was derived from the oncology and transplantation fields. Compared with patients in these fields, rheumatic disease patients continue treatment with multiple immunosuppressants for longer periods. Optimal frequency and duration of HBV-DNA monitoring and reliable markers for discontinuation of nucleoside analogues should be clarified for rheumatic disease patients with resolved HBV infection.

Prevalence and clinical relevance of occult hepatitis B virus infection in patients on the waiting list for kidney transplantation

BACKGROUND

Occult hepatitis B virus (HBV) infection can be defined as the long-lasting persistence of viral genomes in the liver tissue, and sometimes also in the serum at low levels of viremia in individuals with undetectable HBV surface antigen (HBsAg). Viral replication can be reactivated by immunosuppressive therapies or immunologic diseases, leading to the development of typical hepatitis B.

METHODS

All patients on the waiting list for renal transplantation at the only 2 transplant centers in our region (Piemonte, Italy) were checked for the presence of occult HBV infection by an highly sensitive quantitative HBV-DNA polymerase chain reaction (PCR) assay (nested PCR); the only exclusion criterion was HBsAg-positivity. The enrollment lasted from October 1, 2006, to May 31, 2007. The prospective follow-up will continue for 5 years.

RESULTS

HBV-DNA sequences were detected in blood samples from 10 of 300 cases examined (3.3%), being more frequent among Asian (1/3; 33.3%) and African (1/16; 6.25%) subjects as compared with the Caucasians (8/281; 2.8%; P = .011), among anti-hepatitis C virus (HCV) positive versus HCV negative patients (3/32 [9.3%] vs 7/268 [2.6%]; P = .004) and mainly among patients with a previous history of overt liver diseases (3/22 [14%] vs 7/278 [2.5%]; P = .019). HBV-DNA sequences became undetectable at 1 month after renal transplantation in 3 patients; the follow-up is in progress for these and the other patients.

CONCLUSION

Occult HBV infection occurs in patients undergoing renal transplantation. Longer observation and prospective studies will clarify the clinical impact of this occult infection on transplant outcomes and the possibility of viral reactivation related to immunosuppressive therapy.

Immunological analysis of a patient with hepatitis B virus (HBV) reactivation after bone marrow transplantation

Patients with resolved hepatitis B virus (HBV) infection undergoing chemo- or immunosuppressive therapy are at potential risk for HBV reactivation. To determine whether the host immune response contributes to liver injury, we performed an immunological analysis of a patient with HBV reactivation. Consistent with the detection of HBV DNA in the sera, the number of polyclonal HBV-specific cytotoxic T lymphocytes (CTLs) gradually increased; however, the number of CD4(+)CD25(+) regulatory T cells (Treg) decreased. The interaction between HBV-specific CTLs and CD4(+)CD25(+) Treg is an important determinant of liver injury during HBV reactivation. Therefore, monitoring the number of these cells might be a useful modality for the diagnosis of acute hepatitis resulting from HBV reactivation.

Occult hepatitis B virus infection

Occult hepatitis B virus (HBV) infection (OBI) refers to the presence of HBV DNA in the absence of detectable hepatitis B surface antigen. Since OBI was first described in the late 1970s, there has been increasing interest in this topic. The prevalence of OBI varies according to the different endemicity of HBV infection, cohort characteristics, and sensitivity and specificity of the methods used for detection. Although the exact mechanism of OBI has not been proved, intra-hepatic persistence of viral covalently closed circular DNA under the host’s strong immune suppression of HBV replication and gene expression seems to be a cause. OBI has important clinical significance in several conditions. First, OBI can be transmitted through transfusion, organ transplantation including orthotopic liver transplantation, or hemodialysis. Donor screening before blood transfusion, prophylaxis for high-risk organ transplantation recipients, and dialysis-specific infection-control programs should be considered to reduce the risk of transmission. Second, OBI may reactivate and cause acute hepatitis in immunocompromised patients or those receiving chemotherapy. Close HBV DNA monitoring and timely antiviral treatment can prevent HBV reactivation and consequent clinical deterioration. Third, OBI may contribute to the progression of hepatic fibrosis in patients with chronic liver disease including hepatitis C. Finally, OBI seems to be a risk factor for hepatocellular carcinoma by its direct proto-oncogenic effect and by indirectly causing persistent hepatic inflammation and fibrosis. However, this needs further investigation. We review published reports in the literature to gain an overview of the status of OBI and emphasize the clinical importance of OBI.

Persistence of hepatitis B virus covalently closed circular DNA in hepatocytes: molecular mechanisms and clinical significance

Covalently closed circular DNA (cccDNA) is the transcriptional template of hepatitis B virus (HBV). Extensive research over the past decades has unveiled the important role of cccDNA in the natural history and antiviral treatment of chronic HBV infection. cccDNA can persist in patients recovering from acute HBV infection for decades. This explains why HBV reactivation occasionally occurs in patients with resolved hepatitis B receiving intensive immunosuppressive agents. In addition, although advances in antiviral treatment dramatically improve the adverse outcomes of chronic hepatitis B (CHB), accumulating evidence demonstrates that current antiviral treatments alone, be they nucleos(t)ide analogs (NAs) or interferon (IFN), fail to cure most CHB patients because of the persistent cccDNA. NA suppresses HBV replication by directly inhibiting viral polymerase, while IFN enhances host immunity against HBV infection. Viral rebound often occurs after discontinuation of antiviral treatment. The loss of cccDNA can be induced by non-cytolytic destruction of cccDNA or immune-mediated killing of infected hepatocytes. It is known that NA has no direct effect on viral transcription or cccDNA stability. Therefore, the long half-life of hepatocytes leads to a very slow decline in cccDNA in patients under antiviral therapy. Novel antiviral agents targeting cccDNA or cccDNA-containing hepatocytes are thus required for curing chronic HBV infection.

How to achieve immune control in chronic hepatitis B?

Chronic hepatitis B infection remains a major global health problem despite the existence of an effective vaccine. The current treatment options are either nucleos(t)ide analog therapy, which inhibits viral replication, or peginterferon-α, which has mainly immunomodulatory effects. However, treatment-induced HBeAg seroconversion with suppressed viral replication is mostly not sustainable, and loss of HBsAg is a rarely achieved endpoint. In addition, the hepatitis B virus persists in hepatocytes even after HBsAg clearance as covalently closed circular DNA is not eliminated from the hepatocytes. Because the course of chronic hepatitis B is determined by an ongoing interaction between the virus and the host immune system, immunomodulation may be the most logical approach in attempting to accomplish control or even cure of chronic hepatitis B. In the last years, methods for measuring the degree of immune control have been a major area of interest, with an important role for monitoring of HBsAg levels. In addition, new immunomodulatory agents are being developed and tested, providing promising options for future treatment.

Reactivation from occult HBV carrier status is characterized by low genetic heterogeneity with the wild-type or G1896A variant prevalence

BACKGROUND & AIMS

Individuals negative for hepatitis B surface antigen (HBsAg) but positive for antibodies to hepatitis B core antigen (anti-HBc) are at risk of hepatitis B virus (HBV) reactivation under immunosuppressive conditions. We investigated clinical features and viral genetics in patients with reactivation from occult HBV infection triggered by chemotherapy or immunosuppressive therapy.

METHODS

Clinical courses of 14 individuals originally HBsAg-negative but anti-HBc-positive that experienced HBV reactivation were examined. Ultra-deep sequencing analysis of the entire HBV genome in serum was conducted. Prevalence of the G1896A variant in latently infected livers was determined among 44 healthy individuals that were HBsAg-negative but anti-HBc-positive.

RESULTS

In 14 cases, HBV reactivation occurred during (n=7) and after (n=7) termination of immunosuppressive therapy. Ultra-deep sequencing revealed that the genetic heterogeneity of reactivated HBV was significantly lower in patients with reactivation from occult HBV carrier status compared with that in patients from HBsAg carrier status. The reactivated viruses in each case were almost exclusively the wild-type G1896 or G1896A variant. The G1896A variant was detected in 42.9% (6/14) of cases, including two cases with fatal liver failure. The G1896A variant was observed in the liver tissue of 11.4% (5/44) of individuals with occult HBV infection.

CONCLUSIONS

Reactivation from occult HBV infection is characterized by low genetic heterogeneity, with the wild-type G1896 or G1896A variant prevalent.

Hepatitis B virus (HBV) reverse seroconversion (RS) can be prevented even in non-responders to hepatitis B vaccine after allogeneic stem cell transplantation: long-term analysis of intervention in RS with vaccine for patients with previous HBV infection

BACKGROUND

Reactivation of hepatitis B virus (HBV) infection, reverse seroconversion (RS), is a serious complication after allogeneic stem cell transplantation (alloHSCT). We previously conducted a post-transplant hepatitis B vaccine intervention trial and demonstrated the vaccine efficacy in preventing HBV-RS. This report is an update of the hepatitis B vaccine study.

METHODS

In this trial, 21 patients were enrolled and received a standard 3-dose regimen of hepatitis B vaccine after discontinuation of immunosuppressants, whereas 25 transplant recipients with previous HBV infection did not receive the vaccine and served as controls.

RESULTS

None of the 21 patients in the vaccine group developed HBV-RS and 12 controls developed HBV-RS in median follow-up periods of 60 months (range 13-245). HBV vaccine resulted in a positive value of hepatitis B surface antibody (HBsAb) titer in 9 patients, while HBsAb remained negative in 12 patients. Presence of a high titer of HBsAb before vaccination was associated with conversion into HBsAb positivity after vaccination.

CONCLUSION

These results demonstrated the long-term effects of HBV vaccine for preventing HBV-RS after alloHSCT. Of note, no HBV-RS occurred, even in patients who did not achieve conversion into HBsAb positivity after vaccination.

Occult hepatitis B virus and hepatocellular carcinoma

Occult hepatitis B virus (HBV) infection (OBI) is a challenging pathobiological and clinical issue that has been widely debated for several decades. By definition, OBI is characterized by the persistence of HBV DNA in the liver tissue (and in some cases also in the serum) in the absence of circulating HBV surface antigen (HBsAg). Many epidemiological and molecular studies have indicated that OBI is an important risk factor for hepatocellular carcinoma (HCC) development. OBI may exert direct pro-oncogenic effects through the activation of the same oncogenic mechanisms that are activated in the course of an HBsAg-positive infection. Indeed, in OBI as in HBV-positive infection, HBV DNA can persist in the hepatocytes both integrated into the host genome as well as free episome, and may maintain the capacity to produce proteins-mainly X protein and truncated preS-S protein - provided with potential transforming properties. Furthermore, OBI may indirectly favor HCC development. It has been shown that the persistence of very low viral replicative activity during OBI may induce mild liver necro-inflammation continuing for life, and substantial clinical evidence indicates that OBI can accelerate the progression of liver disease towards cirrhosis that is considered the most important risk factor for HCC development.

Hepatitis B virus DNA quantification with the three-in-one (3io) method allows accurate single-step differentiation of total HBV DNA and cccDNA in biopsy-size liver samples

BACKGROUND

Hepatitis B virus (HBV) replicates via reverse transcription converting its partially double stranded genome into the covalently closed circular DNA (cccDNA). The long-lasting cccDNA serves as a replication intermediate in the nuclei of hepatocytes. It is an excellent, though evasive, parameter for monitoring the course of liver disease and treatment efficiency.

OBJECTIVE

To develop and test a new approach for HBV DNA quantification in serum and small-size liver samples.

STUDY DESIGN

The p3io plasmid contains an HBV fragment and human β-actin gene (hACTB) as a standard. Respective TaqMan probes were labeled with different fluorescent dyes. A triplex real-time PCR for simultaneous quantification of total HBV DNA, cccDNA and hACTB could be established.

RESULTS

Three-in-one method allows simultaneous analysis of 3 targets with a lower limit of quantification of 48 copies per 20 μl PCR reaction and a wide range of linearity (R(2)>0.99, p<0.0001) for all measured sequences. The method showed a pan-genotypic specificity among genotypes A-F with serum DNA samples from HBV infected patients. Total HBV DNA and cccDNA could be quantified in 32 and 22 of 33 FFPE preserved liver specimens, respectively. Total HBV DNA concentrations quantified by the 3io method remained comparable with Cobas TaqMan HBV Test v2.0.

CONCLUSIONS

The three-in-one protocol allows the single step quantification of viral DNA in samples from different sources. Therefore lower sample input, faster data acquisition, a lowered error and significantly lower costs are the advantages of the method.

Occult HBV infection: a faceless enemy in liver cancer development

The hepatitis B virus (HBV) represents a worldwide public health problem; the virus is present in one third of the global population. However, this rate may in fact be higher due to occult hepatitis B virus infection (OBI). This condition is characterized by the presence of the viral genome in the liver of individuals sero-negative for the virus surface antigen (HBsAg). The causes of the absence of HBsAg in serum are unknown, however, mutations have been identified that produce variants not recognized by current immunoassays. Epigenetic and immunological host mechanisms also appear to be involved in HBsAg suppression. Current evidence suggests that OBI maintains its carcinogenic potential, favoring the progression of fibrosis and cirrhosis of the liver. In common with open HBV infection, OBI can contribute to the establishment of hepatocellular carcinoma. Epidemiological data regarding the global prevalence of OBI vary due to the use of detection methods of different sensitivity and specificity. In Latin America, which is considered an area of low prevalence for HBV, diagnostic screening methods using gene amplification tests for confirmation of OBI are not conducted. This prevents determination of the actual prevalence of OBI, highlighting the need for the implementation of cutting edge technology in epidemiological surveillance systems.

Lamivudine compared with newer antivirals for prophylaxis of hepatitis B core antibody positive livers: a cost-effectiveness analysis

There is concern over the development of de novo hepatitis B in patients receiving liver transplants from hepatitis B surface antigen negative, hepatitis B core antibody positive donors. Current practice is to place such patients on indefinite lamivudine prophylaxis; however, there is a small risk of breakthrough infection and newer antivirals for hepatitis B are available. The objective of this study was to determine the cost-effectiveness of lamivudine compared with the newer agents, tenofovir and entecavir, in the prophylaxis setting using a Markov model. Three strategies were examined which consisted of either lamivudine or entecavir monoprophylaxis with tenofovir add-on therapy after breakthrough or tenofovir monoprophylaxis with emtricitabine add-on therapy after breakthrough. In the base case scenario, lamivudine was the most cost-effective option at a threshold of $100 000 per quality-adjusted life-year and this remained robust despite parameter uncertainty. Tenofovir had an incremental cost-effectiveness ratio of $3 540 194.77 while other strategies were superior to entecavir therapy. Until drug costs decrease, lamivudine remains the most cost-effective option for hepatitis B prophylaxis in the liver transplant setting.

Use of liver grafts from anti-hepatitis B core-positive donors: a multicenter study in Argentina

Liver transplantation success is limited by the availability of donors. To overcome this limitation, anti-core-positive donors are increasingly being accepted, but underutilization of this resource still occurs. We performed the current study to determine the prevalence of anti-core-positive donors in our region and to describe the management of these donors and their recipients. Between January 2005 and July 2011, the national transplant database included 2,262 registered liver donors among whom 106 (4.7%) were anti-core-positive including 59 (56%) discarded and 47 (44%) implanted organs. A median of 14.5 offers (range 4-60) were rejected before harvesting and implanting the accepted grafts. The only difference between the implanted and the discarded grafts was found for the alanine aminotransferase level, which was higher among the discarded ones (50 ± 59 UI/L vs 25 ± 16, P < .05). Among 40 recipients included in the study, 5 (12.5%) did not receive any prophylaxis; 18 (45%) a nucleos(t)ide analog 11 (25.5%), heptitis B immunoglobulin and nucleos(t)ide analogs and 6 (15%) pretransplant hepatitis B vaccination. Over a mean follow-up of 871 ± 585 days, 4 de novo hepatitis B cases were identified at 545, 720, 748, and 1,080 days posttransplantation. None of these patients had received any prophylaxis. In all cases entecavir successfully controlled viral replication. We believe that better utilization of these donors and careful management of their recipients represent safe strategies to expand the liver donor pool in Argentina.

Intrahepatic cholestasis in common chronic liver diseases

BACKGROUND AND OBJECTIVE

Cholestasis represents the consequence of impaired bile formation and decrease in bile flow, generally classified as extra- and intrahepatic. Cholestasis is the pivotal hallmark of the so-called primary cholestatic liver diseases but may also emerge in other forms of chronic liver injury. The aim now was to summarise the current state of knowledge on intrahepatic cholestasis related to chronic liver diseases.

METHODS

For this overview on intrahepatic cholestasis in chronic liver disorders other than the 'classic' cholestatic liver diseases, selected references were retrieved by literature search in MEDLINE and textbooks were reviewed. All articles were selected that discussed pathophysiological and clinical aspects of intrahepatic cholestasis in the context of alcoholic liver disease, nonalcoholic fatty liver disease, chronic hepatitis B and C virus infections as well as drug-induced and granulomatous liver diseases. Titles referring to primary biliary cirrhosis and sclerosing cholangitis were excluded.

RESULTS AND CONCLUSIONS

Dependent on the aetiology, intrahepatic cholestasis is present at variable frequencies and in different disease stages in chronic liver diseases. Cholestasis secondary to chronic liver injury may denote a severe disease course and development of end-stage liver disease or specific disease variants. These findings indicate that 'secondary intrahepatic cholestasis' (SIC) can occur in the natural course of chronic liver diseases other than the primary cholestatic diseases, in particular in the setting of advanced disease progression.