Kinetics of intrahepatic covalently closed circular DNA and serum hepatitis B surface antigen during antiviral therapy for chronic hepatitis B: lessons from experimental and clinical studies

Addition of PEG-interferon to long-term nucleos(t)ide analogue therapy enhances HBsAg decline and clearance in HBeAg-negative chronic hepatitis B: Multicentre Randomized Trial (PAS Study)

We studied whether 48 weeks of PEG-IFN alfa-2a add-on increases HBsAg-decline and clearance in HBeAg-negative patients on long-term nucleo(s)tide analogue (NA) therapy. In this investigator-initiated, randomized, controlled trial conducted in Europe and Canada, HBeAg-negative patients treated with NA > 12 months, with HBVDNA < 200 IU/mL, were enrolled. Patients were randomized 2:1 to 48 weeks of PEG-IFN alfa-2a add-on (180 μg per week) or continued NA-monotherapy with subsequent follow-up to Week 72. Endpoints were HBsAg decline (≥1 log10 IU/mL) and HBsAg clearance at Week 48. Of the 86 patients in the modified-intention-to-treat analysis, 58 patients received PEG-IFN add-on, and 28 continued NA monotherapy. At Week 48, 16(28%) patients achieved HBsAg decline ≥1 log10 in the add-on arm versus none on NA-monotherapy (p < .001), and HBsAg clearance was observed in 6 (10%) PEG-IFN add-on patients versus 0% NA-monotherapy (p = .01). HBVRNA was only detected in 2% after PEG-IFN treatment versus 19% in NA-monotherapy (p = .002) at Week 48. PEG-IFN add-on therapy was well tolerated in majority of patients. Low baseline HBsAg levels (<10 IU/mL) identified patients most likely to achieve HBsAg loss with PEG-IFN add-on, whereas an HBsAg level > 200 IU/mL at on-treatment Week 12 was highly predictive of non-response (NPV = 100%). Addition of PEG-IFN to long-term NA enhanced HBsAg decline and increased the chance of HBsAg clearance in HBeAg-negative patients on long-term NA. On-treatment HBsAg levels >200 IU/mL identify patients unlikely to benefit from PEG-IFN add-on and could be used as a potential stopping-rule for PEG-IFN therapy. Our findings support further exploration of immune modulation add-on to antiviral therapy, preferably using response-guided strategies, to increase functional cure rates in patients with CHB.

Quantitative Measurement of Serum HBcrAg Can Be Used to Assess the Feasibility of Safe Discontinuation of Antiviral Therapy for Chronic Hepatitis B

Hepatitis B virus (HBV) infection is a serious global health problem, and chronic HBV infection significantly increases the risk of liver fibrosis, cirrhosis, and even hepatocellular carcinoma in patients. Current first-line therapeutics such as nucleos(t)ide analogues and interferons are unable to completely clear cccDNA, so the vast majority of patients need to take long-term or even lifelong medication. However, long-term virological and biochemical responses can be achieved in some patients after drug withdrawal. Successfully screening these patients with drug withdrawal advantages is difficult. Hepatitis-B-core-related antigen (HBcrAg) is a new HBV serological marker that which can reflect the level and transcription activity of cccDNA in hepatocytes. Therefore, HBcrAg has potential value in guiding patients in drug withdrawal. This review summarizes previous reports on HBcrAg and evaluates the application value of HBcrAg in safe drug discontinuation.

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

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

Long-term Hepatitis B Surface Antigen Profile and Seroclearance after Severe Acute Flares of Chronic Hepatitis B

Background/Aims

Hepatitis B surface antigen (HBsAg) seroclearance remains uncommon in chronic hepatitis B (CHB) infection. During acute flares of CHB (AFOCHB), alanine aminotransferase elevation reflects a mounting immune response toward viral clearance. We hypothesized that severe AFOCHB is associated with a greater quantitative HBsAg (qHBsAg) decline and HBsAg seroclearance rate.

Methods

A total of 75 patients with severe AFOCHB with alanine aminotransferase 10× the upper limit of normal were matched to a control group by age and sex in a 1:2 ratio. qHBsAg levels were measured at the time of flare and annually (for both cases and controls) until the last follow-up.

Results

The median follow-up times for patients with severe AFOCHB and controls were 8.8 and 10.5 years, respectively. The cumulative rate of HBsAg seroclearance was higher in the severe AFOCHB group than in the control group (11.8% vs 5.0%, p=0.04) despite the former group having a trend of a higher baseline median qHBsAg (3,127 IU/mL vs 1,178 IU/mL, p=0.076). Compared with the control group, the severe AFOCHB group had a greater annual qHBsAg reduction (-242.4 IU/mL/yr vs -47.3 IU/mL/yr, p=0.002). Increasing age (p=0.049), lower baseline qHBsAg (p=0.002), and severe AFOCHB (p=0.014) were independently associated with HBsAg seroclearance. However, the cumulative rate of hepatocellular carcinoma was significantly higher in the severe AFOCHB group than in the control group (15.8% vs 1.9%, p<0.001).

Conclusions

Severe AFOCHB was associated with a greater incidence of HBsAg seroclearance and qHBsAg decline. However, it was associated with a higher incidence of hepatocellular carcinoma.

Treatment with the Immunomodulator AIC649 in Combination with Entecavir Produces Antiviral Efficacy in the Woodchuck Model of Chronic Hepatitis B

As current interventions for chronic hepatitis B (CHB) rarely induce cure, more effective drugs are needed. Short-term treatment of woodchucks with the novel immunomodulator AIC649, a parapoxvirus-based stimulator of toll-like receptor 9 dependent and independent pathways, has been shown to reduce viral DNA and surface antigen via a unique, biphasic response pattern. The present study evaluated long-term AIC649 treatment in combination with Entecavir for potency and safety in woodchucks. AIC649 monotreatment induced modest reductions in serum viral DNA and surface and e antigens that were associated with the same biphasic response pattern previously observed. Entecavir monotreatment reduced transiently viremia but not antigenemia, while AIC649/Entecavir combination treatment mediated superior viral control. Undetectability of viral antigens and elicitation of antibodies in AIC649/Entecavir-treated woodchucks correlated with the expression of interferons and suppression of viral replication in liver. Combination treatment was well tolerated, and liver enzyme elevations were minor and transient. It was concluded that the AIC649-mediated effects were most likely based on an improvement and/or reconstitution of antiviral immune responses that are typically deficient in CHB. As a combination partner to Entecavir, the antiviral efficacy of AIC649 was markedly enhanced. This preclinical study supports future evaluation of AIC649 for treatment of human CHB.

Hepatitis B surface antigen, core-related antigen and HBV RNA: Predicting clinical relapse after NA therapy discontinuation

BACKGROUND & AIMS

The safe discontinuation of nucleos(t)ide analogue therapy remains challenging in chronic hepatitis B. We investigated the potential role of quantitative hepatitis B surface antigen, hepatitis B core-related antigen and hepatitis B virus RNA at the end of treatment in predicting off-therapy relapse.

METHODS

Patients who fulfilled the stopping criteria of the Asian Pacific Association for the Study of the Liver guideline were enrolled. Virological relapse was defined as hepatitis B virus DNA level greater than 2000 IU/mL, and clinical relapse was defined as virological relapse plus alanine aminotransferase level of more than twice the upper limit of normal.

RESULTS

Ninety-two patients participated. The combination of end-of-treatment hepatitis B core-related antigen and hepatitis B virus RNA levels was most predictive of clinical relapse. Multivariate analysis revealed that end-of-treatment hepatitis B core-related antigen and hepatitis B virus RNA were independently associated with clinical relapse. During follow-up, no patients with undetectable hepatitis B core-related antigen (<3.0 log₁₀ U/mL) and hepatitis B virusRNA (<2.0 log₁₀ copies/mL) at end of treatment developed clinical relapse, in comparison with 22.9% and 62.5% patients with detectable levels of one or both biomarkers respectively. End-of-treatment quantitative hepatitis B surface antigen was linked to a likelihood of hepatitis B surface antigen clearance.

CONCLUSIONS

The combined hepatitis B core-related antigen and hepatitis B virus RNA assays at end of treatment were highly predictive of subsequent clinical relapse. These novel biomarkers could potentially be used to identify patients who could safely discontinue nucleos(t)ide analogue therapy.

Reverse transcriptase droplet digital PCR vs reverse transcriptase quantitative real-time PCR for serum HBV RNA quantification

Serum hepatitis B virus (HBV) RNA is a novel marker reflecting the activity of covalently closed circular DNA. However, the methodology for detecting HBV RNA has been a technical challenge. In this study, the performance of reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) for quantifying HBV RNA was compared with that of reverse transcription quantitative real-time PCR (RT-qPCR) in serum samples collected from treatment-naïve patients with different phases of chronic hepatitis B (CHB). A total of 417 serum samples, including 136 HBeAg-positive CHB and 281 HBeAg-negative CHB were examined. HBV RNA levels measured by RT-ddPCR and RT-qPCR showed a high degree of linearity and quantitative correlation. The limit of detections of RT-ddPCR and RT-qPCR assays were 102 and 103 copies/mL, respectively. Our results also demonstrated that RT-ddPCR was superior to RT-qPCR in terms of its consistency for quantifying HBV RNA across all concentrations. In the HBeAg-positive group, serum HBV RNA levels based on RT-ddPCR were moderately correlated with HBV DNA (r = 0.591, P < .001) and HBsAg (r = 0.502, P < .001). Among patients with HBeAg-negative CHB, serum HBV RNA levels were moderately correlated with HBV DNA (r = 0.603, P < .001) but had weak correlation with HBsAg (r = 0.203, P = .001). In summary, RT-ddPCR could enhance the sensitivity of serum HBV RNA detection, particularly among the HBeAg-negative group with low viral loads. Thus, RT-ddPCR could serve as an optimal method for HBV RNA quantification in clinical practice.

Insights into Hepatitis B Virus DNA Integration-55 Years after Virus Discovery

Hepatitis B virus (HBV), which was discovered in 1965, is a threat to global public health. HBV infects human hepatocytes and leads to acute and chronic liver diseases, and there is no cure. In cells infected by HBV, viral DNA can be integrated into the cellular genome. HBV DNA integration is a complicated process during the HBV life cycle. Although HBV integration normally results in replication-incompetent transcripts, it can still act as a template for viral protein expression. Of note, it is a primary driver of hepatocellular carcinoma (HCC). Recently, with the development of detection methods and research models, the molecular biology and the pathogenicity of HBV DNA integration have been better revealed. Here, we review the advances in the research of HBV DNA integration, including molecular mechanisms, detection methods, research models, the effects on host and viral gene expression, the role of HBV integrations in the pathogenesis of HCC, and potential treatment strategies. Finally, we discuss possible future research prospects of HBV DNA integration.

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HBV DNA integration is associated with hepatocarcinogenesis via multiple mechanisms

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HBV double-stranded linear DNA (dslDNA) is the dominant substrate for integration into the host genome

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The insertion sites of HBV DNA integration occur throughout the whole host genome using the NHEJ or MMEJ DNA repair pathway

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HBV DNA integration should be used as a clinical indicator for disease monitoring and treatment of patients with HBV infection

Baseline and kinetics of serum hepatitis B virus RNA predict response to pegylated interferon-based therapy in patients with hepatitis B e antigen-negative chronic hepatitis B

Serum hepatitis B virus (HBV) RNA has emerged as a novel biomarker of treatment response. This study aimed to investigate the role of this marker in predicting long-term outcome of patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) receiving pegylated interferon (PEG-IFN)-based therapy. Serial serum samples from 91 patients with HBeAg-negative CHB previously treated with PEG-IFN alone or combined with entecavir in a randomized trial were retrospectively analysed. HBV RNA quantification was examined by droplet digital PCR. At the end of 3 years post-treatment follow-up, maintained virological response (MVR, HBV DNA < 2000 IU/mL), and hepatitis B surface antigen (HBsAg) clearance were achieved in 37.4% (34/91) and 7.7% (7/91), respectively. Baseline serum HBV RNA concentrations correlated with HBV DNA and covalently closed circular DNA but did not correlate with HBsAg levels. Multiple regression analysis showed that pre-treatment HBV RNA and HBsAg were independently associated with MVR and HBsAg clearance. Baseline HBV RNA (cut-off 2.0 log₁₀  copies/mL) had a positive predictive value (PPV) and a negative predictive value in predicting MVR of 80.8% and 80.0%, respectively. At the same cut-off value, PPV and NPV for predicting HBsAg clearance were 30.8% and 95.4%, respectively. At week 12 during therapy, HBV RNA level ≥ 2 log₁₀ copies/mL displayed high NPVs of achieving MVR and HBsAg clearance (95% and 100%, respectively). In conclusion, the measurement of HBV RNA prior to PEG-IFN-based therapy could identify patients with high probability of MVR. In addition, HBV RNA kinetics may serve as a promising "stopping rule" in patients infected with HBV genotypes B or C.

Meeting the Challenge of Eliminating Chronic Hepatitis B Infection

Over 257 million people live with chronic hepatitis B virus (HBV) infection and there is no known cure. The effective preventative vaccine has no impact on existing infection. Despite the existence of drugs which efficiently suppress viral replication, treatment is usually life-long and finite therapies that cure HBV infection are urgently required. However, even if such therapies were available today, it is unlikely they would reach all of those who need it most, due to chronic hepatitis B (CHB) being largely undiagnosed across the globe and to the dire need for health systems promoting access to therapy. Considerable challenges to developing and implementing an effective HBV cure remain. Nonetheless, important advances towards a cure are being made, both in the development of a multitude of new therapeutic agents currently undergoing clinical trials, and through the establishment of a new global initiative dedicated to an HBV cure, ICE-HBV, that is working together with existing organisations to fast-track an HBV cure available to all.

Diagnostic and analytical performance of the hepatitis B core related antigen immunoassay in hepatitis B patients

BACKGROUND

Novel serological markers for Hepatitis B virus (HBV) infection are needed for prognosis and guidance of therapy.

OBJECTIVE

We evaluated the diagnostic performance of the Fujirebio Lumipulse G HBcrAg immunoassay on the Fujirebio LUMIPULSE G1200 analyzer.

STUDY DESIGN

Analytical performance was examined using three HBeAg positive HBV samples. Diagnostic specificity was assessed using subpanels of 54 confirmed acute HAV, HCV, HEV, B19, CMV and EBV infections. Diagnostic sensitivity was investigated in well-defined HBV positive patient groups, both treated and untreated, including immunocompromised patients.

RESULTS

The Lumipulse G HBcrAg immunoassay provided a linear measurement at a dilution between 1:100 and1:10,000. Six out of 54 samples showed non-specific reactivity in sera from acute CMV, EBV and HEV infections, of which 2 of them >3 log U/ml. The highest levels of HBcrAg were measured in HBeAg positive patients, in both treated and untreated as well as in immunocompromised patients. Untreated patients had relatively low serum HBcrAg levels in the inactive carrier phase, which increased upon progression into the HBeAg-negative hepatitis phase. Also, we showed that the applicability of HBcrAg to distinguish between patients with resolved HBV infection and false-positive reactivity to solitary anti-HBc is limited.

CONCLUSIONS

Our study demonstrated significant differences in HBcrAg levels depending on HBeAg status, the clinical phase, as well as the treatment status. Specificity of the assay is good; only 2 out of 54 samples showed reactivity above 3 log U/ml. Before implementing the assay in clinical practice, additional research in larger patient cohorts should be carried out.

Correlation between hepatic human males absent on the first (hMOF) and viral persistence in chronic hepatitis B patients

Background

Chronic hepatitis B (CHB) remains a global health dilemma with high morbidity and mortality. Human males absent on the first (hMOF) (a histone acetyltransferase) is responsible for DNA damage repair, tumorigenesis and cell cycle regulation. Persistence of HBV DNA contributes to cirrhosis and hepatocellular carcinoma (HCC) in CHB patients. Histone acetyltransferase enhances HBV replication, however the precise underlying mechanism of hMOF in HBV replication in CHB patients remains to be explored. This study aims to investigate the correlation between hepatic hMOF and HBV DNA replication in CHB patients, and may provide new insights towards the treatment of CHB patients.

Methods

hMOF in liver biopsy (CHB, n = 33 HBeAg⁺; n = 20 HBeAg⁻, and three healthy controls) was determined, using immunohistochemistry, qPCR and Western blot. The correlation between hMOF and HBsAg, as well as, HBeAg were determined.

Results

A positive correlation between hMOF and HBV DNA in overall CHB patients was observed. A distinct positive correlation between hMOF and HBsAg and/or HBeAg in HBeAg⁺ CHB patients was also detected, however not observed between hMOF and HBsAg in HBeAg⁻ CHB patients. No correlation was observed between hMOF and hepatic inflammation severity and fibrotic stage in CHB patients.

Conclusions

Hepatic hMOF might contribute to host HBV clearance in CHB patients and possible pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0215-5) contains supplementary material, which is available to authorized users.

Analysis of intrahepatic total HBV DNA, cccDNA and serum HBsAg level in Chronic Hepatitis B patients with undetectable serum HBV DNA during oral antiviral therapy

BACKGROUND

This study aimed to investigate the relationship between intrahepatic cccDNA and serum HBsAg in chronic Hepatitis B (CHB) patients with undetectable serum HBV DNA during antiviral therapy.

METHODS

We investigated HBsAg serum levels and their relationship to intrahepatic total cccDNA and HBV DNA in CHB patients with undetectable serum HBV DNA during oral antiviral therapy. Intrahepatic cccDNA and HBV DNA quantitation were performed in the same needle biopsy material, while serum HBsAg, HBeAg and HBV DNA levels were measured in samples drawn on the day of the liver biopsy.

RESULTS

A total of 90 patients who had a liver biopsy were enrolled, including 80 patients with CHB and 10 patients with liver cirrhosis (LC). All the CHB patients were divided into HBeAg-positive and HBeAg-negative group. By using real-time PCR detection, we found that intrahepatic cccDNA and HBV DNA levels were higher in CHB patients than those in LC patients (Intrahepatic cccDNA: 6.15±1.19 vs. 6.12±0.36, HBV DNA: 7.26±0.49 vs. 5.59±0.45, both P<0.05). Intrahepatic cccDNA level was positively correlated with serum HBsAg in HBeAg-negative (r=0.66, P=0.02) and lower serum HBeAg (≤50S/CO) CHB patients (r=0.47, P=0.03), but not in higher serum HBeAg (>50S/CO) CHB patients (both P>0.05). In HBeAg negative patients, serum HBsAg level was correlated with intrahepatic total HBV DNA level (r=0.52, P=0.006). However, no relationship between HBsAg level and intrahepatic total HBV DNA level was found in HBeAg positive patients (both P>0.05).

CONCLUSIONS

Serum HBsAg can be used to predict intrahepatic cccDNA and HBV DNA level in CHB patients with low serum HBeAg statues, especially in HBeAg negative patients.

Switching to PegIFNα-2b leads to HBsAg loss in patients with low HBsAg levels and HBV DNA suppressed by NAs

Patients with low hepatitis B surface antigen (HBsAg) levels and hepatitis B virus (HBV) DNA suppression by nucleos(t)ide analogues (NAs) achieve high rate of HBsAg loss through switching to PegIFNα in pre-registration study. The aim of this study was to achieve higher rate of HBsAg loss through extended PegIFN treatment. 98 patients with HBsAg < 2,000 IU/ml and HBV DNA < 20 IU/ml were randomized to receive PegIFNα-2b or continuing NA therapy for 60 weeks. At the end of treatment (EOT) and end of follow-up (EOF), only patients who switched to PegIFNα-2b achieved HBsAg loss (32.6%) and HBsAg seroconversion (27.9% and 25.6%). Patients who switched to PegIFNα-2b also achieved higher HBeAg seroconversion rates (65.1%) and HBeAg loss (81.4% and 90.7%) than those who continued NAs treatment. On-treatment HBsAg declines predicted the responses at EOT, and HBsAg declines at post-baseline times predicted the responses at EOF. The rates of responses were not increased through extended PegIFNα treatment. For patients with low HBsAg and HBV suppression with NAs, switching to PegIFNα-2b significantly increased the rates of HBsAg loss and HBsAg seroconversion. HBsAg decline can predict the response of switching to PegIFNα-2b following from NAs.

EASL 2017 Clinical Practice Guidelines on the management of hepatitis B virus infection

Hepatitis B virus (HBV) infection remains a global public health problem with changing epidemiology due to several factors including vaccination policies and migration. This Clinical Practice Guideline presents updated recommendations for the optimal management of HBV infection. Chronic HBV infection can be classified into five phases: (I) HBeAg-positive chronic infection, (II) HBeAg-positive chronic hepatitis, (III) HBeAg-negative chronic infection, (IV) HBeAg-negative chronic hepatitis and (V) HBsAg-negative phase. All patients with chronic HBV infection are at increased risk of progression to cirrhosis and hepatocellular carcinoma (HCC), depending on host and viral factors. The main goal of therapy is to improve survival and quality of life by preventing disease progression, and consequently HCC development. The induction of long-term suppression of HBV replication represents the main endpoint of current treatment strategies, while HBsAg loss is an optimal endpoint. The typical indication for treatment requires HBV DNA >2,000IU/ml, elevated ALT and/or at least moderate histological lesions, while all cirrhotic patients with detectable HBV DNA should be treated. Additional indications include the prevention of mother to child transmission in pregnant women with high viremia and prevention of HBV reactivation in patients requiring immunosuppression or chemotherapy. The long-term administration of a potent nucleos(t)ide analogue with high barrier to resistance, i.e., entecavir, tenofovir disoproxil or tenofovir alafenamide, represents the treatment of choice. Pegylated interferon-alfa treatment can also be considered in mild to moderate chronic hepatitis B patients. Combination therapies are not generally recommended. All patients should be monitored for risk of disease progression and HCC. Treated patients should be monitored for therapy response and adherence. HCC remains the major concern for treated chronic hepatitis B patients. Several subgroups of patients with HBV infection require specific focus. Future treatment strategies to achieve 'cure' of disease and new biomarkers are discussed.

Predictive role of serum HBsAg and HBcrAg kinetics in patients with HBeAg-negative chronic hepatitis B receiving pegylated interferon-based therapy

OBJECTIVES

To investigate the role of serum hepatitis B core-related antigen (HBcrAg) kinetics in predicting long-term outcome of pegylated interferon (PEG-IFN)-based therapy in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB).

METHODS

A total of 121 Thai patients with HBeAg-negative CHB recruited from a previous randomized trial of 48-week PEG-IFN alone or combined with entecavir were enrolled. Hepatitis B surface antigen (HBsAg) and HBcrAg levels were serially examined. Paired biopsy samples taken at baseline and after treatment were assessed for intrahepatic covalently closed circular DNA (cccDNA).

RESULTS

Persistent virologic remission (PVR, defined by persistent hepatitis B virus (HBV) DNA <2000 IU/mL) and HBsAg clearance at 3 years after treatment were 29% (35/121) and 9% (11/121) respectively. Baseline HBcrAg correlated with HBV DNA and cccDNA but not with HBsAg. Baseline HBsAg, as well as HBsAg and HBcrAg, declines were associated with PVR, while HBsAg decline was predictive of HBsAg clearance. High baseline antigen levels (HBsAg ≥3.4 log₁₀ IU/mL plus HBcrAg ≥3.7 log₁₀ U/mL) yielded high negative predictive values of PVR (45/50, 90%) and HBsAg clearance (50/50, 100%). At week 12, declines of HBsAg, HBcrAg and both antigens combined of <0.5 log₁₀ yielded negative predictive values for PVR of 90% (71/79), 82% (61/74) and 96% (48/50) respectively.

CONCLUSIONS

Quantitative HBcrAg was significantly associated with cccDNA in HBeAg-negative CHB. This novel antigen, together with HBsAg, could identify patients with low probability of PVR and HBsAg clearance in long-term follow-up.

Complete and Incomplete Hepatitis B Virus Particles: Formation, Function, and Application

Hepatitis B virus (HBV) is a para-retrovirus or retroid virus that contains a double-stranded DNA genome and replicates this DNA via reverse transcription of a RNA pregenome. Viral reverse transcription takes place within a capsid upon packaging of the RNA and the viral reverse transcriptase. A major characteristic of HBV replication is the selection of capsids containing the double-stranded DNA, but not those containing the RNA or the single-stranded DNA replication intermediate, for envelopment during virion secretion. The complete HBV virion particles thus contain an outer envelope, studded with viral envelope proteins, that encloses the capsid, which, in turn, encapsidates the double-stranded DNA genome. Furthermore, HBV morphogenesis is characterized by the release of subviral particles that are several orders of magnitude more abundant than the complete virions. One class of subviral particles are the classical surface antigen particles (Australian antigen) that contain only the viral envelope proteins, whereas the more recently discovered genome-free (empty) virions contain both the envelope and capsid but no genome. In addition, recent evidence suggests that low levels of RNA-containing particles may be released, after all. We will summarize what is currently known about how the complete and incomplete HBV particles are assembled. We will discuss briefly the functions of the subviral particles, which remain largely unknown. Finally, we will explore the utility of the subviral particles, particularly, the potential of empty virions and putative RNA virions as diagnostic markers and the potential of empty virons as a vaccine candidate.

Kinetics of serum HBsAg and intrahepatic cccDNA during pegylated interferon therapy in patients with HBeAg-positive and HBeAg-negative chronic hepatitis B

This study was aimed at comparing clinical applicability of serum HBsAg quantification in relation to intrahepatic covalently closed-circular DNA (cccDNA) in patients with HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB) treated with pegylated interferon (PEG-IFN) monotherapy for 48 weeks. Overall, 32 and 36 patients with HBeAg-positive and HBeAg-negative CHB, respectively were recruited. Paired liver biopsies at baseline and end of therapy were analyzed for cccDNA. Virological response (VR) at 48 weeks post-treatment was defined as HBeAg clearance (for HBeAg-positive CHB) and HBV DNA <2,000 IU/ml (for both groups). The results demonstrated that baseline levels of all viral markers were higher in the HBeAg-positive group than the HBeAg-negative group. Baseline HBsAg correlated with cccDNA in the HBeAg-positive group (r = 0.452, P = 0.009) but not in the HBeAg-negative group (r = 0.018, P = 0.919). However, the magnitude of cccDNA and HBsAg decline at end of treatment was not different between groups. The reduction of HBsAg showed a positive correlation with cccDNA decline in HBeAg-positive and HBeAg-negative CHB (r = 0.544, P = 0.001 and r = 0.364, P = 0.029, respectively). Overall, responders had more decline in cccDNA and HBsAg levels compared with non-responders. Patients with serum HBsAg decline of >1.0 log₁₀ IU/ml during treatment archived VR and HBsAg clearance of 80% and 30%, respectively. In conclusion, serum HBsAg represented a better surrogate marker of intrahepatic cccDNA in patients with HBeAg-positive CHB compared to those with HBeAg-negative CHB. On-treatment, HBsAg reduction of 1.0 log₁₀ IU/mL was associated with a high probability of subsequent VR and HBsAg clearance in patients receiving PEG-IFN therapy. J. Med. Virol. 89:130-138, 2017. © 2016 Wiley Periodicals, Inc.

Characterization of hepatitis B virus surface antigen variability and impact on HBs antigen clearance under nucleos(t)ide analogue therapy

For hepatitis B virus (HBV)-related chronic infection under treatment by nucleos(t)ide analogues (NUCs), HBsAg clearance is the ultimate therapeutic goal but very infrequent. We investigated how HBV envelope protein variability could lead to differential HBsAg clearance on NUCs. For 12 HBV genotype D patients receiving NUCs, six resolvers (HBsAg clearance) were compared to six matched nonresolvers (HBsAg persistence). PreS/S amino acid (aa) sequences were analysed with bioinformatics to predict HBV envelope antigenicity and aa covariance. To enrich our analyses on very rare resolvers, these were compared with other HBV genotype D strains in three characterized clinical cohorts including common chronically infected patients. The sT125M+sP127T combination was observed in four nonresolvers of six, corroborated by aa covariance analysis, associated with a lower predicted antigenicity than sT125T+sP127P. Concordant features within this HBV key functional domain, at positions 125 and 127, were reported from two of the three comparative cohorts. In our hands, a lower ELISA reactivity of HBV-vaccinated mice sera was observed against the sT125M mutant. In the S gene, 56 aa changes in minor variants were detected in non-resolvers, mainly in the major hydrophilic region, vs 28 aa changes in resolvers. Molecular features in patients showing HBsAg persistence on NUCs argue in favour of a different aa pattern in the HBV S gene compared to those showing HBsAg clearance. In nonresolvers, a decrease in HBs 'a' determinant antigenicity and more frequent mutations in the S gene suggest a role for the HBV envelope characteristics in HBsAg persistence.

Clinical relevance of the study of hepatitis B virus covalently closed circular DNA

Hepatitis B virus (HBV) remains a public health concern with 240 million people affected worldwide. HBV is an hepadnavirus that replicates its genome in hepatocytes. One of the key steps of the viral life cycle is the formation of cccDNA - covalently closed circular DNA - in the nucleus, the equivalent of a viral mini-chromosome that acts as a template for subsequent virus replication. Current antiviral medications are not effective in eradicating cccDNA, which can persist in the infected liver even in the absence of detectable HBV DNA or HBsAg in the blood. cccDNA cannot be measured in serum, and few surrogate markers have been proposed. Persistent cccDNA has been associated with various clinical events, including viral reactivation induced by immunosuppressive therapies, HBV recurrence after liver transplantation and hepatocellular carcinoma (HCC). cccDNA remains the main target to achieve a cure of HBV infection, thus extensive efforts are being made to develop new antiviral concepts to degrade or silence cccDNA.

Genome-free hepatitis B virion levels in patient sera as a potential marker to monitor response to antiviral therapy

Complete virions of hepatitis B virus (HBV) contain a DNA genome that is enclosed in a capsid composed of the HBV core antigen (HBcAg), which is in turn surrounded by a lipid envelope studded with viral surface antigens (HBsAg). In addition, HBV-infected cells release subviral particles composed of HBsAg only (HBsAg 'spheres' and 'filaments') or HBsAg enveloping HBcAg but devoid of viral DNA ('empty virions'). The hepatitis B e antigen (HBeAg), a soluble antigen related to HBcAg, is also secreted in some HBV-infected patients. The goals of this study were to explore the levels of empty virions in HBV-infected patients before and during therapy with the nucleotide analog tenofovir disoproxil fumarate (TDF) that inhibits HBV DNA synthesis and the relationships of empty virions to complete virions, HBsAg and HBeAg. HBV DNA, HBcAg and HBsAg levels were determined in serum samples from 21 patients chronically infected with HBV and enrolled in clinical TDF studies. Serum levels of empty virions were found to exceed levels of DNA-containing virions, often by ≥ 100-fold. Levels of both empty and complete virions varied and were related to the HBeAg status. When HBV DNA replication was suppressed by TDF, empty virion levels remained unchanged in most but were decreased (to the limit of detection) in some patients who also experienced significant decrease or loss of serum HBsAg. In conclusion, empty virions are present in the serum of chronic hepatitis B patients at high levels and may be useful in monitoring response to antiviral therapy.

Antiviral therapies and prospects for a cure of chronic hepatitis B

Current therapies of chronic hepatitis B (CHB) remain limited to either pegylated interferon-α (Peg-IFN-α), or one of the five approved nucleoside analog (NA) treatments. Although viral suppression can be achieved in the majority of patients with high-barrier-to-resistance new-generation NAs (i.e., entecavir and tenofovir), HBsAg loss is achieved in only 10% of patients with both classes of drugs after a follow-up of 5 years. Attempts to improve the response by administering two different NAs or a combination of NA and Peg-IFN-α have been unsuccessful. Therefore, there is a renewed interest to investigate a number of steps in the hepatitis B virus (HBV) replication cycle and specific virus-host cell interactions as potential targets for new antivirals. Novel targets and compounds could readily be evaluated using both relevant in vitro and newly developed in vivo models of HBV infection. The addition of one or several new drugs to current regimens should offer the prospect of markedly improving the response to therapy, thus reducing the burden of drug resistance, as well as the incidence of cirrhosis and hepatocellular carcinoma (HCC).

Bridging basic science and clinical research: the EASL Monothematic Conference on Translational Research in Viral Hepatitis

The EASL Monothematic Conference on Translational Research in Viral Hepatitis brought together a group of leading scientists and clinicians working on both, basic and clinical aspects of viral hepatitis, thereby building bridges from bench to bedside. This report recapitulates the presentations and discussions at the conference held in Lyon, France on November 29-30, 2013. In recent years, great advances have been made in the field of viral hepatitis, particularly in hepatitis C virus (HCV) infection. The identification of IL28B genetic polymorphisms as a major determinant for spontaneous and treatment-induced HCV clearance was a seminal discovery. Currently, hepatologists are at the doorstep of even greater advances, with the advent of a wealth of directly acting antivirals (DAAs) against HCV. Indeed, promising results have accumulated over the last months and few years, showing sustained virological response (SVR) rates of up to 100% with interferon-free DAA combination therapies. Thus, less than 25 years after its identification, HCV infection may soon be curable in the vast majority of patients, highlighting the great success of HCV research over the last decades. However, viral hepatitis and its clinical complications such as liver cirrhosis and hepatocellular carcinoma (HCC) remain major global challenges. New therapeutic strategies to tackle hepatitis B virus (HBV) and hepatitis D virus (HDV) infection are needed, as current therapies have undeniable limitations. Nucleoside/nucleotide analogues (NUC) can efficiently control HBV replication and reduce or even reverse liver damage. However, these drugs have to be given for indefinite periods in most patients to maintain virological and biochemical responses. Although sustained responses off treatment can be achieved by treatment with (pegylated) interferon-α, only about 10-30% of patients effectively resolve chronic hepatitis B. It was the goal of this conference to review the progress made over the last years in chronic viral hepatitis research and to identify key questions that need to be addressed in order to close the gap between basic and clinical research and to develop novel preventive and treatment approaches for this most common cause of liver cirrhosis and HCC.

Prevention of hepatocellular carcinoma in patients with chronic hepatitis B

Patients with chronic hepatitis B are at significant risk for hepatocellular carcinoma (HCC). Globally, over half a million people each year are diagnosed with HCC, with marked geographical variations. Despite overwhelming evidence for a causal role of hepatitis B virus (HBV) infection in the development of HCC and a well-established relationship between high baseline hepatitis B viral load and cumulative risk of HCC, the molecular basis for this association has not been fully elucidated. In addition, a beneficial role for antiviral therapy in preventing the development of HCC has been difficult to establish. This review examines the biological and molecular mechanisms of HBV-related hepatocarcinogenesis, recent results on the effect of modern nucleos(t)ides on the rate of HCC development in high risk HBV cohorts and the potential mechanisms by which long-term antiviral therapy with potent inhibitors of HBV replication might reduce the risk of HCC in patients with chronic hepatitis B. Although evidence from randomized controlled trials shows the favourable effects of antiviral agents in achieving profound and durable suppression of HBV DNA levels while improving liver function and histology, robust evidence of other long-term clinical outcomes, such as prevention of HCC, are limited.

Quantification of serum hepatitis B surface antigen in predicting the response of pegylated interferon alfa-2a in HBeAg-positive chronic hepatitis B with prior lamivudine exposure

Aims

Majority of previous studies of pegylated interferon α-2a (PegIFNα-2a) forced on naïve chronic hepatitis B (CHB) patients, and the data of PegIFNα-2a in therapy of patients with prior exposure to nucleos(t)ide analogues is rare. This study aimed to investigate the predictive role of serum quantitative hepatitis B surface antigen (HBsAg) in predicting sustained response of PegIFNα-2a in HBeAg-positive CHB patients with prior lamivudine exposure.

Methods

Forty-six patients with prior lamivudine exposure received PegIFNα-2a for 12 months and followed-up for 6 months. The clinical features of responders and non-responders were compared, and the predictive role of quantitative HBsAg in predicting responders at the end of follow-up was evaluated. Responders were defined as an ALT normalization, HBeAg seroconversion and sustained virological response at the end of follow-up.

Results

In this cohort, only 26.1% (12/46) patients were responders. The baseline characteristics of the responders and non-responders were similar; however, the rates of ALT normalization, HBV DNA undetectability and HBeAg seroconversion were all significantly higher in responders than that in non-responders. During the treatment and follow-up, the HBsAg levels were all significantly lower in responders than that in non-responders. In predicting reponders, the serum HBsAg cutoff of 6000 IU/mL at months 6 had a positive predictive value of 73.3 and a negative predictive value of 96.8%, and with an area under the receiver operating characteristic curve of 0.869.

Conclusion

The responders toward PegIFNα-2a in CHB patients with prior lamivudine exposure is not high, and serum HBsAg <6000 IU/Ml at months 6 of on-treatment had a high value to predict long-term outcomes of treatment.