Hepatitis B surface antigen quantification: not what it seems on the surface

Clinical outcomes of treatment-naïve HBeAg-negative patients with chronic hepatitis B virus infection with low serum HBsAg and undetectable HBV DNA

Serum hepatitis B surface antigen (HBsAg) level < 100 IU/ml and undetectable hepatitis B virus (HBV) DNA have been recently proposed as an alternate endpoint of "partial cure" in chronic hepatitis B (CHB). We investigated clinical outcomes of hepatitis B e antigen (HBeAg)-negative CHB patients with HBsAg <100 IU/ml and undetectable HBV DNA. Treatment-naïve HBeAg-negative CHB patients with undetectable HBV DNA and normal alanine aminotransferase were retrospectively included from three institutions. Patients were classified into the low HBsAg group (<100 IU/ml) and the high HBsAg group (≥100 IU/ml). Liver fibrosis was evaluated by noninvasive tests (NITs). A total of 1218 patients were included and the median age was 41.5 years. Patients with low HBsAg were older (45.0 vs. 40.0 years, P < 0.001) than those in the high HBsAg group, while the NIT parameters were comparable between groups. During a median follow-up of 25.7 months, patients with low HBsAg achieved a higher HBsAg clearance rate (13.0% vs. 0%, P < 0.001) and a lower rate of significant fibrosis development (2.2% vs. 7.0%, P = 0.049) compared to patients with high HBsAg. No patient developed HCC in either group. HBsAg level was negatively associated with HBsAg clearance (HR 0.213, P < 0.001) and patients with HBsAg < 100 IU/ml had a low risk of significant fibrosis development (HR 0.010, P = 0.002). The optimal cutoff value of HBsAg for predicting HBsAg clearance was 1.1 Log10 IU/ml. Treatment-naïve HBeAg-negative CHB patients with HBsAg <100 IU/ml and undetectable HBV DNA had favourable outcomes with a high rate of HBsAg clearance and a low risk of fibrosis progression.

Development of monoclonal antibodies to target the large surface protein of hepatitis B virus and their use in therapeutic and diagnostic applications

Over 250 million people are living with chronic infection caused by the hepatitis B virus (HBV). HBV has three surface proteins, namely small (SHBs), medium (MHBs) and large (LHBs), and they play different roles in the virus life cycle. The approved hepatitis B vaccine only contains the SHBs protein and many studies have focused on characterising the functional domains in SHBs. Although the LHBs protein is less studied, recent studies have shown that it plays important roles in mediating viral entry, replication and assembly. Over the years, there have been major advancements in monoclonal antibody (mAb) discovery tools and multiple mAbs have been developed to specifically target the preS1 domain in LHBs. We summarise the HBV infection systems and antibody discovery strategies that have been utilised by various research groups to assess the potential use of anti-preS1 mAbs as therapeutic antibodies against HBV or in the development of new diagnostic assays.

The clinical value of serum hepatic parenchyma cell volume-normalized hepatitis B surface antigen levels in hepatitis B e antigen -positive and -negative chronic hepatitis B patients

BACKGROUND

While serum hepatitis B surface antigens (HBsAg) play an important role in the diagnosis and assessment of treatment results of hepatitis B virus (HBV) infections, it remains unclear whether HBsAg levels normalized to hepatic parenchymal cell volume (HPCV) is a superior indicator of disease state. This study compared the absolute and HPCV-normalized serum HBsAg levels in hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients with chronic hepatitis B (CHB).

METHODS

Patients admitted to our institution with CHB were retrospectively included and categorized into the HBeAg-positive and HBeAg-negative groups. HPCV was calculated based on pathological examination of liver biopsy specimens and theory of sphere geometry. The difference between HBsAg levels and HBsAg normalized to HPCV, and also correlation between HBsAg levels and liver inflammation and fibrosis was analyzed.

RESULTS

Absolute HBsAg levels (P=0.004), but not HPCV-normalized HBsAg levels (P=0.071) were significantly higher in HBeAg-positive patients compared to HBeAg-negative patients. In HBeAg-positive CHB patients, absolute HBsAg levels were positively correlated with liver inflammation grade (R=0.285, P=0.001) and hepatic fibrosis stage (R=0.351, P<0.001), as were HPCV-normalized HBsAg levels (R=0.640 and 0.742, both, P<0.001). However, in HBeAg-negative CHB patients, only HPCV-normalized HBsAg level were correlated with liver inflammation grade and hepatic fibrosis stage (R=0.640 and 0.785, both, P<0.001).

CONCLUSIONS

HPCV-normalized serum HBsAg levels, rather than absolute HBsAg levels, were positively correlated with liver inflammation grade and hepatic fibrosis stage in both HBeAg-positive and HBeAg-negative CHB patients. Thus, HPCV-normalized HBsAg levels may more accurately reflect the pathological progress of CHB patients compared to absolute HBsAg levels.

De novo design of modular and tunable protein biosensors

Naturally occurring protein switches have been repurposed for the development of biosensors and reporters for cellular and clinical applications¹. However, the number of such switches is limited, and reengineering them is challenging. Here we show that a general class of protein-based biosensors can be created by inverting the flow of information through de novo designed protein switches in which the binding of a peptide key triggers biological outputs of interest². The designed sensors are modular molecular devices with a closed dark state and an open luminescent state; analyte binding drives the switch from the closed to the open state. Because the sensor is based on the thermodynamic coupling of analyte binding to sensor activation, only one target binding domain is required, which simplifies sensor design and allows direct readout in solution. We create biosensors that can sensitively detect the anti-apoptosis protein BCL-2, the IgG1 Fc domain, the HER2 receptor, and Botulinum neurotoxin B, as well as biosensors for cardiac troponin I and an anti-hepatitis B virus antibody with the high sensitivity required to detect these molecules clinically. Given the need for diagnostic tools to track the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)³, we used the approach to design sensors for the SARS-CoV-2 spike protein and antibodies against the membrane and nucleocapsid proteins. The former, which incorporates a de novo designed spike receptor binding domain (RBD) binder⁴, has a limit of detection of 15 pM and a luminescence signal 50-fold higher than the background level. The modularity and sensitivity of the platform should enable the rapid construction of sensors for a wide range of analytes, and highlights the power of de novo protein design to create multi-state protein systems with new and useful functions.

De novo design of modular and tunable allosteric biosensors

Naturally occurring allosteric protein switches have been repurposed for developing novel biosensors and reporters for cellular and clinical applications ¹ , but the number of such switches is limited, and engineering them is often challenging as each is different. Here, we show that a very general class of allosteric protein-based biosensors can be created by inverting the flow of information through de novo designed protein switches in which binding of a peptide key triggers biological outputs of interest ² . Using broadly applicable design principles, we allosterically couple binding of protein analytes of interest to the reconstitution of luciferase activity and a bioluminescent readout through the association of designed lock and key proteins. Because the sensor is based purely on thermodynamic coupling of analyte binding to switch activation, only one target binding domain is required, which simplifies sensor design and allows direct readout in solution. We demonstrate the modularity of this platform by creating biosensors that, with little optimization, sensitively detect the anti-apoptosis protein Bcl-2, the hIgG1 Fc domain, the Her2 receptor, and Botulinum neurotoxin B, as well as biosensors for cardiac Troponin I and an anti-Hepatitis B virus (HBV) antibody that achieve the sub-nanomolar sensitivity necessary to detect clinically relevant concentrations of these molecules. Given the current need for diagnostic tools for tracking COVID-19 ³ , we use the approach to design sensors of antibodies against SARS-CoV-2 protein epitopes and of the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein. The latter, which incorporates a de novo designed RBD binder, has a limit of detection of 15pM with an up to seventeen fold increase in luminescence upon addition of RBD. The modularity and sensitivity of the platform should enable the rapid construction of sensors for a wide range of analytes and highlights the power of de novo protein design to create multi-state protein systems with new and useful functions.

A reusable PMMA/paper hybrid plug-and-play microfluidic device for an ultrasensitive immunoassay with a wide dynamic range

Conventional colorimetric enzyme-linked immunosorbent assay (ELISA) is a time-consuming laboratory assay that is not very sensitive and consumes a large amount of samples. Herein, the development of a reusable, cost-effective, and eco-friendly poly(methyl methacrylate) (PMMA)/paper hybrid plug-and-play (PnP) device for high-sensitivity immunoassay by analyte enrichment and efficient passing-through washing has been reported. The PMMA device has multiple slots where a pre-patterned paper substrate can be inserted. The sample flows back-and-forth through a low-cost, 3D paper substrate within the PMMA channels, thereby enhancing the amount of analyte adsorbed and dramatically increasing the sensitivity while decreasing the assay time. After the enrichment assay, the paper substrate can simply be pulled out of the device, and the results can be qualitatively viewed with the naked eye or scanned through a simple desktop scanner for quantitative analysis. The paper substrate can be replaced with a new substrate so that the device can be reused. The limits of detection (LODs) of 200 pg/mL for immunoglobulin G (IgG) and 270 pg/mL for hepatitis B surface antigen (HBsAg) were obtained. This IgG assay is at least 10 times more sensitive than commercial ELISA kits. In addition, the PnP ELISA exhibited a significant increase in the linear dynamic range from 3 orders of magnitude in a common paper-based device to a wide range of six orders of magnitude in the PnP hybrid device. This reusable PnP device has great potential for the low-cost yet high-sensitivity detection of infectious diseases, cancers, and other important biomolecules.

Within-host mathematical models of hepatitis B virus infection: Past, present, and future

Mathematical modeling has been instrumental in enhancing our understanding of the viral dynamics of hepatitis B virus (HBV) infection. We give a primer on HBV infection in humans and a brief overview of the development of within-host mathematical models of HBV infection. In the last decade, models have advanced from considering chronic HBV infections under therapy to the pathogenesis of infection. We also summarize estimates of key viral dynamic parameters that have varied greatly among studies, and show that they impact model predictions. Future directions for mathematical modeling of HBV infection are proposed to better understand emerging therapies, the HBV life cycle, predicting cure, and the mechanisms involved in the immune response to HBV infection.

The Effect of the Hepatitis B Virus Surface Protein Truncated sC69∗ Mutation on Viral Infectivity and the Host Innate Immune Response

Viruses could rapidly diversify into variants, which has long been known to facilitate viral adaption in the host. Recent studies showed that cooperation among variants and wild-type (WT) also increased viral fitness. Here, a mutant of sC69^∗ in small hepatitis B surface protein (SHBs) that resulted in premature stop was investigated and the frequency of sC69^∗ was 4.37% (19/435), most of which coexisted with the WT (78.95%, 15/19), indicating mixed viral populations. Functional studies showed that sC69^∗ mutant was associated with lower viral spread, but could be rescued by coexisting with the WT. The sC69^∗ mutant showed to attenuate host innate immune response during infection and poly (I:C) treatment such as IL29, ISG15, and RIG-I (p < 0.05). The lower immune response was not caused by the lower replication of sC69^∗ mutant. Our data provide information that sC69^∗ coexisting with the WT might facilitate the fitness and persistence of the viral quasispecies in the host.

viGEN: An Open Source Pipeline for the Detection and Quantification of Viral RNA in Human Tumors

An estimated 17% of cancers worldwide are associated with infectious causes. The extent and biological significance of viral presence/infection in actual tumor samples is generally unknown but could be measured using human transcriptome (RNA-seq) data from tumor samples. We present an open source bioinformatics pipeline viGEN, which allows for not only the detection and quantification of viral RNA, but also variants in the viral transcripts. The pipeline includes 4 major modules: The first module aligns and filter out human RNA sequences; the second module maps and count (remaining un-aligned) reads against reference genomes of all known and sequenced human viruses; the third module quantifies read counts at the individual viral-gene level thus allowing for downstream differential expression analysis of viral genes between case and controls groups. The fourth module calls variants in these viruses. To the best of our knowledge, there are no publicly available pipelines or packages that would provide this type of complete analysis in one open source package. In this paper, we applied the viGEN pipeline to two case studies. We first demonstrate the working of our pipeline on a large public dataset, the TCGA cervical cancer cohort. In the second case study, we performed an in-depth analysis on a small focused study of TCGA liver cancer patients. In the latter cohort, we performed viral-gene quantification, viral-variant extraction and survival analysis. This allowed us to find differentially expressed viral-transcripts and viral-variants between the groups of patients, and connect them to clinical outcome. From our analyses, we show that we were able to successfully detect the human papilloma virus among the TCGA cervical cancer patients. We compared the viGEN pipeline with two metagenomics tools and demonstrate similar sensitivity/specificity. We were also able to quantify viral-transcripts and extract viral-variants using the liver cancer dataset. The results presented corresponded with published literature in terms of rate of detection, and impact of several known variants of HBV genome. This pipeline is generalizable, and can be used to provide novel biological insights into microbial infections in complex diseases and tumorigeneses. Our viral pipeline could be used in conjunction with additional type of immuno-oncology analysis based on RNA-seq data of host RNA for cancer immunology applications. The source code, with example data and tutorial is available at: https://github.com/ICBI/viGEN/.

Why, who and when to start treatment for chronic hepatitis B infection

Chronic hepatitis B remains a major global health challenge due to morbidity and mortality from hepatocellular carcinoma and complications of liver cirrhosis. Current treatment regimens are non-curative and, once initiated, treatment is of indefinite duration for the majority. The decision to initiate treatment decisions is based on risk stratification. Advances in our understanding of the natural history of chronic hepatitis B have led to a paradigm shift in recommendations for treatment. Emerging non-invasive biomarkers of disease activity will further enhance disease stratification. In this review, we summarise the guidance from major international societies on treatment for chronic hepatitis B and explore some of the novel approaches to disease assessment.

In Situ Liver Expression of HBsAg/CD3-Bispecific Antibodies for HBV Immunotherapy

Current therapies against hepatitis B virus (HBV) do not reliably cure chronic infection, necessitating new therapeutic approaches. The T cell response can clear HBV during acute infection, and the adoptive transfer of antiviral T cells during bone marrow transplantation can cure patients of chronic HBV infection. To redirect T cells to HBV-infected hepatocytes, we delivered plasmids encoding bispecific antibodies directed against the viral surface antigen (HBsAg) and CD3, expressed on almost all T cells, directly into the liver using hydrodynamic tail vein injection. We found a significant reduction in HBV-driven reporter gene expression (184-fold) in a mouse model of acute infection, which was 30-fold lower than an antibody only recognizing HBsAg. While bispecific antibodies triggered, in part, antigen-independent T cell activation, antibody production within hepatocytes was non-cytotoxic. We next tested the bispecific antibodies in a different HBV mouse model, which closely mimics the transcriptional template for HBV, covalently closed circular DNA (cccDNA). We found that the antiviral effect was noncytopathic, mediating a 495-fold reduction in HBsAg levels at day 4. At day 33, bispecific antibody-treated mice exhibited 35-fold higher host HBsAg immunoglobulin G (IgG) antibody production versus untreated groups. Thus, gene therapy with HBsAg/CD3-bispecific antibodies represents a promising therapeutic strategy for patients with HBV.

Computational design of peptide ligands to target the intermolecular interaction between viral envelope protein and pediatric receptor

The recognition and binding of viral envelope protein to pediatric receptor subverts the membrane-trafficking apparatus to mediate virion export in young children. Here, we described a successful computational design of peptide ligands to target the intermolecular interaction between the virus large envelope protein (LHB) and adaptin receptor (ADT). Based on the crystal structure of ADT in complex with an oligopeptide segment corresponding to the core binding site of LHB, a sequence-specific amino acid preference profile was determined systematically for the ADT-binding peptides using structural bioinformatics approach. With the information harvested from the profile, a genetic evolution procedure was run to improve the biological potency of a peptide population generated randomly from the LHB. A number of potential hits were obtained from the evolution, and four were measured to interact with ADT at micromolar level. A high-affinity hit peptide was then optimized according to computational structural analysis. It is revealed that a potent peptide can be divided into three regions, i.e. a negatively charged region at N-terminus, a hydrophobic core region in middle, and a small, polar region at C-terminal tail. In addition, the two termini of peptide are partially out of the active pocket of ADT, thus contributing moderately to the peptide binding.

Effects of amino acid substitutions in hepatitis B virus surface protein on virion secretion, antigenicity, HBsAg and viral DNA

BACKGROUND & AIMS

As important virological markers, serum hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA levels show large fluctuations among chronic hepatitis B patients. The aim of this study was to reveal the potential impact and mechanisms of amino acid substitutions in small hepatitis B surface proteins (SHBs) on serum HBsAg and HBV DNA levels.

METHODS

Serum samples from 230 untreated chronic hepatitis B patients with genotype C HBV were analyzed in terms of HBV DNA levels, serological markers of HBV infection and SHBs sequences. In vitro functional analysis of the identified SHBs mutants was performed.

RESULTS

Among 230 SHBs sequences, there were 39 (16.96%) sequences with no mutation detected (wild-type) and 191 (83.04%) with single or multiple mutations. SHBs consist of 226 amino acids, of which 104 (46.02%) had mutations in our study. Some mutations (e.g., sE2G, sL21S, sR24K, sT47A/K, sC69stop (sC69∗), sL95W, sL98V, and sG145R) negatively correlated with serum HBsAg levels. HBsAg and HBV DNA levels from this group of patients had a positive correlation (r=0.61, p<0.001). In vitro analysis showed that these mutations reduced extracellular HBsAg and HBV DNA levels by restricting virion secretion and antibody binding capacity. Virion secretion could be rescued for sE2G, sC69∗, and sG145R by co-expression of wild-type HBsAg.

CONCLUSION

The serum HBsAg levels were lower in untreated CHB patients with novel SHBs mutations outside the major antigenic region than those without mutations. Underlying mechanisms include impairment of virion secretion and lower binding affinity to antibodies used for HBsAg measurements.

LAY SUMMARY

The hepatitis B surface antigen (HBsAg) is a major viral protein of the hepatitis B virus (HBV) secreted into patient blood serum and its quantification value serves as an important marker for the evaluation of chronic HBV infection and antiviral response. We found a few new amino acid substitutions in HBsAg associated with lower serum HBsAg and HBV DNA levels. These different substitutions might impair virion secretion, change the ability of HBsAg to bind to antibodies, or impact HBV replication. These could all result in decreased detectable levels of serum HBsAg. The factors affecting circulating HBsAg level and HBsAg detection are varied and caution is needed when interpreting clinical significance of serum HBsAg levels. Clinical trial number: NCT01088009.

Hepatitis B immunopathogenesis and immunotherapy

Worldwide there are over 248 million chronic carriers of HBV of whom about a third eventually develop severe HBV-related complications. Due to the major limitations of current therapeutic approaches, the development of more effective strategies to improve therapeutic outcomes in chronic hepatitis B (CHB) patients seems crucial. Immune activation plays a critical role in spontaneous viral control; therefore, new modalities based on stimulation of the innate and adaptive immune responses could result in the resolution of infection and are promising approaches. Here, we summarize the HBV immunopathogenesis, and discuss the encouraging results obtained from the promising immune-based innovations, such as therapeutic vaccination, cytokine therapy, cell-based therapies and blocking inhibitory receptors, as current and future immunotherapeutic interventions.

Dose-response association between hepatitis B surface antigen levels and liver cancer risk in Chinese men and women

We aimed at evaluating the risk of liver cancer in different levels of HBsAg among Chinese men and women. We carried out a nested case-control study including 363 cases and 3,511 controls in two population-based cohorts in Shanghai. Plasma samples collected at enrollment were quantified for HBsAg levels using the Architect QT assay. Conditional logistic regression was performed to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) for liver cancer, with adjustment for potential confounders. HBsAg was detected in 6.29% of control subjects overall (7.02% in men and 4.98% in women). HBsAg levels were positively associated with liver cancer risk in a dose-response manner (ptrend  < 0.001). Such association showed a significant gender disparity. With increasing levels of HBsAg, liver cancer risks rose more steeply in men than in women. In men, the adjusted ORs increased from 7.27 (95% CI: 3.49-15.15) at the lowest detectable level of HBsAg (5-9 IU/ml) to 7.16 (95% CI: 3.21-15.96), 34.30 (95% CI: 16.94-69.44), and 47.33 (95% CI: 23.50-95.34) at the highest level of HBsAg (≥1,000 IU/ml) compared to those negative for HBsAg. The corresponding ORs were much lower for women, from 1.37 (95% CI: 0.25-7.47), 3.81 (95% CI: 1.09-13.28), 7.36 (95% CI: 2.41-22.46) and 16.86 (95% CI: 7.24-39.27), respectively. HBsAg quantification has potential to distinguish individuals at different risks of liver cancer. Men with the lowest detectable level of HBsAg should still pay attention to their liver cancer risks, but those with a higher level may be given a higher priority in future liver cancer surveillance program.

The correlation between serum HBsAg levels and viral loads depends upon wild-type and mutated HBV sequences rather than the HBeAg/anti-HBe status

Despite several studies regarding the correlation between serum HBsAg titers and viral loads, the association remains uncertain. Eighty‐nine individuals were selected randomly from a Chinese cohort of 2,258 subjects infected persistently with hepatitis B virus (HBV) for cross‐sectional and longitudinal analysis. Viral loads of mutant HBV are lower than those of wild type HBV. The serum HBsAg titers correlate positively with viral loads in both HBeAg positive and negative subjects (r = 0.449, P = 0.013; r = 0.300, P = 0.018, respectively). No correlation between serum HBsAg titer and viral loads was found in any of the four phases of chronic HBV infection. The serum HBsAg titers correlate positively with viral loads in the group with wild type sequences of the PreS/S, basal core promoter (BCP), and preC regions of HBV(r = 0.502, P = 0.040). However, the correlation was not seen in the group with mutations in these regions (r = 0.165, P = 0.257). The correlation between HBsAg titers and viral loads was seen in individuals with wild type PreS/S sequences but not in the subgroup with BCP double mutations or PreC stop mutation, although their sequences in the preS/S regions were wild type. All these findings were confirmed by the longitudinal analysis. In conclusion, the correlation between serum HBsAg levels and viral loads may not differ between HBeAg positive and negative individuals but may depend on wild‐type or mutated genomic sequences. Therefore, HBsAg quantitation may be used as a surrogate for viral loads in only wild‐type HBV infections. J. Med. Virol. 87:1351–1360, 2015. © 2015 The Authors. Journal of Medical Virology Published by Wiley Periodicals, Inc.

Evaluation of changes of serum hepatitis B surface antigen from a different perspective

AIM: To investigate the dynamic changes of serum hepatitis B surface antigen (HBsAg) levels apportioned by the same hepatic parenchyma cell volume (HPCV), namely, hepatic cell quantities.

METHODS: Serum HBsAg levels were detected by electrochemiluminescence and serum HBsAg levels apportioned by the same HPCV were figured out according to the theory of sphere geometry. HBsAg levels were compared among different liver inflammation grades, as well as different hepatic fibrosis stages.

RESULTS: In hepatitis B e antigen-negative chronic hepatitis B, serum HBsAg levels in liver histological inflammation grades 1-4 were 3.66 ± 0.40, 3.74 ± 0.35, 3.74 ± 0.26 and 3.71 ± 0.34 log₁₀ COI (cut off index), respectively, and there were no differences before apportion (P = 0.640). Serum HBsAg levels apportioned by the same HPCV were 5.57 ± 0.62, 5.98 ± 0.65, 6.59 ± 0.50 and 6.81 ± 0.84 log₁₀ COI, respectively, and there were significant differences after apportion (P < 0.001). Serum HBsAg levels in hepatic fibrosis stages I-IV were 3.66 ± 0.43, 3.75 ± 0.33, 3.71 ± 0.28 and 3.75 ± 0.26 log₁₀ COI, respectively, and there were no differences before apportion (P = 0.513). Serum HBsAg levels apportioned by the same HPCV were 5.53 ± 0.66, 5.98 ± 0.53, 6.29 ± 0.46 and 7.06 ± 0.48 log₁₀ COI, respectively, and there were significant differences after apportion (P < 0.001).

CONCLUSION: Serum HBsAg levels apportioned by the same HPCV (hepatic cell quantities), rather than serum HBsAg levels, increase with liver inflammation grades and hepatic fibrosis stages.

Hepatitis B virus PreS/S gene variants: pathobiology and clinical implications

The emergence and takeover of hepatitis B virus (HBV) variants carrying mutation(s) in the preS/S genomic region is a fairly frequent event that may occur spontaneously or may be the consequence of immunoprophylaxis or antiviral treatments. Selection of preS/S mutants may have relevant pathobiological and clinical implications. Both experimental data and studies in humans show that several specific mutations in the preS/S gene may induce an imbalance in the synthesis of the surface proteins and their consequent retention within the endoplasmic reticulum (ER) of the hepatocytes. The accumulation of mutated surface proteins may cause ER stress with the consequent induction of oxidative DNA damage and genomic instability. Viral mutants with antigenically modified surface antigen may be potentially infectious to immune-prophylaxed patients and may account for cases of occult HBV infection. In addition, preS/S variants were reported to be associated with cases of fulminant hepatitis as well as of fibrosing cholestatic hepatitis, and they are associated with cirrhosis and hepatocellular carcinoma development.

Significance of viral status on occurrence of hepatitis B-related hepatocellular carcinoma

Hepatitis B virus (HBV) infection remains a challenging global health problem, with more than 350 million people chronically infected and at risk of developing hepatocellular carcinoma (HCC). Interactions that occur among host, environmental, and viral factors determine the natural course and predict the prognosis of patients with chronic HBV infection. In the past decades, several important viral factors of predictive of HCC have been identified, such as high hepatitis B surface antigen level, seropositivity of hepatitis B e antigen, high viral load, viral genotype, and specific viral sequence mutations. Identification of certain viral risk factors for HCC development and stratification of patient risk are very important to perform future surveillance programs. In this article, we thus reviewed the risk of viral factors involved in hepatocarcinogenesis.

Dynamic changes in serum HBsAg levels in HBeAg-positive chronic hepatitis B patients with different liver inflammation grades and fibrosis stages

AIM: To investigate the dynamic changes in serum HBsAg levels in HBeAg-positive chronic hepatitis B patients with different liver histological inflammation grades and hepatic fibrosis stages.

METHODS: Serum HBsAg levels in HBeAg-positive chronic hepatitis B patients were detected by electrochemiluminescence. Serum HBsAg levels were compared between patients with grades 1, 2, 3 and 4 liver histological inflammation, and between those with stages 1, 2, 3 and 4 hepatic fibrosis.

RESULTS: Serum HBsAg levels in patients with grades 1, 2, 3 and 4 liver histological inflammation were 2998 COI/mL ± 2515 COI/mL, 4064 COI/mL ± 2468 COI/mL, 5513 COI/mL ± 2390 COI/mL and 5736 COI/mL ± 1838 COI/mL, respectively; while the values in patients with stages 1, 2, 3 and 4 hepatic fibrosis were 3159 COI/mL ± 2577 COI/mL, 4075 COI/mL ± 2149 COI/mL, 5670 COI/mL ± 2189 COI/mL and 5976 COI/mL ± 2128 COI/mL, respectively. There were significant differences in serum HBsAg levels between different liver inflammation grades, as well as between different hepatic fibrosis stages (F = 9.986, P < 0.000; F = 13.955, P < 0.000).

CONCLUSION: Serum HBsAg levels increase dynamically along with the damage of hepatic tissues in patients with HBeAg-positive chronic hepatitis B.

Serum HBsAg quantification in treatment-naïve Indian patients with chronic hepatitis B

BACKGROUND AND AIMS

There is paucity of Indian data regarding serum HBsAg levels (qHBsAg) in treatment-naïve chronic hepatitis B (CHB). This study was done to determine correlation of qHBsAg with hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA levels and its ability to independently categorize subgroups of CHB.

METHODS

We studied 131 treatment-naive CHB patients and initially classified them based on HBeAg status. The HBeAg-positive group was further classified into immune tolerance (IT) and immune clearance (IC) phases based on serum alanine aminotransferase. HBeAg-negative patients were classified into low replicators (LR) and HBeAg-negative chronic hepatitis (ENH) based on DNA levels. HBsAg quantification was performed using the Architect chemiluminescence system.

RESULTS

HBeAg-positive patients had higher DNA (7.89 vs. 2.69 log10 IU/mL) and higher qHBsAg (4.60 vs. 3.85 log10 IU/mL) compared to the HBeAg-negative group. Good correlation between qHBsAg and DNA was seen in HBeAg-positive (ρ = 0.6, p < 0.001) but not in HBeAg-negative CHB (ρ = 0.2). A qHBsAg level greater than 4.39 log10 IU/mL predicted HBeAg-positive state with 81 % sensitivity and 85 % specificity. However, among HBeAg-negative CHB, qHBsAg failed to discriminate between LR and ENH.

CONCLUSIONS

A single point estimation of qHBsAg in treatment-naïve patients could predict replicative HBeAg-positive CHB, but was not helpful in defining replicative status in the HBeAg-negative CHB.

Hepatitis B surface antigen quantification in chronic hepatitis B and its clinical utility

Serum HBsAg levels have been quantified extensively in recent years with simple completely automated assays in the various phases of the natural course of chronic HBV infection, have been compared with cccDNA in the liver, with various markers of HBV replication and have been correlated with several viral, host and environmental variables. Low HBsAg levels in inactive carriers predict a spontaneous HbsAg loss. Quantification of HBsAg in serum at baseline and its decline under interferon-alfa based regimens, both in HBeAg-positive and HBeAg-negative CHB, provides important information on the prediction of sustained post-treatment outcomes and on subsequent HBsAg clearance. The value of HBsAg quantification in the monitoring of long term nucleos(t)ide analogue treatment of CHB and in the prediction of sustained response remains unclear. In this review, the most recent data regarding the overall clinical utility of HBsAg measurement in HBeAg-positive and -negative CHB and in their treatment, is critically presented.

Serum hepatitis B surface antigen quantification as a useful assessment for significant fibrosis in hepatitis B e antigen-positive hepatitis B virus carriers

BACKGROUND AND AIMS

The role of serum quantitative hepatitis B surface antigen (qHBsAg) in identifying hepatitis B virus (HBV) carriers with significant fibrosis is unknown. This study aims to evaluate the diagnostic value of qHBsAg for hepatic fibrosis in hepatitis B e antigen (HBeAg)-positive HBV carriers.

METHODS

Consecutive biopsy-proven HBeAg-positive HBV carriers were prospectively recruited in our center from 2009 to 2011 and were randomly divided into training and validation set. Area under receiver-operator curve (AUC) was used to determine the diagnostic accuracy of simple tests for significant fibrosis (Scheuer stage, F ≥ 2).

RESULTS

Overall, a total of 197 eligible patients (median age 31 years; 149 males) were enrolled. The median qHBsAg was 4.20 (log10 IU/mL). Significant fibrosis was confirmed in 112 (56.9%) patients. By logistical regression analysis, qHBsAg and γ-glutamyl transpeptidase were identified as predictors for significant fibrosis in training set (n = 124). Thus, qHBsAg index and γ-glutamyl transpeptidase to qHBsAg ratio (GqHBsR) were selected for the subsequent analysis. In the training set, an AUC of 0.762, 0.826, 0.749, and 0.771 was observed for qHBsAg index, GqHBsR, FIB-4, and aspartate aminotransferase to platelet ratio index, respectively (all P < 0.05). GqHBsR yielded a higher AUC than aspartate aminotransferase to platelet ratio index and FIB-4 (both P < 0.05). Using the optimal cut-off of 7.78, GqHBsR showed a sensitivity of 78.9% and a specificity of 73.6%. About 80% of liver biopsy could be avoided in the entire cohort.

CONCLUSIONS

Serum qHBsAg-based simple tests, especially GqHBsR, can accurately and specifically identify significant fibrosis in treatment-naïve HBeAg-positive HBV carriers.

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.

Hepatitis B virus genotype C encoding resistance mutations that emerge during adefovir dipivoxil therapy: in vitro replication phenotype

INTRODUCTION

Hepatitis B virus (HBV) can be classified into ten genotypes (A-J), with genotypes B and C being the most common in Asia. Recent data suggest that the HBV genotype can influence disease progression, and genotype C has been associated with more aggressive liver disease than that of other genotypes. Although there is a preventative vaccine, chronic infection remains a public health problem with oral nucleos(t)ide analog therapy being the most common treatment. The HBV genome is composed of four partially overlapping reading frames, meaning that substitutions in the HBV polymerase selected during NA therapy may also alter the overlapping HBV surface antigen (HBsAg). We have recently shown that for HBV genotype D, the rtA181T/sW172stop substitution conferring resistance to adefovir dipivoxil (ADV) alters secretion of HBsAg and exerts a dominant-negative effect on wild-type virion secretion. However, the effect of this and other ADV-resistance-associated mutations on HBV replication and HBsAg secretion for the HBV genotype C, the genotype with the most severe clinical prognosis, is unknown.

METHODS/RESULTS

We constructed 1.2-mer infectious cDNA clones of HBV genotype C encoding mutations associated with ADV resistance and established an in vitro replication assay in Huh7 cells. Decreased levels of HBV DNA and HBsAg were detected for all ADV variants relative to the 1.2-mer wild-type polymerase control plasmid. Importantly, less HBsAg was detected in the cells transfected with the rtA181T resistance mutants, and the overlapping sW172stop mutation ablated secretion of HBsAg into cell culture supernatants.

CONCLUSIONS

The identification of secretion-defective HBV in the setting of ADV therapy for HBV genotype C, and to a lesser extent HBV genotype B, has major implications for the diagnosis and treatment of HBV in the Asia-Pacific region, as it is likely that quantitative HBsAg and viral load testing of serum from patients infected with HBV encoding rtA181T and rtN236T substitutions may not accurately reflect the level of replication within hepatocytes.