Expression Of Hepatitis B Core Antigen Research Articles

ENPP1 inhibits the transcription activity of the hepatitis B virus pregenomic promoter by upregulating the acetylation of LMNB1.

Current therapies for hepatitis B virus (HBV) infection can slow disease progression but cannot cure the infection, as it is difficult to eliminate or permanently silence HBV covalently closed circular DNA (cccDNA). The interaction between host factors and cccDNA is essential for their formation, stability, and transcriptional activity. Here, we focused on the regulatory role of the host factor ENPP1 and its interacting transcription factor LMNB1 in HBV replication and transcription to better understand the network of host factors that regulate HBV, which may facilitate the development of new antiviral drugs. Overexpression of ectonucleotide pyrophosphatase/phosphodiesterase 1(ENPP1) in Huh7 cells decreased HBV pregenomic RNA (pgRNA) and hepatitis B core antigen (HBcAg) expression levels, whereas knockdown of ENPP1 increased them. A series of HBV promoter and mutant plasmids were constructed, and a luciferase reporter assay showed that overexpression of ENPP1 caused inhibition of the HBV promoter and its mutants. A DNA pull-down assay showed that lamin B1 (LMNB1), but not ENPP1, interacts directly with the HBV enhancer II/basic core promoter(EnhII/BCP). ZDOCK and PyMOL software were used to predict the interaction of ENPP1 with LMNB1. Overexpression of LMNB1 inhibited the activity of the HBV promoter and its mutant. The acetylation levels at the amino acids 111K, 261K, and 483K of LMNB1 were reduced compared to the control, and an LMNB1 acetylation mutant containing 111R, 261Q, 261R, 483Q, and 483R showed increased promoter activity. In summary, ENPP1 together with LMNB1 increased the acetylation level at 111K and 261K, and LMNB1 inhibited the activity of HBV promoter and downregulated the expression of pregenomic RNA and HBcAg. Our follow-up studies will investigate the expression, clinical significance, and relevance of ENPP1 and LMNB1 in HBV patient tissues, explore the effect of LMNB1 on post-transcriptional progression, and examine whether ENPP1 can reduce cccDNA levels in the nucleus.

Expression and purification of Hepatitis B virus core antigen using Escherichia coli and its utilization for the diagnosis of Hepatitis B virus infections

Hepatitis B virus (HBV) is responsible for most of the viral hepatitis worldwide. HBV is a partially double stranded DNA virus that is composed of four main open reading frames (ORFs) encoding its important antigens, namely hepatitis B surface antigen (HBsAg), hepatitis B core antigen (HBcAg), HBV polymerase and hepatitis B X antigen (HBxAg). In this study, we report a successful method for the cloning and expression of HBcAg. The ORF of HBcAg was successfully amplified using polymerase chain reaction (PCR), cloned into the expression vector pRSET-B and transformed to Escherichia coli (E. coli) BL-21 (DE3) pLysS strain for protein expression. Successful expression of HBcAg was accomplished, in which an induced protein with a molecular weight of 24 kDa was obtained and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The produced HBcAg was successfully used for the diagnosis of HBV infected patient through detection of antibodies against HBcAg (anti-HBcAg) in the serum of the patient utilizing Western blotting. Overall, this study provides a simple, convenient and efficient protocol for the production of HBcAg that can be used as an important candidate to study the diagnosis and prognosis of HBV disease, as well as for understanding the epidemiological prevalence of HBV cases and production of anti-HBcAg.

Multiple optimizations of recombinant plasmid for improving expression of Hepatitis B core antigen in Escherichia coli

Hepatitis B core antigen (HBcAg) can self-assemble into virus-like particles (VLPs) when expressed in Escherichia coli. We optimized the different of the expression plasmid pBV220, including the ribosome bind site (RBS), spacer region, promoter and replication origin (ori), as well as the hbc gene dosage, to enhance HBcAg transcription and translation in E. coli. The optimized construct with a customized RBS6, 6 nt spacer, T7 promoter and pUCori significantly increased the levels of HBc36GFP fusion protein to 3.4-folds compared to the control. Thereafter, we substituted hbc36gfp gene with different copies of the hbc gene and tested the effects of gene dosage on HBcAg expression. The HBcAg-VLPs yield obtained using an engineered strain with three copies of hbc was 842.1 ± 46.8 μg/mL, which was 2.2-folds higher compared to that in the control strain. Thus, our study provides a simple and effective strategy for improving HBcAg expression in E. coli. Since the HBcAg-VLPs are promising carriers for presenting foreign antigen epitopes, an in vitro expression system that can generate high levels of HBcAg-VLPs can serve as a promising tool for developing novel HBV vaccines and drugs.

Impact of Hepatic Steatosis on the Antiviral Effects of PEG-IFNα-2a in Patients with Chronic Hepatitis B and the Associated Mechanism.

Objective To investigate the risk factors for hepatic steatosis in chronic hepatitis B (CHB), to determine its correlation with liver necroinflammation and fibrosis and response to peginterferon alpha-2a (PEG-IFNα-2a) antiviral therapy, and to explore the mechanisms underlying the poor antiviral effect of PEG-IFNα-2a in CHB patients with hepatic steatosis. Methods We analysed the impact of hepatic steatosis on the antiviral effect of PEG-IFNα-2a on CHB patients in a cohort of 226 patients who underwent pretherapeutic liver biopsy. To assess the complete response (CR), virological response (VR), and biochemical response (BR), the 226 patients were treated with PEG-IFNα-2a for 48 weeks and were followed-up for 24 weeks. The expressions of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) in the liver tissue were detected in all patients to explore the possible mechanism of hepatic steatosis with regard to antiviral effects. Results The patients were divided into four groups based on the severity of hepatic steatosis: 119 with no steatosis, 76 with mild steatosis, 22 with moderate steatosis, and 9 with severe steatosis. In the hepatic steatosis groups, the proportions of male patients, patients aged >40 years, patients with hyperuricaemia, patients with a BMI > 23 kg/m2, and total cholesterol (TC), triglyceride (TG), glucose (GLU), and uric acid (UA) levels were significantly higher than those in the group without steatosis, whereas the alanine aminotransferase (ALT) and aspartate transaminase (AST) levels were significantly lower than those in the group without steatosis. The multivariate analysis results indicated that a BMI > 23 kg/m2 was independently associated with CHB patients with hepatic steatosis; the levels of baseline AST and UA were independently associated with CHB patients with significant hepatic steatosis, and the baseline AST level was independently associated with significant liver fibrosis. After 48 weeks of treatment and 24 weeks of follow-up, the rates of CR, VR, and BR had gradually decreased, whereas the severity of hepatic steatosis had increased. Conclusion Hepatic steatosis can reduce the efficacy of PEG-IFNα-2a in the treatment of CHB patients, and its mechanism may be related to the different HBcAg expression patterns in liver tissue.

HBcAg produced in transgenic tobacco triggers Th1 and Th2 response when intramuscularly delivered.

Hepatitis B core Antigen (HBcAg) assembled into Capsid-Like Particles (CLPs) is investigated as a therapeutic vaccine in treatment of chronic hepatitis B (CHB) and in diagnostic tests or as a carrier for various epitopes. While the expression of HBcAg has been thoroughly clarified in E. coli and yeast, it has also been investigated in other expression systems. Stably transformed tobacco expressed HBcAg at a level of 110-250µg/g fresh weight, therefore in view of its large leaf biomass it offers a production platform comparable with transient expression systems regarding the final yield of HBcAg. Several extraction and purification methods were tested and finally the antigen was purified up to 43% using sucrose density gradient centrifugation. The purified HBcAg retained its antigenicity, as confirmed by ELISA and western blot, while maintaining its CLP-structure as observed in TEM. In mice HBcAg intramuscularly delivered at 2×10µg triggered a significant response (serum anti-HBc titre around 150,000), being statistically equivalent to that induced by the reference antigen. Among anti-HBc IgG isotypes, IgG2a and then IgG1 were increasing during immune response. However IgG2b and IgG3 were also induced, especially in mice immunised with the plant-derived antigen. Analysis of the isotype profile indicates mainly Th1 polarisation, but completed with Th2 response. Obtained results indicate a considerable potential of plant-derived HBcAg as a therapeutic vaccine, since a mixed immune response with a stronger Th1 component is particularly required for treatment of CHB.

Expression of Hepatocyte Hepatitis B Core Antigen and Hepatitis B Surface Antigen as a Marker in the Management of Chronic Hepatitis B Patients.

Background/AimsWe aimed to clarify the association of hepatitis B surface antigen (HBsAg)/hepatitis B core antigen (HBcAg) with the disease status and treatment response in patients with chronic hepatitis B (CHB).MethodsWe investigated 171 biopsy-proven entecavir-treated CHB patients (109 hepatitis B e antigen [HBeAg]-positive, 62 HBeAg-negative). HBcAg expression was positive when ≥10% of hepatocytes stained, and classified into nuclear, mixed, and cytoplasmic patterns. HBsAg expressions were intracytoplasmic (diffuse, globular, and submembranous) and membranous. The histologic activity index (HAI) and fibrosis stage followed Ishak system.ResultsIn HBeAg-positive patients, older age, increased HAI score, advanced fibrosis, and reduced viral load were observed when HBcAg expression shifted from nucleus to cytoplasm in HBcAg-positive patients, and HBsAg expression from non-submembranous to submembranous in HBcAg-negative patients (all, p<0.05). In HBeAg-negative patients, only intracytoplasmic HBsAg expression patterns had clinical relevance with decreased ALT levels and viremia. In HBeAg-positive patients without favorable predictors of virologic response, negative HBcAg and membranous HB-sAg expression predicted greater virologic response (both, p<0.05). The probability of HBeAg seroclearance was higher in patients with increased HAI or lacking HBcAg expression (both, p<0.05). Higher serum HBsAg levels and hepatocyte HBcAg positivity were associated with reduced serum HBsAg during first and post-first year treatment, respectively (both, p<0.05).ConclusionsHepatocyte HBcAg/HBsAg expression is a good marker for disease status and predicting treatment response.

Hepatitis B Virus Core Antigen Stimulates IL-6 Expression via p38, ERK and NF-κB Pathways in Hepatocytes

Background: Hepatitis B virus (HBV) causes both acute and chronic liver injury. Viral proteins are involved in the pathological progress. Hepatitis B core antigen (HBcAg), a component of viral nucleocapsid, is not only essential for HBV lifecycle, but also exhibits strong immunogenicity. The cytoplasmic location of HBcAg in liver biopsy is associated with liver injury and inflammation, but the exact mechanisms remain to be elaborated. Methods: Huh7, SMMC-7721 and L-02 cells were transfected with pEGFP-N1-HBcAg to establish an intracellular HBcAg expression model. The mRNA and protein levels of Interleukin (IL)-6 were detected by qPCR and ELISA respectively. The signaling pathway-related proteins were investigated by western blot and immunofluorescence assay. Results: HBcAg increased the expression and secretion of IL-6 through activating extracellular signal-related kinase (ERK), p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB). These activations can be blocked by specific inhibitors of the three pathways. Conclusions: HBcAg actives p38, ERK1/2 and NF-κB to enhance the production of IL-6 in hepatocytes. This provides a molecular mechanism to explain the association of cytoplasmic HBcAg with severe liver injury and inflammation.

The efficacy of zinc finger antiviral protein against hepatitis B virus transcription and replication in tansgenic mouse model.

AimThe zinc finger antiviral protein (ZAP) is a mammalian host restriction factor, and it could inhibit HBV RNA synthesis in vitro experiments. However, the role of ZAP against HBV in vivo environment is unclear. This study aimed to investigate whether ZAP could act against HBV transcription and replication in ZAP tansgenic mouse model.MethodsHBV-replication-competent plasmid pHBV4.1 was transferred to ZAP transgenic ICR mouse via the tail vein using a hydrodynamic in vivo transfection procedure, and ICR mouse were used as controls. HBV RNA and HBV DNA replication intermediates in the liver were respectively analyzed by Northern blotting and Southern blotting. The expression of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) in the liver tissue was detected by immunohistochemical staining.ResultsAs compared to ICR control mouse, the levels of 3.5 kb mRNA in ZAP transgenic mouse were decreased by 8.4%; while the level of HBV DNA replication intermediates was decreased by 82%. In addition, the expression of HBsAg and HBcAg in ZAP transgenic mouse liver were both significantly less than that of ICR control mouse.ConclusionsOur findings suggest that ZAP could inhibit HBV replication in vivo in mice, which offers a new target for anti-HBV drug development.

S-phase arrest after vincristine treatment may promote hepatitis B virus replication.

To observe the effect of vincristine on hepatitis B virus (HBV) replication in vitro and to study its possible mechanisms. Vincristine was added to the cultures of two cell lines stably expressing HBV. Then, the levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antigen (HBcAg) in the supernatants or cytoplasm were examined using by enzyme-linked immunosorbent assay and Western blot. The HBV pregenome RNA (pgRNA) was detected using reverse transcription-PCR and real-time fluorescent quantitative PCR (RT-qPCR), and viral DNA was detected using Southern blot and RT-qPCR. Cell proliferation after drug treatment was detected using the BrdU incorporation test and the trypan blue exclusion assay. Cell cycle and cell apoptosis were examined using flow cytometry and Western blot. Vincristine up-regulated HBV replication directly in vitro in a dose-dependent manner, and 24-h exposure to 0.1 μmol/L vincristine induced more than 4-fold and 3-fold increases in intracellular HBV DNA and the secretion of viral DNA, respectively. The expression of HBV pgRNA, intracellular HBsAg and HBcAg, and the secretion of HBeAg were also increased significantly after drug treatment. Most importantly, vincristine promoted the cell excretion of HBV nucleocapsids instead of HBV Dane particles, and the nucleocapsids are closely related to the HBV pathogenesis. Furthermore, vincristine inhibited the proliferation of cells stably expressing HBV. The higher the concentration of the drug, the more significant the inhibition of the cell proliferation and the stronger the HBV replication ability in cells. Flow cytometry indicated that cell cycle arrest at S-phase was responsible for the cell proliferation inhibition. Vincristine has a strong stimulatory effect on HBV replication and induces cell cycle arrest, and cell proliferation inhibition may be conducive to viral replication.

Role of immunohistochemistry for hepatitis D and hepatitis B virus in hepatitis delta

Immunohistochemical assessment of liver tissue in chronic delta hepatitis (CDH) is underinvestigated. Aim of the study was (i) to assess variables associated with hepatitis D antigen (HDAg), hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) staining in the liver. Demographic, biochemical and virologic data collected from the HIDIT 1 study were used. HBsAg, HBcAg and HDAg immunohistochemical (IHC) staining was semiquantitatively assessed. Hepatitis D antigen immunohistochemical staining displayed positive correlations with age and alanine aminotransferase (ALT) and negative correlations with serum HBsAg (P = 0.01 for all). HBsAg IHC displayed a negative correlation with gamma glutamyl transferase and positive correlations with serum HBV DNA, serum HBsAg levels and HBeAg serology (P < 0.001, P = 0.02 and P = 0.007 respectively). HBcAg staining was mainly nuclear and displayed negative correlations with serum HBsAg and histologic activity (P = 0.002 and P = 0.02 respectively). Pegylated IFN based treatment led to a decline of all IHC markers, however, these markers had no impact on treatment outcome. These data suggest an association of liver injury with HDAg expression in CDH whereas the negative correlation between HBcAg expression and liver injury and the overall nuclear localization of HBcAg suggest that HBcAg does not contribute to liver injury in CDH. HDV cases with high level of HBV replication, high serum HBsAg levels, HBeAg positivity, that are probably in the earlier stages of disease (low gamma-glutamyl transferase), had a more intense HBsAg staining profile. Overall, the data enforce the importance of HDAg and HBsAg in different phases of CDH infection.

High HBcAg Expression in Hepatocytes of Chronic Hepatitis B Patients in Bangladesh

The present study evaluates the intracellular expression of the hepatitis B Virus (HBV) core antigen in chronic hepatitis B (CHB) patients from Bangladesh in relation with serological, virological and histological variables. A cross-sectional study was carried out among 70 patients incidentally diagnosed as HBV chronic carriers who have undergone liver biopsy. Indirect immunofluorescence technique was used to study the intracellular expression of hepatitis B core antigen (HBcAg). The grade and cellular distribution were semiquantitatively scored according to the percentage of stained cells and their nuclear, cytoplasmic or mixed expression pattern respectively. A higher HBcAg grade was related to higher viral load, alanine aminotransferase levels and histological damage. Higher HBV DNA counts and HBcAg grade were found in hepatitis B e antigen (HBeAg)-positive patients. Abbreviations: HBV: Hepatitis B virus; CHB: Chronic hepatitis B; HBcAg: Hepatitis B core antigen; HBeAg; Hepatitis B e antigen.

The Relationship between Intrahepatic Distribution of Hepatitis B Virus Core Antigen and Serum ALT, HBV DNA Levels and HBeAg Status

Abstract Objective The clinical significance of differential distribution of hepatitis B virus (HBV) nucleocapsid antigen in hepatocytes remains unknown. The goal of this study is to determine the relationship between distinct HBV core antigen distribution pattern and alanine transaminase (ALT), liver histological inflammatory activity grades, serum HBeAg status and HBV DNA level.Methods Total of 958 cases with chronic hepatitis B were recruited into this study. Liver function tests, serum HBV DNA level, serological HBV markers and liver immunohistochemistry were examined according to the conventional instructions. Chi Square tests were performed to analyze the differences among these groups.Results It was found that 552 (58%) cases were tested positive for HBV core antigen by immunohistochemical staining. Cytoplasmic hepatitis B core antigen (HBcAg) expression correlated with ALT level and serum HBV DNA and liver inflammatory activity scores, however, nuclear HBcAg expression in hepatocytes was associated with normal ALT level, lower liver inflammatory activity score and higher serum HBV DNA level and rate of HBeAg positivity. Both nuclear and cytoplasmic HBcAg expression in hepatocytes associated with a middle ALT level and liver inflammatory activity score, higher rate of serum detectable HBeAg and a higher HBV DNA level. However, undetectable core antigen was related to a lower ALT level and histological inflammatory activity grade, lower positive HBeAg rate and HBV DNA level.Conclusions Undetectable liver HBcAg is associated with HBV clearance, ALT normalization and hepatitis B e antigen (HBeAg) seroconversion, and cytoplasmic HBcAg expression associated with higher hepatic inflammatory activity. However, nuclear HBcAg expression correlates with immune tolerance characterized with normal ALT and lower liver inflammatory activity, higher HBV replication level and higher rate of HBeAg positivity.

HBcAg18–27 epitope fused to HIV-Tat 49–57 adjuvanted with CpG ODN induces immunotherapeutic effects in transgenic mice

Successful immunotherapy of chronic hepatitis B virus (HBV) infection is expected to be characterized by enhanced activation of immune responses. Combining the specificity of hepatitis B core antigen (HBcAg) cytotoxic T lymphocyte (CTL) epitope, the cell-penetrating property of human immunodeficiency virus-1 (HIV)-Tat peptide, and the adjuvanticity of CpG oligodeoxynucleotides (CpG ODNs) may elicit strong immune responses and therapeutic effects in HBV infection. We synthesized a fusion peptide containing HBcAg18–27 CTL epitope and HIV-Tat 49–57 peptide. The fusion peptide was intramuscularly injected to HBV transgenic mice with CpG ODN as adjuvant at 2-week intervals three times. The percentages of CD3 +, CD4 + and CD8 + cells in spleen lymphocytes and the levels of circulating interferon (IFN)-γ and interleukin (IL)-2 were determined for the evaluation of immune responses and the levels of serum HBV DNA and the expression of hepatitis B surface antigen (HBsAg) and HBcAg in liver tissue were determined for the assessment of therapeutic effects. Our results showed that the synthesized fusion peptide adjuvanted with CpG ODN could induce significant increase of the percentages of CD3 +, CD4 + and CD8 + cells and the levels of IFN-γ and IL-2, indicating the strong immune responses, and reduced HBV DNA levels and decreased expression of HBsAg and HBcAg in liver tissue, suggesting the therapeutic effects. Collectively, our study supports that HBcAg18–27 CTL epitope fused to HIV-Tat 49–57 peptide adjuvanted with CpG ODN may be a promising strategy for immunotherapy of chronic HBV infection.

Hepatitis B Virus Basal Core Promoter Mutation and DNA Load Correlate with Expression of Hepatitis B Core Antigen in Patients with Chronic Hepatitis B

Expression of intrahepatic hepatitis B core antigen (HBcAg) is related to the immunopathogenesis of hepatitis B virus (HBV) infection. This study investigated the role that HBV genotype and basal core promoter (BCP) mutation play in the expression of HBcAg. A total of 70 hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis (genotype B in 52 patients and genotype C in 18 patients; BCP mutation T1762/A1764 in 16 patients) were enrolled. Clinical, virologic, and histologic features were compared with regard to localization and expression of intrahepatic HBcAg. The effects that HBV genotype and BCP mutation T1762/A1764 had on expression of HBcAg were further evaluated by in vitro assays. Cytoplasmic, mixed cytoplasmic/nuclear, and nuclear localization of intrahepatic HBcAg was found in 38 (56.7%), 25 (37.3%), and 4 (6.0%) patients, respectively; HBcAg was not discernible in 3 patients. A total of 58 (82.9%) of these patients expressed a high level of HBcAg. In multivariate analysis, cytoplasmic localization of HBcAg correlated only with a low HBV load in serum (P = .045) and BCP mutation (P = .04). A high expression level of HBcAg also correlated with a high HBV load in serum (P = .015) and with BCP wild-type sequence (P = .037). In vitro assays indicated that the HBV BCP mutant strain had lower subcellular expression of HBcAg than did the BCP wild-type strain. HBV BCP mutation and HBV load, but not genotype, contribute to the expression of intrahepatic HBcAg.

Hepatitis B core antigen expression pattern predicts response to lamivudine therapy in patients with chronic hepatitis B

Negative hepatitis B core antigen (HBcAg) staining in hepatocytes is indicative of viral replication by an active immune response. HBcAg is expressed mainly in the cytoplasm in patients with active hepatitis and hepatocyte regeneration, and mainly in the nuclei of hepatocytes in patients with minimal liver injury in the absence of hepatocyte regeneration. The aim of this study was to elucidate whether the existence and expression pattern of HBcAg predicts the response to antiviral treatment. The study involved 58 patients with biopsy-proven chronic hepatitis B who were treated with lamivudine. Hepatitis B e antigen (HBeAg), antibody to HBeAg, hepatitis B virus DNA, and alanine aminotransferase in serum were recorded every 3 months. The inflammation grade and the fibrosis stage of chronic hepatitis were scored from 0 to 4 according to lobular inflammation, portal inflammation, periportal inflammation, and fibrosis. The 58 patients included 49(84%) HBcAg-positive patients, with HBcAg staining confined to the cytoplasm in 15(31%) and in both cytoplasm and nuclei in 34(69%). The grade of lobular inflammation and the total histology score were significantly higher in patients with cytoplasmic expression of HBcAg than in HBcAg-negative patients (lobular inflammation: 2.9 vs 2.1, P=0.02; total histology score: 12.2 vs 10.3, P=0.04). The virologic responses at 3, 6, 9, and 12 months differed significantly between the cytoplasmic and mixed expression groups (P<0.01). The expression pattern of HBcAg (including its possible absence) before initial therapy appears to predict the response to antiviral treatment.

Correlation of hepatitis B core antigen and β‐catenin expression on hepatocytes in chronic hepatitis B virus infection: Relevance to the severity of liver damage and viral replication

The topographical distribution of hepatitis B core antigen (HBcAg) is related to the pathogenesis of liver damage caused by hepatitis B virus (HBV) infection. beta-catenin plays an important role in both intracellular adhesion and Wnt signaling transduction pathways. This study investigated the intrahepatic expression of HBcAg and beta-catenin in chronic HBV infection, and correlated the results with the degree of liver damage and viral replication. Liver sections from 73 patients with chronic HBV infection were examined immunohistochemically for HBcAg and beta-catenin. The distribution of HBcAg could be classified into four types: only nucleus (C-1), both nucleus and cytoplasm (C-2), only cytoplasm (C-3) and all negative for nucleus and cytoplasm (C-4). Significant differences in serum aminotransferase level, HBV DNA and necroinflammatory score were observed among the different distribution types, and as the distribution of HBcAg changed from C-1 to C-4, fibrosis stage and hepatitis B e antigen (HBeAg) negative/anti-HBe positive rate increased concurrently. The distribution of beta-catenin could be classified into two types: only membrane (B-1) and membrane with nucleus or cytoplasm (B-2). B-2 showed higher serum aminotransferase level and necroinflammatory score than B-1. Between B-1 and B-2, there was no significant difference in serum HBV DNA level or fibrosis stage. In chronic HBV infection, HBcAg distribution may change from C-1 to C-4 gradually, and in correlation with serum aminotransferase, and HBV DNA and HBeAg negative/anti-HBe positive rate. Nuclear or cytoplasmic distribution of beta-catenin, compared with exclusive membranous distribution of beta-catenin, is related to active hepatitis, but not viral replication.

Unrevealing the natural course of the so-called “inactive HBsAg or HBV carrier state”

When hepatitis B surface antigen (HBsAg), originallynamed ‘‘Australia antigen,’’ was discovered in the 1960s[1, 2], its link with viral hepatitis could not be recognizedfor some time, since most individuals carrying this antigenhad little if any evidence of underlying hepatitis. Then,following the identification of its association with viralhepatitis in 1967 and 1968 [3, 4], the glossary was modifiedfrom Australia antigen to Hepatitis Associated, SerumHepatitis, Hepatitis B antigen, and finally to HBsAg.However, regardless of the terms used, all evidence gath-ered over the years has clearly supported the view thatmany HBsAg-positive individuals harbor normal or nearlynormal liver enzymes (alanine/aspartate aminotrasferase,ALT/AST) and have little if any liver damage [5–8].Therefore the terms ‘‘healthy,’’ ‘‘asymptomatic,’’ and‘‘inactive’’ carriers of HBsAg, or of hepatitis B virus(HBV) have been introduced, to distinguish such individ-uals from patients with chronic viral hepatitis B. In supportof this concept were also the findings of serological testingfor hepatitis B e antigen (HBeAg) and its correspondingantibody (anti-HBe) by sensitive radioimmunossay (RIA)methods [9] and the immunohistochemical observations onthe expression of HBV proteins in the liver. Thus, serumHBeAg and liver hepatitis B core antigen (HBcAg), twomarkers of HBV replication, were reported to be negativein these carriers [10] while liver histology was essentiallynormal but with numerous ‘‘ground-glass’’ hepatocytesexpressing abundant hepatitis B surface proteins [11–13]from viral sequences integrated into their genome [12];however, HBcAg expression was clearly negative [14, 15].The wide acceptance of the view that HBsAg-positivepersons who are HBeAg-negative and anti-HBe positivehave inactive HBV infection without associated liver dis-ease dominated worldwide for many years and subse-quently led to doubts on whether HBeAg-negative chronichepatitis B (CHB) described from the early 1980s [16] wasreally existent or not and if it could actually be attributed toHBV replication. Moreover, in clinical practice HBsAg-positive individuals, labeled as healthy or inactive ‘‘carri-ers,’’ attracted little interest and only few investigatorsworldwide took their time to follow-up such carriers pro-spectively. However, with the introduction in clinical re-search of molecular hybridization and polymerase chainreaction (PCR) techniques, HBV cloning and sequencing,and the discovery of replication-competent HBeAg-nega-tive HBV mutants [17], it was soon realized that HBeAg-negativity/anti-HBe-positivity with normal ALT levels isneither synonymous with absence of HBV replication andof HBV-induced liver damage nor it represents a perma-nent, life-lasting condition. Thus the term ‘‘inactiveHBsAg carrier state’’ rather than ‘‘inactive HBV carrier’’has been widely applied and is still recommended in recenthepatitis B guidelines [18–20].Currently, it is generally perceived that the inactiveHBsAg carrier state represents the third phase in the naturalcourse of chronic HBV infection. It follows a previous,immunologically active, phase of HBeAg-positivity withreplicating HBV and increased ALT activity, during whichHBeAg clears and anti-HBe develops [21, 22]. This phasemay remain stably inactive and even finish in resolution ofHBV infection with clearance of HBsAg and development

Hepatitis B core antigen expression pattern reflects the response to anti‐viral treatment

In hepatitis B early antigen (HBeAg)-negative patients, response predictors to current treatment regimens are not well known. Hepatocyte cell cycle may influence hepatitis B virus (HBV) replication and hepatitis B core antigen (HBcAg) expression, which is a major target for antiviral immune response. The aim of the present paper was to evaluate the role of HBcAg expression in liver tissue and the rate of hepatocyte proliferation in response to antiviral treatment in chronic hepatitis B. A total of 33 chronic hepatitis B patients (nine HBeAg positive, 24 HBeAg negative) treated with either lamivudine and interferon combined or lamivudine alone were included. Liver expressions of proliferating cell nuclear antigen (PCNA) and HBcAg were immunohistochemically determined. The HBV-DNA levels were measured by a hybrid capture assay. Complete response was defined as alanine aminotransferase (ALT) normalization and HBV-DNA negativity. At the end of treatment, 23 patients (67.7%) were responders (12 of 23 were sustained responders), while 10 (33.3%) were non-responders. Age, sex, ALT, HBV-DNA levels, HBeAg status, histological activity, fibrosis scores and PCNA labeling index were similar in responders versus non-responders at baseline. The number of patients with positive HBcAg staining was lower in responders compared to non-responders at the end of treatment (17.4% vs 80%, respectively, P < 0.001), although a similar number of sustained responders and non-responders had positive HBcAg staining. Absence or a low level of HBcAg expression may predict the end of treatment response to current therapies, especially in HBeAg (-) patients. The PCNA determination does not predict treatment response.

The effects of hepatitis B virus core promoter mutations on hepatitis B core antigen distribution in hepatocytes as detected by laser-assisted microdissection

Background/Aims: The severity of liver damage in patients with chronic hepatitis B is dependent on several factors such as subcellular localization of hepatitis B core antigen (HBcAg) and mutation of hepatitis B virus (HBV) DNA. Here we studied the interrelationship between these two factors both in situ and in vitro. Methods: Hepatocytes from liver biopsies showing expression of HBcAg only in the cytoplasm ( n=6), only in the nucleus ( n=4) and in both cytoplasms or nucleus of different hepatocytes ( n=5) were picked up by laser-assisted microdissection and were checked for nucleotide sequences of core promoter region of HBV DNA. HepG2 and Huh7 cell lines transfected with wild and mutant HBV DNA were checked for localization of HBcAg. Results: The frequencies of core promoter mutations at nucleotide (nt) 1762 and nt 1764 was significantly higher in hepatocytes with cytoplasmic expression of HBcAg compared to that of nuclear expression of HBcAg ( P<0.05). Cytoplasmic expression of HBcAg was observed more frequently in HepG2 and Huh7 cells transfected with HBV mutant type (nt 1762 and 1764) than HBV wild type ( P<0.05). Conclusions: Cytoplasmic localization of HBcAg was associated with HBV DNA mutations at nt 1762 and 1764.

The degrees of hepatocyte nuclear but not cytoplasmic expression of hepatitis B core antigen reflect the level of viral replication in chronic hepatitis B virus infection.

Although immunodetection of hepatitis B core antigen (HBcAg) in the liver has long been recognized as a marker of active hepatitis B virus (HBV) replication, the correlation between the level of viral replication and the degrees of expression of HBcAg in hepatocytes remains to be established. In this study, we examined the semiquantitative relationship between the level of HBV DNA in serum and the degree of expression of HBcAg in the hepatocyte nucleus or cytoplasm in 80 adults with chronic hepatitis B. Expression of HBcAg in hepatocytes was studied by the avidin-biotin immunoperoxidase method, and the results were scored on a scale of 0 to 4, values corresponding to the positivity of 0, 1 to 10, 11 to 25, 26 to 50, and > 50%, respectively, of hepatocytes examined. Serum HBV DNA was tested by a liquid hybridization assay, and the results were scored on a scale of 0 to 5, values corresponding to undetectable levels and levels of < or = 50, 51 to 100, 101 to 150, 151 to 200, and > 200 pg/ml, respectively. The results revealed a highly significant, positive correlation between the level of HBV DNA in serum and the degree of expression of HBcAg in nuclei (Spearman rank correlation coefficient [rs] = 0.653, P < 0.001). The mean scores (95% confidence intervals) of levels of HBV DNA in sera of patients whose levels of expression of HBcAg in nuclei received a score of 0 (n = 33), 1 or 2 (n = 35), and 3 or 4 (n = 12) were 1.3 (1.1 to 1.5), 2.5 (2.1 to 2.9), and 3.9 (3.1 to 4.7), respectively. However, no correlation between the level of HBV DNA in serum and the degree of expression of HBcAg in the cytoplasm was noted (rs = 0.026, P > 0.8). In conclusion, the degree of expression of HBcAg in the hepatocyte nucleus but not the cytoplasm can accurately reflect the level of viral replication in patients with chronic hepatitis B.