Analysis of hepatitis B surface antigen (HBsAg) using high‐sensitivity HBsAg assays in hepatitis B virus carriers in whom HBsAg seroclearance was confirmed by conventional assays

Aim

We investigated the utility of high‐sensitivity hepatitis B surface antigen (HBsAg) assays compared with conventional HBsAg assays.

Methods

Using serum samples from 114 hepatitis B virus (HBV) carriers in whom HBsAg seroclearance was confirmed by conventional HBsAg assays (cut‐off value, 0.05 IU/mL), the amount of HBsAg was re‐examined by high‐sensitivity HBsAg assays (cut‐off value, 0.005 IU/mL). Cases negative for HBsAg in both assays were defined as consistent cases, and cases positive for HBsAg in the high‐sensitivity HBsAg assay only were defined as discrepant cases.

Results

There were 55 (48.2%) discrepant cases, and the range of HBsAg titers determined by high‐sensitivity HBsAg assays was 0.005–0.056 IU/mL. Multivariate analysis showed that the presence of nucleos(t)ide analog therapy, liver cirrhosis, and negative anti‐HBs contributed to the discrepancies between the two assays. Cumulative anti‐HBs positivity rates among discrepant cases were 12.7%, 17.2%, 38.8%, and 43.9% at baseline, 1 year, 3 years, and 5 years, respectively, whereas the corresponding rates among consistent cases were 50.8%, 56.0%, 61.7%, and 68.0%, respectively. Hepatitis B virus DNA negativity rates were 56.4% and 81.4% at baseline, 51.3% and 83.3% at 1 year, and 36.8% and 95.7% at 3 years, among discrepant and consistent cases, respectively. Hepatitis B surface antigen reversion was observed only in discrepant cases.

Conclusions

Re‐examination by high‐sensitivity HBsAg assays revealed that HBsAg was positive in approximately 50% of cases. Cumulative anti‐HBs seroconversion rates and HBV‐DNA seroclearance rates were lower in these cases, suggesting a population at risk for HBsAg reversion.     

Novel hepatitis B virus surface antigen mutations associated with occult genotype B hepatitis B virus infection affect HBsAg detection

The causative factors of occult hepatitis B infection are complicated and not yet been fully elucidated. Mutations in hepatitis B virus (HBV) S gene are one of the factors may contributing to occult infection. In this study, 89 blood donors with genotype B occult HBV infection were investigated. Fifty‐seven hepatitis B surface antigen (HBsAg)‐positive/HBV DNA‐positive blood donors served as control group for comparison. Occult HBV‐related mutations with a high incidence (P < .05) in the S gene were identified. To further verify these occult infection‐related mutations, a conservative full‐gene expression vector of HBV B genotype (pHBV1.3B) was constructed. Then, the mutant plasmids on the basis of pHBV1.3B were constructed and transfected into HepG2 cells. Extracellular as well as intracellular HBsAg was analysed by electrochemical luminescence and cellular immunohistochemistry. Ten occult infection‐related mutations (E2G, Q101R, K122R, M133T, D144E, G145R, V168A, S174N, L175S and I226S) were significantly more frequent in the occult infection group (P < .05). Five of the ten mutations (E2G, D144E, G145R, V168A and S174N) strongly decreased extracellular HBsAg level (P < .05) in the transfection system. Notably, the E2G mutation had the most significant impact on the ratio of extracellular HBsAg (3.8% vs pHBV1.3B) and intracellular HBsAg (239.3% vs pHBV1.3B) (P < .05), and the fluorescence density of E2G mutant HBsAg was significantly higher than that of pHBV1.3B (P < .0001). Hence, ten mutations were associated with genotype B occult HBV infection; E2G and V168A were novel mutations which we confirmed significantly affect HBsAg detection. E2G might cause HBsAg secretion impairment that results in intracellular accumulation and a decrease in HBsAg secretion.     

Changes in levels of hepatitis B virus markers in patients positive for low-titer hepatitis B surface antigen

Aim: Recently, patients positive for the low-titer hepatitis B surface antigen (HBsAg) have been found occasionally owing to the increase in the accuracy of detection methods. The aim of this study is to clarify the clinical status of acute hepatitis B virus (HBV) infection in patients positive for low-titer HBsAg. Method: Eight patients, who were positive for HBsAg at low titers and diagnosed as having acute HBV infection, were enrolled in this study. Assays of HBsAg, hepatitis B core antibody (anti-HBc), hepatitis B e-antigen (HBeAg), hepatitis B e-antibody (anti-HBe), hepatitis B surface antibody (anti-HBs) and HBV DNA, and biochemical tests were basically conducted every 4 weeks for at least 24 weeks. Result: The average cut-off index of HBsAg was 8.7 ± 9.6 (range, 1.0–25.7). All the patients were negative for anti-HBc, HBeAg, anti-HBe and HBV DNA on their initial visit. The genotype of HBV could be determined in four patients: two were infected with genotype B/HBV, one was infected with genotype A/HBV, and the remaining patient was infected with genotype C/HBV. Although HBsAg clearance was observed within 4 months in all the patients, none of the other HBV markers seroconverted during the observation period. Conclusion: HBV infection terminating with seronegativity for HBV markers may occur in transient HBV infection.     

Prevalence and clinical features of patients with concurrent HBsAg and anti‐HBs: Evaluation of the hepatitis B research network cohort

The prevalence of concurrent HBsAg and anti‐HBs in plasma of persons with chronic hepatitis B virus (HBV) infection is variable and its clinical significance enigmatic. We examined the prevalence and clinical and virological features of concurrent HBsAg and anti‐HBs in children and adults with chronic HBV infection living in North America. A total of 1462 HBsAg positive participants in the Hepatitis B Research Network paediatric and adult cohorts were included (median age 41 (range 4‐80) years, 48% female, 11% white, 13% black, 73% Asians). Only 18 (1.2%) were found to be anti‐HBs positive (≥10 mIU/mL) at initial study evaluation. Distributions of sex, race, HBV genotype and ALT were similar between participants with and without concurrent anti‐HBs. Those who were anti‐HBs positive appeared to be older (median age 50 vs 41 years, P = .06), have lower platelet counts (median 197 vs 222 × 103/mm³, P = .07) and have higher prevalence of HBeAg (44% vs 26%, P = .10). They also had lower HBsAg levels (median 2.0 vs 3.5 log₁₀ IU/mL, P = .02). Testing of follow‐up samples after a median of 4 years (range 1‐6) in 12 of the 18 participants with initial concurrent anti‐HBs showed anti‐HBs became undetectable in 6, decreased to <10 mIU/mL in 1 and remained positive in 5 participants. Two patients lost HBsAg during follow‐up. In conclusion, prevalence of concurrent HBsAg and anti‐HBs was low at 1.2%, with anti‐HBs disappearing in some during follow‐up, in this large cohort of racially diverse children and adults with chronic HBV infection living in North America. Presence of concurrent HBsAg and anti‐HBs did not identify a specific phenotype of chronic hepatitis B, nor did it appear to affect clinical outcomes.     

Clinical and virological factors associated with hepatitis B virus reactivation in HBsAg‐negative and anti‐HBc antibodies‐positive patients undergoing chemotherapy and/or autologous stem cell transplantation for cancer

Summary. We studied clinical outcome and clinico‐virological factors associated with hepatitis B virus reactivation (HBV‐R) following cancer treatment in hepatitis B virus surface antigen (HBsAg)‐negative/anti‐hepatitis B core antibodies (anti‐HBcAb)‐positive patients. Between 11/2003 and 12/2005, HBV‐R occurred in 7/84 HBsAg‐negative/anti‐HBcAb‐positive patients treated for haematological or solid cancer. Virological factors including HBV genotype, core promoter, precore, and HBsAg genotypic and amino acid (aa) patterns were studied. Patients presenting with reactivation were men, had an hepatitis B virus surface antibody (HBsAb) titre <100 IU/L and underwent >1 line of chemotherapy (CT) significantly more frequently than controls. All were treated for haematological cancer, 3/7 received haematopoietic stem cell transplantation (HSCT), and 4/7 received rituximab. Using multivariate analysis, receiving >1 line of CT was an independent risk factor for HBV‐R. Fatal outcome occurred in 3/7 patients (despite lamivudine therapy in two), whereas 2/4 survivors had an HBsAg seroconversion. HBV‐R involved non‐A HBV genotypes and core promoter and/or precore HBV mutants in all cases. Mutations known to impair HBsAg antigenicity were detected in HBV DNA from all seven patients. HBV DNA could be retrospectively detected in two patients prior cancer treatment and despite HBsAg negativity. HBV‐R is a concern in HBsAg‐negative/anti‐HBcAb‐positive patients undergoing cancer therapy, especially in males presenting with haematological cancer, a low anti‐HBsAb titre and more than one chemotherapeutic agent. HBV DNA testing is mandatory to improve diagnosis and management of HBV‐R in these patients. The role of specific therapies such as rituximab or HSCT as well as of HBV aa variability deserves further studies.     

Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody

AIMS: This study aims to examine the genomic variants of the 'a' epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). METHODS: Eighteen HBV carriers were studied. Hepatitis B virus (HBV) DNA was extracted and the 'a' epitope region was amplified and sequenced. RESULTS: Eighteen Chinese asymptomatic HBV carriers were studied. There were 13 patients who were positive for both HBsAg and anti-HBs. Of these, one patient had only wild-type HBV, three had a viral mixture, and five had only 'a' epitope variant HBV. Of the three patients with a viral mixture, all had variants in the less conserved region (123-137). Of the five patients with pure HBsAg mutants, three had variants in the less conserved region while two had variants in the highly conserved region. In this study with a limited number of patients, the serum alanine aminotransferase (ALT) levels were higher in patients with wild-type HBV, compared with those with either 'a' epitope variants or a viral mixture consisting of wild type and variants. CONCLUSION: Eight of the nine (89%) patients positive for both HBsAg and anti-HBs harbored an 'a' epitope variant. The lower ALT levels seen in patients who had either pure 'a' epitope variant or a mixture of wild type and mutants suggest that a closer monitoring of these 'a' epitope variants should be required, as patients carrying these infectious viral strains may remain asymptomatic.     

Hepatocyte hepatitis B surface antigen expression in chronic hepatitis B virus carriers in Singapore: Correlation with viral replication and liver pathology

The hepatocyte hepatitis B surface antigen (HBsAg) expression in 149 liver biopsies from 124 chronic hepatitis B virus (HBV) carriers was correlated with serum HBV DNA status and histologic activity. Hepatocyte HBsAg was stained by the peroxidase-antiperoxidase method and serum HBV DNA was determined by dot blot hybridization. Sixty-five biopsies (44%) showed minimal changes (MC), 82 biopsies (55%) showed chronic liver disease (CLD) and 2 biopsies (1%) showed hepatocellular carcinoma. Hepatocyte HBsAg was found in 144 biopsies (97%). It was present in the cytoplasm of 141 specimens (95%) and/or plasma membrane of 48 specimens (32%). Approximately half (45%) of the cytoplasmic HBsAg-positive biopsies showed discrete distribution, while the other half (55%) were grouped. Fifty-five per cent (77 of 141) of cytoplasmic HbsAg-positive biopsies had CLD, while 44% (62 of 141) showed MC. There was no relationship between the presence of cytoplasmic HBsAg or its topographic distribution with disease activity. Membrane HBsAg distribution was similar for both groups of patients (MC vs CLD: 25 of 65 (38%) vs 23 of 82 (28%); P = NS). Serum HBV DNA was detected in 98 patients (66%) and was seen mostly in association with CLD (CLD vs MC: 61% vs 39%, P less than 0.001). It was also detected more often in the sera of patients with membrane HBsAg than in those with cytoplasmic HBsAg staining (41 of 48 (85%) vs 97 of 141 (67%); P less than 0.02). However, discrete distribution of cytoplasmic HBsAg was associated with positive serum HBV DNA when compared with grouped distribution (52 of 63 (83%) vs 43 of 78 vs (55%); P less than 0.005).     

Efficacy and safety of an intravenous monoclonal anti‐HBs in chronic hepatitis B patients

Abstract: Background/Aims: In this study the safety and efficacy of a monoclonal anti‐HBs, Tuvirumab (Mab), were investigated. Tuvirumab is a human monoclonal antibody recognizing the stable ‘a’‐determinant of the HBsAg. Methods: We included ten chronic hepatitis B patients: four received monotherapy, and six combination therapy with interferon alpha 2b. Results: Because the development of insoluble [HBsAg–HBsAb] complexes led to adverse events, the Mab dose had to be reduced in seven patients. In nine patients treatment was stopped prematurely because of lack of efficacy, i.e. neutralization of HBsAg in serum. However, temporary HBsAg levels were reduced by at least 50% in all patients; in three patients receiving combination therapy, background levels of HBsAg in serum were reached. A loss of serum HBV‐DNA was seen in three patients in the combination group, followed by HBeAg seroconversion in two patients. Conclusions: We conclude that Mab was not effective in achieving primary efficacy as assessed by neutralization of circulating HBsAg. Whether a combination of Mab with an antiviral agent that reduces the HBsAg load – and therefore minimizes the risk of adverse events – may result in clinical efficacy should be investigated.     

HBsAg疫苗冲击树突状细胞联合乙肝免疫球蛋白对慢性乙型肝炎及HBV携带者的疗效

目的:观察HBsAg疫苗冲击的树突状细胞与乙肝免疫球蛋白联合应用对慢性乙型肝炎的疗效．方法:慢乙肝患者66例每月1次注射HBsAg疫苗(106／次)冲击的树突状细胞,乙肝免疫球蛋白200 U／次,6次为1疗程,共2疗程,治疗结束后检查肝功能,HBV DNA定量及乙肝标志．结果:HBeAg阳性慢乙肝27例治疗后有7例显示完全应答,14例显示部分应答．HBeAg阴性的慢乙肝15例中有4例出现完全应答,8例显示部分应答．慢性HBV携带者13例中5例显示完全应答,2例表现为部分应答．11例非活动性 HBsAg携带者中2例出现完全应答．结论:HBsAg疫苗冲击的树突状细胞与乙肝免疫球蛋白联合可试用于慢乙肝的治疗．     

Loss of HBsAg antigen during treatment with entecavir or lamivudine in nucleoside‐naïve HBeAg‐positive patients with chronic hepatitis B*

Summary. This retrospective analysis was conducted to describe the characteristics of nucleoside‐naïve hepatitis B e antigen (HBeAg)‐positive patients with chronic hepatitis B, who achieved hepatitis B surface antigen (HBsAg) loss during entecavir or lamivudine therapy. HBeAg‐positive adults with chronic hepatitis B, elevated serum alanine aminotransferase, and compensated liver disease were randomized to double‐blind treatment for up to 96 weeks with entecavir 0.5 mg/day or lamivudine 100 mg/day. HBsAg and hepatitis B virus (HBV) DNA were measured at regular intervals during and off‐treatment follow‐up. Through a maximum duration of 96 weeks on‐treatment and 24 weeks off‐treatment, HBsAg loss was confirmed in 18/354 (5.1%) patients treated with entecavir and 10/355 (2.8%) patients treated with lamivudine. Among the 28 patients with confirmed HBsAg loss, 27 (96%) achieved HBV DNA <300 copies/mL, and 27 (96%) achieved confirmed HBeAg loss. All entecavir recipients with HBsAg loss had HBV DNA <300 copies/mL. Caucasian patients, and those infected with HBV genotype A or D, were significantly more likely to lose HBsAg. This retrospective analysis of data from a randomized, global phase three trial shows that confirmed loss of HBsAg occurred in 5% of nucleoside‐naïve HBeAg‐positive patients treated with entecavir, and that HBsAg loss is associated with sustained off‐treatment suppression of HBV DNA.     

T‐ and B‐cell responses and previous exposure to hepatitis B virus in ‘anti‐HBc alone’ patients

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

Predictors of sustained functional cure in hepatitis B envelope antigen‐negative patients achieving hepatitis B surface antigen seroclearance with interferon‐alpha–based therapy

Hepatitis B surface antigen (HBsAg) loss is considered a functional cure in chronic hepatitis B (CHB). However, the durability of HBsAg loss after stopping treatment remains unknown. This study aimed to assess the sustained functional cure achieved by interferon therapy in hepatitis B envelope antigen (HBeAg)‐negative CHB patients. In this prospective study, 176 HBeAg‐negative CHB patients with functional cure were enrolled for 12 weeks of cessation treatment, and treatment information and baseline data were collected. Hepatitis B virus (HBV) biomarkers and clinical biochemical indicators were evaluated every 3 months; liver imaging examinations were performed every 3‐6 months during the 48‐week follow‐up. The sustained functional cure was evaluated. After the 48‐week follow‐up, the sustained functional cure rate was 86.63%. The cumulative rates of HBsAg reversion and HBV DNA reversion were 12.79% and 2.33%, respectively. Consolidation treatment ≥ 12 weeks after HBsAg loss achieved a significantly higher rate of sustained functional cure and significantly lower rate of HBsAg reversion than consolidation treatment < 12 weeks (76.19% vs 90.00%, P = 0.022 and 23.81% vs 9.23%, P = 0.014, respectively). Patients with hepatitis B surface antibody (HBsAb) had higher rate of sustained functional cure than patients achieving HBsAg loss but without HBsAb (89.86% vs 73.53%, P = 0.012). Consolidation treatment ≥ 12 weeks (odds ratio [OR] 16.478; 95% confidence interval [CI], 2.135‐127.151; P = 0.007) and high HBsAb levels (OR 8.312; 95% CI, 1.824‐37.881; P = 0.006) were independent predictors of sustained functional cure. Results suggested that 12 weeks of consolidation therapy after HBsAg clearance and elevated HBsAb levels help to improve functional cure.     

Hepatitis B virus precore mutants in HBeAg carriers with chronic hepatitis treated with interferon

Summary. Precore mutants of hepatitis B virus (HBV) were looked for in 18 hepatitis B e antigen (HBeAg) carriers who were treated with recombinant interferon-a (rIFN) and the results were compared with those obtained in 12 untreated carriers who underwent spontaneous HBeAb seroconversion. Molecular analysis of the HBV precore region was carried out by polymerase chain reaction (PCR) amplification and direct sequencing. Precore mutants with a stop codon at codon 28 were detectable at baseline in 19/30 carriers. However, wild-type strains predominated in the baseline sera of both treated ( n = 16) and untreated ( n = 10) patients. Sera from the remaining four patients contained predominantly or exclusively mutant virions. Following IFN treatment, there was a shift from the wild-type pattern to the mutant pattern in all patients, with the precore pattern prevailing in long-term responders (six out of nine) compared with the non-responders (none of nine). The wild-type pattern predominated among the non-responders (eight vs three), suggesting that the long-term response to IFN was associated with take-over of precore mutants. There were no relationships between any pre-treatment precore molecular pattern and disease severity or outcome of treatment. Precore mutants also took over in 10 of the 12 untreated patients (83%), who underwent spontaneous HBeAb seroconversion. Thus, a shift from wild-type to precore mutant pattern occurs in most Italian patients undergoing IFN-induced or spontaneous HBeAb seroconversion.     

Comparison between quantitative hepatitis B surface antigen,hepatitis B e‐antigen and hepatitis B virus DNA levels for predicting virological response to pegylated interferon‐α‐2b therapy in hepatitis B e‐antigen‐positive chronic hepatitis B

Aim: The aim of this study was to compare the clinical applicability of quantitative serum hepatitis B surface antigen (HBsAg), hepatitis B e‐antigen (HBeAg) and hepatitis B virus (HBV) DNA for predicting virological response (VR) to pegylated interferon (PEG‐IFN) therapy. Methods: Thirty HBeAg‐positive chronic hepatitis B patients who received PEG‐IFN‐α‐2b for 48 weeks were enrolled. Quantitative HBsAg, HBeAg and HBV DNA were measured before, during and after the therapy. Paired liver biopsies were performed before and after treatment for covalently closed circular (ccc)DNA and intrahepatic HBV DNA analysis. Results: VR at 48 weeks post‐treatment, defined as HBeAg seroconversion and HBV DNA less than 10 000 copies/mL was achieved in 10 (33.3%) patients. Responders had significantly lower baseline HBsAg, HBeAg, cccDNA and intrahepatic HBV DNA levels than non‐responders. Baseline and reduced levels of log₁₀ HBsAg and log₁₀ HBeAg correlated well with those of log₁₀ cccDNA and log₁₀ total intrahepatic HBV DNA. Responders showed consistent decrease in serum HBsAg, HBeAg and HBV DNA levels during therapy. HBeAg level of 2.0 log₁₀ sample to cut‐off ratio at week 24 on therapy provided the best prediction of sustained virological response, with sensitivity and negative predictive values of 85% and 92%, respectively. One patient (3.3%) who cleared HBsAg at follow up exhibited a more rapid decline in serum HBsAg during therapy than those who developed VR without HBsAg clearance. Conclusion: Quantitative measurement of serum HBeAg during therapy may be superior to serum HBsAg and HBV DNA as a prediction of HBeAg seroconversion. Kinetics of HBsAg levels on therapy may help predict HBsAg clearance after treatment.