Evaluation of an enzyme-linked immunosorbent assay for detection and quantification of hepatitis B virus PreS1 envelope antigen in serum samples: comparison with two commercial assays for monitoring hepatitis B virus DNA

An in-house sensitive and easy-to-use solid-phase enzyme-linked immunoassay (ELISA) was adapted for the detection and quantification of hepatitis B virus (HBV) PreS1 envelope antigen in serum, and compared with the HBV DNA Hybrid Capture^™ system from Murex and the polymerase chain reaction (PCR) Amplicor^™ HBV Monitor assay from Roche. Twenty-five patients with chronic hepatitis B after liver transplantation were included in this study. The sensitivity of our ELISA was found to be 50 pg of HBsAg/PreS1Ag ml^–1. The linearity was between 0.1 and 100 ng ml^–1. Intra-assay reproducibility was obtained with a standard deviation of <1%. No correlation between the presence of serum PreS1 antigen and viral DNA detected by direct hybridization (Murex) was observed. In contrast, there was a significant 96% correspondence in the presence of PreS1 antigen and viral DNA detected and quantified by the PCR assay (Roche). In conclusion, the most important and reliable markers for monitoring residual HBV replication in serum were HBV DNA by the PCR assay, and virus envelope PreS1Ag by our in-house ELISA. Thus, PreS1Ag disappearance in serum could be used for evaluating the efficacy of antiviral therapies.     

Predictive value of aminotransferase and hepatitis B virus DNA levels on response to interferon therapy for chronic hepatitis B

In a previously reported randomized controlled trial of interferon-α (IFN-α) for chronic hepatitis B, we found a significant difference in response between Chinese adults with elevated vs normal pretreatment aminotransferase (ALT) levels. The aim of this study was to determine the correlation between serum hepatitis B virus (HBV) DNA levels and response to IFN therapy. HBV DNA levels in residual stored sera from patients who participated in the above trial were quantified by a branched DNA (bDNA) assay. Nominal logistic regression was used to estimate the probability of response to IFN treatment as a function of pretreatment ALT and/or HBV DNA levels. We found a significant ( P <0.01) correlation between the HBV DNA levels at midtreatment and response to IFN therapy. Response was achieved in 53% of patients who had undetectable HBV DNA levels at midtreatment but in only 17% of those who remained HBV DNA positive ( P <0.01). In contrast, the probabilities of response for patients with baseline HBV DNA levels over the range 10 to 10000 million equivalents (MEq)ml^–1 were almost identical. We also found a significant correlation between the pretreatment ALT levels and response to IFN therapy. The probabilities of response for patients with pretreatment ALT levels of 500 and 100IUl^–1 were higher than for patients with normal ALT levels by two and onefold, respectively. Our findings may help to improve the cost-effectiveness of IFN therapy for chronic hepatitis B by guiding the selection of patients for therapy and in optimizing the duration of treatment for the individual patient.     

Substitution rate of the hepatitis B virus surface gene

Summary.  Molecular epidemiology of hepatitis B virus (HBV) often relies on the comparison of HBV surface (S) gene sequences, although little is known about the substitution rate of the HBV S-gene. In this study, we compared HBV S-gene sequences in longitudinal sample pairs of 40 untreated, chronically HBV-infected patients, spanning 210 years of cumulative follow-up. The 40 patients included HBV e-antigen positive and negative persons; with HBV DNA levels ranging from 10³ to 10⁹ cps/mL and belonging to HBV genotypes A, B, C, D and E. In the 40 sample pairs, 70 nucleotide changes occurred in the HBV S-gene (0–8 per patient), resulting in an average substitution rate of 5.1 × 10⁻⁴ nucleotide changes/site/year (range: 0–1.3 × 10⁻²). Surprisingly, the number of substitutions was strongly associated with the inverse level of viremia; and only weakly with the duration of follow-up: in 11 highly viremic patients (HBV DNA ≥10⁸ cps/mL), only four substitutions occurred despite a cumulative observation period of 56 years (substitution rate: 1.1 × 10⁻⁴), while in the 10 patients with viremia below 10⁴ cps/mL, 29 substitutions occurred during 30 years of follow-up (substitution rate: 14.6 × 10⁻⁴). We conclude that in chronic hepatitis B virus infection the rate of nucleotide substitution in the HBV S-gene is inversely related to the level of viremia and thus varies widely from person to person; hampering the phylogenetic analysis of possible chains of HBV infection.     

Low Level Hepatitis B Viremia Detected by Polymerase Chain Reaction Accompanies the Absence of HBe Antigenemia and Hepatitis in Hepatitis B Virus Carriers

Objectives: Because outcome of antiviral treatment in patients with chronic hepatitis (CH) B is difficult to predict, we compared the severity of hepatitis with serum hepatitis B virus (HBV) DNA concentration. Methods: We studied 40 HBV carriers with distinct stages of chronic infection, 32 HBe antigen (HBeAg) -negative or low-grade positive carriers whose HBV strains did not contain a point mutation at nucleotide 1896, 37 HbeAg-negative carriers with or without hepatitis, and 51 HBeAg-positive CH patients treated with interferon. Serum HBV DNA concentration was measured by the end-point dilution method using a polymerase chain reaction (PCR). The point mutation at nucleotide 1896 was detected by restriction fragment length polymorphism with PCR. Results: Among the stages of chronic HBV infection, the serum HBV DNA concentration was lowest (10^{0.67 ± 0.71} copies/μl) in HbeAg-negative asymptomatic carriers. A low-level viremia (10^{2.10 ± 1.45} copies/μl) of HBV strains without the mutation at nucleotide 1896 was associated with an HBeAg-negative state. In HBeAg-negative carriers, the serum HBV DNA concentration in those without hepatitis was significantly lower than in those with hepatitis (10^{1.00 ± 0.89} vs 10^{3.31 ± 1.25} copies/μl, p < 0.0001); 20 of 21 asymptomatic carriers had an HBV DNA concentration below 10² copies/μl. Patients with serum HBV DNA concentrations below 10¹ copies/μl at the end of interferon treatment maintained normal serum alanine aminotransferase concentrations. Conclusions: A serum HBV DNA concentration below 10¹ copies/μl is an important goal for successful treatment of CH-B. PCR is necessary to assess such low-level viremias.     

Preoperative serum levels of wild-type and hepatitis B e antigen-negative hepatitis B virus (HBV) and graft infection after liver transplantation for HBV-related hepatocellular carcinoma

Allograft infection in hepatitis B surface antigen (HBsAg)-positive patients undergoing liver transplant (OLT) is still significant, despite post-transplant prophylaxis with high doses of immunoglobulin to HBsAg. Baseline status and post-OLT levels of viraemia and wild-type and hepatitis B e antigen (HBeAg)-negative hepatitis B virus (HBV) were correlated with the clinical course of 16 consecutive HBsAg carriers, positive for hepatitis B e antibody, with hepatocellular carcinoma who underwent OLT and received permanent post-OLT prophylaxis with antibody to HBsAg (HBsAb). Fourteen patients had less than 10³ HBV genome equivalentsml^–1 (eqml^–1) at baseline and remained HBV free after a median of 36 months following OLT. Two patients with mean pre-OLT viraemia higher than 10⁵ genome eqml^–1 and prevalent HBeAg-negative HBV viraemia before OLT suffered a severe graft hepatitis. Interferon-α2b (3MUm^–2 per day) was able to reduce viraemia in both patients and to revert the clinical course of the infection in one, who remained infection-free 22 months after IFN treatment. Fourteen patients had less than 10³ HBV genomeeqml^–1 at baseline and remained HBV free, after a median of 36 months following OLT, with permanent HBsAb immunoprophylaxis. These observations suggest that the quantitative analysis of HBV pre-OLT viraemia levels may provide a very useful tool for predicting the ideal time of liver replacement. Clinical trials on the use of antiviral drugs capable of inhibiting HBV serum levels before liver transplantation should be pursued on this premise.     

Assessment of hepatitis C virus RNA and genotype from 6807 patients with chronic hepatitis C in the United States

Hepatitis C virus (HCV) RNA status and HCV genotype have become important tools in the diagnosis and monitoring of therapy in chronic HCV infection. To establish a database with respect to HCV genotype and serum HCV RNA concentrations in chronic hepatitis C patients in the United States, we analysed 6807 chronic hepatitis C patients who had HCV RNA and HCV genotype tests conducted at a central laboratory. The HCV RNA concentration cut-off for the lower 25th percentile of this population (low titre) was 0.9 × 10⁶ copies ml^–1. The median HCV RNA concentration was 3.5 × 10⁶ copies ml^–1 and the cut-off for the upper 25th percentile (high titre) was 5 × 10⁶ copies ml^–1. Male patients had a median HCV RNA concentration of 3.9 × 10⁶ copies ml^–1, which was significantly higher than the median HCV RNA level for females (2.75 × 10⁶ copies ml^–1; P  < 0.001). HCV genotype 1 was detected in 73% of patients; genotype 2 in 14%; genotype 3 in 8%; mixed genotype in 4%; and genotypes 4, 5 and 6 with a frequency of < 1%. Patients from the Northeast, Southeast and Midwest had significantly ( P  < 0.001) more infections with genotype 1 than patients from the Western and Southern regions. African–American patients were more likely to be infected with genotype 1 when compared with Caucasian, Hispanic or Asian Pacific Islanders ( P  < 0.001). Patients infected with HCV genotype 1 and mixed HCV genotypes had significantly higher serum HCV RNA concentrations when compared with HCV genotypes 2 and 3 ( P  < 0.001 for all comparisons).     

Lamivudine treatment during pregnancy to prevent perinatal transmission of hepatitis B virus infection

Summary.  Vertical transmission of hepatitis B virus (HBV) can occur occasionally despite vaccination of the child. This vaccination breakthrough has been associated with high maternal viraemia. We treated eight highly viraemic (HBV-DNA ≥ 1.2 × 10⁹ geq/mL) mothers with 150 mg of lamivudine daily during the last month of pregnancy. HBV-DNA, hepatitis B surface antigen (HBsAg), anti-HBs and anti-HBc of their offspring were measured at birth and at 3, 6 and 12 months, respectively. Twenty-four children, born to untreated HBsAg-positive mothers with HBV-DNA levels ≥1.2 × 10⁹ geq/mL served as historical controls. All children received passive-active immunization at birth and were followed-up for 12 months. In the lamivudine group one of the eight children (12.5%) was still HBsAg and HBV-DNA positive at the age of 12 months. All other children seroconverted to anti-HBs and maintained seroprotection. In three children, HBV-DNA was temporarily detected by polymerase chain reaction. In the untreated historical control group, perinatal transmission occurred in seven of 25 children (28%). In highly viraemic HBsAg-positive mothers, reduction of viraemia by lamivudine therapy in the last month of pregnancy may be an effective and safe measure to reduce the risk of child vaccination breakthrough. This approach should be evaluated in a large controlled trial.     

HBcAg-pulsed dendritic cell vaccine induces Th1 polarization and production of hepatitis B virus-specific cytotoxic T lymphocytes

Aim:  Dendritic cells (DCs) pulsed with HBsAg efficiently reverse the immune tolerance to hepatitis B virus (HBV) and induce HBV-specific cytotoxic T lymphocyte (CTL) responses in transgenic mice and healthy volunteers. However, it is not clear whether HBV core antigen (HBcAg)-pulsed DCs can effectively induce CD4⁺ helper T cells polarization into Th1, which contribute to the induction and maintenance of HBV-specific CD8⁺ T cells in chronic hepatitis B (CHB) patients. To address this issue, we conducted this study and investigated whether HBcAg-pulsed DCs could polarize Th1 cells and induce an HBcAg-specific CTL response.
Methods:  HBcAg-pulsed DCs were generated from 21 CHB patients. The capacity of the HBcAg-pulsed DC vaccine to stimulate CD4⁺ and CD8⁺ T cells to produce IFN-γ and IL-4 was estimated by intercellular cytokine staining, and the HBcAg-pulsed DCs derived from 10 humam leucocyte antigen (HLA)-A2⁺ CHB patients were tested for the induction of HBV-specific CTLs from autologous T cells by pentamer staining. The cytotoxicity of these CTLs was evaluated in vitro by flow cytometry.
Results:  The HBcAg-pulsed DCs derived from CHB patients exhibited a stronger capacity to stimulate autologous CD4⁺ and CD8⁺ T cells to release IFN-γ rather than IL-4, which could induce HBV core 18-27 specific CTLs, suggesting a specific cytotoxicity against T2 cells that had been loaded with the HBV core 18-27 peptide in vitro .
Conclusion:  HBcAg-pulsed DC vaccine derived from CHB patients efficiently induced autologous T cell polarization to Th1 and generation of HBV core 18-27 specific CTLs.     

Guidelines for the treatment of chronic hepatitis and cirrhosis due to hepatitis B virus infection for the fiscal year 2008 in Japan

In the 2008 guidelines for the treatment of patients with cirrhosis, who are infected with hepatitis B virus (HBV), the main goal is to normalize levels of alanine and aspartate aminotransferases by eliminating HBV or reducing viral loads. In patients with compensated cirrhosis, the clearance of HBV from serum is aimed for by entecavir, as the main resort, for histological improvement toward the prevention of hepatocellular carcinoma (HCC). In patients with decompensated cirrhosis, by contrast, meticulous therapeutic strategies are adopted for the reversal to compensation, toward the eventual goal of decreasing the risk of HCC. For maintaining liver function and preventing HCC, branched chain amino acids and nutrient supplements are applied, in addition to conventional liver supportive therapies. For patients with chronic hepatitis B, separate guidelines are applied to those younger than 35 years and those aged 35 years or older. Even for patients with chronic hepatitis who are negative for hepatitis e antigen (HBeAg), but who harbor HBV DNA in titers of 7 log copies/mL or more, a "drug-free state" is aimed for by sequential treatment with interferon (IFN) plus entecavir as the first line. For patients with chronic hepatitis B aged 35 years or older, who are HBeAg-negative and carry HBV DNA in titers of less than 7 log copies/mL, long-term IFN for 24–48 weeks is adopted anew. To HBeAg-negative patients who have either or both platelet counts of less than 150 × 10³/mm³ and less than 7 log copies of HBV DNA, also, long-term IFN for 24–48 weeks is indicated.     

A novel primer-extension assay for the detection of a G to A mutation in the distal precore region of hepatitis B virus DNA

The roles of genetic heterogeneity of the hepatitis B virus (HBV) precore gene in the pathogenesis of HBV infection are unclear. Various methods have been used to detect nucleotide (nt) 1896 precore mutants. We established a new primer-extension assay to facilitate the detection of these mutants. This assay is based upon the fact that there is no adenine in the distal precore region of wild-type HBV. Polymerase chain reaction (PCR)-amplified template DNA was denatured and annealed to the [γ-³²P]-labelled primer. During primer extension in the presence of DNA polymerase and dCTP, dGTP, dTTP and ddATP, the reaction terminates if there is a nucleotide A. When mixtures of different ratios of wild-type and nt 1896 precore mutants were analysed in the primer-extension assay, correlation between the percentage known amounts and the percentage measured amounts of nt 1896 precore mutants was excellent (r²=0.9669). When the primer-extension assay and direct sequencing were compared in hepatitis B e antigen (HBeAg)-positive and -negative chronic active hepatitis B patients, the primer-extension assay detected a greater number of nt 1896 precore mutants than direct sequencing and thus most HBV infections were found to be mixed infections. In conclusion, the primer-extension assay is a reliable and sensitive method for the detection of nt 1896 precore mutants.     

Detection and quantitation of hepatitis B virus DNA: comparison of two commercial hybridization assays with polymerase chain reaction

Summary. Serum hepatitis B virus (HBV) DNA is now the most important and reliable marker for monitoring hepatitis B viral replication. Quantitative detection of HBV DNA in serum is based on commercial standardized molecular hybridization test systems. We compared two hybridization assays, the Digene Hybrid Capture assay (Digene Diagnostics, Beltsville, MD) and the Abbott HBV DNA assay (Abbott Laboratories, North Chicago, EL, USA) with the polymerase chain reaction (PCR) technique, for detection and quantitative measurement of serum HBV DNA. Forty-two patients with various HBV serological marker profiles were included in this study. The patients were divided into four groups according to their HBV DNA values after HBV DNA determination in the serum by the Abbott assay. For each patient HBV DNA was then determined by the Digene assay and by PCR. In the case of Digene and PCR there was a 97.6% correspondence in the outcome of the two methods, whereas in the Abbott assay and PCR there was only 69% correspondence. The McNemar test of symmetry showed no statistically significant difference between the Digene assay and PCR, whereas there was a significant difference ( P < 0.01) in the Abbott assay and PCR. For low positive HBV DNA values between 1.5 and 20 pg ml^-1 the Abbott assay yields inconclusive results. Differences observed between the two hybridization assays underline the need for standardization of HBV DNA quantitation.     

Occult hepatitis B virus infection and its clinical implications

Occult hepatitis B virus (HBV) infection is characterized by presence of HBV infection with undetectable hepatitis B surface antigen (HBsAg). Serum HBV level is usually less than 10⁴ copies/mL in these patients. Diagnosis of occult HBV infection requires sensitive HBV-DNA PCR assay. Several possibilities have been hypothesized as the mechanisms of occult HBV infection. These include: (i) mutations of HBV-DNA sequence; (ii) integration of HBV-DNA into host's chromosomes; (iii) infection of peripheral blood mononuclear cells by HBV; (iv) formation of HBV-containing immune complex; (v) altered host immune response; and (vi) interference of HBV by other viruses. The precise prevalence of occult HBV infection remains to be defined. The clinical implications of occult HBV infection involve different clinical aspects. First of all, occult HBV infection harbours potential risk of HBV transmission through blood transfusion, haemodialysis, and organ transplantation. Second, it may serve as the cause of cryptogenic liver disease, contribute to acute exacerbation of chronic hepatitis B, or even fulminant hepatitis. Third, it is associated with development of hepatocellular carcinoma. Fourth, it may affect disease progression and treatment response of chronic hepatitis C. Most of the previous studies utilized retrospective observation without control groups, and lacked direct association of occult HBV infection with specific pathological changes and disease progression. Highly sensitive, quantitative, and functional molecular analyses of HBV, combined with a well-designed prospective clinical assessment will provide the best approach for the future study of occult HBV infection.     

High hepatitis B virus (HBV) DNA viral load is an important risk factor for HBV reactivation in breast cancer patients undergoing cytotoxic chemotherapy

Summary.  Hepatitis B virus (HBV) reactivation during cytotoxic chemotherapy for cancer may complicate treatment and cause liver damage. The complication has been reported to occur in 10% to over 50% of HBV carriers, but the factors that determine which patients will develop reactivation remain unclear. The objective of the study is to test the hypothesis that the prechemotherapy HBV DNA level is a risk factor for the development of HBV reactivation. We studied 41 women undergoing cytotoxic chemotherapy for breast cancer, 17 of whom developed reactivation and 24 who did not. We developed a novel, ultra-sensitive, real-time polymerase chain reaction assay for the measurement of HBV DNA. The sera of 37 patients (16 who developed reactivation and 21 who did not) were available for measurement of HBV DNA using this technique. The results showed that patients in the reactivation group had a significantly higher median HBV DNA load (1.03 × 10⁶ copies/mL; range <2.9 × 10³ to 8.723 × 10⁷) than did the nonreactivation group (<2.9 × 10³ copies/ml; range <2.9 × 10³ to 6.331 × 10⁷) ( P  < 0.001). The optimal cut-off between the two groups was found to be at serum HBV DNA level of 3 × 10⁵, which gave a sensitivity of 81.0% and a specificity of 85.0%. In conclusion, for breast cancer patients receiving standard cytotoxic chemotherapy, a high HBV viral load prior to the administration of cytotoxic chemotherapy is a significant predictive factor for the development of HBV reactivation. Such information may be useful in determining which patients would benefit most from prophylactic antiviral therapy during cytotoxic chemotherapy.     

Hepatitis B virus genomic heterogeneity: variation between quasispecies may confound molecular epidemiological analyses of transmission incidents

Nucleotide sequence variability studies were conducted on a 263-base pair fragment of the core-coding genomic region of hepatitis B virus (HBV), amplified by the polymerase chain reaction (PCR) from three surgeons with varying circulating levels of HBV, all of whom were thought to have transmitted HBV to their patients post-surgically. DNA sequencing was applied to amplicons obtained directly from serum and those cloned into plasmid vectors, and from single HBV molecules in serum separated by a limiting dilution procedure. In one surgeon, who had a titre of ~3×10⁵ genome equivalentsml^–1, the direct sequence was identical to none of 29 other sequences and differed by one base substitution from the sequence amplified from the single patient he infected. In another surgeon, who had a titre of ~2×10⁶ genome equivalentsml^–1, the direct sequence was identical to 17 of 36 (47%) sequences; however, the sequence common to all three infected patients was identical to a unique sequence in the surgeon that differed by three base substitutions from the direct sequence. By contrast, the direct sequence in the third surgeon, who had a titre of ~4×10⁷ genome equivalentsml^–1, was identical to 25 of 38 (66%) sequences, and to the sequence common to all 11 infected patients. Assessment of HBV DNA sequences directly amplified from clinical specimens may not be appropriate to studies of transmission in which the source of infection harbours a relatively dilute, heterogenous mix of viral variants.     

Sensitivity and specificity of capillary blood HBsAg as a surrogate marker for HBeAg in pregnant women

Infants at high risk of acquiring hepatitis B virus (HBV) infection from their hepatitis B e antigen (HBeAg)-positive mothers are prime targets for early HBV immunization. The usefulness of fingerprick blood of pregnant women as a surrogate marker to identify infants who would need immunization soon after birth was evaluated. Using HBeAg from venous blood as the standard, the detection of hepatitis B surface antigen (HBsAg) by reverse passive haemagglutination in capillary blood yielded an overall sensitivity of 97% and a specificity of 96% for detecting HBeAg at a cutoff titre of 2^2.5. Pregnant women with a capillary HBsAg titre of 2^2.5 or greater are 24 times more likely to infect their babies, while the chances of transmitting HBV infection with a titre lower than the cutoff point are almost nil. When the cost of HBV vaccine eventually comes down to levels suitable for public health use, a cutoff titre of 2^2.5 is suggested in order to identify infants who should be vaccinated soon after birth.     

Composition of peripheral blood lymphocyte populations during different stages of chronic infection with hepatitis B virus

To characterize the immunological populations associated with different stages of chronic infection with hepatitis B virus (HBV), we performed flow cytometric analyses on the peripheral blood leucocytes of 29 patients with various forms of chronic hepatitis B. The clinical spectrum of the patients ranged from asymptomatic infections, in the presence of high virus production, to intermittent or recurrent exacerbations of liver injury alternating with relatively normal liver function. Patients with partial resolution of disease who experienced an initial acute flare followed by prolonged seroconversion showed decreased percentages of CD3⁺ cells during the seroconversion phase when levels of serum alanine transferase (ALT) had normalized. These CD3⁺ cells were predominantly CD4⁺ cells bearing the αβ⁺ T-cell receptor (TCR). In addition, we saw an increase in CD4⁺ and CD8⁺ cells bearing the γδTCR in those patients who had seroconverted. No significant differences were seen between any of the groups with respect to percentage of cells with a naive (CD45RA) or memory (CD45RO) phenotype, or of cells displaying the activation markers CD38, HLA-DR or CD57. Longitudinal analyses of 15 patients failed to show any consistent pattern of changes in the immunophenotypic profile during acute flares and their resolution. Our results indicate that the turnover of circulating T lymphocytes during the apparent quiescent phase of chronic infections is higher than that during acute exacerbations, suggesting an active immunosurveillance role of T-cell subpopulations in maintaining low virus levels during seroconversion.     

2',3'-dideoxy-3'-fluoroguanosine inhibits duck hepatitis B virus in vivo

SUMMARY. Duck hepatitis B virus (DHBV) belongs to the same virus family as the human hepatitis B virus (HBV). Domestic ducks infected with DHBV can be used as an animal model for chronic hepatitis B virus infection in therapeutic trials. In this study the antiviral effect of the guanosine analogue 2',3'-dideoxy-3'-fluoroguanosine (FLG) was tried in vivo on chronically DHBV-infected ducks. The ducks were either congenitally infected, or inoculated with DHBV immediately post-hatch. FLG was given as intraperitoneal injections twice daily, at different dosages. Serum DHBV levels were determined by DNA dot-blot hybridization. A strong inhibition of serum DHBV DNA was observed with FLG doses down to 1 mg kg^-1 day^-1. given for 7 to 10 days. With the corresponding thymidine analogue, 2',3'-dideoxy-3'-fluorothymidine; however, no inhibition was obtained. This difference may be due to different phosphorylation mechanisms. Independently of FLG dose, serum DHBV DNA returned to pretreatment levels within a few days after cessation of therapy. After a long-term trial (FLG, 5mg kg^-1 day^-1 for 33 days), the same relapse of DHBV production was seen. Thus, FLG is an efficient inhibitor of DHBV replication, and is a candidate for treatment of HBV infections. However, the effect is transient, and therefore combination with other types of anti-HBV drugs should be considered.     

The natural history of chronic hepatitis B

Summary.  The natural history of chronic hepatitis B is dependent on the age of acquiring the hepatitis B infection. Those who are infected at adolescence or adulthood (including most of the Caucasians) tend to have stable disease after hepatitis B e antigen seroconversion with normal serum alanine aminotransaminase (ALT) and hepatitis B virus (HBV) DNA levels <10⁵ copies/mL (20 000 IU/mL). In contrast, those who are infected at birth or early childhood (including the majority of the world's hepatitis B carriers, i.e. Asians) have a prolonged immune tolerance phase followed by a prolonged immune clearance phase. A proportion of these patients have progressive disease after HBeAg seroconversion with HBV DNA <10⁴ copies/mL (<2000 IU/mL) and ALT between 0.5 and 2× upper limit of normal. Core promoter mutations may play a part in the development of cirrhosis-related complications. However, continuing viral replication, even at a relatively low level of <10⁴ copies/mL (<2000 IU/mL), is probably the most important factor for the development of complications.     

Hepatitis B e antigen negative chronic active hepatitis: hepatitis B virus core mutations occur predominantly in known antigenic determinants

Summary. In chronic hepatitis B virus (HBV) infection seroconversion from hepatitis B e antigen (HBeAg) to hepatitis B e antibody (HBeAb) may be followed either by remission of the disease with low-level viraemia, or by continuing inflammation with high-level viraemia. In both situations the virus may acquire a mutation in the precore sequence which prevents it from encoding HBeAg. We now show that the number of amino acid substitutions in the HBV core is low in viral sequences from patients with HBeAg positive chronic liver disease and HBeAg negative HBeAb positive patients in remission, but the frequency of substitutions is high in HBeAg, negative HBeAb positive patients with active liver disease. Furthermore we show that these substitutions cluster in the promiscuous CD4⁺ T-helper-cell epitope and in HBV core/e antibody binding determinants, but are not found in regions recognized by major histocompatability complex (MHC) restricted cytotoxic T lymphocytes. Sequential viral sequences from patients before and after HBeAg/HbeAb seroconversion shows that core mutations arise either at the same time or after the precore stop mutation which prevents the virus from encoding HBeAg. These results are consistent with the hypothesis that after clearance of HBeAg, mutations in regions of the virus recognized by CD4⁺ helper T cells and B cells allow persistence of the HBe negative virus in HBeAb positive patients with viraemia and active hepatitis.