Hepatitis B infection: pathogenesis and management

Distribution of hepatitis B virus genotypes in patients with chronic hepatitis B in Turkey

AIM: Hepatitis B virus (HBV) strains isolated worldwide has been classified into eight genomic groups deduced from genome comparisons and designated as genotypes A to H. We aimed to investigate prevalence of HBV genotypes and subtypes in Turkey.

METHODS: A total of 88 chronic hepatitis B (CHB) patients from 15 hospitals throughout the country were included. Patients who were HBsAg positive in serum at least for 6 mo, who had HBV-DNA in serum and elevation of ALT levels more than two times upper limit of normal, and who had percutaneous liver biopsy within 6 mo were included. Genotyping of HBV was done by restriction fragment length polymorphism (RFLP). The patients received subcutaneous 9 MU interferon-α 2a thrice a week for a period of 6 mo.

RESULTS: Genotype D was detected in 78 of 88 (88.7%) patients, however, genotyping failed in two patients (2.3%), while no product was obtained in eight (9.0%) patients. Regarding subtypes, D2 was more prevalent (67 patients between 78% and 85.9%) followed by subtype D2+deletion (seven patients of 78 or 8.9%), subtype D1 (three patients of 78% or 3.9%) and subtype D3 (one patient of 78% or 1.3%). Thirty-three patients (37.5%) were HBeAg positive compared to 55 (62.5%) anti-HBe positive patients. The endpoint for the viral response of HBeAg positive patients was 27.2%, while it was found 52.7% in HBeAg negative patients (P<0.05). Long-term persistent viral response was 29.5% for all patients.

CONCLUSION: This multi-center study indicates that the predominant genotype with CHB patients in Turkey like in other Mediterranean countries is genotype D.

In vivo immunization by vaccine therapy following virus suppression by lamivudine: a novel approach for treating patients with chronic hepatitis B

BACKGROUND

Both the hepatitis B virus (HBV) and the immune response of the hosts to HBV play important roles in the pathogenesis of chronic hepatitis B (CHB). Lamivudine is a potent antiviral agent with minimal immune modulator capacity. Moreover, lamivudine causes severe side effects like breakthrough of HBV DNA and breakthrough hepatitis in patients with CHB. On the other hand, vaccine therapy, a recently-developed immune therapy, exhibits potent immune modulatory potentials and almost no side effects, but possesses little antiviral capacity in patients with CHB.

OBJECTIVES

The aim of this clinical trial is to evaluate the efficacy of a combination therapy of lamivudine and vaccine in patients with CHB.

STUDY DESIGN

Seventy-two patients with CHB (hepatitis B e antigen (HBeAg)-positive, 40; antibody to HBeAg (anti-HBe)-positive, 32). All patients received lamivudine at a dose of 100 mg daily for 12 months. Fifteen patients (HBeAg+, 9; anti-HBe+, 6) receiving oral lamivudine were also given a vaccine containing 20 microg of hepatitis B surface antigen, intradermally, once every 2 weeks for 12 times (combination therapy).

RESULTS

Twelve months after the start of therapy, serum HBV DNA became negative in 9 of 9 (100%) HBeAg+ CHB patients receiving combination therapy and in 15 of 31 (48%) HBeAg+ CHB patients receiving lamivudine monotherapy (P < 0.05). The rate of seroconversion from HBeAg to anti-HBe was also significantly higher in patients receiving combination therapy (56% versus lamivudine monotherapy, 16%, P < 0.05). Of the 57 patients receiving lamivudine monotherapy, breakthrough of HBV DNA was found in 10 and breakthrough hepatitis was found in 4; however, these were not seen in any patient receiving combination therapy.

CONCLUSIONS

Combination therapy represents a better therapeutic regimen with few complications in patients with CHB.

Production of hepatitis B surface antigen-pulsed dendritic cells from immunosuppressed murine hepatitis B virus carrier: evaluation of immunogenicity of antigen-pulsed dendritic cells in vivo

Vaccines containing hepatitis B surface antigen (HBsAg) induce antibody to HBsAg (anti-HBs) in most normal individuals and protects them from hepatitis B virus (HBV) infection. However, these vaccines are not efficient at inducing anti-HBs in immunosuppressed individuals, especially in immunosuppressed HBV carriers. The aim of this study was to prepare and to assess the efficacy of a dendritic cell (DC)-based vaccine in an immunosuppressed HBV transgenic mouse (HBV-Tg), an animal model of the HBV carrier state. In order to prepare immunosuppressed HBV-Tg, HBV-Tg were injected with FK-506, an immunosuppressive agent, once daily, intraperitoneally for 15 days. Spleen cells of immunosuppressed HBV-Tg expressed very little mRNAs for interleukin-2 and interferon-gamma. DCs were isolated from the spleen of immunosuppressed HBV-Tg and cultured with HBsAg (100 microg) for 48 h to prepare HBsAg-pulsed DCs. Immunosuppressed HBV-Tg expressing HBsAg in the sera were administered with HBsAg-pulsed DCs or unpulsed DCs or HBsAg in adjuvant for different durations. Immunosuppressed HBV-Tg (n = 8) twice administered with HBsAg-pulsed DCs expressed anti-HBs in the sera within 6 weeks of first injection. Seven of eight immunosuppressed HBV-Tg remained positive for anti-HBs in the sera for the next 12 weeks of observation in spite of receiving daily injection of FK-506 for the entire duration. However, immunosuppressed HBV-Tg administered with unpulsed DCs or HBsAg in adjuvant did not express anti-HBs in the sera. The data show that DCs from immunosuppressed HBV-Tg can be loaded with HBsAg to prepare immunogenic HBsAg-pulsed DCs. HBsAg-pulsed DCs induced anti-HBs in immunosuppressed HBV-Tg. This approach may be of use to induce and maintain anti-HBs in immunosuppressed human HBV carriers.

Toxicity of novel anti-hepatitis drug bicyclol: A preclinical study

AIM: To study the toxicity of bicyclol to animals.

METHODS: Acute toxicity test was performed in Kunming strain mice that were orally given bicyclol at the doses of 3 and 5 g/kg body weight, respectively. Wistar rats were orally administered bicyclol at a dose of 5 g/kg body weight. Death and clinical symptoms of animals were recorded within 7 d. Sub-acute toxicity test was carried out in rats that were treated with various doses of bicyclol (150, 300, 600 mg/kg) once daily for 14 d. Animal behaviors, blood biochemical markers, blood and urine pictures were examined. Chronic toxicity test was conducted in 80 Wistar rats of both sexes. The animals were orally administered with various doses of bicyclol [150, 300, 600 mg/kg, 100-400 folds corresponding to the proposed therapeutic dose (1.5 mg/(kg·d)) of bicyclol for patients] once daily for 6 mo except for Sunday. The control group was given the same volume of 0.2% sodium carboxyl methylcellulose (Na-CMC). Twenty-one beagle dogs received bicyclol (25, 75, 225 mg/kg, 16.6, 50, 150 folds corresponding to the proposed therapeutic dose of bicyclol for patients) once a day for 6 mo except for Sunday. The body weight, food intake, urine and feces, blood picture, blood biochemical markers, and pathological examination of main organs were determined. Mutagenicity and teratogenicity were determined. Mutagenicity assay included Ames’s test, chromosome aberration test in CHL cells and micronucleus test in mice. For the teratogenicity assay, pregnant Wistar rats weighing 200-250 g were treated with 0.2, 1.0 g/kg bicyclol once daily from the 7th d of gestation for 10 d.

RESULTS: The oral LD₅₀ of bicyclol was over 5 g/kg in mice and rats. No noticeable alterations in subacute and chronic toxicity of rats and dogs were demonstrated. No mutagenicity and teratogenicity of bicyclol were found.

CONCLUSION: Bicyclol has no detectable chronic toxicity as well as mutagenicity and teratogenicity in animals.

Impaired functional capacities of liver dendritic cells from murine hepatitis B virus (HBV) carriers: relevance to low HBV-specific immune responses

The chronic hepatitis B virus (HBV) carrier exhibits ongoing replication of HBV and expresses abundant amounts of HBV-related antigens in the liver. However, HBV-specific immune responses are either absent or narrowly focused in these subjects. With the postulation that impaired functional abilities of liver dendritic cells (DCs) might be responsible for this, we assessed the functions of liver DCs in HBV transgenic mice (HBV-TM), an animal model of the HBV carrier state. Liver DCs were isolated from normal C57BL/6 mice and HBV-TM without the use of cytokines or growth factors. Lymphoproliferative assays were conducted to evaluate the ability of liver DCs to induce the proliferation of allogenic T lymphocytes and hepatitis B surface antigen (HBsAg)-enriched T lymphocytes. Liver DCs were stimulated with viral and bacterial products to assess their cytokine-producing capacities. In comparison to liver DCs from normal C57BL/6 mice, liver DCs from HBV-TM exhibited significantly decreased T cell proliferation-inducing capacities in allogenic mixed leucocyte reaction (P <0.05) and HBsAg-enriched T lymphocytes proliferation assays (P <0.05). Liver DCs from HBV-TM produced significantly lower levels of interleukin-12p70, tumour necrosis factor-alpha, interferon-gamma, and interleukin-6 (P <0.05) compared to liver DCs from normal C57BL/6 mice. This study provides evidence that liver DCs from HBV-TM had impaired ability to induce both innate and adaptive immune responses. This might account for a weak and almost undetectable HBV-specific immune response in chronic HBV carriers. This inspires hope that up-regulation of the functions of liver DCs in situ may have therapeutic implications in chronic HBV carriers.

CD26/DPPIV and response to hepatitis B vaccination

The prevention of hepatitis B is important, since it is responsible for significant morbidity and mortality around the world. Unfortunately, hepatitis B vaccine does not always induce protective immunity. The lack of immune response to vaccine (non-responders) can depend on individual characteristics. The objective of this study was to correlate the CD26/DPPIV cellular expression and DPPIV serum activity with HBV vaccine response and its possible role as an indicator of immune competence acquisition. We also determined the cellular expression of CD3, CD19, CD56 and CD25 in peripheral blood T lymphocytes. Blood samples were obtained from 28 healthy human volunteers who were enrolled with a vaccination program. There were "responders" (RM = 13) and "non-responders" (NRM = 15), after vaccination. The lymphocyte populations were identified by flow cytometry. DPPIV serum activity was measured fluorimetrically. CD26 expression in responders (55.9 +/- 7.7%) versus in non-responders (51.9 +/- 7.0%) did not show a significant difference. The DPPIV serum activity in responders compared to in non-responder subgroup (59.9 +/- 8.4/50.3 +/- 10.6U/L) showed, however, a significant difference (P < 0.05). The expression of CD3, CD19 and CD56 on peripheral lymphocytes was similar between responders and non-responders. The expression of CD3CD26 (52.2 +/- 8.6%) and CD3CD25 (10.9 +/- 3.8%) in responders versus the expression of CD3CD26 (48.0 +/- 5.7%) and CD3CD25 (8 +/- 4.6%) in non-responders did not show statistically significant difference. CD25 referred as a marker of T lymphocyte activation was increased in responders (15.8 +/- 4.5%) versus in non-responders (10.1 +/- 4.8%), showing a significant difference (P = 0.003). It was, however, impossible to demonstrate an increase in CD3CD25 and CD3CD26 in the responder subgroup. This suggests that different lymphocyte subsets other than T cells are implicated in the response to hepatitis B vaccination.

Efficacy of hepatitis B vaccination and interferon-alpha-2b combination therapy versus interferon-alpha-2b monotherapy in children with chronic hepatitis B

BACKGROUND

Although interferon (IFN) has been approved in the treatment of chronic hepatitis B in children, it is effective only in 30-40% of patients. In some studies it has been suggested that therapeutic use of anti-hepatitis B virus (HBV) vaccine may be beneficial in patients with chronic hepatitis B. The aim of the present study was to compare the efficacy of hepatitis B vaccination and IFN-alpha-2b in combination and IFN-alpha-2b monotherapy in children with chronic hepatitis B.

METHODS

Fifty treatment-naive children with chronic hepatitis B infection were randomly assigned to receive either 5 million units/m(2) recombinant IFN-alpha-2b subcutaneously three times per week for 9 months, and pre-S2/S vaccine at the beginning and 4 and 24 weeks after initiation of IFN therapy (n = 25) or recombinant IFN-alpha-2b (5 million units/m(2) subcutaneously thrice weekly) alone for 9 months (n = 25). Children were followed for at least 6 months after the end of therapy.

RESULTS

There was no statistically significant difference in the mean alanine aminotransferase levels, histologic activity index and fibrosis scores between combination and IFN monotherapy groups at the end of the therapy and end of the follow-up period. When combination and monotherapy groups were compared, the mean HBV-DNA values were significantly reduced in combination group at the end of the therapy (P = 0.004), but no statistically significant difference was found at the end of the follow up. Sustained HBeAg seroconversion with clearance of HBV-DNA was obtained in 13 of 25 children (52%) treated with combination therapy, and in eight of 25 patients (32%) treated with IFN monotherapy (P = 0.251).

CONCLUSION

Although the difference was statistically insignificant, the sustained response rates were better in the combination therapy group than in the monotherapy group. The potential benefit of combining IFN and hepatitis B vaccine should be investigated in further studies with different regimens of combination therapy.

Generation of Anti-Idiotypic Antibodies that Mimic HBsAg and Vaccination against Hepatitis B Virus

The advent of hybridoma technology has opened up a new avenue in vaccine development, and antigen-mimicking properties of anti-idiotypic antibodies have provided promising alternatives in the generation of experimental anti-idiotypic vaccines. In the present study, mice were immunized with anti-hepatitis B virus (HBV) mouse monoclonal and anti-HBV goat polyclonal antibody to produce anti-idiotypic antibodies. Two mouse monoclonal antibodies (6C9, 6H9) were obtained from the fusions, and the immunogenic properties and specificity of antibodies were analyzed. BALB/c mice were immunized with varying concentrations of anti-idiotypic antibodies (25, 50, 75, and 100 micrograms of anti-Id), and it was shown that anti-idiotypic antibodies generated hepatitis B surface antigen (HBsAg), as well as a BSA-specific antibody response. A simple method for the purification of monoclonal antibodies by dialyzing antibody against water has also been reported.

Effects of autoantibodies against β1-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca2+ currents

AIM: To investigate the effects of autoantibodies against β₁-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca²⁺ currents.

METHODS: Fifteen samples of autoantibodies against β₁-adrenoceptor positive sera of patients with hepatitis virus myocarditis were obtained and IgGs were purified by octanoic acid extraction. Binding of autoantibodies against β₁-adrenoceptor to guinea pig cardiac myocytes was examined by immunofluorescence. Using the patch clamp technique, the effects on the action potential and I_Ca-L of guinea pig cardiac myocytes caused by autoantibodies against β₁-adrenoceptor in the absence and presence of metoprolol were investigated. Cell toxicity was examined by observing cell morphology and permeability of cardiac myocytes to trypan blue.

RESULTS: The specific binding of autoantibodies against β₁-adrenoceptor to guinea pig cardiomyocytes was observed. Autoantibodies against β₁-adrenoceptor diluted at 1:80 prolonged APD₂₀, APD₅₀ and APD₉₀ by 39.2%, 29.1% and 15.2% respectively, and only by 7.2%, 5.3% and 4.1% correspondingly in the presence of 1 μmol/L metoprolol. Autoantibodies against β₁-adrenoceptor diluted at 1:80, 1:100 and 1:120 significantly increased the I_Ca-L peak current amplitude at 0 mV by 55.87 ± 4.39%, 46.33 ± 5.01% and 29.29 ± 4.97% in a concentration-dependent manner. In contrast, after blocking of β₁-adrenoceptors (1 μmol/L metoprolol), autoantibodies against β₁-adrenoceptor diluted at 1:80 induced a slight increase of I_Ca-L peak amplitude only by 6.81 ± 1.61%. A large number of cardiac myocytes exposed to high concentrations of autoantibodies against β₁-adrenoceptor (1:80 and 1:100) were turned into rounded cells highly permeable to trypan blue.

CONCLUSION: Autoantibodies against β₁-adrenoceptor may result in arrhythmias and/or impairment of myocardiums in HVM, which would be mediated by the enhancement of I_Ca-L.

Multicenter evaluation of the VERSANT hepatitis B virus DNA 3.0 assay

The VERSANT hepatitis B virus (HBV) 3.0 Assay (branched DNA [bDNA]) (referred to herein as VERSANT 3.0) was evaluated at four external sites for analytical sensitivity, specificity, reproducibility, linearity of quantification, and limits of detection. In addition, each of the test evaluation sites provided HBV DNA-positive clinical samples that were previously analyzed by one of three commercially available HBV DNA quantitative tests: Digene Hybrid Capture II HBV DNA Test (Digene); VERSANT HBV DNA 1.0 Assay (bDNA) (VERSANT 1.0); and COBAS AMPLICOR HBV Monitor Test (COBAS AMPLICOR). These samples were reexamined using VERSANT 3.0. The results from these studies showed that VERSANT 3.0 has high specificity (99.3%), excellent reproducibility (between-run coefficient of variation [CV] = 1.6 to 9.4%; within-run CV = 6.5 to 20.7%), and a broad linear range of quantification (2.0 x 10(3) to 1.0 x 10(8) HBV DNA copies/ml) that facilitate the monitoring of HBV DNA levels at diagnosis and throughout the course of treatment. In general, correlation was very good between results obtained from clinical samples analyzed by VERSANT 3.0 and the comparative HBV DNA quantitative assays (VERSANT 1.0, R(2) = 0.900; Digene, R(2) = 0.985; COBAS AMPLICOR, R(2) = 0.771). The greatest differences in comparative quantitation occurred at HBV DNA levels approaching the limits of the dynamic ranges for the comparative assays. The performance characteristics of the new VERSANT 3.0 assay demonstrated that it provides a reliable and robust method for routinely monitoring serum HBV DNA levels in assessing disease activity and determining response to antiviral treatment.

Molecular epidemiology of hepatitis B and C virus infections in Asia

The present paper provides a review of the current literature regarding the molecular-based epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV), which are very important viruses underlying the etiology of blood-borne infectious diseases worldwide. Particularly, both HBV and HCV are widespread on the Asian continent and are associated with acute and chronic liver diseases, including hepatocellular carcinoma. HBV has been classified into genotypes A through G and shown to have a distinct geographic distribution. In Asia, genotypes B and C of HBV prevail, and genotype C has been shown to cause more serious liver disease than genotype B. High prevalence of HBV mutants with various forms, such as the pre-S mutant, basal core promoter mutant, YMDD motif mutant and vaccine escape mutant, were seen in Asia and these were found to be related to the severity of liver disease and sensitivity to therapy. HCV has also been classified into multiple genotypes and associated with geographic distribution. HCV genotype 1 is less sensitive to interferon therapy and may be associated with the presence of more serious liver disease than the other genotypes. Data on the relation among the HBV/HCV genotypes, their pathogenicity in chronic liver diseases including hepatocellular carcinoma and their effect on therapy are awaited with great interest, especially in Asia, which is an endemic region of blood-borne hepatitis viruses.

Genotype C of hepatitis B virus can be classified into at least two subgroups

A genomic characterization of hepatitis B virus (HBV) was done for 56 pre-S1/pre-S2 genes and 10 full-length HBV genotype C isolates from five Asian countries. Phylogenetic analysis of the pre-S1/pre-S2 genes revealed two major groups within genotype C: one for isolates from southeast Asia including Vietnam, Myanmar and Thailand (named HBV/C1) and the other for isolates from Far East Asia including Japan, Korea and China (named HBV/C2). This finding was confirmed by phylogenetic analysis based on the full-length sequence of 32 HBV genotype C isolates, including 22 from database entries. Two isolates from Okinawa, the island off the southern end of Japan, formed a different branch. Specific amino acid sequence changes were identified in the large S protein (amino acids 51, 54, 60, 62 and 73) and P protein (amino acids 231, 233, 236, 248, 252 and 304). Our results indicate that genotype C of HBV can be classified into at least two subgroups.

Occult hepatitis B virus infection in HBsAg negative patients undergoing liver transplantation: clinical significance

Occult Hepatitis B virus (o-HBV) infection has been reported in HB surface antigen (HBsAg)-negative liver donors whose risk of transmitting HBV justifies a specific prophylaxis in liver recipients. The clinical significance of o-HBV infection in HBsAg-negative recipients and their need for prophylaxis is unknown. Liver samples collected during surgery from 23 HBsAg-negative patients (9 liver donors and 14 recipients) and 20 HBsAg-positive recipients (controls) were studied by polymerase chain reaction with an independent set of primers mapping the core and surface HBV genes. Intrahepatic HBV DNA was detected as core and surface genes in all the HBsAg-positive recipients, in none of the HBsAg-negative donors and in 9/14 (64%) of the HBsAg-negative recipients (2 HCV negative, 7 HCV positive). The intrahepatic amount of HBV was significantly lower in HBsAg-negative than in HBsAg-positive livers (median values 1.36 Log(10)/microg DNA vs. 3.66 Logs, p<0.0001, core gene, and 1.13 vs. 6.21 Logs p<0.0001, surface gene). No HBV DNA was detected in plasma from o-HBV recipients; one of them tested positive in lymphocytes. No correlation was found between o-HBV and serologic markers of previous HBV exposure, response to vaccination, acute rejection, hepatitis D and G virus-infections. None of o-HBV carriers experienced a de novo hepatitis B after transplantation (median follow-up: 477 days). Occult HBV is frequent in HBsAg-negative liver recipients. It is not associated with increased episodes of acute rejection, coinfection with hepatotropic viruses, different responses to HBV vaccination, or the development of de-novo hepatitis B. In o-HBV infection a particular virus-host interaction can explain the low intrahepatic HBV content and the lack of extrahepatic HBV replication, thus justifying the low risk of hepatitis B reactivation, in absence of specific prophylaxis, once the recipient liver is removed.

Characteristics of core promoter and precore stop codon mutants of hepatitis B virus in Vietnam

In Asia, genotypes B and C are the most common genotypes of hepatitis B virus (HBV); and genotype C causes more severe liver disease. Core promoter/precore (CP/PC) mutants, known to be linked to these genotypes, could have an impact on the progression and severity of liver disease. Sera of 115 patients, including 39 acute and 76 chronic Vietnamese HBV infected patients, were tested for their liver profile, HBeAg, HBV genotypes, and HBV DNA level. Fragments of 282 nucleotides covering CP/PC were amplified, sequenced, and analysed. In the acute group, CP/PC mutants accounted for 38.4 and 25.6%, respectively. Genotype B was found to be predominant (74.3%, P < 0.05) and linked to the PC mutant (A1896) (P < 0.05). In the chronic group, CP/PC mutants accounted for 61.7 and 32.8%. CP mutants, especially the T1762/A1764 double mutant, were found to correlate with genotype C (81%, P < 0.001), liver cirrhosis, and hepatocellular carcinoma (P < 0.05). Therefore, genotype C in Vietnam, which carried high rate of C-1858 (70%), could play an important role in causing severe chronic liver disease.

Short- and long-term effects of treatment of chronic hepatitis B and delta virus by IFN

Chronic hepatitis B virus (HBV) infection is a common infectious disease in the world. Two percent of the patients with chronic HBV infection will develop cirrhosis each year, and will die prematurely from cirrhosis or hepatocellular carcinoma. So far interferon alfa and lamivudine are the only effective drugs. Interferon alfa can be used at the dosage of 9-10 million units thrice a week for 4-6 months either intramuscularly or subcutaneously for standard treatment. Interferon provides sustained response in 1/3 of the patients when HBe Ag is (+). Response rate to interferon therapy in HBe Ag(-) patients was similar to that reported in HBe Ag(+) ones. However the responses were not sustained in many patients, serum HBV-DNA reappear in most after stopping the treatment. Extension of therapy to 1 year may be needed in patients who are unresponsive to therapy and having HBV-DNA levels <10 pg/ml and ALT >100 IU. Establishment of unresponsiveness in early phases of the therapy is important and careful follow up of serum HBe Ag may be helpful. Interferon alfa treatment of chronic HDV infection may result in temporary normalization of ALT values. Disappearance of HBV-DNA and HBs Ag from the serum upon completion of therapy dictates sustained response in chronic HDV infection. The long term effect of interferon with respect to virological and histopathological responses is poor in HDV infection and longer periods of therapy in higher doses may be beneficial.

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Impact of liver biopsy size on histological evaluation of chronic viral hepatitis: the smaller the sample, the milder the disease

BACKGROUND/AIMS

In chronic viral hepatitis, liver biopsy is performed for assessing disease activity and fibrosis. In this study, we evaluated the impact of the size of liver biopsy on the grading and staging.

METHODS

We selected 161 liver biopsies from patients with chronic types B and C hepatitis on the basis of their length (> or =3 cm) and width (1.4 mm). Ishak scoring system was used for grading and staging. The score was blindly repeated reducing the length of the specimen from > or =3 to 1.5 cm and to 1 cm long and width from 1.4 to 1 mm.

RESULTS

Reducing the length of the biopsy led to an increase of cases with mild grades: 49.7% in > or =3 cm, 60.2% in 1.5 cm and 86.6% in 1 cm long specimens (P<0.001). Similarly, cases staged as having mild fibrosis significantly increased in the shorter specimens: 59% in > or =3 cm, 68.3% in 1.5 cm and 80.1% in 1 cm long specimens (P<0.001). As for the width, both grade and stage were significantly underscored in the 1 mm samples, regardless of their length.

CONCLUSIONS

Liver biopsy size strongly influences the grading and staging of chronic viral hepatitis. The use of fine needles should be discouraged in this setting.

Inhibition of HBV targeted ribonuclease enhanced by introduction of linker

AIM: To construct human eosinophil-derived neurotoxin(hEDN) and HBV core protein (HBVc) eukaryotic fusion expression vector with a linker (Gly₄Ser)₃ between them to optimize the molecule folding, which will be used to inhibit HBV replication in vitro.

METHODS: Previously constructed pcDNA3.1(-)/TR was used as a template. Linker sequence was synthesized and annealed to form dslinker, and cloned into pcDNA3.1(-)/TR to produce plasmid pcDNA3.1(-)/HBc-linker. Then the hEDN fragment was PCR amplified and inserted into pcDNA3.1(-)/HBc-linker to form pcDNA3.1(-)/TNL in which the effector molecule and the target molecule were separated by a linker sequence. pcDNA3.1(-)/TNL expression was identified by indirect immunofluorescence staining. Radioimmunoassay was used to analyse anti-HBV activity of pcDNA3.1(-)/TNL. Meanwhile, metabolism of cells was evaluated by MTT colorimetry.

RESULTS: hEDN and HBVc eukaryotic fusion expression vector with a linker (Gly4Ser)3 between them was successfully constructed. pcDNA3.1(-)/TNL was expressed in HepG2.2.15 cells efficiently. A significant decrease of HBsAg concentration from pcDNA3.1(-)/TNL transfectant was observed compared to pcDNA3.1(-)/TR (P = 0.036, P < 0.05). MTT assay suggested that there were no significant differences between groups (P = 0.08, P > 0.05).

CONCLUSION: Linker introduction enhances the inhibitory effect of HBV targeted ribonuclease significantly.

Treatment of chronic hepatitis B: current challenges and future directions

The clinical management of chronic hepatitis B infection has entered a new era with the introduction and widespread use of oral nucleoside analogues such as lamivudine and nucleotides such as adefovir dipivoxil. From this, new challenges have now emerged in terms of preventing antiviral drug resistance, promoting viral clearance and improving long-term survival. For example, the natural history of nucleoside or nucleotide analogue-associated hepatitis B virus resistant mutants has yet to be determined. Furthermore, the increasing prevalence of HBeAg negative disease with its reduced response to current therapies represents an ongoing challenge to attempts to improve standard of care. There is increasing recognition of the pivotal role that viral load and genotype, and their complex interactions with the host immune response, play in determining the outcome of these treatment interventions. The purpose of this paper is to highlight several key factors that should be considered in the context of future clinical research and management of chronic hepatitis B.

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HBXIP functions as a cofactor of survivin in apoptosis suppression

Survivin is an anti-apoptotic protein that is overexpressed in most human cancers. We show that survivin forms complexes with a cellular protein, hepatitis B X-interacting protein (HBXIP), which was originally recognized for its association with the X protein of hepatitis B virus (HBX). Survivin-HBXIP complexes, but neither survivin nor HBXIP individually, bind pro-caspase-9, preventing its recruitment to Apaf1, and thereby selectively suppressing apoptosis initiated via the mitochondria/cytochrome c pathway. Viral HBX protein also interacts with the survivin- HBXIP complex and suppresses caspase activation in a survivin-dependent manner. Thus, HBXIP functions as a cofactor for survivin, and serves as a link between the cellular apoptosis machinery and a viral pathogen involved in hepatocellular carcinogenesis.

Individualization of interferon therapy using serum hepatitis B virus DNA to reduce viral relapse in patients with chronic hepatitis B: a randomized controlled trial

OBJECTIVE

In patients with chronic hepatitis B, viral relapse following interferon (IFN) therapy may be the result of a treatment duration that is too short to prevent hepatitis B virus (HBV) from replicating later. To reduce viral relapse in patients with chronic hepatitis B who responded to IFN, we individualized the duration of therapy according to serum HBV-DNA levels.

METHOD

Treatment duration was prolonged to maintain negative serum HBV-DNA levels for the next 6 months in 30 patients who became HBV-DNA-negative following IFN therapy (group A). Another 35 patients were treated for only 6 months (group B). All patients had HBV-DNA as well as hepatitis B surface antigen (HBsAg) in their sera for more than 6 months and were proven histologically to have chronic hepatitis. Interferon alfa (IFN-alpha) was administered subcutaneously at a dose of 5 MU/m2 three times a week.

RESULTS

There were no differences in age, gender, hepatitis B e antigen (HBeAg) positivity, serum alanine aminotransferase (ALT) levels, or serum HBV-DNA levels between the two groups. The mean duration of IFN therapy in group A was 7.2 months. At the end of treatment, serum HBV-DNA was negative in 16 patients in group A and in 18 patients in group B. The loss of serum HBV-DNA was maintained to the end of follow-up in 13 patients in group A but in only eight patients in group B. Similarly, serum ALT levels were normal in 14 patients in group A but in only nine patients in group B at the end of follow-up.

CONCLUSION

Individualization of the duration of treatment to maintain serum HBV-DNA negativity for at least 6 months may reduce the viral relapse rate following IFN therapy.

Oxidative stress in viral and alcoholic hepatitis

Liver damage ranges from acute hepatitis to hepatocellular carcinoma, through apoptosis, necrosis, inflammation, immune response, fibrosis, ischemia, altered gene expression and regeneration, all processes that involve hepatocyte, Kupffer, stellate, and endothelial cells. Reactive oxygen and nitrogen species (ROS, RNS) play a crucial role in the induction and in the progression of liver disease, independently from its etiology. They are involved in the transcription and activation of a large series of cytokines and growth factors that, in turn, can contribute to further production of ROS and RNS. The main sources of free radicals are represented by hepatocyte mitochondria and cytochrome p450 enzymes, by endotoxin-activated macrophages (Kupffer cells), and by neutrophils. The consequent alteration of cellular redox state is potentiated by the correlated decrease of antioxidant and energetic reserves. Indices of free radical-mediated damage, such as the increase of malondialdehyde, 4-hydroxynonenal, protein-adducts, peroxynitrite, nitrotyrosine, etc., and/or decrease of glutathione, vitamin E, vitamin C, selenium, etc., have been documented in patients with viral or alcoholic liver disease. These markers may contribute to the monitoring the degree of liver damage, the response to antiviral therapies and to the design of new therapeutic strategies. In fact, increasing attention is now paid to a possible "redox gene therapy." By enhancing the antioxidant ability of hepatocytes, through transgene vectors, one could counteract oxidative/nitrosative stress and, in this way, contribute to blocking the progression of liver disease.

Effect of the G1896A precore mutation on drug sensitivity and replication yield of lamivudine-resistant HBV in vitro

Hepatitis B e antigen (HBeAg) negative chronic hepatitis B (CHB) is frequently caused by a mutation (G1896A) in the hepatitis B virus (HBV) precore (PC) reading frame that creates a stop codon, causing premature termination of the PC protein. During lamivudine treatment, drug resistance develops at a similar rate in HBeAg positive and HBeAg negative CHB. Lamivudine-resistant HBV mutants have been shown to replicate inefficiently in vitro in the absence of PC mutations, but it is unknown whether the presence of PC mutations affects replication efficiency or antiviral sensitivity. This study utilized the recombinant HBV baculovirus system to address these issues. HBV baculoviruses encoding the G1896A PC stop codon mutation were generated in wild-type (WT) and lamivudine-resistant (rtM204I and rtL180M + rtM204V) backgrounds, resulting in a panel of 6 related recombinant baculoviruses. In vitro assays were performed to compare the sensitivities of the PC mutant viruses with lamivudine and adefovir and to compare relative replication yields. The PC mutation did not significantly affect sensitivities to either adefovir or lamivudine. WT HBV and PC mutant HBV showed similar replication yields, whereas the replication yields of the lamivudine-resistant mutants were greatly reduced in HBeAg positive HBVs, confirming previous observations. However, the presence of the PC mutation was found to compensate for the replication deficiency in each of the lamivudine-resistant mutants, increasing the replication yields of each virus. In conclusion, the PC stop codon mutation appears to increase the replication efficacy of lamivudine-resistant virus but does not affect in vitro drug sensitivity.

Distribution of nitric oxide synthase in normal and cirrhotic human liver

Chronic liver disorders represent a serious health problem, considering that 300 million people worldwide are hepatitis B virus carriers, and 8,000-10,000 patients per year, in the U.S. alone, die as a result of liver failure caused by hepatitis C infection. Nitric oxide synthase (NOS) regulates hepatic vasculature; however, the patterns of expression and activity of NOS proteins in healthy and diseased human livers are unknown. Sections of diseased (n = 42) and control livers (n = 14) were collected during orthotopic liver transplants and partial hepatectomy. The diseased sections included alcoholic cirrhosis, viral hepatitis, cholestasis, acute necrosis, and uncommon pathologies including alpha(1)-anti-trypsin disorder. The endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) were studied by using the citrulline assay, Western immunoblot, immunohistochemistry, and in situ hybridization. The systemic generation of plasma NO metabolites was measured by HPLC. In control livers, Ca(2+)-dependent and -independent NOS activities were identified by Western analysis as eNOS and iNOS, respectively. The eNOS was uniformly distributed in the hepatocytes and also detected in the endothelium of hepatic arteries, terminal hepatic venules, sinusoids, and in biliary epithelium. The iNOS was detected in hepatocytes and localized mainly in the periportal zone of the liver acinus. This pattern of distribution of eNOS and iNOS in normal liver was confirmed by in situ hybridization. In diseased livers, there was a significant increase in Ca(2+)-independent NOS with the corresponding strong appearance of iNOS in the cirrhotic areas. The eNOS was translocated to hepatocyte nuclei. Thus, eNOS and iNOS proteins are differentially expressed in healthy human liver, and this expression is significantly altered in cirrhotic liver disorders.

Transfusion-transmitted HBV infection in an endemic area: the necessity of more sensitive screening for HBV carriers

BACKGROUND

By NAT, HBV DNA is occasionally detectable in blood donors with past HBV infection but negative for HBsAg. Whether or not these donors can cause transfusion-transmitted HBV infections is uncertain.

STUDY DESIGN AND METHODS

To determine whether or not donors with past HBV infection but negative for HbsAg can cause HBV transfusion-transmitted infections, recipients followed for blood transfusion in a university medical center in Taiwan were studied. HBV DNA and serologic markers were tested in donors and recipients.

RESULTS

Of 1,038 enrolled recipients, 910 completed the 6-month post-transfusion follow-up visit. Of these, only 39 patients (4.3%) tested negative on the pretransfusion sample for HBsAg, anti-HBs, anti-HBc, and HBV DNA by PCR. These 39 HBV-naive recipients had been transfused with blood from 147 donations for which stored samples were available for HBV DNA testing by PCR; 11 of these HBsAg-negative samples tested positive for HBV DNA and anti-HBc. Two of the 11 patients who received the HBV-DNA-positive donations (18%) became positive for HBV DNA, and one seroconverted to anti-HBc and finally to anti-HBs, with a mild transient elevation of serum ALT activities. Based on the one confirmed case of HBV transmission, a projection was made that approximately 200 post-transfusion HBV infections could occur in one million units of transfused blood in Taiwan.

CONCLUSIONS

In HBV-endemic areas like Taiwan, where blood donors are screened for HBsAg only, the risk of transfusion-transmitted HBV appears to be substantial. Implementation of NAT for blood screening in these settings warrants consideration.

[Role of interferons in the treatment of hepatitis B and hepatitis C virus infections]

BACKGROUND

Since the discovery of hepatitis C (HCV), the efficacy of treatment has significantly progressed using standard mono-therapy: with Interferon alpha (IFN) during six months we obtained approximately 10% sustained response and currently with the association of pegylated IFN and Ribavirin a 55% sustained response was achieved.

CURRENT POSITION AND MAJOR POINTS

HCV infection continues to present therapeutic problems which have not entirely been solved, mainly related to clinical and biological tolerance, and non-responders. Moreover, the care of patients with extra-hepatic localization, cirrhotic patients, as well as therapeutic problems of co-infected HIV-HCV patients. As regards hepatitis B (HBV) new effective treatments against this virus have appeared, IFN then nucleoside analogs, some of which are available in France (i.e. lamivudine, adefovir, dipovoxil). The main objective of chronic hepatitis B treatment is to obtain the complete inhibition of the HBV virus by Hbe-antigen antibody seroconversion which would therefore significantly increase patient survival. In this article the advantages and disadvantages of the different treatments are assessed.

FUTURE PERSPECTIVES

Despite the considerable and rapid progress obtained in the therapeutic treatment of infection due to HCV and HBV a number of unknown factors remain, which warrants further trials, in particular to evaluate the efficacy as well as the tolerance of the antiviral agent association.

Oral ganciclovir for treatment of lamivudine-resistant hepatitis B virus infection: a pilot study

Although liver disease seems to be stable in most patients who are infected with lamivudine-resistant mutant hepatitis B virus (HBV) in the short term, it may progress to more-advanced disease in some patients. In our pilot study, we investigated the efficacy of oral ganciclovir for the treatment of lamivudine-resistant HBV infection. Six patients infected with lamivudine-resistant HBV (3 patients had decompensated cirrhosis and 3 had chronic active hepatitis without cirrhosis) were included. Ganciclovir was administered at a dosage of 3 g daily for 6 months. Four of 6 patients completed the 6-month treatment period. Two patients with cirrhosis completed only 2 months of ganciclovir treatment because they died of cirrhosis complications. None of the patients had a > or =2-log(10) reduction of HBV DNA and complete alanine aminotransferase normalization at the end of their treatment regimens. In conclusion, 6 months of ganciclovir treatment is not effective for suppression of lamivudine-resistant HBV infection.

Selection and characterization of human antibodies against hepatitis B virus surface antigen (HBsAg) by phage-display

Hepatitis B virus (HBV) is one of the main pathogens of hepatitis and hepatocarcinoma. Human plasma-derived antibody to HBV is being used as a prophylactic for postexposure to HBV and liver transplantation currently. However, it is required to replace the plasma-derived anti-HBs antibody (Ab) to a recombinant antibody because of limited availability of human plasma with high anti-HBs Ab titer and possible contamination of human pathogens. We constructed an anti-HBs Ab-enriched phage-display library from peripheral blood B cells of vaccinated volunteers and the size of library was approximately 1.0 x 10(7). The library was panned against hepatitis B surface antigen (HBsAg) and five different clones were isolated. All five clones exhibited the same heavy chain sequence; in contrast, light-chain exhibited one lambda and four different kappa sequences. The Fabs were expressed soluble in E. coli and exhibited affinities of 2.1 x 10(8) approximately 7.7 x 10(8) M(-1).

Phenylpropenamide derivatives AT-61 and AT-130 inhibit replication of wild-type and lamivudine-resistant strains of hepatitis B virus in vitro

The phenylpropenamide derivatives AT-61 and AT-130 are nonnucleoside analogue inhibitors of hepatitis B virus (HBV) replication. They inhibited the replication of wild-type HBV with 50% inhibitory concentrations of 21.2 +/- 9.5 and 2.40 +/- 0.92 micro M, respectively, compared to 0.064 +/- 0.020 micro M lamivudine. There were no significant differences in sensitivity between wild-type and nucleoside analogue-resistant (rtL180M, rtM204I, and rtL180M + rtM204V) HBV.

Different expression of hepatitis B surface antigen between hepatocellular carcinoma and its surrounding liver tissue, studied using a tissue microarray

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and is highly associated with chronic liver disease, including hepatitis B viral infection. In order to study the association between hepatitis B virus (HBV) infection and HCC development, tissue microarrays were used to detect the expression of hepatitis B surface antigen (HBsAg) in 194 HCCs and their surrounding liver tissues, using anti-HBsAg monoclonal antibody. The results showed that the expression of HBsAg is significantly lower in tumour tissue than in non-tumour tissue. Among the 138 cases with positive serum HBsAg, expression of HBsAg was more frequently detected in non-tumour tissue (103 cases, 75%) than in tumour tissue (11 cases, 8%). RT-PCR and Southern blot analysis were performed to explore the mechanism of the decreased expression of HBsAg in tumour cells. The RT-PCR results showed that absence or decreased expression of the HBV S gene was detected in 3/15 (20%) and 6/15 (40%) HCCs, respectively. Integration of HBV in 23 pairs of HCCs and their matched non-tumour liver tissues was studied by Southern blot. The results showed that the integrated HBV S gene sequence was detected in 19/23 tumours (83%) and 1/23 non-tumour tissues (4%), whereas the free replicative virus form was observed in 3/23 tumours (13%) and 14/23 non-tumour tissues (61%). These findings suggest that HBsAg-negative results in tumour tissues were directly related to HBV DNA insertion and provide new insights into the involvement of HBsAg in hepatocarcinogenesis.

Global control of hepatitis B virus infection

Worldwide about 350 million people are chronic carriers of the hepatitis B virus (HBV). The infection can cause acute and chronic liver disease including cirrhosis and hepatocellular carcinoma (HCC). Hepatocellular injuries of HBV infection are predominantly immune-mediated, and the natural history of chronic infection can be divided into three phases based on virus-host interactions-namely, immune tolerance, immune clearance, and viral integration phases. Four serotypes (adw, ayw, adr, and ayr) and seven genotypes (A to G) of HBV have been identified, and they show some distinct geographic distributions. The HBV genotypes may have clinical relevance and are currently under investigation. On the basis of disease burden and the availability of safe and effective vaccines, the WHO recommended that by the end of the 20th century hepatitis B vaccine be incorporated into routine infant and childhood immunisation programmes for all countries. The efficacy of universal immunisation has been shown in different countries, with striking reductions of the prevalence of HBV carriage in children. Most important, hepatitis B vaccination can protect children against HCC and fulminant hepatitis, as has been shown in Taiwan. Nevertheless, the implementation of worldwide vaccination against HBV requires greater effort to overcome the social and economic hurdles. Safe and effective antiviral treatments are available but are still far from ideal, a situation that, hopefully, will be improved soon. With hepatitis B immunisation, the global control of HBV infection is possible by the end of the first half of 21st century.

Nucleoside analogues for chronic hepatitis B: antiviral efficacy and viral resistance

Nucleoside analogues have been recently introduced in the management of chronic hepatitis B virus (HBV) infection. They mainly act by inhibition of HBV polymerase activity resulting in decrease of viral replication. They are administered orally, and most of them have an excellent tolerance and safety profile. Lamivudine is the only nucleoside analogue licensed for chronic hepatitis B. It has potent activity against HBV, and a 12-month course achieves clearance of hepatitis B e antigen (HBeAg) in 20-30% of HBeAg-positive patients and both biochemical and virological remission in more than 65-70% of HBeAg-negative chronic hepatitis B patients. Famciclovir and ganciclovir are less effective, whereas other nucleoside or nucleotide analogues, such as adefovir, entecavir, and emtricitabine, are currently under evaluation. Prolonged effective antiviral therapy is required for eradication of chronic HBV infection, but long-term treatment with nucleoside analogues has been found to be associated with progressively increasing rates of viral resistance because of emergence of resistant HBV mutant strains. Virological breakthroughs usually develop after the first 6 months of lamivudine monotherapy, and their rate ranges between 15% and 30% at 12 months and exceeds 50% after 3 yr of therapy. Resistant HBV mutant strains harbor point mutations in the HBV polymerase gene and predominantly in the well-conserved YMDD motif. Although resistant HBV strains may have impaired replication capacity compared with the wild HBV, their clinical significance has not been completely clarified yet. No significant biochemical or clinical event may develop in some cases, whereas severe biochemical breakthroughs with or without deterioration of liver function may develop in others. To date, there is no proven effective therapy for the resistant HBV mutant strains, although adefovir and entecavir seem to be interesting candidates.

Subtype specificity of anti-HBs antibodies produced by human B-cell lines isolated from normal individuals vaccinated with recombinant hepatitis B vaccine

Hepatitis B surface antigen (HBsAg) constitutes of an immunodominant determinant common to all subtypes of hepatitis B virus (HBV) and four major subtypic determinants. Subtype specificity of the human antibody response to HBsAg has already been partially studied in vivo at serum level. No comprehensive data, however, is available at the cellular level. In this study, the methods of Epstein-Barr virus (EBV) transformation and limiting dilution assay (LDA) were used to establish a large number of B-cell lines secreting anti-HBs antibody from 34 adult individuals who were good-responders to the recombinant hepatitis B vaccine (HBsAg/adw). Specificity of 222 B-cell lines was assayed by sandwich ELISA and immunoblotting, of which 216 samples (97.3%) were identified to be anti-a, 5 samples (2.3%) as anti-d and one sample (0.4%) as anti-w. The isotype of most of the anti-HBs antibodies was IgG and belonged to the IgG1 subclass. These findings which have not already been extensively investigated at the cellular level in human confirm and extend previous circumstantial results achieved in mouse and further prove the immunodominant role of the "a" determinant of HBsAg in antibody response in human.

[Study of hepatitis B virus replication and infection by other hepatitis viruses in patients with chronic hepatitis B virus infection]

AIM

To study hepatitis B virus (HBV) replication in a series of patients with HBV infection and to analyze the frequency of associated hepatitis C virus (HCV) and hepatitis D (HDV) infection.

PATIENTS AND METHOD

Serological markers of HBV, HCV and HDV, transaminase values and HBV DNA were studied in serum samples from 463 patients with chronic HBV infection.

RESULTS

Three hundred ninety-six (85.5%) were classified as hepatitis B, 33 (7.1%) as hepatitis B and C, 17 (3.6%) as hepatitis B and D and 17 (3.6%) as hepatitis B, C and D. Sixty-seven percent of patients with hepatitis B and 33% of those with chronic hepatitis B were asymptomatic HBsAg carriers. HVB DNA was identified in 27.7% of patients with hepatitis B, in 24% of those with hepatitis B and C, in 11.7% of those with hepatitis B and D and in 29.4% of those with hepatitis B, C and D. HBV DNA and elevated transaminase levels were found in 63% of HBeAg-positive patients and in only 16% of those who were anti-HBe-positive. These latter were considered candidates for antiviral treatment.

CONCLUSIONS

In our environment, most patients with HBV infection are asymptomatic HBsAg carriers. Viral replication and elevated alanine aminotransferase levels were found in 22% of the patients. Consequently, these patients are candidates for antiviral treatment. Between 3.6% and 7.1% of patients with hepatitis B presented coinfection with HCV or HDV, or both. No significant differences were found in HBV replication among the different groups.

Serum hepatitis B virus DNA levels and liver histology in inactive HBsAg carriers

BACKGROUND/AIMS

A recent NIH research workshop on hepatitis B virus (HBV) revisited the definition of healthy HBsAg carriers. The new definition inactive surface antigen (HBsAg) carriers includes an estimated serum HBV DNA level below 105 copies/ml. However, this cut-off value needs to be confirmed.

METHODS

Eighty-five consecutive patients, HBsAg-positive/HBeAg-negative with persistently normal alanine aminotransferase (ALT) and undetectable serum HBV DNA with standard assay (Versant HBV DNA Assay (bDNA), Bayer) were prospectively followed for 3.2+/-2.6 (range 0.5-11) years; 58 underwent a liver biopsy. Serum HBV DNA was quantified with a sensitive polymerase chain reaction assay (Cobas Amplicor HBV Monitor, Roche) (sensitivity 200 copies/ml), and liver histology was assessed using the Ishak scoring system.

RESULTS

The median serum HBV DNA level was 1300 copies/ml (<200-179 x 10(3) copies/ml), 16% of the subjects had no detectable serum HBV DNA and 98% had levels below 10(5) copies/ml. Histologic lesions were mild (total score <7) in all cases. Loss of HBsAg was observed in three patients, three patients experienced a transient increase in ALT (<2 x upper limit of normal), and serum HBV DNA levels remained stable (1-6 years) in 97% of the 38 patients retested.

CONCLUSIONS

In our study of inactive HBsAg carriers, the median serum HBV DNA level was 1300 copies/ml, the serum HBV DNA level was below 10(5) copies/ml in 98% of the patients, and remained stable; histological lesions were mild in all cases.

Anti-HBV hairpin ribozyme-mediated cleavage of target RNA in vitro

AIM

To study the preparation and cleavage activity of HpRz directed against the transcript of HBV core gene in vitro.

METHODS

HpRz gene designed by computer targeting the transcript of HBV core gene was cloned into the vector p1.5 between 5'-cis-Rz and 3'-cis-Rz. 32p-labeled HpRz transcript proved whether the vector fit for the preparation of hairpin ribozyme in vitro. 32p-labeled pKC transcript containing HBV core region as target-RNA was transcribed using T7 RNA polymerase and purified by denaturing PAGE. Cold HpRz transcript was incubated with 32p-labeled target-RNAs under different conditions and radio autographed after denaturing polyacrylamide gel electrophoresis.

RESULTS

HpRz has the specific ability of cleavage of target RNA at 37 degrees and 12 mM MgCl2. Km=26.31 nmol/L, Kcat=0.18/min. These results revealed that the design of HpRz was correct.

CONCLUSION

HpRz prepared in this study possesses specific catalytic activity from the identification of cleavage activity. These results indicate that hairpin ribozyme may intracellularly inhibit the replication of HBV, therefore it may become a novel potent weapon for the treatment of hepatitis B.

Immunopathogenesis of hepatitis B e antigen negative chronic hepatitis B infection

Hepatitis B e antigen (HBeAg) negative chronic hepatitis B represents currently the predominant form of chronic hepatitis due to the hepatitis B virus (HBV) in several parts of the world. In this review, recent data regarding the process of HBeAg negative HBV strain selection during the course of chronic HBV infection are presented and the potential virus and/or host-mediated mechanisms that lead to chronic liver necroinflammation, i.e. chronic hepatitis are outlined.

Diagnosis and management of pre-core mutant chronic hepatitis B

Chronic hepatitis due to pre-core hepatitis B virus (HBV) mutants presents as hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). HBeAg-negative CHB represents a late phase in the natural course of chronic HBV infection that develops after HBeAg loss and seroconversion to anti-HBe. It is usually associated with pre-core stop codon mutation at nucleotide 1896 (mainly selected in non-A HBV genotypes), but also with other pre-core changes or with mutations in the basic core promoter region (mainly in HBV genotype A). In chronic HBV infections, pre-core mutants can be detected both in patients with HBeAg-negative CHB and in inactive hepatitis B surface antigen (HBsAg) carriers. The diagnosis of HBeAg-negative CHB is based on HBsAg positivity, HBeAg negativity, and mainly on increased alanine aminotransferase (ALT) and serum HBV-DNA levels and exclusion of other causes of liver disease. The differential diagnosis between patients with CHB and inactive HBsAg carriers can be made only by close follow-up of aminotransferase activity and viraemia levels, although the cut-off level of serum HBV DNA has not been definitely determined. IgM anti-HBc levels have also been suggested as an index that increases the diagnostic accuracy for transient hepatitis flares, while liver biopsy confirms the diagnosis and evaluates the severity of the liver disease. Interferon-alpha (IFN-alpha) and lamivudine are the two drugs that have been tried, mainly in the management of HBeAg-negative CHB. A 12-month course of IFN-alpha achieves sustained biochemical remission in about 20% of patients, which has been associated with improvement in the long-term outcome of this subset. A 12-month course of lamivudine is rather ineffective, maintaining remission in less than 15% of patients after cessation of therapy. Long-term lamivudine is associated with progressively increasing rate of virological and subsequent biochemical breakthroughs due to YMDD mutants, with approximately 30% of patients remaining in remission in the third year of therapy. Several other antiviral agents are currently being evaluated in this setting with combined regimens being the most reasonable step for the near future.

Possible role of retinoids in hepatitis B virus-associated liver damage

Liver damage following hepatitis B virus (HBV) infection may be due to the action of retinoids as modulators of viral replication. The reduced rate of survival of liver grafts in patients with HBV infection could also be due to the continued presence of the virus, stimulated by retinoids in the graft tissue. Subject to obtaining empirical support for this hypothesis, the use of retinoid-blocking agents could be explored to reduce the risk of liver damage in HBV infection and to enhance the survival of liver grafts. Continued use of such agents may need to be used in conjunction with anti-viral modalities such as HBV hyperimmune globulin and lamivudine to prevent recurrent liver damage and to increase the long-term viability of the graft.

Enumeration of hepatitis B surface antigen-specific B lymphocytes in responder and non-responder normal individuals vaccinated with recombinant hepatitis B surface antigen

Determination of the frequency of specific B lymphocytes has important implications for investigation of the immune response to different antigens and pathogens. Unresponsiveness to some viruses and antigens, such as hepatitis B virus (HBV) and its surface antigen (HBsAg), has been attributed to lack or insufficient production of the specific B-cell repertoire. In this study, peripheral blood B lymphocytes of 45 adult normal individuals vaccinated with recombinant hepatitis B vaccine were transformed with Epstein-Barr virus (EBV) and cultured at different dilutions on human fetal fibroblasts as a feeder layer. The vaccinees were classified into good, poor and non-responder groups. Following 2 to 3 weeks of incubation, culture supernatants were collected from wells containing transformed and proliferating B lymphocytes. The supernatants were subsequently screened for the presence of total immunoglobulin and antibody to HBsAg (anti-HBs) by enzyme-linked immunosorbent assay (ELISA). Accordingly, positive and negative wells were enumerated in each plate and the frequency of B lymphocytes producing anti-HBs antibody was estimated based on the Poisson statistical analysis. The total number of CD19+ B lymphocytes were counted in the peripheral blood of all subjects by flow cytometry. Our results demonstrated a similar precursor frequency of specific B lymphocytes in all subject groups before vaccine administration (< 2 x 10(-5)). Following vaccination, however, a significant increase in the number of specific B lymphocytes was observed in good-responder (1.5 x 10(-4)) and to a lesser extent poor-responder (3.5 x 10(-5)) individuals, but not in non-responders. These findings suggest a defect in either the primary B-cell repertoire or helper T-cell function in non-responder individuals.

In vitro susceptibilities of wild-type or drug-resistant hepatitis B virus to (-)-beta-D-2,6-diaminopurine dioxolane and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil

Prolonged treatment of chronic hepatitis B virus (HBV) infection with lamivudine ([-]-beta-L-2',3'-dideoxy-3' thiacytidine) or famciclovir may select for viral mutants that are drug resistant due to point mutations in the polymerase gene. Determining whether such HBV mutants are sensitive to new antiviral agents is therefore important. We used a transient transfection system to compare the sensitivities of wild-type HBV and four lamivudine- and/or famciclovir-resistant HBV mutants to adefovir [9-(2-phosphonyl-methoxyethyl)-adenine; PMEA] and the nucleoside analogues (-)-beta-D-2, 6-diaminopurine dioxolane (DAPD) and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU). The drug-resistant mutants contained amino acid substitutions in the polymerase protein. We found that the M550I and M550V plus L526M substitutions, which confer lamivudine resistance, did not confer cross-resistance to adefovir or DAPD, but conferred cross-resistance to L-FMAU. The M550V substitution in isolation conferred a similar phenotype to M550I, except that it did not confer significant resistance to L-FMAU. The L526M substitution, which is associated with famciclovir resistance, conferred cross-resistance to L-FMAU but not to adefovir or DAPD. Inhibition of HBV secretion by DAPD, L-FMAU, and adefovir did not always correlate with inhibition of the generation of intracellular HBV replicative intermediates, suggesting that these analogs may preferentially inhibit specific stages of the viral replication cycle.

Duck hepatitis B virus replication in primary bile duct epithelial cells

Primary cultures of intrahepatic bile duct epithelial (IBDE) cells isolated from duckling livers were successfully grown for studies of duck hepatitis B virus (DHBV). The primary IBDE cells were characterized by immunohistochemistry using CAM 5.2, a cytokeratin marker which was shown to react specifically to IBDE cells in duck liver tissue sections and in primary cultures of total duck liver cells. Immunofluorescence assay using anti-duck albumin, a marker for hepatocytes, revealed that these IBDE cultures did not appear to contain hepatocytes. A striking feature of these cultures was the duct-like structures present within each cell colony of multilayered IBDE cells. Normal duck serum in the growth medium was found to be essential for the development of these cells into duct-like structures. When the primary cultures of duck IBDE cells were acutely infected with DHBV, dual-labeled confocal microscopy using a combination of anti-DHBV core proteins and CAM 5.2 or a combination of anti-pre-S1 proteins and CAM 5.2 revealed that the IBDE cell colonies contained DHBV proteins. Immunoblot analysis of these cells showed that the DHBV pre-S1 and core proteins were similar to their counterparts in infected primary duck hepatocyte cultures. Southern blot analysis of infected IBDE preparations using a digoxigenin-labeled positive-sense DHBV riboprobe revealed the presence of hepadnavirus covalently closed circular (CCC) DNA, minus-sense single-stranded (SS) DNA, double-stranded linear DNA, and relaxed circular DNA. The presence of minus-sense SS DNA in the acutely infected IBDE cultures is indicative of DHBV reverse transcriptase activity, while the establishment of a pool of viral CCC DNA reveals the ability of these cells to maintain persistent infection. Taken collectively, the results from this study demonstrated that primary duck IBDE cells supported hepadnavirus replication as shown by the de novo synthesis of DHBV proteins and DNA replicative intermediates.

Cross-resistance testing of antihepadnaviral compounds using novel recombinant baculoviruses which encode drug-resistant strains of hepatitis B virus

Long-term nucleoside analog therapy for hepatitis B virus (HBV)-related disease frequently results in the selection of mutant HBV strains that are resistant to therapy. Molecular studies of such drug-resistant variants are clearly warranted but have been difficult to do because of the lack of convenient and reliable in vitro culture systems for HBV. We previously developed a novel in vitro system for studying HBV replication that relies on the use of recombinant baculoviruses to deliver greater than unit length copies of the HBV genome to HepG2 cells. High levels of HBV replication can be achieved in this system, which has recently been used to assess the effects of lamivudine on HBV replication and covalently closed circular DNA accumulation. The further development of this novel system and its application to determine the cross-resistance profiles of drug-resistant HBV strains are described here. For these studies, novel recombinant HBV baculoviruses which encoded the L526M, M550I, and L526M M550V drug resistance mutations were generated and used to examine the effects of these substitutions on viral sensitivity to lamivudine, penciclovir (the active form of famciclovir), and adefovir, three compounds of clinical importance. The following observations were made: (i) the L526M mutation confers resistance to penciclovir and partial resistance to lamivudine, (ii) the YMDD mutations M550I and L526M M550V confer high levels of resistance to lamivudine and penciclovir, and (iii) adefovir is active against each of these mutants. These findings are supported by the limited amount of clinical data currently available and confirm the utility of the HBV-baculovirus system as an in vitro tool for the molecular characterization of clinically significant HBV strains.

Individualizing care of hepatitis B in older adults and Asians

PURPOSE

To review the pathophysiology of hepatitis B virus (HBV) as it relates to special groups such as older adults and Asian populations and to stratify preventive services relative to these particular populations.

DATA SOURCES

Selected scientific literature and practice guidelines.

CONCLUSIONS

The HBV is one of the most common causes of viral hepatitis. Acute infection is mostly self-limiting with nonspecific symptoms. Chronic infection is characterized by persistent serum levels of Hepatitis B surface antigen (HBsAg) for more than six months.

IMPLICATIONS FOR PRACTICE

Chronic HBV is a major risk factor for hepatocellular carcinoma. Special populations, such as older adults with decreased immune response and Asians from places with high endemic HBV infection, are at particularly high risk for progression of HBV infection to chronic states and serious liver damage.

Significant interference with hepatitis B virus replication by a core-nuclease fusion protein

Hepatitis B virus (HBV), a small DNA containing virus that replicates via reverse transcription, causes acute and chronic B-type hepatitis in humans. The limited success of current therapies for chronic infection has prompted exploration of alternative strategies. Capsid-targeted viral inactivation is a conceptually powerful approach that exploits virion structural proteins to target a degradative enzyme specifically into viral particles. Its principal feasibility has been demonstrated in retroviral model systems but not yet for a medically relevant virus outside the retrovirus family. Recently, we found that C proximal fusion to the HBV capsid protein of the Ca(2+)-dependent nuclease (SN) from Staphylococcus aureus yields a chimeric protein, coreSN, that in Escherichia coli coassembles with the wild-type capsid protein into particles with internal SN domains. Here we show that, in HBV co-transfected human hepatoma cells, less than 1 coreSN protein per 10 wild-type core protein subunits reduced titers of enveloped DNA containing virions by more than 95%. The antiviral effect depends on both an enzymatically active SN and on the core domain. CoreSN does not block assembly of RNA containing nucleocapsids but interferes with proper synthesis of viral DNA inside the capsid, or leads to rapid DNA degradation. Our data suggest an intracellular nuclease activation that, owing to the characteristics of HBV morphogenesis, is nonetheless highly virus specific. HBV may therefore be particularly vulnerable to the capsid-targeted viral inactivation approach.

High incidence of hepatitis B infections among chronic hepatitis cases of unknown aetiology

BACKGROUND/AIMS

In approximately 5% of chronic liver disease cases, no aetiology can be identified. We selected sera from 50 patients with chronic hepatitis of unknown aetiology who were enrolled in this follow-up study whose aim is to gain insight into the possible role of viruses and to define potential clinical outcomes.

METHODS

Patients' sera were screened with highly sensitive polymerase chain reaction assays for hepatitis B (HBV), C, D, and G viruses and TT virus. Sera were also retested for antibodies against the core antigen of HBV.

RESULTS

Surprisingly, HBV DNA was detected in both serum and liver in 15/50 (30%) patients. Immunostaining for HBV antigens on biopsies from patients positive for HBV DNA showed HBcAg and/or HBsAg expression at low levels in 9/15 samples. Eleven of the fifteen patients were anti-HBc positive. With one exception, all patients carried HBV genomes at low levels (10(4) copies/ml or less). Histological signs of chronic liver disease were observed in all patients.

CONCLUSION

Unrecognised HBV infections may account for a high proportion of chronic hepatitis cases of unknown aetiology. Improved HBV detection tests, which appear mandatory for the diagnosis and management of non-A non-E hepatitis as well as for improved safety of transfusions and transplantations are needed.