Intrahepatic hepatitis B virus covalently closed circular DNA can be a predictor of sustained response to therapy

Antiviral therapy of chronic hepatitis B: prevention of drug resistance

The emergence of viral resistance during treatment is becoming an important clinical issue for hepatitis B virus (HBV) antiviral therapy. Considerable progress has been achieved in the efficacy of treatment, with the development of new drugs that allow a sustained suppression of HBV replication, or at least maintain the viral load below a clinically relevant threshold. Although most drugs currently registered for the treatment of chronic hepatitis B are effective in suppressing viral load, long-term therapy is required to avoid viral reactivation and progression of liver disease. Because of the variability of the HBV genome, such long-term treatments are associated with the emergence of resistant viral strains, which may compromise the initial clinical benefit of the treatment.

Safety and tolerability of sequential pegylated IFN-alpha2a and tenofovir for hepatitis B infection in HIV(+) individuals

Chronic hepatitis B virus infections are a major cause of morbidity and mortality in HIV co-infected patients. The standard of care for treating HCV co-infection has been guided by major clinical trials, but the treatment of HBV co-infection has not been as thoroughly studied and the standard of care remains largely untested. The single pill formulation of tenofovir with emtricitabine has become a standard treatment approach in HBV co-infected patients. WU114 was a phase 1 clinical trial that examined the safety and tolerability of sequential treatment of HBV with pegylated interferon-alpha2a plus delayed-initiation tenofovir in HIV co-infected individuals. We postulated that initial HBV viral load reduction with pegylated interferon prior to initiation of nucleoside/nucleotide therapy would increase seroconversion events and durability of HBV virologic suppression. No severe pegylated IFN-alpha2a drug toxicities were seen in either the monotherapy or delayed tenofovir arms. Sequential pegylated interferon and tenofovir-based therapy was tolerable and should be compared with dual nucleoside/nucleotide suppression to determine relative frequencies of seroconversion and durability of HBV suppression in co-infected patients.

Impaired intrahepatic hepatitis B virus productivity contributes to low viremia in most HBeAg-negative patients

BACKGROUND & AIMS

Knowledge of factors regulating transcriptional activity of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) may help in understanding mechanisms of viral decay and how these processes are thwarted in chronically HBV-infected patients.

METHODS

Liver biopsies from 119 treatment-naive chronically infected patients (42 HBeAg-positive and 77 HBeAg-negative) were determined for HBV transcriptional and replicative activity.

RESULTS

Significantly lower median serum HBV DNA (-4 log), intrahepatic HBV DNA (-2 log), and cccDNA (-1 log) amounts were measured in HBeAg-negative versus HBeAg-positive patients. Despite a good correlation found between intrahepatic amounts of progeny virions and serum HBV DNA in all patients, cccDNA levels did not correlate with serum titers in HBeAg-negative individuals. Analysis of HBV RNA transcripts showed that impaired virion productivity in HBeAg-negative individuals was due to lower steady-state levels of pregenomic RNA produced per cccDNA. Interestingly, preS/S RNA levels and serum HBsAg concentrations did not differ between HBeAg-positive and HBeAg-negative patients when normalized for cccDNA contents, showing that subviral particle production was not impaired in HBeAg-negative patients and correlated with cccDNA levels. Although the majority of HBeAg-negative individuals harbored cccDNA with common precore and/or basal core promoter mutations, occurrence of these variants was not responsible for reduced viral replication. Instead, replacement of wild-type cccDNA with core promoter mutants reestablished high virion productivity.

CONCLUSIONS

Lower viremia in HBeAg-negative individuals is not only due to lower cccDNA content but also to impaired virion productivity, which can arise without emergence of HBeAg variants and without affecting HBsAg production.

Presence of intrahepatic (total and ccc) HBV DNA is not predictive of HBV recurrence after liver transplantation

Previous studies reported that hepatitis B virus (HBV) deoxyribonucleic acid (DNA) can be detected in livers of patients who received transplants for hepatitis B despite the absence of serological markers of HBV recurrence. Quantification of HBV DNA was not performed and presence of covalently closed circular (ccc) DNA was not analyzed in most studies. We aimed to quantify total and ccc HBV DNA in explant liver and post-orthotopic liver transplantation (OLT) biopsies and to correlate the values with HBV recurrence post-OLT. Frozen liver tissue from 34 patients (9 with explant liver only, 9 with explant liver and post-OLT liver biopsies, and 16 with post-OLT biopsies only) in the National Institutes of Health HBV-OLT study was examined using real-time polymerase chain reaction (PCR). Among the 18 patients with explant liver, 7 were hepatitis B e antigen (HBeAg)-positive, 8 had detectable serum HBV DNA, and 10 received antiviral therapy prior to OLT. Total and ccc HBV DNA was detected in explant livers of 17 and 16 patients, respectively. Of the 10 patients who received antiviral therapy pre-OLT, serum HBV DNA was undetectable in 8 at transplantation but 7 had detectable total and ccc HBV DNA in their explant liver. Of the 25 patients with post-OLT biopsies, total HBV DNA was detected in 83% and ccc DNA in 17% of 47 biopsies, although only 2 patients had HBV recurrence. In conclusion, total and ccc HBV DNA could be detected in explant livers of most patients despite antiviral therapy pre-OLT. Total but not ccc HBV DNA could be detected in post-OLT liver biopsies of most patients despite undetectable serum HBV DNA and hepatitis B surface antigen (HBsAg). Our findings suggest that occult HBV reinfection occurs in most HBV patients after OLT and continued administration of appropriate prophylactic therapy is important in preventing overt HBV recurrence.

Virological Response to Different Combination Regimes of Peginterferon α-2b and Lamivudine in Hepatitis B e Antigen Positive Chronic Hepatitis B

Objective

To investigate whether simultaneous commencement of peginterferon α-2b and lamivudine treatment has more potent hepatitis B virus (HBV) DNA suppression than staggered regimes.

Methods

Thirty HBeAg-positive chronic hepatitis B patients were randomized in 1:1:1 ratio to 32-week peginterferon started simultaneously with lamivudine (group 1), eight weeks before lamivudine (group 2) or eight weeks after commencement of lamivudine (group 3). All patients received lamivudine until week 104.

Results

At week 52, the log HBV DNA reduction in group 1 (6.38) was more profound than that in group 2 (3.43, P=0.022) and tended to be superior to that in group 3 (4.44, P=0.060). HBeAg seroconversion developed in six (67%) patients in group 1, three (33%) patients in group 2 ( P=0.35 versus group 1) and one (10%) patient in group 3 ( P=0.037 versus group 1). At week 104, the log HBV DNA reduction in group 1 (6.13) versus that in group 2 (5.24) and group 3 (5.15) was insignificantly different. Lamivudine resistance was found in four (14%) patients at week 104. There was 1.22 and 2.52 median log reduction in covalently closed circular DNA and total intrahepatic HBV DNA, respectively, at week 104, but there was no difference among the three groups. At 24 weeks post-treatment, sustained HBeAg seroconversion was observed in five (56%), three (33%) and four (40%) of the patients in groups 1, 2 and 3, respectively ( P>0.05).

Conclusions

Simultaneous commencement of peginterferon and lamivudine tend to provide more profound viral suppression than staggered regimes in the early phase of treatment.

Molecular testing in the diagnosis and management of chronic hepatitis B

Hepatitis B virus (HBV) is an enveloped virus with a small (3.2-kb) partially double-stranded DNA genome that causes acute and chronic infections. The impact of these infections on public health worldwide is enormous, with an estimated prevalence of 2 billion acute infections and 360 million chronic infections globally. This review focuses on chronic hepatitis B and the molecular assays used in its diagnosis and management. Background information, including that about features of the hepatitis B virion, viral replication, and epidemiology of infection, that is important for understanding chronic hepatitis B and molecular diagnostic tests for HBV is provided. To facilitate an understanding of the utility of molecular testing for chronic hepatitis B, the four stages of chronic hepatitis B infection that are currently recognized, as well as an additional entity, occult hepatitis B, that can be diagnosed only by sensitive nucleic acid amplification methods, are reviewed in detail, including available therapeutic agents. The molecular diagnostic content focuses on tests for HBV DNA quantification, genotyping, and mutation detection (including precore/core promoter and antiviral resistance mutations). The discussion of these tests encompasses their current utility and performance characteristics, drawing from current clinical guidelines and other studies from the literature. In recognition of the continual evolution of this field, the final section describes emerging molecular markers with future diagnostic potential.

Future prospectives for the management of chronic hepatitis B

Chronic hepatitis B virus infection affects about 400 million people around the globe and causes approximately one million deaths a year. Since the discovery of interferon-α as a therapeutic option the treatment of hepatitis B has evolved fast and management has become increasingly complicated. The amount of viral replication reflected in the viral load (HBV-DNA) plays an important role in the development of cirrhosis and hepatocellular carcinoma. The current treatment modalities for chronic hepatitis B are immunomodulatory (interferons) and antiviral suppressants (nucleoside and nucleotide analogues) all with their own advantages and limitations. An overview of the treatment efficacy for both immunomodulatory as antiviral compounds is provided in order to provide the clinician insight into the factors influencing treatment outcome. With nucleoside or nucleotide analogues suppression of viral replication by 5-7 log₁₀ is feasible, but not all patients respond to therapy. Known factors influencing treatment outcome are viral load, ALT levels and compliance. Many other factors which might influence treatment are scarcely investigated. Identifying the factors associated with response might result in stopping rules, so treatment could be adapted in an early stage to provide adequate treatment and avoid the development of resistance. The efficacy of compounds for the treatment of mutant virus and the cross-resistance is largely unknown. However, genotypic and phenotypic testing as well as small clinical trials provided some data on efficacy in this population. Discontinuation of nucleoside or nucleotide analogues frequently results in viral relapse; however, some patients have a sustained response. Data on the risk factors for relapse are necessary in order to determine when treatment can be discontinued safely. In conclusion: chronic hepatitis B has become a treatable disease; however, much research is needed to tailor therapy to an individual patient, to predict the sustainability of response and determine the best treatment for those failing treatment.

Serum HBV RNA is a predictor of early emergence of the YMDD mutant in patients treated with lamivudine

Lamivudine (LAM) is a nucleoside analogue widely used for the treatment of chronic hepatitis B virus (HBV) infection. Emergence of resistant strains with amino acid substitutions in the tyrosine-methionine-aspartate-aspartate (YMDD) motif of reverse transcriptase is a serious problem in patients on LAM therapy. The amount of covalently closed circular DNA in the serum is reported to be higher in patients who develop YMDD mutants than in those without mutants. However, there is no useful serum marker that can predict early emergence of mutants during LAM therapy. Analysis of patients who were treated with entecavir (n=7) and LAM (n=36) showed some patients had high serum levels of HBV RNA. Median serum levels of HBV RNA were significantly higher in patients in whom the YMDD mutant had emerged within 1 year (n=6, 1.688 log copies/ml) than in those in whom the YMDD mutant emerged more than 1 year after treatment (n=12, 0.456 log copies/ml, P=0.0125) or in whom the YMDD mutant never emerged (n=18, 0.688 log copies/ml, P=0.039). Our results suggest that HBV RNA is a valuable predictor of early occurrence of viral mutation during LAM therapy.

Formation of hepatitis B virus covalently closed circular DNA: removal of genome-linked protein

Hepatitis B virus (HBV) contains a small, partially double-stranded, relaxed circular (RC) DNA genome. RC DNA needs to be converted to covalently closed circular (CCC) DNA, which serves as the template for all viral RNA transcription. As a first step toward understanding how CCC DNA is formed, we analyzed the viral and host factors that may be involved in CCC DNA formation, using transient and stable DNA transfections of HBV and the related avian hepadnavirus, duck hepatitis B virus (DHBV). Our results show that HBV CCC DNA formed in hepatoma cells was derived predominantly from RC DNA with a precise junction sequence. In contrast to that of DHBV, HBV CCC DNA formation in cultured cells was accompanied by the accumulation of a RC DNA species from which the covalently attached viral reverse transcriptase (RT) protein was removed (protein-free or PF-RC DNA). Furthermore, whereas envelope deficiency led to increased CCC DNA formation in DHBV, it resulted mainly in increased PF-RC, but not CCC, DNA in HBV, suggesting that the envelope protein(s) may negatively regulate a step in CCC DNA formation that precedes deproteination in both HBV and DHBV. Interestingly, PF-RC DNA, in contrast to RT-linked RC DNA, contained, almost exclusively, mature plus-strand DNA, suggesting that the RT protein was removed preferentially from mature RC DNA.

Hepatitis B virus genetic variability and evolution

Hepatitis B virus has been evolving gradually over a long period of time, resulting in a large amount of genetic diversity, despite the constraints imposed by the complex genetic organization of the viral genome. This diversity is partly due to virus/host interactions and partly due to parallel evolution in geographically distinct areas. Recombination also appears to be an important element in HBV evolution. Also, human intervention in the form of mass vaccination and antiviral treatment will reduce the burden of HBV-related liver disease but may also be accelerating evolution of the virus.

Flowcytometric quantitation of hepatitis B viral antigens in hepatocytes from regular and fine-needle biopsies

The aim of the study was to investigate the use of flow cytometry, as an alternative for immunohistochemistry, for the detection of viral antigens in the liver of patients with chronic hepatitis B virus (HBV) infection. Hepatocytes were obtained from regular- and fine-needle biopsy from HBV positive (n=17) and negative (n=7) patients and quantified by flow cytometry for intracellular hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). Number of HBsAg positive hepatocytes ranged from 0 to 83%. A significant correlation was found between the percentage of infected hepatocytes and the intracellular expression level of HBsAg (R=0.841, p<0.001). The specificity and sensitivity of flow cytometry was similar to immunohistochemistry. Of the patients on anti-viral treatment with undetectable serum HBV DNA (<400 copies/ml), two had high HBsAg expression in the liver. HBcAg staining was found in 3 out of 15 patients, with 2-3% positive hepatocytes. The results obtained with fine-needle aspiration biopsy (n=12) were comparable to regular biopsy. In conclusion, flowcytometric quantitation of HBV antigens is sensitive and provides relevant information on the course of infection. The minimally invasive fine-needle biopsy provides a useful alternative for regular-needle biopsy for monitoring intrahepatic antiviral responses during therapy.

Future therapy for hepatitis B

Therapy for hepatitis B virus (HBV) infection, the most common worldwide cause of viremia and chronic liver disease, is currently limited to interferon preparations and nucleoside or nucleotide analogs. Although these treatments result in suppression of HBV replication, virologic rebounds are common when treatment is ended or when viral resistance emerges. This review considers novel approaches targeting viral or host factors involved in the HBV lifecycle, as well as immunomodulatory strategies that are likely to be used concomitantly with antiviral drugs in future research.

Prediction of treatment-related HBsAg loss in HBeAG-negative chronic hepatitis B: a clue from serum HBsAg levels

BACKGROUND

Quantification of HBsAg in serum may be of clinical importance in predicting HBsAg seroconversion and complete response to treatment.

METHODS

Serum HBsAg was quantified by ADVIA Centaur in 63 patients with HBeAg-negative chronic hepatitis B (CHBe-). A total of 42 had received interferon-alpha2b (IFN-alpha2b) (median 12.1 months; 19 sustained responders including 12 HBsAg-seroconvertors; 23 non-sustained responders) and 21 were on lamivudine (LAM) (median 33.0 months). Measurements were done at baseline, during and at the end of treatment, and during and at the end of follow-up.

RESULTS

Baseline median [interquartile range (IQR)] HBsAg levels in all patients were 3286 (1602-7458) IU/ml, not different between IFN- and LAM-treated (P = 0.139). IFN significantly depressed HBsAg in all patients except IFN non-responders, but HBsAg decline persisted only in sustained responders. Low pretreatment HBsAg level was the only significant prognostic variable of HBsAg seroconversion by multivariate analysis. LAM treatment also suppressed HBsAg levels but at a significantly slower rate compared with IFN (P = 0.022). The median (IQR) estimated time to HBsAg undetectability (ETU-HBsAg), derived from best curve fitting, was 127 (87.6-263.5) months for LAM virological responders and 65.3 (36.3-95.0) months for IFN sustained responders (P = 0.002). In 12 HBsAg seroconvertors, ETU-HBsAg was similar to the real time of HBsAg loss (P = 0.525) and seroconversion (0.056).

CONCLUSIONS

In CHBe-, IFN induces a sharper decrease in serum HBsAg compared with LAM and low pretreatment levels are significantly associated with HBsAg serocon-version. Serial HBsAg measurements may be useful for prediction of HBsAg loss and our data suggest that to achieve this, 5.4 years of sustained response to IFN or 10.6 years of effective LAM therapy are probably needed.

Quantitative analysis of HBV cccDNA from clinical specimens: correlation with clinical and virological response during antiviral therapy

Attempts to investigate changes in various forms of intrahepatic hepatitis B virus (HBV) DNA during antiviral therapy have been hampered by limitations in technologies and scarcity of adequate tissue for analysis. We used a sensitive, specific assay to detect and quantitate covalently closed circular DNA (cccDNA) from total intrahepatic HBV DNA in clinical liver specimens. Total HBV DNA and cccDNA from 21 needle-biopsy specimens were quantified, with levels ranging from 0.1 to 9.8 copies/cell and 0.3 to 491.0 copies/cell, respectively. Then, we performed the same determinations on baseline and week-52 liver needle-biopsy specimens from eight patients enrolled in a clinical trial and evaluated the association between intrahepatic HBV DNA levels and serological and virological endpoints. In most patients, levels of intrahepatic HBV DNA, including cccDNA, decreased over the 52-week study, regardless of therapy or serological outcome. Higher ratios of cccDNA to total HBV DNA were detected at week 52 than at baseline indicating a shift in predominance of nonreplicating virus in posttreatment specimens. In patients who achieved treatment-related or spontaneous hepatitis B e antigen (HBeAg) responses, including those harbouring tyrosine-methionine-aspartate-aspartate-mutant HBV, levels of intrahepatic and serum HBV DNA suppression were greater than those in patients without HBeAg responses. In conclusion, this pilot study of intrahepatic HBV replicative forms in patients with chronic hepatitis B indicated that total intrahepatic and, specifically, cccDNA levels are not static but change as a reflection of serological and virological events.

Intrahepatic levels and replicative activity of covalently closed circular hepatitis B virus DNA in chronically infected patients

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is responsible for viral persistence in the natural course of chronic HBV infection and during prolonged antiviral therapy and serves as the template for the production of HBV pregenomic RNA (pgRNA), the primary step in HBV replication. In this study, we have developed and applied sensitive and specific quantitative real-time polymerase chain reaction (PCR) assays for the measurement of intrahepatic concentration, pgRNA production, and replicative activity of cccDNA in liver biopsy samples from 34 non-treated patients with chronic hepatitis B (CHB); 12 hepatitis B e antigen (HBeAg)(+) and 22 HBeAg(-). Median copy number for cccDNA was 1.5 per cell and for pgRNA significantly higher, 6.5 copies per cell, with a good correlation between cccDNA and pgRNA levels in all samples. In HBeAg(-) patients, median values of cccDNA and pgRNA levels were 10-fold and 200-fold lower than in HBeAg(+), respectively, reflecting the differences in viral activity and clinical characteristics of the two groups. Furthermore, the replicative activity of intrahepatic cccDNA was significantly lower in HBeAg(-) patients harboring mutant HBV strains than in HBeAg(+) patients: median 3.5 versus 101 pgRNA copies per cccDNA molecule. In conclusion, the levels of both HBV cccDNA, a marker of HBV persistence, and pgRNA, an indicator of viral replication, in the liver of chronically infected patients correlate with viral activity and the phase of HBV infection. The combined measurement of cccDNA and pgRNA levels provides valuable information on the presence and replicative activity of intrahepatic HBV cccDNA.

Peginterferon alpha-2b plus adefovir induce strong cccDNA decline and HBsAg reduction in patients with chronic hepatitis B

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is responsible for persistent infection of hepatocytes. The aim of this study was to determine changes in intrahepatic cccDNA in patients with chronic hepatitis B (CH-B) during 48 weeks of antiviral therapy and its correlation to virological, biochemical, and histological parameters. Twenty-six HBsAg-positive CH-B patients received combination treatment with pegylated interferon alpha-2b (peg-IFN) and adefovir dipivoxil (ADV) for 48 weeks. Paired liver biopsies from before and at the end of treatment were analyzed for intrahepatic HBV-DNA. Median serum HBV-DNA had decreased by -4.9 log10 copies/mL at the end of treatment and was undetectable in 13 individuals (54%). Median intrahepatic total HBV-DNA and cccDNA had decreased by -2.2 and -2.4 log10, respectively. Changes in intracellular HBV-DNA positively correlated with HBsAg serum reduction and were accompanied by a high number of serological responders. Eight of 15 HBeAg-positive patients lost HBeAg, and five developed anti-HBe antibodies during treatment. These eight patients exhibited lower cccDNA levels before and at the end of therapy than did patients without HBeAg loss. Four patients developed anti-HBs antibodies. ALT normalized in 11 patients. The number of HBs-antigen- and HBc-antigen-positive hepatocytes was significantly lower after treatment, suggesting the involvement of cytolytic mechanisms. In conclusion, combination therapy with peg-IFN and ADV led to marked decreases in serum HBV-DNA and intrahepatic cccDNA, which was significantly correlated with reduced HBsAg.

Hepatitis B virus RNA is measurable in serum and can be a new marker for monitoring lamivudine therapy

BACKGROUND

Changes in the serum hepatitis B virus (HBV) RNA level during lamivudine therapy were compared to those in the serum HBV DNA and HBV core-related antigen (HBVcrAg) levels in 24 patients with chronic hepatitis B.

METHODS

For measurement of HBV RNA, total nucleic acid was extracted from serum samples and treated with RNase-free DNase I. After cDNA synthesis from extracted RNA, HBV RNA was measured by real-time detection polymerase chain reaction.

RESULTS

The peak fraction of HBV RNA in serum samples was consistent with peak fractions of HBV DNA and HBV core protein in a sucrose gradient analysis, indicating that HBV RNA was incorporated into virus particles. All levels of HBV DNA, HBV RNA, and HBVcrAg decreased gradually during lamivudine therapy (P < 0.001 for all). The amount of decrease from the start of lamivudine therapy was significantly higher for HBV DNA than for HBV RNA or HBVcrAg during 6 months of lamivudine therapy (P < 0.001 for all). However, a similar difference was not seen between HBV RNA and HBVcrAg levels during that period. The HBV RNA level was significantly correlated (P < 0.001 for all) with levels of HBV DNA and HBVcrAg both at the beginning and 2 months after the start of lamivudine therapy.

CONCLUSIONS

HBV RNA is detectable in serum in a form indicating incorporation into virus particles, and its serum level might serve as a new viral marker with a significance different from that of HBV DNA in lamivudine therapy.

Tenofovir for patients with lamivudine-resistant hepatitis B virus (HBV) infection and high HBV DNA level during adefovir therapy

Incomplete virological response to adefovir dipivoxil (ADV) has been observed in patients with lamivudine-resistant hepatitis B virus (HBV) infection and may be associated with developing resistance and disease progression. We therefore investigated whether the efficacy of viral suppression could be improved by replacing ADV with tenofovir disoproxil fumarate (TDF). Twenty patients with chronic HBV infection (18 HBeAg+), viral breakthrough during lamivudine therapy, and persistent viral replication (>10(4) copies/mL) after 15 months of ADV monotherapy (range 4-28 months) were treated with TDF 300 mg daily and were retrospectively analyzed. A screening for nucleoside/nucleotide analogue resistance mutations within the HBV polymerase gene was performed in all patients by direct sequencing. Within a median of 3.5 months, application of TDF led to undetectable HBV DNA in 19 of 20 patients, as demonstrated by suppression of HBV DNA below the detection limit of 400 copies/mL. Initially elevated ALT levels had normalized in 10 of 14 patients by the end of follow-up (median 12 months, range 3-24 months). Four patients lost HBeAg, after 3, 4, 5, and 16 months, and one patient seroconverted to anti-HBs after 16 months of TDF therapy. Lamivudine-associated mutations (rtV173L, rtL180M, rtM204V/I) could be detected in 6 patients at baseline of TDF, but this obviously did not influence the response. ADV-resistant mutations were not detected. No side effects were reported. In conclusion, these preliminary observations strongly suggest that TDF might be a highly effective rescue drug for HBV-infected patients with altered responsiveness to treatment with lamivudine and ADV.

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Genetic polymorphisms of interleukin-1-beta in association with sustained response to anti-viral treatment in chronic hepatitis B in Chinese

BACKGROUND

Interleukin-1beta is a pro-inflammatory cytokine that may influence host defence against viral infection.

AIM

To investigate the impact of interleukin-1beta gene polymorphism on the response to anti-viral treatment.

METHOD

Hepatitis B e antigen-positive chronic hepatitis B patients who have completed a randomized study of peginterferon alpha-2b and lamivudine combination vs. lamivudine monotherapy were included. Sustained responders were patients who had persistent hepatitis B e antigen loss and less than two occasions with hepatitis B virus DNA >100 000 copies/mL at any time up to week 76 post-treatment. Polymorphisms at interleukin-1beta-511, -31 and -3954 and interleukin-1 receptor antagonist (RN) were studied.

RESULTS

Eighty-eight patients were studied and 18 (20%) patients developed sustained response. Near complete linkage disequilibrium was observed between interleukin-1beta-511 and -31 loci. After adjustment for the potential confounding effects of treatment allocation, hepatitis B virus genotype, pre-treatment alanine aminotransferase and hepatitis B virus DNA levels, genotype C/T at interleukin-1beta-511 was found to be associated with higher sustained response than genotype C/C (adjusted odds ratio 10.4, 95% CI 1.1, 96.9, P = 0.040). The proportion of sustained responders tend to be higher among patients with allele T at interleukin-1beta-511 (83%) than those without (70%) (P = 0.058).

CONCLUSION

High interleukin-1beta production genotype at position -511 has a favourable response to anti-viral treatments.

The clinical virology of hepatitis B

Hepatitis B virus (HBV) is a major human health problem as approximately 8% of the world’s population are chronic carriers and there are over a million HBV-related deaths annually. Treatment of HBV is extremely difficult, as the unique viral replication strategy results in both a continual source of stable DNA molecules that are the template for viral replication and gene expression, and a pool of viral quasispecies from which different isolates may emerge as selection pressures alter. Although the use of antiviral therapies has improved outcomes significantly for many chronically infected individuals, the emergence of drug-resistant and immune/vaccine-escape viruses ensures there is a continuing need for the development of new and imaginative approaches to control and eventually eradicate HBV.

Hepatitis B virus drug resistance: mechanism and clinical implications for the prevention of treatment failure

Hepatitis B virus (HBV) infection remains a major public health problem worldwide. Recently, the research efforts to identify new inhibitors enabled the development of antiviral agents to treat patients chronically infected by HBV. In clinical practice, the use of nucleoside analogs, which inhibit viral polymerase activity, induces suppression of viral replication accompanied by an improvement in biochemical and histological conditions in most patients. However, many clinical studies revealed the emergence of drug-resistant mutants during extended treatment. This review focuses on the mechanism of HBV drug-resistant mutant selection and on the clinical implications of HBV drug resistance for the prevention of treatment failure.

Antiviral therapy of chronic hepatitis B

Treatment of chronic hepatitis B remains a clinical challenge. Long-term viral suppression is a major goal of antiviral therapy to improve the clinical outcome of the patients. Antiviral treatment of chronic hepatitis B relies currently on immune modulators such as interferon alpha and its pegylated form, and viral polymerase inhibitors. Because of the slow kinetics of viral clearance and the spontaneous viral genome variability, viral mutants resistant to nucleoside analogs may be selected. However, the development of new antiviral agents is rapidly improving the offing of therapy of chronic hepatitis B. These new therapeutic advances are reviewed in this manuscript.

Therapy of hepatitis B -- viral suppression or eradication?

The practicing clinician is currently faced with a number of treatment options for chronic hepatitis B. Beginning in 1998 with the licensing of lamivudine and subsequently adefovir, the treatment paradigm shifted from 4 to 6 months of conventional alfa interferon to a year of nucleoside analog therapy. However, prolonged treatment with nucleoside analogs is often needed to optimize virological response. Recently, a 48-week regimen of pegylated interferon for hepatitis B e antigen (HBeAg)-positive and HBeAg-negative chronic hepatitis B has been shown to be effective, and long-term nucleoside analog therapy has been demonstrated to maintain viral suppression. These findings have added to the complexity of decision-making and have raised questions about whether a finite course of pegylated interferon or nucleoside analog therapy, with possible long-term maintenance, is better as first-line therapy. Each of these fundamentally different approaches has advantages and limitations, and both have a place in the therapeutic armamentarium against chronic hepatitis B. Long-term therapy with nucleoside analogs, however, raises a number of practical concerns that have not been fully addressed as of yet. I will present evidence in support of the recommendation that antiviral therapy should ideally be directed toward achieving the highest rate of viral clearance with the shortest interval of treatment.

Detection of hepatitis B virus cccDNA with modified polymerase chain reaction

AIM: To establish a simple and fast hepatitis B virus covalently closed circular DNA(cccDNA) detecting method based on polymerase chain reaction(PCR) with satisfactory sensitivity and specificity.

METHODS: The cccDNA and the relaxed circular DNA (rcDNA) were extracted from HepG2.2.15 cells and supernatant, respectively, and then purified. Two pairs of specific PCR primes were designed to cover the single strand area of rcDNA. And two pairs of non-specific PCR primes were designed to cover the double strand area of rcDNA. Before and after digested by single-strand-specific mung bean nuclease(MBN), cccDNA and rcDNA samples were amplified by specific primes and non-specific primes. Whether the digested cccDNA can be amplified by specific primes, without amplifying the digested rcDNA, was observed. The PCR parameters such as substrate amount and circulation times were changed during amplification. The HBV genome plasmid was used as control; and the HBV samples from patient with hepatitis B was used for practical test.

RESULTS: Different amounts of rcDNA template were amplified by specific and non-specific primes. More than 10⁴ and 10² rcDNA template molecules were amplified by two pairs of specific and non-specific primes, respectively. The specific primes could not discriminate between rcDNA and cccDNA when the template molecules were overabundant. Before and after the digestion by MBN, different amounts of cccDNA were amplified by specific and non-specific primes; and after the digestion, rcDNA templates were amplified by non-specific primes, but not by specific primes. With this strategy, we found the virus samples from the serum of the patient with chronic hepatitis B contained mainly rcDNA and a small quantity of cccDNA, while the samples from hepatocytes contained mainly cccDNA.

CONCLUSION: The combination of MBN selective digestion and specific PCR amplification of the cccDNA is a simple, fast, sensitive and specific method for the detection of HBV cccDNA.