Interferon monotherapy in chronic hepatitis B

Hepatitis B surface antigen could contribute to the immunopathogenesis of hepatitis B virus infection

Various findings concerning the clinical significance of quantitative changes in hepatitis B surface antigen (HBsAg) during the acute and chronic phase of hepatitis B virus (HBV) infection have been reported. In addition to being a biomarker of HBV-replication activity, it has been reported that HBsAg could contribute to the immunopathogenesis of HBV persistent infection. Moreover, HBsAg could become an attractive target for immune therapy, since the cellular and humeral immune response against HBsAg might be able to control the HBV replication and life cycle. However, several reports have described the immune suppressive function of HBsAg. HBsAg might suppress monocytes, dendritic cells (DCs), natural killer (NK), and natural killer T (NK-T) cells by direct interaction. On the other hand, cytotoxic T lymphocytes (CTLs) and helper T (Th) cells were exhausted by high amounts of HBsAg. In this paper, we focused on the immunological aspects of HBsAg, since better understanding of the interaction between HBsAg and immune cells could contribute to the development of an immune therapy as well as a biomarker of the state of HBV persistent infection.

Toll-like receptors signaling contributes to immunopathogenesis of HBV infection

Innate and adaptive immune systems have important role in the pathogenesis of acute and chronic infection with hepatitis B virus (HBV). These immune responses are mediated through complex interactions between the innate immune response and adaptive immune response. Toll-like receptors (TLRs) are a family of innate immune-recognition receptors that recognize the molecular patterns associated with microbial pathogens. So far, TLR1 to 13 were found in human or mice and investigated to detect the target molecules and the downstream mechanisms of these unique systems. Stimulation by their ligands initiates the activation of complex networks of intracellular signaling transduction and innate and adaptive immune-related cells (NK, NK-T, monocytes, dendritic cells, T cells, B cells, and Tregs, etc.). However, reports on such relationships between HBV and TLRs have been relatively rare in comparison to those on HCV and TLRs, but have recently been increasing. Thus, a review of TLRs involved in the pathogenesis of HBV infection may be needed toward better understanding of the immunopathogenesis of HBV infection.

An overview of treatment response rates to various anti-viral drugs in Pakistani hepatitis B virus infected patients

Hepatitis B virus (HBV) is one of the leading health problem with up to 350 million affected people worldwide including 4.5 million only in Pakistan. It has mortality rate of 0.5 to 1.2 million per year worldwide. Pakistan lies in the endemic region with 3-5% HBV carrier rate in the country. The present article reviews the literature on the treatment response of HBV prevalent in Pakistani population. The average treatment response of Lamivudine and interferon-α is 25.81% and 47.95%, respectively. Peg-Interferon was shown to be not effective against the HBV/HCV (hepatitis C virus)/HDV (hepatitis Delta virus) co-infection. The present study reveals that interferon-α is the most effective therapy available for HBV infection prevalent in Pakistani population. Genotype C & D are the most common HBV genotypes in Pakistan and are associated with increased severity and less response to interferon therapy. This poses a great challenge for physicians and researchers and further studies are needed to describe the outcome of the current therapies recommended against HBV infection in Pakistani population.

Effect of conventional interferon-α in patients with HBeAg-positive chronic hepatitis B: a systematic review and meta-analysis

BACKGROUND

Although a few studies have tested the effect of interferon-α on chronic hepatitis B, its treatment effect remains uncertain, and the association of treatment effect with intervention characteristics has not been thoroughly explored. This study examined the effect of IFN-α in patients with HBeAg-positive chronic hepatitis B, and investigated the characteristics associated with treatment effect.

METHODS

We searched MEDLINE, Scientific Citation Index, Current Content Connect, Cochrane Controlled Trial Register, and Chinese Biomedical Database, all up to 15 September 2009. We included randomized trials comparing IFN-α to placebo, no treatment, or standard care (SC) in patients with HBeAg-positive chronic hepatitis B. Two reviewers assessed the risk of bias and extracted data, independently and in duplicate. We conducted meta-analyses of the included studies, and subgroup analyses to examine the association of pre-specified characteristics (eg, dose, treatment duration) with treatment effect.

RESULTS

A total of 31 randomized controlled trials, involving 2164 patients, were included. The risk of bias varied across studies. Compared with placebo, no treatment, or SC, IFN-α improved loss of HBeAg (OR 2.36, 95% CI 1.83 to 3.04), HBV DNA undetectability (OR 2.04, 95% CI 1.28 to 3.32), HBeAg seroconversion (OR 1.82, 95% CI 1.26 to 2.62), ALT normalization (OR 1.24, 95% CI 1.01 to 1.56), and loss of HBsAg (OR 2.45, 95% CI 1.22 to 4.91). Treatment effects differed in high versus low dose, and long versus short duration of IFN-α. The effect of high dose IFN-α (OR 3.28, 95% CI 2.31 to 4.66) is statistically larger than that of low dose IFN-α (OR 1.58, 95% CI 1.10 to 2.28) on loss of HBeAg (interaction P = 0.017), and longer IFN-α treatment durations produce greater effects (OR 3.28, 95% CI 2.16 to 5.00) than do shorter durations (OR 1.94, 95% CI 0.42 to 2.66, interaction P = 0.038). High dose IFN-α had a significant effect on HBV DNA undetectability (OR 2.80, 95% CI 2.03 to 3.86), while low dose IFN-α did not (OR 0.93, 95% CI 0.61 to 1.41, interaction P = 0.01); longer treatments significantly improved HBV DNA undetectability (OR 2.58, 95% CI 1.62 to 4.12), but shorter durations did not (OR 1.28, 95% CI 0.83 to 1.97, interaction P = 0.024).

CONCLUSIONS

IFN-α can improve serological, biomedical, and virological response. Higher doses and prolonged treatments appear to have larger treatment benefits than lower doses and shorter treatments. However, the increased adverse reactions and costs associated with higher doses and prolonged treatment warrant caution in applying these results.

Immunopathogenesis of hepatitis B persistent infection: implications for immunotherapeutic strategies

It has been shown that cellular immunity, especially by cytotoxic T lymphocytes (CTLs), NK cells and NK-T cells, plays a central role in the control of virus infection. In addition, CD4+ T cells facilitate both CTL and B-cell responses. Hyporesponsiveness of HBV-specific T cells in peripheral blood has been shown in patients with chronic HBV infection. Interferon and nucleos(t)ide analogs, such as lamivudine, adefovir, entecavir and tenofovir, are the currently available treatments. Unfortunately, the efficacy of nucleos(t)ide analogs is limited by viral reactivation by the emergence of escaped mutants in cases of prolonged treatment. Therefore, immunotherapy is one of the significant options to eradicate or control HBV replication without drugs. The aim of immunotherapies is to decrease the levels of viral replication and to eradicate infected hepatocytes. For this reason, new strategies for immunotherapies by vaccination target not only the induction or stimulation of CD4+ and CD8+ T cell responses, but also the induction of proinflammatory cytokines capable of controlling viral replication. We will review the immunopathogenesis of persistent HBV infection, especially focusing on the mechanisms of immune suppression. Then we will review the immunotherapy for HBV persistent infection.

Reviews for APASL guidelines: immunomodulator therapy of chronic hepatitis B

The primary aim of immunomodulator therapy is to help the natural human immune system to mount a defense against hepatitis B virus. IFN-alpha has been used for the treatment of HBeAg-positive and HBeAg-negative chronic hepatitis B for over two decades and has been shown to be effective in suppressing HBV replication and in inducing serological response leading to long-term clinical benefits. IFN-alpha has been used in patients with well-compensated cirrhosis with comparable or better response to that in non-cirrhotic patients. IFN-alpha therapy in patients with cirrhosis has a similar side effect profile as in those without cirrhosis. However, IFN-alpha is contraindicated in patients with overt or decompensated cirrhosis. Pegylated IFN-alpha has been shown to be effective in treatment of chronic hepatitis B with sustained response rate in about one-third of the treated patients. Peg IFN-alpha treatment in non-responders to lamivudine or adefovir dipivoxil showed similar response rate to that seen in naïve patients. Thymosin alpha(1) is effective in treatment of HBeAg-positive and HBeAg-negative chronic hepatitis B with a significantly increasing virological response over time after therapy.

Hepatitis B virus polymerase inhibits the interferon-inducible MyD88 promoter by blocking nuclear translocation of Stat1

Previous studies have suggested that hepatitis B virus (HBV) blocks expression of the alpha interferon (IFN-alpha)-inducible myeloid differential primary response protein (MyD88) gene. To study the molecular mechanism(s) of the inhibition of MyD88 expression by HBV, MyD88 promoter reporter plasmids and vectors expressing different HBV viral proteins were constructed. Co-transfection experiments showed that IFN-induced MyD88 promoter activity was inhibited by HBV polymerase expression in a dose-dependent manner and that the terminal protein (TP) domain of HBV polymerase was responsible for this antagonistic activity. Analysis of site mutants showed that the region targeted by the polymerase protein contained the signal transducer and activator of transcription (Stat) binding site. Chromatin immunoprecipitation analysis showed that the IFN-induced DNA-binding activity of Stat1 was affected. Further study demonstrated that the HBV polymerase protein inhibited the Stat1 nuclear translocation induced by IFN-alpha, but did not induce Stat1 degradation nor interfere with its phosphorylation. In addition, HBV polymerase could inhibit the transcriptional activity of other IFN-stimulated response element-driven promoters and the expression of interferon-stimulated genes (ISGs), such as Stat1 and ISG15. In summary, these results indicate that HBV polymerase is a general inhibitor of IFN signalling and can inhibit IFN-inducible MyD88 expression by inhibiting the activity of the MyD88 promoter through blocking the nuclear translocation of Stat1.

Serum levels of preS antigen (HBpreSAg) in chronic hepatitis B virus infected patients

Background

Hepatitis B virus (HBV) infection is a serious health problem worldwide. Treatment recommendation and response are mainly indicated by viral load, e antigen (HBeAg) seroconversion, and ALT levels. The S antigen (HBsAg) seroconversion is much less frequent. Since HBeAg can be negative in the presence of high viral replication, preS antigen (HBpreSAg) might be a useful indicator in management of chronic HBV infection.

Results

A new assay of double antibody sandwich ELISA was established to detect preS antigens. Sera of 104 HBeAg-negative and 50 HBeAg-positive chronic hepatitis B patients have been studied and 23 HBeAg-positive patients were enrolled in a treatment follow-up study. 70% of the HBeAg-positive patients and 47% of the HBeAg-negative patients showed HBpreSAg positive. Particularly, in the HBeAg-negative patients, 30 out of 47 HBpreSAg positive patients showed no evidence of viral replication based on HBV DNA copies. A comparison with HBV DNA copies demonstrated that the overall accuracy of the HBpreSAg test could reach 72% for active HBV replication. HBpreSAg changes were well correlated with changes of HBsAg, HBV DNA and ALT levels during the course of IFN-α treatment and follow-up. HBeAg positive patients responded well to treatment when reduction of HBpreSAg levels was more pronounced.

Conclusion

Our results suggested that HBpreSAg could be detected effectively, and well correlated with HBsAg and HBV DNA copies. The reduction of HBpreSAg levels in conjunction with the HBV DNA copies appears to be an improved predictor of treatment outcome.

Restoration in vitro of impaired T-cell responses in patients with chronic hepatitis B by autologous dendritic cells loaded with hepatitis B virus proteins (R2)

BACKGROUND

The purpose of the present paper was to investigate dendritic cell (DC) and T-cell functions in patients with chronic hepatitis B (CHB) and determine whether therapeutic DC vaccines could restore T-cell function in those patients in vitro.

METHODS

Twelve patients with CHB and 10 normal control subjects with positivity for antibodies to hepatitis B surface and core antigens (anti-HBs and anti-HBc positivity) were enrolled in the present study. Phenotype analysis and allogeneic mixed lymphocyte reaction assay of DC from CHB patients and normal controls were made in the absence or presence of a cocktail of cytokines: interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)), IL-6 and tumor necrosis factor-alpha (TNF-alpha). Autologous T-cell proliferation assays and the enzyme-linked immunospot (ELISPOT) method for detecting interferon-gamma (IFN-gamma)-producing CD8(+) T cells were used to evaluate the efficacy of DC loaded in vitro with HBsAg or HBcAg.

RESULTS

The DC from CHB patients had a lower expression of costimulatory molecules CD80, CD86 and impaired allogeneic mixed lymphocyte reaction capacity compared to those from normal controls. However, the impaired DC function could be restored partially by cytokine cocktail supplemented in vitro. Mature DC loaded with HBsAg or HBcAg showed a greater capacity for autologous T-cell proliferation and antigen-specific IFN-gamma production than immature DC. Moreover, as a DC -loading antigen, HBcAg was more immunogenic than HBsAg.

CONCLUSIONS

The impaired function of DC in patients with CHB may be restored by supplementation in vitro with a cocktail of cytokines, and therapeutic DC vaccines might be effective to treat CHB infection in humans.

Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2005 update

BACKGROUND/AIMS

A large amount of new data on the treatment of chronic hepatitis B has become available such that the 2003 consensus statement requires revision and update.

METHODS

New data were presented, discussed and debated in an expert pre-meeting to draft a revision. The revised contents were finalized after discussion in a general meeting of APASL.

RESULTS

Conceptual background, including the efficacy and safety profile of currently available and emerging drugs, was reviewed. Nineteen recommendations were formed and unresolved issues and areas for further study were suggested.

CONCLUSION

The current therapy of chronic hepatitis B is modestly effective but not satisfactory. The development of new drugs and new strategies is required to further improve the outcomes of treatment.

Decreased numbers and impaired function of circulating dendritic cell subsets in patients with chronic hepatitis B infection (R2)

BACKGROUND AND AIM

To investigate the frequencies, numbers and function of circulating dendritic cell (DC) subsets in patients with hepatitis B virus (HBV) infection, we assayed the circulating precursor DC subsets (including pDC1 and pDC2) and their ability in patients at various stages of HBV infection in vitro.

METHODS

Circulating pDC1 and pDC2 frequencies in peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometric analysis. Costimulatory molecule expression and allostimulatory mixed lymphocyte reaction (AMLR) of DC1, cultured from PBMC in vitro, were detected in patients with chronic hepatitis B (CHB). On behalf of pDC2, interferon (IFN)-alpha production of PBMC was determined by the ELISA method in HBV-infected patients.

RESULTS

The number of circulating pDC1 decreased only in patients with liver cirrhosis (LC) compared with that in normal controls. However, pDC2 numbers decreased in both CHB and LC patients. DC1 from CHB patients showed lower expression of costimulatory molecules CD80, CD86 and impaired allostimulatory mixed lymphocyte reaction (AMLR) compared with those in normal controls. The ability of PBMC to secrete IFN-alpha also decreased significantly in patients with chronic HBV infection.

CONCLUSIONS

Our results suggest that patients with chronic HBV infection have a significantly lower expression of costimulatory molecules and impaired AMLR of pDC1, as well as decreased number and impaired function of circulating pDC2, which may be partially related to HBV disease progression in these patients.

Current antiviral therapy for chronic hepatitis B

During the past decade, major breakthroughs have been achieved in treatment of chronic hepatitis B. Currently, three therapeutic agents are approved for chronic hepatitis B: interferon-alpha, lamivudine and adefovir dipivoxil. In patients with HBeAgpositive chronic hepatitis B, all of these drugs achieve HBeAg loss (24-33%) and anti-HBe seroconversion (12-30%) rates that are superior to those observed in untreated controls. Interferon-alpha has several drawbacks, such as the parenteral administration and the development of frequent and potentially serious side effects. Lamivudine is a safe drug with rare and generally mild side effects. Lamivudine induces an initial virological remission in 70-90% of patients, but only 30-40% of patients remain in remission after the third year due to progressively increasing viral resistance. The main advantage of adefovir dipivoxil is the rare emergence of resistance, which has been identified in less than 2% of patients at 2 yr of treatment. Adefovir is also effective against lamivudine-resistant strains. This review will focus on the natural history and recently gained knowledge on the treatment of chronic hepatitis B.

Lack of Interferon Sensitivity-Determining Region in the Genome of Hepatitis B Virus Genotype Ba

Background/aims

In chronic hepatitis B, both host and viral factors may predict the response to interferon (IFN) treatment. Whether IFN sensitivity-determining regions exist within the hepatitis B virus (HBV) genomic background remains largely unknown. We therefore performed full-length viral genomic comparison between HBVs obtained from IFN responders and non-responders.

Methods

We enrolled 18 HBV genotype Ba patients who had received 24-week IFN 5 MU three times weekly and were followed monthly for 12 months post-treatment. There were 10 responders and eight non-responders. Pretreatment full-length viral nucleotide consensus sequence was obtained. In six non-responders and four responders, post-treatment viral nucleotide sequence was further compared with their corresponding pre-treatment specimens. In addition, the average number of nucleotide substitutions of the HBV quasispecies was compared between three responders and three non-responders.

Results

HBV nucleotide consensus sequence was identical between responders and non-responders. We found 0–15 (mean 7.7) nucleotide substitutions in the post-treatment HBV genome in the six non-responders and 0–14 (mean 3.8) nucleotide substitutions in the four responders, respectively. Genetic complexity of HBV quasispecies was comparable between responders and non-responders.

Conclusions

Our results suggest that an IFN sensitivity-determining region might not exist within the genome of HBV genotype Ba. Host factors and virus–host interactions may be more important in determining the response to IFN treatment.

Anti-HBV effect of TAT- HBV targeted ribonuclease

AIM: To prepare and purify TAT-HBV targeted ribonuclease fusion protein, evaluate its transduction activity and investigate its effect on HBV replication in 2.2.15 cells.

METHODS: The prokaryotic expression vector pTAT containing TR gene was used in transforming E.coli BL21 (DE3) LysS and TR was expressed with the induction of IPTG. The TAT-TR fusion protein was purified using Ni-NTA-agrose and PD-10 desalting columns, and analyzed by SDS-PAGE. Transduction efficiency of TAT-TR was detected with immunofluorescence assay and the concentration of HBeAg in the supernatant of the 2.2.15 cells was determined via solid-phase radioimmunoassay (spRIA). MTT assay was used to detect the cytotoxicity of TAT-TR.

RESULTS: The SDS-PAGE showed that the TAT-TR fusion protein was purified successfully, and the purity of TAT-TR was 90%. The visualization of TAT-TR by immunofluorescence assay indicated its high efficiency in transducing 2.2.15 cells. RIA result suggests that TAT-TR could inhibit the replication of HBV effectively, it didn’t affect cell growth and had no cytotoxicity.

CONCLUSION: TAT-TR possesses a significant anti-HBV activity and the preparation of TAT-TR fusion protein has laid the foundation for the use of TR in the therapeutic trial of HBV infection.

A novel HBV antisense RNA gene delivery system targeting hepatocellular carcinoma

AIM

To construct a novel HBV antisense RNA delivery system targeting hapatocellular carcinoma and study its inhibitory effect in vitro and in vivo.

METHODS

GE7,a 16-peptide specific to EGFR, and HA20,a homologue of N-terminus of haemagglutinin of influenza viral envelope protein, were synthesized and conjugated with polylysin. The above conjugates were organized into the pEBAF-as-preS2, a hepatocarcinoma specific HBV antisense expression vector, to construct a novel HBV antisense RNA delivery system, named AFP-enhancing 4-element complex. Hepatocelluar carcinoma HepG2.2.15 cells was used to assay the in vitro inhibition of the complex on HBV. Expression of HBV antigen was assayed by ELISA. BALB/c nude mice bearing HepG2.2.15 cells were injected with AFP-enhancing 4-element complex. The expression of HBV antisense RNA was examined by RT-PCR and the size of tumor in nude mice were measured.

RESULTS

The AFP-enhancing 4-element complex was constructed and DNA was completely trapped at the slot with no DNA migration when the ratio of polypeptide to plasmid was 1:1. The expression of HBsAg and HBeAg of HepG2.2.15 cells was greatly decreased after being transfected by AFP-enhancing 4-element complex. The inhibitory rates were 33.4 % and 58.5 % respectively. RT-PCR showed HBV antisense RNA expressed specifically in liver tumor cells of tumor-bearing nude mice. After 4 injections of AFP-enhancing 4-element complex containing 0.2 micro g DNA, the diameter of the tumor was 0.995 cm+/-0.35, which was significantly smaller than that of the control groups(2.215 cm+/-0.25, P<0.05).

CONCLUSION

AFP-enhancing 4-element complex could deliver HBV antisense RNA targeting on hepatocarcinoma and inhibit both HBV and liver tumor cells in vitro and in vivo.

Durability of lamivudine-induced HBeAg seroconversion for chronic hepatitis B patients with acute exacerbation

BACKGROUND/AIMS

Lamivudine-induced hepatitis B e antigen (HBeAg) seroconversion in patients with chronic hepatitis B was reported to be durable by several studies but controversy still exists. The aim of this study was to evaluate the durability of the responses of lamivudine treatment.

METHODS

Among 53 chronic hepatitis B patients who had acute exacerbation and had finished lamivudine therapy after at least 6 months of treatment, 31 patients achieved full HBeAg seroconversion twice at least 1 month apart, and subsequently stopped lamivudine therapy. Post-treatment monitoring was continued for up to 87 weeks. Alanine transaminase (ALT), HBeAg and hepatitis B virus (HBV) DNA were used as indicators for relapse.

RESULTS

The cumulative relapse rates at 48 and 72 weeks post-treatment were 45.4% and 56.3%, respectively. During follow up, normal ALT levels precluded relapse while ALT levels over two times the upper limit of normal indicated relapse, which correlated well with HBeAg or HBV DNA reappearance. Patients older than 25 years were more likely to experience post-treatment relapse.

CONCLUSIONS

Lamivudine-induced full HBeAg seroconversion was not durable in the Taiwanese population. ALT levels were useful for relapse detection. Age was the only independent predictive factor for relapse.

Management of patients with chronic hepatitis B

Better understanding of hepatitis B virus (HBV) replication and the natural history and immunopathogenesis of chronic hepatitis B, together with the introduction of effective agents with different mechanisms of action, is the basis for better therapeutic strategies against chronic hepatitis B. Substantial experience has now been accumulated in the use of some of these drugs, and an Asia-Pacific Consensus has been reached on indications for their use. The goals of therapy and aspects of general management will be reviewed here. Among currently available drugs, alpha-interferon therapy gives a response rate (hepatitis B e antigen (HBeAg) seroconversion) of 30-40% compared with 10-20% in matched controls, but patients with lower alanine aminotransferase (ALT), higher HBV-DNA, and immunosuppressed patients have a poorer response, and alpha-interferon can be dangerous in cirrhosis. Meta-analysis of four controlled trials also suggests that thymosin-alpha1 is effective, but more studies are needed. Lamivudine has been most extensively studied. It is effective in terms of HBV-DNA loss, ALT normalization, HBeAg seroconversion, and improvement in histology, as well as being well tolerated. After 1 year of treatment, HBeAg seroconversion rate increased with higher pretherapy ALT levels, suggesting that patients with stronger endogenous antiviral defenses to kill hepatocytes harboring covalently closed circular DNA have a better response to direct antiviral effects. Lamivudine is also beneficial in HBeAg negative chronic hepatitis B, and patients with decompensated cirrhosis and HBV replication. However, genotypic-resistant tyrosine-methionine-aspartate-aspartate (YMDD) mutations start to emerge after 9-10 months of lamivudine therapy, and their incidence increases more quickly than the HBeAg seroconversion rate durating prolonged therapy. Thus the benefits of long-term lamivudine must be balanced against concern about YMDD mutations, and the durability of treatment response. There are encouraging preliminary results for adefovir dipivoxil, entecavir, emtricitabine, clevudine and other nucleoside/nucleotide analogs in the early stages of appraisal; entecavir and adefovir dipivoxil appear effective in patients with YMDD mutants. Further development of new drugs and new strategies, such as combination or sequential therapy, may help to better achieve the goals of treatment for chronic hepatitis B in the new century.

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.

Hepatitis B infection in China

Chronic HBV infection is a serious health threat in the Asian-Pacific region. The introduction of lamivudine has greatly improved the hope of these patients and is undoubtly a milestone in the management of chronic HBV infection. The combination of lamivudine with another nucleotide or nucleoside analogue or immunomodulatory agent to improve its therapeutic efficacy further must be investigated. Also, the use of lamivudine to prevent HBV reactivation on withdrawal of immunosuppressive therapy should be explored.