Inhibition of hepatitis B virus DNA replicative intermediate forms by recombinant interferon-γ

AIM: To evaluate the in vitro anti-HBV activity of recombinant human IFN-γ, alone and in combination with lamivudine. METHODS: A recombinant baculovirus-HBV/HepG2 culture system was developed which could support productive HBV infection in vitro. Expression of HBsAg and HBeAg in infected HepG2 culture medium was detected by commercial enzyme immunoassays. HBV DNA replication intermediates were detected in infected cells by Southern hybridization and viral DNA load was determined by dot hybridization. RESULTS: IFN-γat 0.1 to 5μg/L efficiently down regulated HBsAg expression in transduced HepG2 cells. At 5μg/L, IFN-γalso suppressed HBV DNA replication in these cells. While treatment with a combination of lamivudine and IFN-γshowed no additive effect, sequential treatment first with lamivudine and then IFN-γwas found to be promising. In this culture system the best HBV suppression was observed with a pulse of 2μmol/L lamivudine for two days, followed by 1μg/L IFN-γfor another four days. Compared to treatment with lamivudine alone, the sequential use of 0.2μmol/L lamivudine for two days, followed by 5μg/L IFN-γfor six days showed a 72% reduction in HBV cccDNA pool. CONCLUSION: This in vitro study warrants further evaluation of a combination of IFN-γand lamivudine, especially in IFN-αnon-responder chronic hepatitis B patients. A reduced duration of lamivudine treatment would also restrict the emergence of drug-resistant HBV mutants.     

Inhibition of hepatitis B virus DNA replicative intermediate forms by recombinant interferon-γ

AIM: To evaluate the in vitro anti-HBV activity of recombinant human IFN-γ, alone and in combination with lamivudine.METHODS: A recombinant baculovirus-HBV/HepG2 culture system was developed which could support productive HBV infection in vitro. Expression of HBsAg and HBeAg in infected HepG2 culture medium was detected by commercial enzyme immunoassays. HBV DNA replication intermediates were detected in infected cells by Southern hybridization and viral DNA load was determined by dot hybridization.RESULTS: IFN-γ at 0.1 to 5 μg/L efficiently down regulated HBsAg expression in transduced HepG2 cells.At 5 μg/L, IFN-γ also suppressed HBV DNA replication in these cells. While treatment with a combination of lamivudine and IFN-γ showed no additive effect,sequential treatment first with lamivudine and then IFN-γ was found to be promising. In this culture system the best HBV suppression was observed with a pulse of 2 μmol/L lamivudine for two days, followed by 1 μg/L IFN-γ for another four days. Compared to treatment with lamivudine alone, the sequential use of 0.2 μmol/L lamivudine for two days, followed by 5 μg/L IFN-γ for six days showed a 72% reduction in HBV cccDNA pool.CONCLUSION: This in vitro study warrants further evaluation of a combination of IFN-γ and lamivudine,especially in IFN-α non-responder chronic hepatitis B patients. A reduced duration of lamivudine treatment would also restrict the emergence of drug-resistant HBV mutants.     

乙型肝炎病毒cccDNA研究动态

乙型肝炎病毒（HBV）生命周期中关键的一步是共价闭合环状DNA（covalently closed circular DNA．cccDNA）的形成。HBVcccDNA给病毒复制和前基因组mRNA的合成提供模板，与HBV在肝细胞中的持续感染及抗病毒治疗的复发有重要关系。本文就有关HBV cccDNA的研究现状作如下综述。     

Guidelines for avoiding risks resulting from discontinuation of nucleoside/nucleotide analogs in patients with chronic hepatitis B

Nucleoside/nucleotide analogs (NUC) can lead to rapid reduction in hepatitis B virus (HBV) DNA levels in blood and normalization of alanine aminotransferase levels in many patients. They also provide histological improvement which results in a reduction in liver carcinogenesis. However, it is difficult to completely remove viruses even by NUC and there are some problems such as emergence of resistant strains and hepatitis relapse resulting from discontinuation of treatment. One of the reasons for this is that NUC reduce the HBV DNA level in blood but have almost no effects on the HBV cccDNA level in hepatocyte nuclei, which are the origins of HBV replication, and HBV cccDNA remains for a long period. For treatment with NUC in patients with hepatitis B, it is considered that NUC should not be easily discontinued because discontinuation often results in hepatitis relapse. However, it has not been clearly revealed when and how hepatitis relapses after discontinuation. Although some patients do not experience hepatitis relapse after discontinuation of NUC, or experience only mild relapse and finally achieve a stable condition, it has not been established how to identify such patients efficiently. We performed research to investigate characteristics of the course after discontinuation of treatment and definition of hepatitis relapse and estimate the relapse rate. “Guidelines for avoiding risks resulting from discontinuation of NUCs 2012” is summarized based on the study results. Because the guidelines are written in Japanese, we explain them in English as a review article.     

Randomised controlled trial: effect of metformin add-on therapy on functional cure in entecavir-treated patients with chronic hepatitis B

Introduction and ObjectivesHepatitis B surface antigen (HBsAg) clearance, indicating functional cure or resolved chronic hepatitis B (CHB), remains difficult to achieve via nucleos(t)ide analogue monotherapy. We investigated whether metformin add-on therapy could help achieve this goal in entecavir-treated patients with hepatitis B e antigen (HBeAg)-negative CHB.Patients and MethodsPatients with HBeAg-negative CHB who met eligibility criteria (entecavir treatment for > 12 months, HBsAg < 1000 IU/mL) were randomly assigned (1:1) to receive 24 weeks of either metformin (1000 mg, oral, once a day) or placebo (oral, once a day) add-on therapy. The group allocation was blinded for both patients and investigators. Efficacy and safety analyses were based on the intention-to-treat set. The primary outcome, serum HBsAg level (IU/mL) at weeks 24 and 36, was analysed using mixed models.ResultsSixty eligible patients were randomly assigned to the metformin (n = 29) and placebo (n = 31) groups. There was no substantial between-group difference in the HBsAg level at week 24 (adjusted mean difference 0.05, 95% confidence interval -0.04 to 0.13, p = 0.278) or week 36 (0.06, -0.03 to 0.15, p = 0.187), and no significant effect of group-by-time interaction on the HBsAg level throughout the trial (p = 0.814). The occurrence of total adverse events between the two groups was comparable (9 [31.0%] of 29 vs. 5 [16.1%] of 31, p = 0.227) and no patient experienced serious adverse events during the study.ConclusionAlthough it was safe, metformin add-on therapy did not accelerate HBsAg clearance in entecavir-treated patients with HBeAg-negative CHB.     

PCR-微流芯片法检测HBV感染者外周血HBV cccDNA和HBV DNA

目的：探讨HBV感染的肝病患者血中HBV cccDNA、HBV DNA的临床意义。方法：采用PCR-微流芯片法检测105例HBV感染者血清HBV DNA、HBVccc DNA、白细胞中HBV cccDNA（3例进行肝组织HBV cc-cDNA检测）,以6例非乙型肝炎患者作为对照。结果：6例非乙型肝炎患者HBVM、HBV DNA、HBV cccDNA均阴性;HBV感染者中41.9%（44/105）白细胞HBVccc DNA阳性,其中2例阳性PCR产物经基因测序得到验证;HBVDNA≥105copy/ml中HBV cccDNA阳性率57.4%（35/61）显著高于HBV DNA〈105copy/ml者20.5%（9/44,P〈0.01）;18.9%HB VDNA〈103copy/mlHBV感染者HBV cccDNA阳性;抗病毒治疗的慢性肝病患者HBV cccDNA阳性率显著低于未抗病毒治疗者（5/25 VS 34/65,P〈0.01）。结论：HBV感染的患者外周血中存在HBV cccDNA;HBV DNA高浓度者HBV cccDNA检出率高;外周血白细胞HBV cccDNA、血清HBVDNA联合检测更能准确判断抗病毒治疗效果及提高HBV复制检出率。     

Predictive role of serum HBsAg and HBcrAg kinetics in patients with HBeAg-negative chronic hepatitis B receiving pegylated interferon–based therapy

ObjectivesTo investigate the role of serum hepatitis B core-related antigen (HBcrAg) kinetics in predicting long-term outcome of pegylated interferon (PEG-IFN)-based therapy in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB).MethodsA total of 121 Thai patients with HBeAg-negative CHB recruited from a previous randomized trial of 48-week PEG-IFN alone or combined with entecavir were enrolled. Hepatitis B surface antigen (HBsAg) and HBcrAg levels were serially examined. Paired biopsy samples taken at baseline and after treatment were assessed for intrahepatic covalently closed circular DNA (cccDNA).ResultsPersistent virologic remission (PVR, defined by persistent hepatitis B virus (HBV) DNA <2000 IU/mL) and HBsAg clearance at 3 years after treatment were 29% (35/121) and 9% (11/121) respectively. Baseline HBcrAg correlated with HBV DNA and cccDNA but not with HBsAg. Baseline HBsAg, as well as HBsAg and HBcrAg, declines were associated with PVR, while HBsAg decline was predictive of HBsAg clearance. High baseline antigen levels (HBsAg ≥3.4 log₁₀ IU/mL plus HBcrAg ≥3.7 log₁₀ U/mL) yielded high negative predictive values of PVR (45/50, 90%) and HBsAg clearance (50/50, 100%). At week 12, declines of HBsAg, HBcrAg and both antigens combined of <0.5 log₁₀ yielded negative predictive values for PVR of 90% (71/79), 82% (61/74) and 96% (48/50) respectively.ConclusionsQuantitative HBcrAg was significantly associated with cccDNA in HBeAg-negative CHB. This novel antigen, together with HBsAg, could identify patients with low probability of PVR and HBsAg clearance in long-term follow-up.     

乙型肝炎病毒cccDNA定量与乙型肝炎临床及病理关系

目的探讨慢性乙型肝炎（CHB）肝组织HBVcccDNA定量与乙型肝炎的关系。方法分别采用荧光定量PCR、酶联免疫吸附分析法（ELISA）检测48例CHB肝组织HBVcccDNA定量、肝组织和血清HB VDNA定量、乙型肝炎病毒标志物。同时用链霉菌抗生素蛋白-过氧化物酶连接法（SP）检测肝细胞中HBcAg表达。分析肝组织HBVcccDNA与组织和血清HBV DNA、HBeAg、肝细胞内HBcAg水平及肝脏炎症活动度的关系.结果1．肝组织HBVcccDNA定量与组织和血清HBV DNA定量呈正相关（r=0．837，P〈0．001；r=0．627，P〈0．005）；2．肝组织HBV cccDNA定量与肝细胞内HBcAg半定量呈正相关（r=0．618，P〈0．005）；3．肝组织HBV cccDNA定量与肝脏炎症活动度尤明显相关（P〉0．05）：4．HBeAg阳性较抗-HBe阳性患者肝组织HBV cccDNA定量、肝组织和血清HBV DNA定量高（P〈0．05）。结论荧光定量PCR法检测肝组织HBV cccDNA定量是评价HBV复制最直接可靠的指标，在CHB的诊断和抗病毒治疗中有重要意义。但与肝组织炎症无明显相关。