Molecular mechanism of hepatitis B virus X protein function in hepatocarcinogenesis

Many factors are considered to contribute to hepatitis B virus(HBV)-associated hepatocellular carcinoma(HCC),including products of HBV,HBV integration and mutation,and host susceptibility. HBV X protein(HBx) can interfere with several signaling pathways associated with cell proliferation and invasion,and HBx C-terminal truncation has been suggested to impact the development of HCC. This review focuses on the pathological functions of HBx in HBV-induced hepatocarcinogenesis. As a transactivator,HBx can affect regulatory non-coding RNAs(nc RNAs),including micro RNAs and long nc RNAs. HBx is also involved in epigenetic modification and DNA repair. HBx interacts with various signal-transduction pathways,such as the p53,Wnt,and nuclear factor-κB pathways. We conclude that HBx hastens the development of hepatoma.     

Host RNA circles and the origin of hepatitis delta virus

Recent reports show that many cellular RNAs are processed to form circular species that are relatively abundant and resistant to host nucleases.In some cases,such circles actually bind host microRNAs.Such depletion of available microRNAs appears to have biological roles;for instance,in homeostasis and disease.These findings regarding host RNA circles support a speculative reappraisal of the origin and mode of replication of hepatitis delta virus,hepatitis delta virus(HDV),an agent with a small circular RNA genome;specifically,it is proposed that in hepatocytes infected with hepatitis B virus(HBV),some viral RNA species are processed to circular forms,which by a series of chance events lead to an RNA that can be both replicated by host enzymes and assembled,using HBV envelope proteins,to form particles some of which are infectious.Such a model also may provide some new insights into the potential pathogenic potential of HDV infections.In return,new insights into HDV might provide information leading to a better understanding of the roles of the host RNA circles.     

HBV感染自然史研究进展

病毒复制与宿主免疫之间的动态平衡在HBV感染自然史进展和发病机制中起重要作用。多数免疫能力正常的成人感染HBV后呈自限性,而在婴幼儿则多发展成为慢性HBV感染。慢性HBV感染分为4期：免疫耐受期、HBeAg阳性慢性肝炎期、非复制的HBsAg携带期和HBeAg阴性慢性肝炎期。HBVDNA水平、HBeAg的状态以及ALT水平可以预测HBV感染的长期结局如肝硬化或肝细胞癌。本文对HBV感染自然史分期、慢性HBV感染的结局和预后进行了综述。     

Long noncoding RNAs in hepatitis B virus replication and oncogenesis

Several diverse long noncoding RNAs (lncRNAs) have been identified to be involved in hepatitis B virus (HBV) replication and oncogenesis, especially those dysregulated in HBV-related hepatocellular carcinoma (HCC). Most of these dysregulated lncRNAs are modulated by the HBV X protein. The regulatory mechanisms of some lncRNAs in HBV replication and oncogenesis have been characterized. Genetic polymorphisms of several lncRNAs affecting HBV replication or oncogenesis have also been studied. The prognosis of HCC remains poor. It is important to identify novel tumor markers for early diagnosis and find more therapeutic targets for effective treatments of HCC. Some dysregulated lncRNAs in HBV-related HCC may become biomarkers for early diagnosis and/or the therapeutic targets of HCC. This mini-review summarizes these findings briefly, focusing on recent developments.     

Autophagy and microRNA in hepatitis B virus-related hepatocellular carcinoma

Approximately 350 million people worldwide are chronically infected by hepatitis B virus (HBV). HBV causes severe liver diseases including cirrhosis and hepatocellular carcinoma (HCC). In about 25% of affected patients, HBV infection proceeds to HCC. Therefore, the mechanisms by which HBV affects the host cell to promote viral replication and its pathogenesis have been the subject of intensive research efforts. Emerging evidence indicates that both autophagy and microRNAs (miRNAs) are involved in HBV replication and HBV-related hepatocarcinogenesis. In this review, we summarize how HBV induces autophagy, the role of autophagy in HBV infection, and HBV-related tumorigenesis. We further discuss the emerging roles of miRNAs in HBV infection and how HBV affects miRNAs biogenesis. The accumulating knowledge pertaining to autophagy and miRNAs in HBV replication and its pathogenesis may lead to the development of novel strategies against HBV infection and HBV-related HCC tumorigenesis.     

Construction of a replication-competent hepatitis B virus vector carrying secreted luciferase transgene and establishment of new hepatitis B virus replication and expression cell lines

BACKGROUND Previously, we have successfully constructed replication-competent hepatitis B virus(HBV) vectors by uncoupling the P open reading frame(ORF) from the preC/C ORF to carefully design the transgene insertion site to overcome the compact organization of the HBV genome and maintain HBV replication competence. Consequently, the replication-competent HBV vectors carrying foreign genes, including pCH-BsdR, carrying blasticidin resistance gene(399 bp),and pCH-hrGFP, carrying humanized renilla green fluorescent protein gene(720 bp), were successfully obtained. However, the replication efficiency of the former is higher but it is tedious to use, while that of the latter is poor and cannot be quantified. Hence, we need to search for a new reporter gene that is convenient and quantifiable for further research.AIM To establish a helpful tool for intracellular HBV replication and anti-viral drugs screening studies.METHODS We utilized the replication-competent HBV viral vectors constructed by our laboratory, combined with the secreted luciferase reporter gene, to construct replication-competent HBV vectors expressing the reporter gene secretory Nanoluc Luciferase(SecNluc). HepG2.TA2-7 cells were transfected with this vector to obtain cell lines with stably secreted HBV particles carrying sec Nluc reporter gene.RESULTS The replication-competent HBV vector carrying the SecNluc reporter gene p CHs NLuc could produce all major viral RNAs and a full set of envelope proteins and achieve high-level secreted luciferase expression. HBV replication intermediates could be produced from this vector. Via transfection with pTRE-sNLuc and selection by hygromycin, we obtained isolated cell clones, named HBV-NLuc-35 cells, which could secrete sec NLuc recombinant viruses, and were sensitive to existing anti-HBV drugs. Using differentiated Hepa RG cells, it was verified that recombinant HBV possessed infectivity.CONCLUSION Our research demonstrated that a replication-competent HBV vector carrying a secreted luciferase transgene possesses replication and expression ability, and the established HBV replication and expression cell lines could stably secrete viral particles carrying sec Nluc reporter gene. More importantly, the cell line and the secreted recombinant viral particles could be used to trace HBV replication or infection.     

MicroRNA-mediated interactions between host and hepatitis C virus

Micro RNAs(mi RNAs) are small noncoding RNAs. More than 2500 mature mi RNAs are detected in plants, animals and several types of viruses. Hepatitis C virus(HCV), which is a positive-sense, singlestranded RNA virus, does not encode viral mi RNA. However, HCV infection alters the expression of host mi RNAs, either in cell culture or in patients with liver disease progression, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma. In turn, host mi RNAs regulate HCV life cycle through directly binding to HCV RNAs or indirectly targeting cellular m RNAs. Increasing evidence demonstrates that mi RNAs are one of the centered factors in the interaction network between virus and host. The competitive viral and host RNA hypothesis proposes a latent cross-regulation pattern between host m RNAs and HCV RNAs. High loads of HCV RNA sequester and de-repress host mi RNAs from their normal host targets and thus disturb host gene expression, indicating a means of adaptation for HCV to establish a persistent infection. Some special mi RNAs are closely correlated with liver-specific disease progression and the changed levels of mi RNAs are even higher sensitivity and specificity than those of traditional proteins. Therefore, some of them can serve as novel diagnostic/prognostic biomarkers in HCVinfected patients with liver diseases. They are also attractive therapeutic targets for development of new anti-HCV agents.     

An overview of occult hepatitis B virus infection

Occult hepatitis B virus (HBV) infection (OBI), alternatively defined as occult hepatitis B (OHB), is a challenging clinical entity. It is recognized by two main characteristics: absence of HBsAg, and low viral replication. The previous two decades have witnessed a remarkable progress in our understanding of OBI and its clinical implications. Appropriate diagnostic techniques must be adopted. Sensitive HBV DNA amplification assay is the gold standard assay for detection of OBI. Viral as well as host factors...     

X基因——抗乙型肝炎病毒治疗的新靶点

X基因是乙型肝炎病毒(hepatitis B virus,HBV)的四个基因之一.最近的研究表明,他不仅参与HBV感染宿主过程,还影响HBV病毒基因的复制和表达,直接或/和间接通过宿主的免疫反应或其他作用,导致HBV致病的系列病理过程,而且在HBV生命周期中具有非常重要的作用.降低或去除X基因转录,或者封闭X蛋白某些功能以及使X基因表达沉默均能显著抑制病毒复制水平.本文通过对X基因在HBV复制和基因表达中的作用以及针对X基因的干预对HBV复制和基因表达的影响的最新研究成果进行综述,提出X基因是乙肝抗病毒治疗的一个新靶点.     

载脂蛋白质B mRNA编辑酶催化多肽3G抑制乙型肝炎病毒和鸭乙型肝炎病毒复制

目的了解载脂蛋白质BmRNA编辑酶催化多肽3G（APOBEC3G）对乙型肝炎病毒（HBV）和鸭乙型肝炎炎病毒（DHBV）复制的抑制作用。方法从健康人外周血单个核细胞提取RNA，逆转录聚合酶链反应扩增APOBEC3G，将产物克隆到pXF3H载体的EcoRⅠ和Hind Ⅲ酶切位点以构建真核表达质粒；以ayw亚型HBV全长质粒构建具有复制能力的1．3倍HBV质粒（pHBV1．3）。不同剂量的APOBEC3G真核表达质粒与pHBV1．3共转染HepG2细胞；酶联免疫吸附法检测细胞培养上清液的乙型肝炎表面抗原和e抗原水平，Southernblot和Northernblot分析HBV核衣壳相关DNA和RNA的水平变化。不同剂量APOBEC3G真核表达质粒与头尾相接的2倍DHBV质粒共转染LMH鸡肝癌细胞，Southernblot分析DHBV核衣壳相关DNA水平变化。结果成功构建APOBEC3G真核表达质粒和具有复制能力的1．3倍HBV质粒。APOBEC3G抑制乙型肝炎表面抗原和e抗原的分泌，转染细胞内HBV核衣壳相关RNA表达水平下降，而对核心蛋白质的表达没有影响；APOBEC3G对转染细胞内HBV和DHBV核衣壳相关DNA水平具有剂量依赖的抑制效应。结论APOBEC3G对HBV和DHBV复制具有抑制作用。