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标题: B型肝炎病毒感染的病理学新见解 [打印本页]
作者: MP4 时间: 2012-7-2 15:08 标题: B型肝炎病毒感染的病理学新见解
http://www.ncbi.nlm.nih.gov/pubmed/22504921
全文
http://gut.bmj.com/content/61/Suppl_1/i6.abstract
PDF
http://gut.bmj.com/content/61/Suppl_1/i6.full.pdf+html
Gut 2012;61:i6-i17 doi:10.1136/gutjnl-2012-302056
New insight in the pathobiology of hepatitis B virus infection+ Author Affiliations
1Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany - 2Research and Molecular Development, Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia
- Correspondence to Dr Maura Dandri, Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Martinistr 52, D-20246, Hamburg, Germany; [email protected]
AbstractChronic hepatitis B virus (HBV) infection remains a major health burden and the main risk factor for the development of hepatocellular carcinoma worldwide. However, HBV is not directly cytopathic and liver injury appears to be mostly caused by repeated attempts of the host's immune responses to control the infection. Recent studies have shown that the unique replication strategy adopted by HBV enables it to survive within the infected hepatocyte while complex virus–host interplays ensure the virus is able to fulfil its replication requirements yet is still able to evade important host antiviral innate immune responses. Clearer understanding of the host and viral mechanisms affecting HBV replication and persistence is necessary to design more effective therapeutic strategies aimed at improving the management of patients with chronic HBV infection to eventually achieve viral eradication. This article focuses on summarising the current knowledge of factors influencing the course of HBV infection, giving emphasis on the use of novel assays and quantitative serological and intrahepatic biomarkers as tools for predicting treatment response and disease progression.
作者: MP4 时间: 2012-7-2 15:12
以下配GOOGLE翻译
2012年肠道; 61：I6-I17 DOI：10.1136/gutjnl-2012-302056
Review检讨
New insight in the pathobiology of hepatitis B virus infection在B型肝炎病毒感染的病理学的新见解
Maura Dandri 1 , 莫拉Dandri 1 ，
Stephen Locarnini 2 斯蒂芬Locarnini 2
+ Author Affiliations +作者背景
1Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany 1内科，汉堡Eppendorf公司，德国汉堡大学医学中心
2Research and Molecular Development, Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia 2Research和分子发展，维多利亚传染病参考实验室，澳大利亚墨尔本，
Correspondence to Dr Maura Dandri, Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Martinistr 52, D-20246, Hamburg, Germany; [email protected]作者莫拉Dandri博士，内科，大学医学中心的汉堡Eppendorf公司，Martinistr 52 D-20246，汉堡，德国; m.dandri @ uke.de
Contributors Both authors contributed equally to this manuscript.投稿两位作者同样这个手稿。
Abstract抽象
Chronic hepatitis B virus (HBV) infection remains a major health burden and the main risk factor for the development of hepatocellular carcinoma worldwide.慢性乙型肝炎病毒（HBV）感染仍然是一个主要的健康负担和发展全球肝癌的主要危险因素。 However, HBV is not directly cytopathic and liver injury appears to be mostly caused by repeated attempts of the host's immune responses to control the infection.但是，HBV不直接病变，似乎大多是由宿主的免疫反应反复尝试，以控制感染引起的肝损伤。 Recent studies have shown that the unique replication strategy adopted by HBV enables it to survive within the infected hepatocyte while complex virus–host interplays ensure the virus is able to fulfil its replication requirements yet is still able to evade important host antiviral innate immune responses.最近的研究表明，乙型肝炎病毒通过独特的复制策略，使受感染的肝细胞内生存，而复杂病毒主机interplays，确保能够履行其复制的要求，但仍然是能够回避重要宿主抗病毒先天免疫反应的病毒是。 Clearer understanding of the host and viral mechanisms affecting HBV replication and persistence is necessary to design more effective therapeutic strategies aimed at improving the management of patients with chronic HBV infection to eventually achieve viral eradication.更清楚了解主机和影响HBV的复制和持久性病毒的机制是必要的设计更有效的治疗策略，旨在改善慢性乙肝病毒感染，最终实现病毒消灭患者管理。 This article focuses on summarising the current knowledge of factors influencing the course of HBV infection, giving emphasis on the use of novel assays and quantitative serological and intrahepatic biomarkers as tools for predicting treatment response and disease progression.本文着重总结了当前的乙肝病毒感染的过程中影响因素的知识，新颖的检测和定量的血清和肝内的生物标志物作为预测治疗反应和疾病进展的工具的使用上给予重点。
作者: MP4 时间: 2012-7-2 15:13
Introduction
The human hepatitis B virus (HBV) is a small enveloped DNA virus causing acute and chronic hepatitis. Despite the availability of an effective vaccine, more than 360 million people are chronically infected worldwide and about 1 million people die per year due to HBV-associated liver pathologies.1 Although HBV replication is not considered directly cytopathic, HBV infection leads to a wide spectrum of liver disease ranging from acute to chronic viral hepatitis, which often progresses to liver cirrhosis and development of hepatocellular carcinoma (HCC). Even though numerous epidemiological studies indicated that chronic HBV (CHB) infection represents the main risk factor for liver cancer development,2–4 the molecular mechanisms determining HBV persistence and pathogenesis are still poorly defined. HBV displays a unique genomic organisation and replication strategy which confers on the virus the ability to persist in infected hepatocytes. A hallmark of HBV infection is the formation in hepatocyte nuclei of a stable HBV-DNA minichromosome, the so-called covalently closed circular DNA (cccDNA), which serves as template to generate all RNAs necessary for protein production and viral replication. Even if it is known that failure of viral clearance and relapse of viral activity after cessation of antiviral therapy with polymerase inhibitors are mostly due to the persistence of the cccDNA in chronically infected individuals, the virological and immunological mechanisms that prevent virus eradication leading to the development of chronic infection are still poorly understood. The development of innovative experimental infection models and quantitative serological and intrahepatic biomarkers is starting to provide new insight into the mechanisms of HBV persistence and pathogenesis.
Previous SectionNext SectionHBV virology
HBV is a member of the Hepadnaviridae family, which are the smallest DNA-containing, enveloped animal viruses known so far. Characteristic of HBV is its high tissue and species specificity, and a unique genomic organisation and replication mechanism. Despite decades of research, essential steps of the viral life cycle, such as viral entry and organisation of the cccDNA minichromosome, are still poorly understood.5 Only recently, innovative infection models and molecular techniques have opened new possibilities to investigate specific steps of the lifecycle and virus–host interactions influencing viral activity in infected hepatocytes.6
Infectious HBV has a spherical structure of 42–44 nm and the hepatitis B surface antigen (HBsAg) envelops the viral nucleocapsid, which is formed by the core protein (HBcAg). The encapsidated viral genome is typically organised as a relaxed circular partially double-stranded DNA (rcDNA) of around 3200 bp, covalently linked to the terminal protein of the viral polymerase (figure 1). The HBV genome displays four overlapping open reading frames (ORFs)1: the preS/S encoding the three viral surface proteins; the precore (PC)/core encoding the core protein and the non structural PC protein, also known as secreted e-antigen (HBeAg); the pol ORF encoding the viral polymerase, which possesses reverse transcriptase, DNA polymerase and RNase H activities, and the terminal protein for priming; and the X ORF, encoding the small regulatory X protein, which is essential in vivo for viral replication.7 8 All four ORFs use a single common polyadenylation signal motif; hence, the HBV-RNA transcripts are polyadenylated and capped.9
作者: MP4 时间: 2012-7-2 15:17
本帖最后由 MP4 于 2012-7-2 15:31 编辑
介绍
人类B型肝炎病毒（HBV）是一种小型的包膜的DNA病毒引起的急性和慢性肝炎。尽管提供一种有效的疫苗，超过360万人，慢性感染全世界每年约100万人死于因HBV相关肝脏pathologies.1虽然乙肝病毒复制不被视为直接病变，乙肝病毒感染导致很宽的频谱肝病从急性到慢性病毒性肝炎，往往会发展为肝硬化和肝细胞癌（HCC）的发展。虽然许多流行病学研究表明，慢性乙肝病毒（HBV）感染的主要危险因素为肝癌的发展,2-4确定乙肝病毒的持久性和发病的分子机制仍然知之甚少定义。 HBV显示了独特的基因组织和复制策略，赋予病毒感染的肝细胞的能力，坚持。乙肝病毒感染的一个特点是在肝细胞核形成一个稳定的HBV-DNA的微小染色体，所谓的共价闭合环状DNA（cccDNA），它作为模板来生成所有的RNA蛋白生产和病毒复制所必需的服务。即使它被称为，大多是由于持久的慢性感染者中的cccDNA的清除病毒和病毒活动停止聚合酶抑制剂的抗病毒药物治疗后复发的失败，病毒学和免疫学机制，防止病毒根除导致发展慢性感染仍然知之甚少。创新实验感染模型和定量的血清和肝内的生物标志物的发展，开始将乙肝病毒的持久性和发病机制提供新的见解。
以前SectionNext SectionHBV病毒学
乙型肝炎病毒的Hepadnaviridae家庭，这是最小的DNA中，笼罩迄今已知的动物病毒是一个成员。乙肝病毒的特点是高的组织和种属特异性，和一个独特的基因组组织和复制机制。尽管几十年的研究必不可少的步骤，病毒的生命周期，如病毒cccDNA的微小染色体的入境和组织，仍然知之甚少understood.5直到最近，创新感染模型和分子生物学技术开辟了新的可能性，以探讨生命周期的具体步骤和病毒宿主相互作用的影响在感染hepatocytes.6病毒活性
感染乙肝病毒的42-44纳米的球形结构和乙型肝炎表面抗原（HBsAg）笼罩的病毒核衣壳，这是形成核心蛋白（HBcAg的）。通常宽松的圆形部分病毒聚合酶的终端（图1）蛋白质共价连接到约3200 bp的双链DNA（rcDNA）举办encapsidated病毒的基因组。 HBV基因组显示四个重叠的开放阅读框（ORF）1：三个病毒表面蛋白的preS / S编码前C（PC）/核心编码核心蛋白和非结构性PC蛋白，也称为分泌e抗原（e抗原）; POL的ORF编码病毒聚合酶，具有逆转录酶，DNA聚合酶和核糖核酸酶H活动，并吸末端蛋白;和X的ORF，编码小监管的X蛋白，这是必不可少的病毒在体内replication.7 8所有四个ORFs的使用一个共同的加尾信号的主题，因此，乙肝病毒RNA转录加尾和capped.9
[attach]323623[/attach]
作者: MP4 时间: 2012-7-2 15:21
Figure 1 The lifecycle of hepatitis B virus (HBV). After binding to still unknown hepatocyte-specific receptor(s), the nucleocapsid is released into the cytoplasm and the HBV genome transferred to the cell nucleus, where it is converted into the covalently closed circular DNA (cccDNA) minichromosome. Viral replication takes place in the cytoplasm after encapsidation and reverse transcription of a over-length pregenomic RNA (pgRNA). Through Golgi and endoplasmic reticulum apparatus the core particles acquire the envelope and are secreted. Via viral entry and re-transporting of newly synthesised relaxed circular partially double-stranded DNA (rcDNA) into the cell nucleus, the cccDNA pool can be amplified. Transcription of the preS/S mRNAs leads to the production of L, M, S envelope proteins, which are needed for virion secretion and to produce the non-infectious spherical and filamentous subviral particles (SVPs). The regulatory HBx protein, which can affect gene expression and various cellular pathways, is translated from a shorter X mRNA and is essential for cccDNA-driven HBV replication. The secreted e-antigen (HBeAg) is a non-structural form of the nucleoprotein which, like the SVPs, was shown to display immunomodulating functions (see also figure 3). TIR, toll-interleukin-1 receptor; TLR, toll-like receptor; PPR, pattern recognition receptor.
图1
B型肝炎病毒（HBV）的生命周期。结合后仍是未知的肝细胞特异性受体（S），核衣壳释放到细胞质和HBV基因转移到细胞核内，它被转换成共价闭合环状DNA（cccDNA）微小染色体。在细胞质后的长度比前基因组RNA（pgRNA）包壳和逆转录病毒复制的地方。通过高尔基体和内质网设备的核心颗粒收购的信封，并分泌。通过病毒进入和重新传输的新合成宽松的圆形部分双链DNA（rcDNA）进入细胞核，cccDNA的池可以被放大。的preS / S基因的转录导致生产的L，M的信封蛋白病毒颗粒的分泌，这需要和生产非传染病的球形和丝状亚病毒颗粒（SVPS）。监管HBx蛋白，这可能会影响基因的表达和各种细胞的途径，从一个较短的x mRNA表达翻译和cccDNA的驱动HBV复制至关重要。分泌的E-抗原（HBeAg）是一种非结构形式的核蛋白，像SVPS，显示免疫调节功能（参见图3）。公路运输，收费白细胞介素1受体，Toll样受体，Toll样受体; PPR的模式识别受体。
作者: MP4 时间: 2012-7-2 15:22
All three envelope proteins, large (L), middle (M) and small (S) share the same C-terminal domain, which contains the HBsAg, while the L and M proteins display progressive N-terminal extensions.5 The anti-HBs neutralisation domain has been mapped to amino acids 99–170 of the S-protein and is referred to as the α or ‘a’ determinant.10 Characteristic of HBV infection is the presence of non-infectious structures, the spherical and filamentous subviral particles (SVPs), which are exclusively composed of viral envelope proteins and host-derived lipids5 and are secreted in a 103–106-fold excess into the blood of infected individuals (figure 1).
HBV also produces and secretes a non-structural form of the nucleoprotein, the PC protein or HBeAg, which is not required for viral replication, but displays immune-modulating functions and hence contributes to viral persistence. The HBeAg is translated initially as the PC protein P25, and then undergoes cleavage of the N-terminal signal sequence in the ER/Golgi complex, producing a 22 kDa protein (P22), which can either undergo further processing to form the secreted 17 kDa HBeAg (P17), or traffic to the cytosol where it remains localised.11 Except for a 10-amino-acid N-terminal extension, which is highly conserved in all orthohepadnaviruses and contains a putative toll-interleukin-1 receptor (TIR) domain,12 HBeAg shares significant homology with the core protein (P21), which is translated using the core AUG codon of the same ORF.13
The first step in HBV infection involves a non-cell-type specific primary attachment which is then followed by an irreversible binding of the virus to a still unknown hepatocyte-specific receptor.5 14 Following viral entry, the capsids accumulate at the nuclear membrane, where interactions with the nuclear pore complex may favour the release of the HBV genome (rcDNA) into the cell nucleus.15 To establish a productive HBV infection host components of the cellular replicative machinery are needed to remove the covalently attached terminal protein and to complete the positive-DNA strand to form a super-coiled cccDNA molecule, which after being associated with histone and non-histone proteins, is incorporated into the host chromatin.6 9 16 Unlike the provirus DNA of retroviruses, the cccDNA does not need to be integrated into the host genome. Albeit integrations of HBV-DNA sequences do occur in infected hepatocytes, particularly in the presence of DNA damage17 and cell turnover,18 19 these are typically truncated.
Camouflaged as a minichromosome, and hence undetectable by innate immune defense mechanisms, the cccDNA utilises the cellular transcriptional machinery to produce all transcripts necessary for protein production and viral replication, which takes place in the cytoplasm after reverse transcription (rt) of a over-length pregenomic RNA (pgRNA).9 Viral transcription is under the control of two enhancer elements and four distinct viral promoters. Similarly to cellular chromatin, the transcription of the different viral genes is regulated by the activity and dynamic interplay of numerous cellular transcription factors, coactivators, corepressors and chromatin modifying enzymes.6
Experimental studies in the duck model indicated that the cccDNA can be formed from incoming virions and from newly synthesised nucleocapsids, which instead of being enveloped and secreted into the blood, are rather transported into the nucleus to ensure accumulation, and later maintenance, of the cccDNA pool9 20 (see figure 1).
Although a high cccDNA copy number is detected in chronically infected ducks and woodchucks,21 22 lower cccDNA intrahepatic loads are generally determined in human liver biopsies (median 0.1–1 cccDNA copy/cell)23–28 and in HBV chronically infected human liver chimeric uPA/severe combined immunodeficient (SCID) mice,29–32 suggesting that different viral and host mechanisms may control cccDNA dynamics and cccDNA pool size in human infected hepatocytes.6 In this regard, a recent study elegantly showed that HBV converted the rcDNA into cccDNA less efficiently than DHBV in the same human cell background.33 Although the cccDNA pool appears to be very stable in the absence of cell division, accumulating evidence indicates that hepatocyte proliferation can induce drastic reduction of the intrahepatic cccDNA loads in vivo.19 32 Since the cccDNA lacks centromere structures ensuring correct migration during mitosis, immune-mediated cell death and compensatory hepatocyte regeneration may facilitate cccDNA loss. This could represent a weak point in HBV persistence deserving further investigation as new therapeutic concepts are explored.32
The next crucial step in HBV replication is the packaging and rt of pgRNA within the newly formed capsids. After rt and concomitant degradation of the pgRNA, first a single-stranded DNA of minus polarity, whose 5′ end remains covalently linked to the terminal protein of the polymerase, and then a complementary plus-strand DNA are synthesised to form the rcDNA.9 34 Assembly and release of the DNA-containing nucleocapsids appears to require a balanced co-expression of the small and large envelope proteins to recruit the nucleocapsid to the site of budding. Although the role of the envelope proteins in regulating viral particle release and cccDNA amplification is not well understood, recent studies indicate that the lack of envelope protein expression increases cccDNA levels, while co-expression of the envelope proteins favours viral secretion with limited completion of the plus strand.35
Previous SectionNext SectionPhases of CHB
The natural history of CHB
The immunopathogenesis of hepatitis B depends on a complex interplay of host and viral factors. Factors such as age, gender and immune status are important. Perinatal and childhood infection results in chronic infection in 90–95% and 50% of cases respectively, whereas greater than 95% of immunocompetent adults with acute HBV spontaneously clear the infection. Furthermore, CHB infection is more common in immunocompromised hosts (eg, HIV infection). Viral factors such as HBeAg status are also important. Under normal circumstances viral replication is not cytopathic, and it is the host's immune response, which is typically ineffective and inappropriate, that causes much of the damage associated with CHB.
The natural history of CHB is generally regarded as consisting of four phases36: immune tolerant; HBeAg-positive CHB (immune clearance); immune control (low or non-replicative); and HBeAg negative CHB (immune escape). These phases have been identified on the basis of specific biochemical, serological and virological characteristics, including serum alanine aminotransferase (ALT) levels, HBeAg serostatus, HBV DNA titre, and more recently, HBsAg level (figure 2). It is important to note that these phases do not occur in all individuals with CHB and do not always occur sequentially.37 It is patients in either the immune clearance or immune escape phases that are potential candidates for the currently approved antiviral and immune modulatory treatments.
作者: MP4 时间: 2012-7-2 15:25
本帖最后由 MP4 于 2012-7-2 16:27 编辑
所有三个包膜蛋白，大（L），中（M）和小（S）的份额相同的C-端结构域，其中包含了乙肝表面抗原，而L和M蛋白显示进步的N-末端extensions.5抗-HBs α或“determinant.10乙肝病毒感染的特征是存在非传染性结构，球形和丝状的亚病毒颗粒（已失效域映射到99-170的S-蛋白氨基酸，被称为SVPS），这是完全由病毒包膜蛋白和主机派生lipids5到超过103-106-倍（图1）感染者的血液中分泌。
乙肝病毒也产生和分泌的非结构形式的核蛋白，蛋白质或HBeAg的电脑，这是不是病毒复制所需的，但显示免疫调节功能，从而有助于病毒的持久性。 HBeAg是最初的PC蛋白P25的翻译，然后经过ER /高尔基复合体的N-末端的信号序列的切割，产生22 kDa蛋白（P22的），它可以经过进一步加工，形成17 kDa的分泌e抗原（P17），或细胞质中，它仍然localised.11除一个10个氨基酸的N-末端的延伸，这是高度保守的在所有orthohepadnaviruses和包含一个假定的收费白细胞介素1受体（TIR）域交通，12显着同源性的核心蛋白（P21蛋白）八月密码子使用的相同ORF.13的核心，这是翻译HBeAg的股
在乙肝病毒感染的第一步涉及非细胞型的具体主要附件，然后由病毒绑定到一个未知的肝细胞特定receptor.5 14以下病毒进入不可逆转的，衣壳积聚在核膜与核孔复合体的相互作用，可能有利于HBV基因组（rcDNA）释放到细胞nucleus.15要建立一个高效的乙肝病毒感染的细胞复制机械主机部件需要删除的共价连接的末端蛋白，并完成积极的DNA链，形成一个超级盘绕cccDNA的分子，这与组蛋白和非组蛋白的蛋白质后，将主机与逆转录病毒前病毒DNA chromatin.6 9月16日注册成立，cccDNA水平并不需要整合到宿主基因组。尽管HBV-DNA序列的整合发生在感染的肝细胞，尤其是在存在damage17的DNA和细胞的营业额，18 19这些都是典型的截断。
cccDNA的利用伪装成一个微小染色体，先天免疫防御机制，因此无法检测，细胞的转录机制，以产生所有必要的生产蛋白质和病毒复制，这需要在细胞质中的反转录（RT）的长度过的地方后的成绩单前基因组RNA（pgRNA）.9病毒的转录是两个增强子和四个不同的病毒发起人的控制下。同样的细胞染色，不同的病毒基因的转录调控许多细胞转录因子的活性和动态的相互作用，活化因子，抑制因子和染色质修饰enzymes.6
鸭模型中的实验研究表明，cccDNA水平可以从传入的病毒粒子，并形成新合成的核衣壳，而不是被笼罩和分泌到血液中，而进入细胞核运输，以确保积累，后期维护，对cccDNA的pool9 20（见图1）。
虽然高cccDNA的拷贝数检测在慢性感染鸭和旱獭，低21 22 cccDNA的肝内负荷一般确定在人类肝活检（中位数0.1-1 cccDNA的拷贝/细胞）23-28乙型肝炎病毒慢性感染人类肝嵌合尿激酶/严重联合免疫缺陷（SCID）小鼠,29-32，这表明不同的病毒和宿主的机制，可以控制cccDNA的动态和人类感染hepatocytes.6在这方面的cccDNA的池大小，最近的一项研究典雅表明，乙肝病毒转化成cccDNA的rcDNA少效率比background.33在同一个人体细胞乙型肝炎病毒cccDNA的游泳池虽然似乎是在细胞分裂的情况下非常稳定，越来越多的证据表明，肝细胞增殖，可诱导肝内cccDNA的负载由于cccDNA的急剧减少，在vivo.19 32缺乏着丝粒结构，确保正确的有丝分裂过程中迁移，免疫介导的细胞死亡和补偿性的肝细胞再生，可能有助于cccDNA的损失。这可能代表了乙肝病毒的持久性的薄弱点，值得进一步调查作为新的治疗概念explored.32
乙肝病毒复制中的下一个关键步骤是新形成的衣壳内pgRNA的包装和RT。经过RT和随之而来的pgRNA退化，第一单链DNA的正负极性，其5'端仍然共价连接到终端的聚合酶蛋白，然后互补加链DNA的合成，形成了rcDNA.9 34大会和释放的DNA含有核衣壳出现需要的平衡合作的小型和大型的包膜蛋白表达聘请核衣壳萌芽的网站。虽然还不是很清楚的包膜蛋白，调节病毒颗粒释放和cccDNA扩增的作用，最近的研究表明，缺乏包膜蛋白表达增加cccDNA水平，而有限完成的病毒包膜蛋白的共同表达赞成与分泌加strand.35
慢性乙型肝炎上一页SectionNext SectionPhases
慢性乙型肝炎的自然史
乙肝免疫发病取决于宿主和病毒因素的复杂的相互作用。是重要的因素，如年龄，性别和免疫状态。围产期和儿童感染在90-95％和50％的病例分别为慢性感染的结果，而大于95％的急性乙肝免疫的成年人自发清除感染。此外，慢性乙型肝炎病毒感染多见于免疫功能低下的主机（例如，艾滋病毒感染）。病毒因素，如HBeAg状态也很重要。病毒复制，在正常情况下是没有病变，它是宿主的免疫反应，这是典型的无效和不适当的，这会导致许多慢性乙型肝炎相关的损害。
慢性乙型肝炎的自然史一般认为四个组成：
1.免疫耐受
2.HBeAg阳性慢性乙型肝炎免疫清除
3.免疫控制（低或非复制）
4.HBeAg阴性慢性乙型肝炎（免疫逃逸）
这些阶段已经确定具体的生化，血清学和病毒学特征，包括血清谷丙转氨酶（ALT）水平，HBeAg的血清状况，血清HBV DNA滴度，最近，HBsAg水平（图2）的基础上。重要的是要注意，这些阶段不发生在慢性乙型肝炎患者的所有个人和不经常发生顺序.
这是患者在免疫清除或免疫逃逸阶段，是目前批准的抗病毒药物和免疫调节治疗的潜在候选。
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作者: MP4 时间: 2012-7-2 15:33
Figure 2
Phases of chronic hepatitis B (CHB) infection: serum and liver compartment. ALT, alanine aminotransferase; cccDNA, covalently closed circular DNA; HBeAg, hepatitis B secreted e-antigen; HbsAg, hepatitis B surface antigen; HBV, hepatitis B virus; ORF, open reading frame; PC/C, precore/core; PE, Paul Ehrlich Institute; rcDNA, relaxed circular partially double-stranded DNA.
图2
慢性乙型肝炎（CHB）感染阶段：血清和肝车厢。 （ALT），谷丙转氨酶; cccDNA的，共价闭合环状DNA，e抗原，乙型肝炎分泌e抗原，乙肝表面抗原，乙肝表面抗原，乙肝病毒，乙肝病毒的ORF，开放阅读框;电脑前C区/核心/ C，PE，保罗·埃利希研究所; rcDNA，宽松的圆形部分双链DNA。
作者: MP4 时间: 2012-7-2 15:40
本帖最后由 MP4 于 2012-7-2 16:33 编辑
The immune tolerant phase is characterised by positivity for serum HBeAg, high levels of HBV DNA, normal serum ALT levels and normal/near normal histological profile in the liver. The levels of HBV DNA typically exceed 20 000 IU/ml while HBsAg levels range from 4.5 to 5.0 log IU/ml.38 39 Patients in the immune tolerant phase are usually young and were infected early in life. The immune tolerant phase can last for more than 20 years. In contrast, individuals progressing to chronic infection following adulthood infection do not typically undergo a prolonged immune tolerant phase, and may instead enter directly into the immune clearance phase.
When CHB infection is acquired from an early age, the immune clearance phase usually occurs between ages 20 and 40 years, and is characterised by HBeAg positivity, elevated serum ALT levels, fluctuating HBV DNA levels (>20 000 IU/ml), lower levels of HBsAg (approx 4.3 log IU/ml) and histological damage. During this phase, the virus is under intense immune pressure and the emergence of dominant PC and/or basal core promoter (BCP) variants may occur, with eventual HBeAg seroconversion (SC) and control of HBV replication. Alternatively, HBV escapes from immune clearance with the person then developing HBeAg-negative CHB (figure 3). Following successful HBeAg SC, the majority of patients enter an immune control or low/non-replicative phase, characterised by low/undetectable viral replication and normal ALT levels. A serum HBV DNA of <2000 IU/ml and a quantitative HBsAg level of <1000 IU/ml have been suggested to differentiate the immune control and escape phases.40 41 A subset of patients can enter into the HBeAg-negative hepatitis phase, whereby HBV DNA levels >2000 IU/ml and increased quantitative HBsAg (3.5 log IU/ml) are found with increasing serum ALT levels and consequent further histological damage (figure 2).
免疫耐受期的特点是阳性血清HBeAg，HBV DNA的水平高，血清ALT水平正常和正常/接近正常肝脏组织概况。 HBV DNA水平通常超过20 000国际单位/毫升，而HBsAg水平范围从4.5到5.0日志IU/ml.在免疫耐受期患者通常是年轻，在生命的早期感染。免疫耐受期，可以持续20年以上。相比之下，个人发展为慢性感染的成年感染后通常不接受长期免疫耐受阶段，并可能，而不是直接进入免疫清除期。
从小获得慢性乙型肝炎病毒感染时，免疫清除期通常发生在20岁和40岁之间，HBeAg阳性，血清ALT水平升高，波动的HBV DNA水平（>20 000 IU/毫升），水平较低的特点乙肝表面抗原（约4.3日志国际单位/毫升）和组织损伤。在这个阶段，是强烈的免疫压力下，出现主导的PC和/或基本核心启动子（BCP）的变异，可能会出现与最终的HBeAg血清转换（SC）和控制乙肝病毒复制，病毒。另外，乙肝病毒逃避免疫清除与发展HBeAg阴性慢性乙型肝炎（图3）的人。继成功HBeAg的资深大律师，多数患者进入免疫控制或低/非复制阶段，特点是低/检测不到的病毒复制和ALT水平正常。一个血清HBV DNA<2000 IU/ ml和的定量HBsAg水平<1000 IU / ml的建议已分化的免疫控制和逃避phases.部分患者HBeAg阴性肝炎阶段，即可以进入HBV DNA水平> 2000 IU / ml和增加定量乙肝表面抗原（3.5日志IU/毫升）被发现与血清ALT水平的提高和随之而来的进一步的组织损伤（图2）。
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作者: MP4 时间: 2012-7-2 15:42
Figure 3
Proposed interactions between hepatitis B virus (HBV) proteins and components of the innate immune system. The diagram shows the intracellular effects of the precore/hepatitis B secreted e-antigen (HBeAg) on hepatocyte signalling via the MyD88-dependent (toll-like receptor (TLR)-2) and MyD88-independent (TLR-4) pathways. The terminal protein of the HBV polymerase was also reported to hinder the type I interferon (IFN)-mediated transcription of IFN-stimulated genes by impairing nuclear translocation of signal transducer and activator of transcription (STAT) proteins, while HBx expression was shown to inhibit the retinoic acid inducible gene I (RIG-I)–MAVS signalling. Circulating subviral particles (SVPs) were shown to repress TLR-9 signalling by enhancing SOCS expression in dendritic cells (pDCs). Furthermore, secreted HBeAg was shown to interact and downregulate TLR-2 expression on hepatocytes. In HBeAg-negative chronic hepatitis B (CHB), the absence of HBeAg results in upregulation of TLR-2 and secretion of the proinflammatory cytokines, including tumour necrosis factor α (TNFα). IRF, interferon regulatory factor; ISG, interferon-stimulated gene; MDA5, melanoma differentiation associated gene 5; NF-κB, nuclear factor κB; TRAM, TRIF-related adaptor molecule; MAVS, mitochondrial antiviral signaling; TRIF, TIR-domain containing adaptor protein inducing interferon–β; TRAF, TNF receptor-associated factor MAL; MyD88-adapter-like protein.
图3
建议B型肝炎病毒（HBV）的蛋白质和先天免疫系统的组成部分之间的相互作用。图中显示的前C/ B型肝炎分泌E-抗原（HBeAg）对肝细胞信号通过细胞内MyD88的依赖（toll样受体（TLR）-2）和MyD88的独立途径（TLR-4）的影响。 HBV多聚酶的末端蛋白也阻碍我干扰素（IFN）干扰素刺激基因的转录介导的损害的信号转导和转录激活子（STAT）蛋白，核转HBx基因的表达，而被证明能够抑制型维甲酸诱导基因（RIG-）MAVS信号。被压制的TLR-9的信号增强，SOCS表达在树突状细胞（PDC）的循环亚病毒颗粒（SVPS）。此外，HBeAg的分泌，表明TLR-2的表达对肝细胞进行互动，并下调。在HBeAg阴性慢性乙型肝炎（CHB）没有上调TLR-2和分泌的炎性细胞因子，包括肿瘤坏死因子α（TNFα）在HBeAg的结果。调节因子，干扰素调节因子; ISG，干扰素刺激基因; MDA5，黑色素瘤分化相关基因5的NF-κB，核因子κB，电车，TRIF相关的接头分子;小牛，线粒体抗病毒信号; TRIF的TIR域包含适配器蛋白诱导β-干扰素; TRAF，肿瘤坏死因子受体相关因子仲裁法; MyD88的适配器样蛋白。
作者: zzwwtt 时间: 2012-7-2 15:42
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作者: MP4 时间: 2012-7-2 15:47
It is generally accepted that the extent of chronic liver disease is directly linked to the frequency, duration and severity of hepatic flares occurring in either the HBeAg-positive (immune clearance) and/or HBeAg-negative phases. HBeAg SC is predictive of a sustained multi-log reduction in HBV DNA (>3 log10 IU/ml), a decrease in intrahepatic inflammatory activity and an improved prognosis.42 For these reasons, HBeAg SC has been traditionally used as an important therapeutic endpoint in the management of HBeAg-positive CHB. Not surprisingly, then, delayed HBeAg SC, particularly in patients >40 years old, is associated with higher fibrosis scores on liver biopsy. HBsAg SC is associated with a favourable long-term clinical prognosis,43 but unfortunately, spontaneous HBsAg loss and/or SC, now regarded as an important immune control endpoint, is rare in CHB with approximately a 1% annual rate.44
Spontaneous HBV reactivation in the low/non-replicative phase is clinically significant, since this is typically followed by increased hepatitis activity and ALT flares.45 The annual incidence of hepatic flare has been reported to be over 10% in HBeAg-negative patients.45 These hepatic flares are due to the resurgence of host immunity against HBV-infected hepatocytes and severe hepatic flares can be complicated by hepatic decompensation in 2–3% of patients. These adverse events typically drive the development of advanced fibrosis, which in time, eventually leads to cirrhosis.
Major virological events during the natural history of CHBViral evolution is important in the pathogenesis of chronic viral diseases such as hepatitis C,46 HIV47 and HBV.48 For example, during the immune clearance phase, Lim et al demonstrated that before HBeAg SC actually occurred, the viral sequence diversity in the PC/BCP region was significantly higher in HBeAg seroconverters compared with non-seroconverters.48 The selection pressure driving this diversity was found to be in effect at least 3 years before HBeAg SC actually occurred, and interestingly, the viral diversity increased further after viral load reduction. These results extended previous work demonstrating that viral mutation rates are increased in the immunoelimination phase compared with patients in the immunotolerant phase of CHB.49 Lim and colleagues also demonstrated that nucleotide substitution rates persisted at high levels after HBeAg SC, with viral diversity increasing further.48 Thus, it appears that this phase is far from being a ‘non-replicative state’, and that there is an ongoing dynamic post-SC process, albeit at lower levels of viral load, with viral diversity likely being driven by an immune-based selection pressure such as significant production of anti-HBe antibody.
Occult HBV infection: the final phase of CHB?Occult HBV infection (OBI) can be defined as the presence of HBV DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals testing HBsAg negative by currently available assays. When detectable, the amount of serum HBV DNA is typically very low (<200 IU/ml). The molecular basis of OBI is related to the long-lasting persistence of HBV cccDNA in hepatocyte nuclei.20 Although some HBV isolates from OBI cases may harbour ‘a’/α determinant mutations that prevent HBsAg detection by antibodies against the wild type virus, almost all OBI cases are infected with replication-competent HBV rather than escape variants, and so the lack of HBsAg in the peripheral compartment is regarded as a possible reflection of ‘strong immune control’ or suppression of viral gene expression of the infecting virus.50 51 The role of OBI in the development of chronic liver disease and as a risk factor for HCC development appears significant50 and further molecular studies are needed to elucidate the underlying pathogenetic mechanisms.51
Previous SectionNext Section
Viral biomarkers in the blood compartment: research and diagnostic toolsSpecific serology has proven to be the mainstay of diagnostic testing for hepatitis B. Several commercial immunoassays are available for the various hepatitis B markers of viral antigens and antibodies.52 Recently, sensitive and reliable assays have been developed to quantify serum HBsAg and HBeAg. Quantitative HBsAg levels are reported in IU/ml, with 0.1 IU/ml being equivalent to approximately 0.1 ng/ml of HBsAg,53 which is in turn equivalent to 2×107 subviral HBsAg particles or 5×106 virions. For HBeAg measurement, most quantitative assays are modified by reference to an external standard, such as the Paul Ehrlich (PE) Institute reference standard for HBeAg, and results are expressed in PE IU/ml.54
The presence of large amounts of HBsAg and HBeAg in the serum, however, may affect the ability to detect circulating antibodies and may obscure the onset of HBeAg or HBsAg SC. The available commercial assays usually detect anti-HBs and anti-HBe antibodies only after the respective antigens have been cleared from the serum. By using more sensitive immunoassays it was possible to detect antibody in the presence of excess serum antigen.55 These approaches identified serological responses in the context of active viral replication. For example, all patients with ‘active’ CHB and the majority of patients in the so-called tolerant phase demonstrated ongoing humoural immune responses, including anti-HBe and anti-HBs production. Anti-HBe and anti-HBs production may coexist with virions and subviral HBsAg particles for many years before viral clearance and loss of antigenemia eventually occur. HBeAg SC almost certainly accounts for increased quasispecies diversity in PC/core and BCP regions.48 The clinical picture of a relatively non-overlapping SC from HBeAg-positive to anti-HBe-positive status during CHB should be replaced by a more dynamic interplay of a potent host selection pressure (eg, B-cell response) targeted to key epitopes of HBV that result in emergence of escape variants that now have a replicative fitness advantage above the rest of the pool of HBV quasispecies.
The molecular detection tools for HBV DNA are useful for resolving ambiguous serological patterns, in staging patients in the various phases of CHB (see figure 3), and for monitoring patients undergoing antiviral therapy. Sustained suppression of HBV replication as assessed by HBV DNA measurement currently represents the cornerstone of evaluation of antiviral efficacy which must aim to reduce HBV DNA to as low a level as possible, ideally below the lower limit of detection by real-time PCR assays (<10–15 IU/ml). Thus, the goal of antiviral therapy is to suppress viral replication to a level that will lead to biochemical remission, histological improvement and prevention of disease progression.36 However, recent studies have indicated that even potent nucleos(t)ide analogue (NA) therapy minimally impacts on the HBsAg levels in blood. This is not surprising since NAs block the HBV DNA replication pathway (via inhibiting rt) and have no direct effect on transcription or translation of the Pre-S1/Pre-S2/S, Pre-core and X genes.56 In contrast, immune-based therapies do reduce transcription57 and viral protein levels58 59 through non-cytolytic and cytolitic60 mechanisms, as part of their broader antiviral activity.
HBsAg SC is now being regarded as the new treatment endpoint because HBsAg loss has been associated with successful immunological control of HBV and durable suppression of viral replication, thereby representing an endpoint for patients to be able to cease oral NA or immune-based therapies. Assessment of on-treatment changes in HBsAg titres may facilitate new management algorithms and future trials aimed at achieving this important endpoint. For example, the role of quantitative HBsAg in predicting response to pegylated interferon (IFN) therapy has been the focus of several recent studies.61–63 In HBeAg-positive patients, reduction of HBsAg levels to <1500 IU/ml at week 12 has been shown to be an early favourable sign of future HBsAg clearance. Over 50% of patients on pegylated IFN who achieved this level at week 12 were found to have HBeAg SC 6 months post treatment and nearly 20% of these patients achieved subsequent HBsAg clearance at 6 months post treatment. In contrast, a HBsAg level of >20 000 IU/ml at week 12 was associated with a very low rate of HBeAg SC and so may become a potential stopping rule of therapy.63 64 In HBeAg-negative patients treated with pegylated IFN, the decline in HBsAg titre at week 12 has also been shown to be a useful predictor of achieving an undetectable viral load at 24 weeks post therapy.61 Among patients who achieved HBsAg decline ≥10% from baseline at week 12 of treatment almost 50% achieved HBV DNA ≤2000 IU/ml at 1 year post treatment and 40% of these individuals achieved HBsAg clearance at 5 years post treatment. Rijckborst and colleagues65 proposed a clinically useful algorithm in HBeAg-negative CHB that any HBsAg decline at week 12 with a 2 log drop or more in HBV DNA could predict almost 40% of sustained responders in their cohort. If patients did not achieve a HBsAg decline or only had a <2 log drop in HBV DNA, then the chance of responding was 0%.
Quantitative HBeAg testing has proved to be more problematic mainly because of the lack of commercially available assays and studies have used mainly in-house techniques with reference to external standards such as the one available from the PE Institute. Fried and colleagues54 demonstrated a moderately significant relationship between baseline HBeAg level and subsequent HBeAg SC in patients treated with pegylated IFN. A level of ≤31 PE IU/ml at baseline was associated with a greater than 50% chance of HBeAg SC. The on-treatment week 12 and 24 HBeAg levels were more likely to be associated with a negative predictive response; for example, only 14% of patients at week 12 with a qHBeAg of >100 PE IU/ml went on to a HBeAg SC at week 72 whereas just 4% of patients with a qHBeAg of >100 PE IU/ml at week 24 achieved HBeAg SC at week 72, possibly forming the basis of another stopping rule.
作者: MP4 时间: 2012-7-2 15:48
它被普遍接受，慢性肝病的严重程度有直接联系的频率，持续时间和严重肝耀斑发生，无论是在HBeAg阳性（免疫清除）和/或HBeAg阴性的阶段。 HBeAg的SC是多日志的HBV DNA持续下降（> 3 log10的国际单位/毫升），在肝内炎症活动的减少和改进prognosis.42由于这些原因，HBeAg的资深大律师已经作为一个重要的治疗终点传统使用的预测在HBeAg阳性慢性乙型肝炎的管理。不出意外的话，延迟HBeAg的资深大律师，特别是在> 40岁的患者，肝活检纤维化评分较高有关。乙肝表面抗原与SC是一个有利的长期临床预后，43，但不幸的是，自发HBsAg消失和/或SC，现在作为一个重要的免疫控制端点，是罕见的慢性乙型肝炎约1％的年度rate.44
自发乙肝病毒重新在低/非复制阶段是临床上重要的，因为这通常是由肝炎活动增加和ALT flares.45每年肝耀斑的发生率已超过10％，在HBeAg阴性patients.45这些肝耀斑是由于宿主免疫对HBV感染的肝细胞和严重肝耀斑死灰复燃，可并发肝功能失代偿的患者在2-3％。这些不良事件通常为驱动器，时间，最终导致肝硬化晚期肝纤维化发展。
慢性乙型肝炎的自然历史过程中的主要病毒学事件
病毒进化重要的是，在慢性病毒疾病的发病机制，如C型肝炎，46 HIV47和HBV.48例如，在免疫清除期，Lim等证明，HBeAg的资深大律师前实际发生的，在PC /病毒的基因多样性口岸地区在HBeAg seroconverters的显着高于非seroconverters.48选择压力，驾驶这种多样性被发现至少3年的HBeAg的资深大律师前实际发生的，有趣的效果，病毒的多样性进一步增加后，病毒载量下降。这些结果扩展以前的工作表明，病毒的突变率相比，核苷酸替代率持续在SC后HBeAg的水平高，与病毒的多样性进一步增加，患者的免疫耐受阶段CHB.49 Lim和同事也证明增加的immunoelimination阶段。 48因此，看来，这个阶段是从“非复制状态”，有一个持续的动态后SC过程，尽管在较低水平的病毒载量可能是由于病毒多样性，免疫如抗-HBe抗体的重要生产为基础的选择压力。
隐匿性HBV感染：慢性乙型肝炎的最后阶段？
在肝脏中存在的HBV DNA（检测或检测不到血清中HBV DNA）测试现有的检测HBsAg阴性的人可以被定义为隐匿性HBV感染（欧倍德）。检测时，通常是血清HBV DNA含量非常低（<200 IU /毫升）。欧倍德的分子基础相关的HBV cccDNA的长期肝nuclei.20的持久性，虽然一些乙肝病毒隔离从欧倍德案件可能海港'一'/α行列式突变，防止对野生型病毒表面抗原抗体检测，几乎所有欧倍德例感染与复制能力的HBV，而不是逃避变种，所以在外围舱表面抗原缺乏被视为一个可能反映强烈的免疫控制或抑制病毒基因的表达，感染virus.50 51欧倍德在慢性肝病的发展和作为肝癌发展的危险因素的作用似乎significant50和分子生物学研究需要进一步澄清的潜在致病mechanisms.51
上一页SectionNext SectionViral生物标志物在血室：研究和诊断工具
特定的血清已被证明是几个商业免疫可用于各种肝炎病毒抗原乙标记和antibodies.52近日，灵敏，可靠的检测已发展到定量血清HBsAg和HBeAg B型肝炎的诊断测试的中流砥柱。报告定量HBsAg水平在国际单位/毫升，0.1 IU /毫升，相当于约0.1纳克/毫升53岁的乙肝表面抗原，这又是相当于2×107亚病毒表面抗原颗粒或5×106病毒颗粒。对于大多数定量检测HBeAg的测量，是由外部的标准，如保罗·埃利希（体育）对于HBeAg研究所的参考标准，结果，修改体育IU/ml.54表示
HBsAg和HBeAg的血清中的大量存在，但是，可能会影响循环抗体检测能力，并可能掩盖了发病的HBeAg或HBsAg的资深大律师。可用的商业检测，通常检测抗-HBs和抗-HBe抗体后，才各自的抗原已经从血清中清除。通过使用更敏感的免疫有可能存在多余的血清antigen.55这些方法在病毒复制活跃的背景下确定的血清学反应的抗体检测。例如，“主动”CHB和广大患者在所谓的宽容相所有患者表现出持续humoural免疫反应，包括抗-HBe和抗-HBs生产。抗-HBe和抗-HBs生产可能共存的病毒颗粒和亚病毒HBsAg颗粒多年之前，清除病毒和抗原的损失最终发生。 HBeAg的资深大律师几乎可以肯定在PC /核心和BCP regions.48相对非重叠SC从HBeAg阳性，抗-HBe阳性慢性乙型肝炎过程中的地位的临床表现为增加的准种多样性的帐目应改为一个更加动态的相互作用一个强有力的主机选择压力（例如，B细胞的反应）针对乙肝病毒的主要抗原表位，在逃生的变种，现在有一个以上的HBV准种池的其余部分复制健身的优势出现的结果。
HBV DNA的分子检测工具是有用的含糊不清的血清学模式，为解决举办例慢性乙型肝炎的各个阶段（见图3），监测患者接受抗病毒治疗。乙肝病毒复制的持续抑制HBV DNA的测量评估目前占抗病毒药物疗效评价的基石，它必须以尽可能低的水平，理想的下面实时PCR检测（检测低限，减少血清HBV DNA < 10-15国际单位/毫升）。因此，抗病毒治疗的目标是抑制病毒的复制水平，但最近的研究表明，这将导致生化缓解，组织学改善和预防疾病progression.36的，甚至有力的核苷（酸）类似物IDE（NA）的治疗微创影响血液中的HBsAg水平。自定居块HBV DNA复制的途径，这是不奇怪的（通过抑制RT），并有相反的转录或翻译Pre-S1/Pre-S2/S没有直接的影响，前核心和X genes.56，免疫为基础的治疗减少transcription57和病毒蛋白59 levels58通过非杀伤和cytolitic60的机制，为他们更广泛的抗病毒活性的一部分。
HBsAg的SC是现在被视为新的治疗终点，因为HBsAg消失已成功HBV和持久抑制病毒复制的免疫控制，从而代表能够停止口服NA或免疫疗法的患者的端点。在HBsAg滴度在处理变化的评估可能会推动旨在实现这一目标的重要端点的新的管理算法和未来的审判。例如，乙肝表面抗原定量的预测聚乙二醇干扰素（IFN）治疗中的作用一直是最近几studies.61-63在HBeAg阳性患者，减少乙肝表面抗原水平在12周<1500 IU / ml的焦点被证明是有利于未来的HBsAg清除早期标志。超过50％的患者对聚乙二醇干扰素12周达到这个水平，发现HBeAg的资深大律师后6个月的治疗，并取得近20％的患者在随后的6个月治疗后HBsAg清除。相比之下，HBsAg水平的> 20 000 IU /毫升12周相关与HBeAg的SC率非常低，因此有可能成为一个潜在的停止规则therapy.63 64聚乙二醇干扰素治疗HBeAg阴性患者，在12周时HBsAg的滴度下降，也被证明是有用的预测实现在24周后therapy.61在实现从基线HBsAg的下降≥10％，在治疗12周的患者近50％，达到乙肝病毒载量检测不到DNA≤2000 IU /毫升1年治疗后，40％以上的个人取得表面抗原清除治疗后5年。 rijckborst和colleagues65建议在HBeAg阴性慢性乙型肝炎的临床有用的算法，可以预测任何在第12周时乙肝表面抗原2日志下降或更多的HBV DNA下降近40％的持续应答者在他们的队列。如果病人没有达到乙肝表面抗原的下降或只在乙型肝炎病毒DNA下降<2日志，然后响应为0％的机会。
HBeAg的定量测试已被证明是更主要是因为缺乏市售的分析和研究，主要用于与外部标准，如一个从体育学院内部技术问题。油油炸和colleagues54表明基线HBeAg的水平，随后与聚乙二醇干扰素治疗的患者HBeAg的资深大律师之间的适度显著的关系。 A级≤31 IU / ml的在体育基线与HBeAg的SC大于50％的机会。在治疗12周和24 HBeAg的水平，更可能与阴性预测反应相关，例如，只有14％的患者在12周> 100 PE IU / ml的qHBeAg了一个HBeAg的资深大律师72周，而只有4％的患者> 100体育国际单位/毫升在24周达到72周时HBeAg的资深大律师，可能形成另一个停车规则的基础上qHBeAg。
作者: MP4 时间: 2012-7-2 16:00
Viral biomarkers in the liver
The effects of antiviral therapy on serum HBV DNA levels are well documented; while less information is available about their effects on intrahepatic virological parameters. The development of highly selective quantitative real-time PCR assays has provided the necessary tools to determine intrahepatic HBV DNA levels, including the quantification of cccDNA loads23 27 28 66 67 and transcriptional activity25 26 in liver biopsy specimens. For example, by measuring ‘virion productivity’ (defined as the ratio of intrahepatic rcDNA/cccDNA) and ‘transcriptional activity’ (defined as the level of pgRNA) it was observed that patients with HBeAg-negative CHB had significantly lower levels of viraemia, intrahepatic cccDNA (>1 log lower) and rcDNA (>2 log lower).26 Furthermore, virion productivity per cccDNA molecule was found to be fivefold lower than in HBeAg-positive disease. Levels of pgRNA were correspondingly reduced, suggesting that the low virion productivity resulted from lower amounts of pgRNA. In contrast to patients with HBeAg-positive CHB, there was no correlation between serum viral load and the amount of cccDNA in the HBeAg-negative patients, consistent with the observed impairment of virion productivity (figure 2). Although HBsAg titres were significantly lower in the HBeAg-negative cohort, pre-S/S mRNA levels and HBsAg titres per cccDNA molecule appeared similar between HBeAg-positive and HBeAg-negative patients, indicating that the production of SVPs was not impaired in the HBeAg-negative phase, but rather that the replication pathway might be selectively blocked. The study of Volz and colleagues26 also indicated that patients' transition through SC into HBeAg-negative disease is clearly not a ‘black and white’ immunological event, as suggested by existing commercial serological assays. Rather, a progressive increase in the viral diversity with positive selection of viral quasi-species defective for HBeAg production was observed. Identifying these selection pressures will be essential for understanding the host–virus interplay determining the course of CHB.
Although independent reports have shown that cccDNA loads vary significantly in the different phases of CHB infection, the correlation between antigenemia and intrahepatic cccDNA levels has not been well established and the results conflicting.26 68–70 The reason for such discrepancies may be multifactorial and due to virological factors (HBV genotype differences,71 emergence of mutations72 73) and host-mediated factors, which may affect cccDNA activity causing fluctuations in serum HBsAg concentrations among patients presenting similar cccDNA levels. Differences in cccDNA amounts determined by needle liver biopsy may also reflect uneven distributions of the cccDNA in different parts of the liver. The acquisition of viral DNA integrations containing an intact preS/S ORF may also contribute to the production of HBsAg and alter such correlations.
Polymerase inhibitors do not directly block formation and activity of the cccDNA, a significant decrease in cccDNA levels (approximately 1 log reduction) has often been observed after 1 year of therapy.23 28 66 67 Such reduction is supposed to derive from the lack of incoming viruses from the blood and insufficient recycling of viral nucleocapsids to the nucleus, due to suppression of viral DNA synthesis in the cytoplasm. However, mathematical modelling indicated that many years of nucleos(t)ide drug administration are needed to achieve cccDNA depletion. Thus, persistence of the cccDNA minichromosome remains the key factor responsible for failure of viral clearance and relapse of viral activity after cessation of antiviral therapy with polymerase inhibitors in chronically infected individuals. Furthermore, if viral suppression is not complete, the selection of resistant variants escaping antiviral therapy is likely to occur.20 74 Under antiviral pressure, such variants will contribute to the production and further selection of replication-competent resistant mutants, which will spread to other hepatocytes and, eventually, may replace the wild-type cccDNA molecules in the liver.
More potent HBV suppression using combination therapy has been achieved with 99% inhibition of intrahepatic virion productivity in patients who had received 1 year of pegylated IFNα and adefovir dipivoxil,28 while viral suppression appeared reduced to 76% during the following 2 years, after patients were shifted to ADV monotherapy. Recent studies also showed that reduction of circulating HBsAg is more marked in patients treated with pegylated IFNα alone or in combination with nucleoside analogues, in comparison to patients receiving monotherapy with polymerase inhibitors.62 Such differences are important and not entirely surprising because IFNα displays immune-modulating capacities and can induce direct antiviral effects, preventing the formation of viral RNA-containing core particles, accelerating pgRNA degradation and the decay of core particles.59 75 76 Furthermore, the most recent studies performed in vitro and in HBV-infected human-liver chimeric uPA/SCID mice showed that IFNα administration inhibits the transcription of all HBV-RNAs by inducing epigenetic repression of the cccDNA.57 Thus, these results identify a molecular mechanism whereby IFNα can reduce virion DNA productivity and the levels of HBsAg.
Although understanding of the molecular mechanisms influencing intrahepatic virion productivity is just starting to emerge, these studies indicate that quantitative measurements of serological viral parameters may become useful to monitor and predict treatment response within individual patients, while further studies employing better standardised intrahepatic assays and well characterised patient cohorts are needed to resolve previous differences in particular studies.
Previous SectionNext SectionFactors influencing HBV pathogenesis
Persistence of chronic HBV infection is due to the ability of the cccDNA to survive within the hepatocytes and to the successful establishment of a complex network of virus–host interactions permitting the virus to manipulate the cellular machinery to meet its replication and propagation requirements, and to evade the antiviral response of the host. Over the years, mutual attempts to control each other may set the stage for the development of severe liver pathologies, such as liver cirrhosis and HCC.
Immuno-pathogenesis of HBV infection: general considerations
The innate immune system represents an immediate, first-line defence against foreign pathogens and plays a fundamental role in regulating the adaptive immune response. While the role of the adaptive immune system in the resolution of HBV infection has been studied extensively,77–79 knowledge of the innate immune processes occurring in HBV infection has been limited by the restricted availability of in vitro and in vivo infection systems and technical difficulties in recruiting patients at the earlier stages of infection. Despite these limitations, studies in acute infected patients80 and chimpanzees81 documented a lack of type I IFN induction and proinflammatory cytokine production in acute HBV infection.81 In contrast to these observations, recent in vitro studies indicated that the innate immune response of the hepatocytes may sense the infection and limit the spread of HBV.82–84 A modest activation of IFN-stimulated genes was also shown in human hepatocytes after HBV infection in chimeric mice.30 Induction of the antiviral state and production of type 1 IFN (α/β) can be mediated by pathogen recognition receptors, such as toll-like receptors (TLRs).84 In turn, type 1 IFN production stimulates antigen-presenting cells such as dendritic cells and Kupffer cells (resident intrahepatic macrophages) to produce interleukins (IL-8, IL-12, IL-18) and other cytokines.85 IL-12 and IL-18 subsequently induce natural killer (NK) and natural killer T (NKT) cells.86 NK cells can also be activated by the major histocompatibility complex I molecules on the surface of infected hepatocytes or by recognition of stress-induced molecules.87 Although NK and NKT cells can promote liver damage through direct cytotoxic effects,88 their role in HBV persistence and mechanisms regulating NK cell function in HBV infection are still controversial.89
The hepatocellular injury caused by HBV infection is predominately immune mediated.90 91 The immune attack by the host against HBV is mainly mediated by a cellular response to small epitopes of HBV proteins, especially HBcAg, presented on the surface of liver cells. HLA class I restricted CD8 cells recognise HBV peptide fragments derived from intracellular processing and presentation on the liver cell surface by class I molecules. This process leads to direct cell killing by the CD8 cytotoxic T lymphocytes. It is important to note that B and T lymphocytes are only activated following recognition of HBV by the innate immune system. Ultimately, it is the breadth and strength of this specific adaptive immune response which determines the outcome of acute and chronic HBV infection. Animal and clinical studies demonstrated that in acute self-limited HBV infection, the CD8 T-cell and CD4 T-cell responses to HBV proteins92 are strong, polyclonal and multispecific, while in chronic HBV infection, the responses are weak and narrowly focused.89 Besides having a direct cytolytic effect, as discussed above, CD8 T cells also have a non-cytolytic effect through the production of IFNγ and tumour necrosis factor α (TNFα) (also produced by NK and NKT cells), which are known to elicit antiviral effects via multiple mechanisms.93 Indeed, studies have shown that IFNα and IFNβ significantly suppress HBV gene expression in vivo, indicating that non-cytolitic direct antiviral effects elicited by the immune response may play a determinant role in controlling HBV infection in immunological normal adults.30 57 75 Thus the current concept is that non-cytolytic and cytolytic mechanisms are requisite for successful HBV control and eventual clearance.
HBV interactions with innate immune responses of the hepatocytes
The limited induction of innate immune responses determined upon HBV infection may also be due to recently recognised abilities of HBV to evade innate immune recognition. TLRs are evolutionary conserved germline-encoded pattern recognition receptors that play a crucial role in early host defences by recognising pathogen-associated molecular patterns and also serve as an important bridge between the innate and the adaptive immune response. HBeAg was shown to act as an immune decoy for the core antigen by depleting HBeAg-specific and HBcAg-specific T-helper cells and exerting a tolerogenic effect in utero.94 Furthermore, HBeAg has been shown to potentially downregulate genes involved in cell signalling, RNA transport and processing, cytosol-nuclear trafficking and innate immune responses.95 Lang et al12 confirmed the presence of a Box-2-like TIR motif within the unique N-terminal 10-amino-acid sequence of PC/HBeAg protein which could antagonise TLR signalling pathways via blocking the adapter proteins Mal, TRAM and TRIF but not MyD-88, thereby suppressing TIR-induced nuclear factor κB and IFNβ activation (table 1). These findings provide a possible mechanism of the ‘HBeAg immunomanipulation’ of the innate immune response, including the induction of ‘tolerance’ in the first phase of CHB, especially following perinatal HBV transmission. In patients with HBeAg-positive CHB, the expression of TLR-2 on hepatocytes, Kupffer cells and peripheral blood monocytes was shown to be significantly downregulated, while upregulation of the TLR-2 pathway and increased TNFα production was found during HBeAg-negative chronic hepatitis96 (Table 1). Although these clinical studies have indicated a role for HBeAg in downregulating immune surveillance of HBV, loss of HBeAg synthesis commonly occurs during chronic HBV infection and the emergence of HBeAg-negative variants may present selective advantages, possibly by limiting the cytotoxic T-lymphocyte (CTL)-mediated clearance of infected hepatocytes.97 However, the selection of HBeAg variants is associated with increased viral activity,26 more severe liver disease and worse prognosis.44
In support of the concept that HBV has evolved mechanisms to sabotage pathways of the IFN response, a recent study in human-liver chimeric mice showed that administration of regular IFNα failed to promote detectable nuclear translocation of signal transducer and activator of transcription 1 (STAT-1) in HBV-infected human hepatocytes, although STAT-1 nuclear accumulation and enhancement of antiviral defence mechanisms were promptly induced in uninfected human hepatocytes.30 Furthermore, in vitro studies indicated that HBV may affect STAT methylation98 and activity of cellular DNA methyltransferases (DNMT).99 100 The non-structural HBx protein has been shown to also interfere with the innate immunity by downregulating mitochondrial antiviral signalling protein101 by suppressing the retinoic acid inducible gene I (RIG-I)–melanoma differentiation associated gene 5 (MDA5) pathway in vitro. Interactions between HBx, mitochondrial antiviral signalling and members of the cellular epigenetic machinery have been also reported.101 Furthermore, plasma-derived HBsAg SVPs were reported to inhibit TLR-9 mediated IFNα production by plasmacytoid dendritic cells, probably via stimulation of suppressor of cytokine signalling 1 expression.102 Although most of these analyses were performed in systems that overexpressed HBx and further analyses are needed in more relevant infection systems, taken together, these studies suggest that distinct virus-mediated mechanisms may contribute to the limited effectiveness of the innate immune responses and subsequent adaptive immune responses in HBV infection and thereby may significantly contribute to viral persistence.
作者: MP4 时间: 2012-7-2 16:01
在肝病毒标志物
抗病毒药物治疗对血清HBV DNA水平的影响是有据可查的，同时可以用较少的信息是他们的关于肝内病毒学参数的影响。高度选择性的实时定量PCR检测的发展提供了必要的工具，以确定肝内HBV DNA水平，包括量化cccDNA的loads23的27 28 66 67和肝活检标本中的转录activity25 26。例如，通过测量的病毒粒子生产力“（定义为肝内rcDNA / cccDNA的比例）和”转录活性（定义为pgRNA水平）有人指出，HBeAg阴性慢性乙型肝炎患者病毒血症的水平显着降低，肝内cccDNA水平（> 1日志较低）和rcDNA（> 2的日志下）.26此外，被认为是病毒颗粒每cccDNA的分子生产力五倍，比HBeAg阳性的疾病。 pgRNA水平相应减少，这表明低的病毒粒子生产力pgRNA较低的数额。在HBeAg阳性慢性乙型肝炎患者血清病毒载量和HBeAg阴性患者的cccDNA的量之间的相关性，也没有观察到病毒粒子生产力的障碍（图2）一致。虽然乙肝表面抗原滴度均明显HBeAg阴性队列，前S / S的mRNA水平和乙肝表面抗原HBeAg阳性和HBeAg阴性患者之间滴度每cccDNA的分子出现，表明，SVPS生产不受损在HBeAg的负相，而是复制途径可能有选择性地封锁。在福尔茨和colleagues26的研究还表明，HBeAg阴性疾病患者通过SC过渡到显然不是“黑色和白色的免疫活动，通过现有的商业血清学检测的建议。相反，在逐步增加病毒的多样性与HBeAg的生产缺陷病毒准种的积极选择进行了观察。确定这些选择压力，将是为了解宿主 - 病毒相互作用，确定慢性乙型肝炎过程中是必不可少的。
虽然独立报告表明，cccDNA的负载慢性乙型肝炎病毒感染的不同阶段的显着变化，抗原和肝内cccDNA水平之间的相关性并没有得到很好的建立和结果conflicting.26 68-70这种差异的原因可能是多方面的，由于病毒学因素（HBV基因型的差异，出现71 mutations72 73）和主机介导的因素，这可能会影响cccDNA的活动提出类似的cccDNA水平的患者血清HBsAg浓度波动引起的。 cccDNA的针肝活检确定的金额的差异，也可以反映肝脏的不同部位的cccDNA的分布不均。病毒DNA整合，包含一个完整的preS / S的框的收购也可能导致生产的HBsAg和修改等相关。
聚合酶抑制剂不直接阻挡的cccDNA的形成和活动，在cccDNA水平的显着减少（约减少1日志）经常被发现后1年的therapy.23 28 66 67这种减少应该从传入缺乏派生从血液中的病毒核衣壳和不足，回收到细胞核内的病毒，由于抑制病毒DNA的合成在细胞质中。然而，数学模型表明，核苷（酸）IDE给药多年实现cccDNA的枯竭。因此，持续的cccDNA的微小染色体仍然负责停止聚合酶抑制剂在慢性感染者抗病毒药物治疗后复发病毒活性的病毒清除和失败的关键因素。此外，如果是不完整的病毒抑制，逃避抗病毒治疗耐药变异的选择可能到occur.20 74抗病毒药物的压力下，这种变异将有助于生产和进一步选择复制能力的抗突变，这将波及到其他肝细胞，最终可能会取代在肝脏cccDNA的野生型分子。
已使用联合疗法更有效的HBV抑制达到99％，抑制肝内病毒颗粒的生产力，谁收到了聚乙二醇化干扰素α，阿德福韦酯，28 1年，而抑制病毒出现在以下2年降低到76％，患者术后患者转移到ADV单药治疗。最近的研究也表明，减少循环的HBsAg是在与聚乙二醇干扰素α单独或与核苷类似物联合治疗的患者更明显，在患者接受单一聚合酶inhibitors.62这种差异比较重要的，并不完全令人惊讶，因为干扰素α显示免疫和调节能力，可以引起直接抗病毒的作用，防止形成病毒的RNA含有核心颗粒，加快的pgRNA退化和核心particles.59的衰变75 76此外，最近进行的研究在体外和乙肝病毒感染人体肝嵌合UPA / SCID小鼠表明，IFNα的管理所有的乙肝病毒的RNA转录抑制诱导后生镇压cccDNA.57因此，这些结果识别的分子机制干扰素α可以减少病毒体DNA的生产力和乙肝表面抗原的水平。
虽然影响肝内病毒颗粒生产力的分子机制的了解才刚刚开始出现，这些研究表明，血清学病毒性参数的定量测量，可能会成为有用的监测和预测个别患者在治疗的反应，而进一步的研究，采用更好的标准化肝内检测和特点病人同伙需要解决，特别是研究以前的差异。
影响乙肝发病以前SectionNext SectionFactors
慢性乙肝病毒感染的持久性是由于存活的肝细胞内，并成功地建立了一个复杂的网络病毒的主机，允许病毒的相互作用，操纵细胞的机制，以满足其复制和传播要求的cccDNA的能力，并逃避宿主的抗病毒反应。多年来，相互控制对方的企图，可能为严重的肝脏病变，如肝硬化和肝癌的发展阶段。
乙肝病毒感染的免疫发病机理：一般考虑
先天免疫系统的代表立即，反对外来病原体的第一线防御和调节适应性免疫反应中起着根本的作用。而在乙肝病毒感染的决议的自适应免疫系统的作用已被广泛研究,77-79的先天免疫过程发生在乙肝病毒感染的知识已被限制在体外和体内感染的系统和技术上的困难禁区可用性在招募病人在感染的早期阶段。尽管有这些限制，在急性感染patients80和chimpanzees81研究记录了我诱导干扰素和炎性细胞因子的生产，在急性HBV infection.81在这些意见中，最近在体外研究表明，肝细胞的先天免疫反应可能会感到缺乏型感染和限制蔓延HBV.82-84-干扰素刺激基因的一个温和激活也显示出在人类肝细胞后，在乙肝病毒感染的抗病毒药物的状态和生产1型干扰素（α/β）诱导嵌合mice.30可以通过介导病原体识别受体，Toll样受体（TLRs）.79反过来，如1型干扰素的产生刺激抗原提呈细胞，如树突状细胞和Kupffer细胞（居民肝内巨噬细胞）产生白细胞介素（IL-8 ，其后IL-12，IL-18）和其他cytokines.85 IL-12和IL-18诱导自然杀伤（NK）和自然杀伤T（NKT）cells.86 NK细胞也可通过主要组织相容性复合体的激活，我感染的肝细胞表面或molecules.87诱导应力的认可，虽然NK和NKT细胞可促进肝功能损害，通过直接的细胞毒作用的分子，88他们在乙肝病毒的持久性和机制调节NK细胞功能在HBV感染的作用尚有争议。 89
乙肝病毒感染引起的肝细胞损伤是为主免疫mediated.90 91由主机对HBV的免疫系统的攻击主要是小表位乙型肝炎病毒蛋白介导的细胞反应，尤其是HBcAg的肝细胞表面。人类白细胞抗原I类限制性CD8细胞承认衍生肽乙肝病毒从细胞内加工和I类分子的肝细胞表面上的介绍片段。这个过程导致直接由CD8细胞毒性T淋巴细胞的细胞杀死。重要的是要注意，B和T淋巴细胞激活乙肝病毒的先天免疫系统识别以下。最终，它是这一特定的适应性免疫反应，这就决定了急性和慢性乙肝病毒感染的结果的广度和强度。动物和临床研究表明，在急性自限性HBV感染，CD8 + T细胞和CD4 T细胞的反应，乙肝病毒proteins92强，多克隆和multispecific的，而在慢性乙肝病毒感染的反应是软弱和狭义focused.89除了有直接杀伤作用，如上所述，CD8 T细胞也有通过γ干扰素和肿瘤坏死因子α（TNFα）（NK和NKT细胞生产）的生产，这是众所周知的抗病毒药物引起的非杀伤效果通过多个mechanisms.93事实上的影响，有研究显示，IFNα和IFNβ显着抑制体内的乙肝病毒基因的表达，说明引起免疫反应，可能在一个决定因素的作用，控制乙肝病毒感染免疫正常的成人，的非cytolitic直接抗病毒作用。 30 57 75因此，目前的概念是成功的乙肝病毒的控制，并最终清除非细胞毒性和细胞毒性的机制是必要的。
乙肝病毒与肝细胞的先天免疫反应的相互作用
有限诱导乙肝病毒感染后确定的先天免疫反应，也可能是由于最近确认乙肝病毒逃避先天免疫识别能力。 TLRs是进化保守的生殖编码模式识别受体早期宿主防御中发挥了至关重要的作用，通过识别病原体相关的分子模式，并作为先天免疫和适应性免疫反应之间的重要桥梁。 HBeAg的结果表明，以行动作为核心抗原的免疫诱饵，通过消耗特定的HBeAg和HBcAg特异性T辅助细胞和1耐受性作用发挥utero.94此外，e抗原可能下调参与细胞信号转导的基因已被证明， RNA的运输和处理，细胞质核贩运和先天免疫responses.95郎等[12]证实存在一箱-2一样的TIR主题，独特的N-端10个氨基酸的电脑序列内/ e抗原蛋白可对抗TLR信号通路通过阻塞适配器蛋白质玛，电车和TRIF但不MYD-88，从而抑制引起的TIR核因子κB和IFNβ激活（表1）。这些发现提供了先天免疫反应，包括诱导“宽容”在第一阶段的CHB HBeAg的immunomanipulation“的可能机制，特别是母婴传播。在HBeAg阳性慢性乙型肝炎患者的肝细胞，Kupffer细胞和外周血单核细胞TLR-2的表达被证明是显著下调，而上调的TLR-2通路和增加TNFα产生HBeAg阴性慢性hepatitis96期间被发现（见表1）。虽然这些临床研究表明HBeAg的下调对HBV的免疫监视，HBeAg的合成损失的作用通常发生在慢性乙肝病毒感染，并出现HBeAg阴性变异可能存在选择性的优势，可能通过限制细胞毒性T淋巴细胞（CTL感染hepatocytes.97）介导的间隙，但选择与HBeAg的变种病毒活性增加，26更严重的肝脏疾病恶化prognosis.44
在支持的概念，乙肝病毒已经演变机制破坏干扰素反应的途径，在人类肝嵌合体小鼠的最新研究表明，普通IFNα的政府未能促进探测信号转导和转录激活因子1的核易位（STAT- 1）在人类肝细胞HBV感染，虽然STAT-1核积累和增强抗病毒的防御机制，及时诱导在未受感染的人类hepatocytes.30此外，在体外研究表明，HBV可能会影响STAT methylation98和细胞DNA甲基转移酶的活性（转移酶非结构性的HBx蛋白）0.99 100已被证明还与先天免疫的干扰，通过抑制维甲酸诱导基因I（RIG-I），黑色素瘤分化相关基因5（MDA5）通路下调线粒体抗病毒信号protein101体外。 HBx蛋白，线粒体抗病毒信号和细胞后生机械成员之间的相互作用也已reported.101此外，血源性乙肝表面抗原SVPS据报道，抑制浆细胞树突状细胞的TLR-9介导IFNα的生产可能是通过刺激细胞因子信号抑制， 1 expression.102虽然大多数这些分析系统过度表达的HBx和进一步分析，需要更多相关的感染系统，合计，这些研究表明，不同的病毒介导的机制，可能有助于先天免疫反应的效果有限及后续的适应性免疫反应在乙肝病毒感染，从而可能大大有助于病毒的持久性。
作者: MP4 时间: 2012-7-2 16:02
Table 1
Main factors that influence HBV persistence and pathogenesis
Immune-mediated factors:
Lack of robust type-1 IFN production
Weak CD8 T- and CD4 T-cell responses
NK-, NKT cell-mediated liver damage
Virological factors:
cccDNA stability
Interference with the innate immune system of the hepatocytes:
(a) HBeAg-mediated inhibition of TLR-2 signalling
(b) HBx-mediated inhibition of RIG-1 pathways
(c) SVPs-mediated inhibition of TLR-9 signalling
(d) Impairment of STAT translocation/methylation
Alteration of cellular pathways
(a) Cell-signalling pathways
(b) Mitochondria functions
(c) Lipid metabolism
(d) Epigenetic status of host genome
Emergence of HBV variants:
Induced by immune pressure (PC/BCP)
Induced by antiviral therapy with polymerase inhibitors
Co-infection with other viruses:
HBV/HCV
HBV/HDV
HBV/HIV
作者: MP4 时间: 2012-7-2 16:05
表1
影响乙肝病毒的持久性和发病的主要因素
免疫介导的因素：
缺乏强大的1型干扰素的生产
弱CD8 + T和CD4 T细胞的反应
NK细胞，NKT细胞介导的肝损害
病毒学因素：
cccDNA的稳定
肝细胞的先天免疫系统的干扰：
（一）e抗原介导的抑制TLR-2信号
（二）的RIG-1通路HBx蛋白介导的抑制
（三）的SVPS介导抑制的TLR-9信号
（四）资产减值STAT易位/甲基
细胞通路的改造
（一）细胞信号通路
（二）线粒体功能
（三）脂代谢
（四）后生的宿主基因组中的地位
对乙肝病毒的变种出现：
诱导免疫压力（电脑/ BCP）
诱导聚合酶抑制剂的抗病毒药物治疗
与其他病毒感染：
HBV/ HCV合并
乙肝/ HDV
HBV/艾滋病毒
作者: MP4 时间: 2012-7-2 16:10
Mutual interplays influencing HBV activity and cellular pathwaysThe incidence of HCC development has been shown to correlate with the levels of HBV replicative activity.103 This highlights the importance of elucidating the mechanisms modulating viral activity because these factors will affect both cccDNA loads and cellular pathways, thus influencing the clinical course of infection.
Numerous transcription factors implicated in the activation of hepatic metabolic processes, such as hepatocyte nuclear factor, cAMP responsive element binding protein, retinoid X receptor and peroxisome proliferator-activated receptors, are known to bind the HBV genome and the recruitment of liver-enriched transcription factors on the cccDNA minichromosome appears essential for controlling viral gene expression.6 104 However, interactions between viral components and cellular factors may also impact the liver metabolism. Glucocorticoids are steroid hormones playing major roles in glucose homeostasis and the presence of a glucocorticoid response element on HBV genome can explain the so-called HBV reactivation observed in patients receiving steroid-based immunosuppressive agents. Although a clinical association between HBV and glucose homeostasis is lacking,104 HBV was shown to promote lipogenesis and fatty acid accumulation in HBV-replicating transgenic mice105 and in the liver of HBV-infected patients.106 Such metabolic alterations are likely to contribute to disease progression. Furthermore, a multitude of in vitro transfection experiments showed that HBx can modify cellular pathways by altering the activity of numerous transcription factors, kinases of the Src family, of the Ras-Raf-mitogen-activated protein kinase cascade and members of the protein kinase C pathway, and by affecting mitochondria function and protein degradation.107 108 Whether HBx, expressed at levels comparable to those present in infected human livers, also similarly affects these cellular functions awaits further investigation.
CccDNA-based chromatin immunoprecipitation (ChIP) assays indicated a correlation between viraemia levels and acetylation status of cccDNA-bound histones,109 suggesting that epigenetic modifications may affect the cccDNA transcriptional status in the different phases of chronic infection. Using ChIP assays HBx was shown to be recruited to the cccDNA minichromosome,110 where by favouring cccDNA-bound histone acetylation, HBx appears to play an essential role in initiating the cccDNA-driven transcription of the HBV RNAs (figure 1).8 However, epigenetic modifications, such as DNA hypermethylation, may induce suppression of cccDNA transcription, since increased expression of DNMTs has been correlated with increased cccDNA methylation and decreased HBV transcription in advanced HBV infection.111 Moreover, HBx was shown to act as a potent epigenetic modifying factor in human liver by modulating the transcription of DNMT required for maintenance of hypomethylation of tumour suppressor genes.99 The HBx-promoted hypermethylation of tumour suppressor genes suggests a novel mechanism by which this promiscuous transactivating protein may accelerate hepatocarcinogenesis.
Numerous cellular factors, such as microRNAs, may affect HBV productivity by binding directly to HBV transcripts or by targeting cellular transcription factors relevant for cccDNA transcription.112 Further studies based on a combination of bioinformatic and miRNA expression screenings are needed to determine whether specific patterns of miRNA expression could serve as diagnostic biomarkers for liver disease prediction.
A number of studies identified host variations that may contribute to the outcome of HBV infection. Genome-wide association studies determined, for instance, polymorphisms in the human leucocyte antigen (HLA) allele DRB1,113 HLA-DP114 and the oestrogen receptor115 that were associated with the susceptibility to HBV clearance or persistence. Similarly, naturally occurring sequence variations in the promoter region of CXCL10 gene were shown to result in the altered expression of the CXCL10 protein, which is important for the intrahepatic recruitment of inflammatory cells, thereby impacting disease progression of patients with chronic HBV infection.116
Emergence of virus quasi-species and infection with other virusesThe selective pressure induced by host immune responses and/or during antiviral therapy with polymerase inhibitors promotes the emergence of mutations. For instance, single amino acid substitutions have been shown to impair HBsAg recognition and lead to the development of acute or chronic HBV infection despite immunoprophylaxis. The region of the genome encoding for the rt domain of the HBV polymerase overlaps completely with the envelope; therefore, mutations emerging during nucleos(t)ide analogue treatment may lead to changes in the viral envelope. In vitro studies have shown that the rtA181T mutation, which introduces a nonsense mutation in the overlapping envelope gene, leads to intracellular retention of the truncated surface proteins and viral particles.72 As discussed above, during the immune competent HBeAg-positive phase, the host immune system may set the stage for the selection of PC/BCP mutations with reduced or absent HBeAg secretion.25 117 Sequencing of cccDNA amplicons indicated that the replacement of wild type cccDNA with populations of BCP mutations was associated with the re-establishment of high virion productivity26 (figure 3). In agreement with these observations, studies in chimpanzees indicated that HBeAg-negative viruses induce more severe hepatitis118 and the accumulation of BCP mutations have been shown to be associated with worsening of clinical manifestations and development of HCC.119
HBV/HCV and HBV/hepatitis D virus (HDV) co-infection are known to lead to a rapid and more severe progression of chronic liver disease. Although the virological profiles in the setting of co-infection appears to be widely divergent and fluctuating levels of viraemia120 are observed, information about the mechanisms responsible for such variations are scant. Although immune-mediated mechanisms may play a major role in suppressing HBV replication in the setting of co-infection,69 121 122 recent studies in chimeric mice31 showed that HDV lowered HBV productivity even in the absence of adaptive immune responses, indicating that complex virus–virus and virus–host interactions may affect replication levels and disease progression in the course of HBV/HDV co-infection.
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Concluding remarks and future directionIn the past decade, there has been an explosion of knowledge and research in the field of hepatitis B molecular diagnostics. The availability of innovative human hepatocyte-based HBV infection systems and the development of molecular techniques permitting molecular analysis, such as cccDNA quantification, ChIP and transcriptome assays, in patient liver biopsies have started to provide new insight about host and viral factors regulating the activity of the cccDNA minichromosome. Furthermore, results showing the existence of interferences between HBV and pathways of the innate immune response suggest that manipulation of TLRs via TLR ligands may have therapeutic potential for the treatment of CHB by reducing viral replication and by promoting improved immune control. Because of the limitations encountered by using different experimental systems, cellular and molecular analyses based on human blood and liver biopsy samples remain indispensable to improve our knowledge of the pathobiology of HBV infection. It can be envisaged that the future understanding of the natural history of CHB will continue to evolve and that management algorithms will become more individualised, incorporating quantitative serology and possibly genotyping and markers of the innate and adaptive immune responses.
作者: MP4 时间: 2012-7-2 16:16
本帖最后由 MP4 于 2012-7-2 16:19 编辑
影响乙肝病毒活性和细胞通路的相互interplays
肝癌发展的发病已被证明与各级HBV复制activity.103的关联，这突出阐明病毒活性调节机制的重要性，因为这些因素都将影响cccDNA的负荷和细胞的途径，从而影响临床感染过程。
在肝脏代谢过程，如肝细胞核因子，cAMP反应元件结合蛋白，维甲酸X受体和过氧化物酶体增殖物激活受体，激活牵连众多转录因子，被称为绑定HBV基因组和肝富集转录因子的招聘cccDNA的微小染色体上出现必要的控制病毒基因expression.6 104然而，病毒成分和细胞因子之间的相互作用，也可能影响肝脏代谢。糖皮质激素类固醇激素，打葡萄糖稳态和糖皮质激素反应元件对HBV基因组的存在可以解释所谓的HBV再激活在接受类固醇免疫抑制剂的患者中观察到的主要角色。虽然缺乏临床协会之间HBV和葡萄糖稳态，104乙型肝炎病毒被证明是促进脂肪生成和脂肪酸的积累，在乙肝病毒复制的基因mice105在乙肝病毒感染的肝，patients.106这种代谢改变可能有助于病情恶化。此外，许多在体外转染实验表明，HBx可修改改变了众多的转录因子，Src家族激酶，RAS-RAF-丝裂原活化蛋白激酶级联和蛋白激酶C的活性细胞的途径通路，并等待进一步调查，通过影响线粒体功能和蛋白质degradation.107 108表示，那些目前在感染人体肝脏的水平相媲美，无论是HBx蛋白，也同样会影响这些细胞的功能。
基于cccDNA水平的染色质免疫沉淀（ChIP）实验表明病毒血症水平与cccDNA的绑定组蛋白的乙酰化状态，表明表观遗传修饰在慢性感染的不同阶段可能会影响到cccDNA的转录状态109之间的相关性。采用芯片检测的HBx蛋白被证明是招募cccDNA的微小染色体，110 cccDNA的绑定有利于组蛋白乙酰化，HBx基因似乎发挥了至关重要的作用，但是在启动驱动cccDNA的乙肝病毒的RNA转录（图1）.8表观遗传修饰，如DNA甲基化，可能会导致cccDNA的转录抑制，因为增加转移酶的表达已与增加cccDNA的甲基化和降低HBV的转录先进乙肝infection.111中，此外，HBx蛋白被证明是一个强有力的后生修改因子作为在人体肝脏调节维持低甲基化抑癌genes.99的需要转移酶转录的HBx蛋白促进肿瘤抑制基因的甲基化建议混杂式激活蛋白，这可能加速肝癌的一种新的机制。
众多的细胞因子，如小分子RNA，可能会影响HBV直接绑定到乙肝病毒转录或需要，以确定是否特定的模式，通过针对细胞转录因子的基础上，结合生物信息学和miRNA表达放映cccDNA的transcription.112进一步研究有关生产力miRNA表达可作为肝脏疾病预测诊断标志物。
一些研究发现主机的变化，可能有助于乙肝病毒感染的结果。全基因组关联研究决定，例如，在人类白细胞抗原（HLA）等位基因DRB1基因多态性，113 HLA-DP114和雌激素receptor115与乙肝病毒清除或持久的易感性相关。同样，中自然产生的CXCL10的基因启动子区域序列变异导致的CXCL10的蛋白质，这是重要的炎性细胞肝内招聘表达的改变，从而影响慢性乙肝患者的疾病进展infection.116
病毒准种的出现和与其他病毒感染
宿主的免疫反应和/或诱导聚合酶抑制剂的抗病毒药物治疗期间的选择性压力，促进突变的出现。例如，单一氨基酸替换已被证明损害乙肝表面抗原识别和导致急性或慢性乙型肝炎病毒感染的发展，尽管免疫预防。 RT域完全信封HBV聚合酶重叠的基因编码的地区，因此，核苷（酸）IDE模拟处理过程中的突变可能会导致病毒包膜的变化。体外研究表明，rtA181T突变，它引入了一个在重叠的信封基因的无义突变，导致细胞内保留截断的表面蛋白和病毒particles.72如上所述，在免疫主管HBeAg阳性阶段，主机免疫系统可能会为减少或消失，HBeAg的secretion.25 117 cccDNA的扩增测序PC / BCP变异与选择的阶段表明，人口的BCP突变的野生型cccDNA的更换高病毒颗粒的重新建立关联productivity26（图3）。在同意这些意见，在黑猩猩的研究表明，HBeAg阴性的病毒引起更严重的hepatitis118和积累的BCP突变已被证明与相关的临床表现和发展的HCC.119恶化
被称为乙肝病毒/丙肝病毒和乙肝病毒/丁型肝炎病毒（HDV）共同感染导致的慢性肝病的迅速和更严重的恶化。虽然在共同感染的设置病毒学概况似乎大相径庭水平波动viraemia120观察，有关负责这些变化的机制的信息，是很少的。虽然免疫介导的机制，可能会起到抑制乙肝病毒复制了重要作用，在共同感染的设置，69 121 122在嵌合mice31最近的研究表明的HDV降低HBV的生产力，甚至在适应性免疫反应的情况下，这表明复杂的病毒病毒和病毒宿主相互作用的HBV / HDV联合感染的过程中可能会影响复制水平和病情恶化。
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在过去十年中，一直在乙肝分子诊断领域的知识和研究爆油油炸。提供创新的人类肝细胞的HBV感染的系统和分子允许的分子分析技术，如cccDNA的定量分析，芯片和转录分析的发展，在病人肝活检已经开始提供新的见解，有关主机和调节活性的病毒因子cccDNA的微小染色体。此外，结果显示HBV和先天免疫反应的途径之间存在干扰，建议，通过TLR为配体TLRs的操纵可能通过减少病毒复制，促进提高免疫控制治疗慢性乙型肝炎的治疗潜力。因为人体血液和肝活检标本仍是不可或缺的，以改善我们的乙肝病毒感染的病理学知识的基础上，通过不同的实验系统，细胞和分子生物学分析所遇到的限制。可以设想，未来的认识慢性乙型肝炎的自然史将继续发展和管理算法将变得更加个性化，结合定量血清学和可能的先天免疫和适应性免疫反应的基因分型和标记。
作者: 9病成医 时间: 2012-7-2 17:51
很好，谢谢楼主！
要是把翻译的汉语搞得再通顺明白一些就更好了；
在通顺明白的基础上，把要点整理出来就更更好了。
作者: 咬牙硬挺 时间: 2012-7-2 19:09
楼主辛苦了，用代理上来顶你
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