丁型肝炎病毒载体携带核酶在小鼠体内抑制乙型肝炎病毒复制

目的：研究用丁型肝炎病毒（HDV）作为载体携带乙型肝炎病毒（HBV）特异性的锤头状核酶所构建的重组体，在细胞体系及转染动物模型中对HBV基因表达和复制的影响。方法：将HDV-核酶重组体和HBV的共表达质粒转染Huh-7细胞以分析HDV-核酶重组体对HBV基因表达的影响；用小鼠尾静脉快速注射法将共表达质粒转染到小鼠体内，检测重组体在动物体内对HBV基因表达和复制的抑制作用。结果：转染细胞中，重组体对HBsAg的抑制与HDV重组位点和核酶靶位都有关；水压法注射的质粒在小鼠肝内得到表达，与对照相比重组HDV-核酶可有效抑制在肝和血清中HBV的基因表达以及复制。与细胞中的结果一致。结论：此项体内实验为进一步构建治疗性重组HDV病毒，发现靶向性抗病毒基因治疗手段奠定基础。     

HDV核酶对乙型肝炎病毒抑制作用的研究

目的研究HDV核酶在细胞内对乙型肝炎病毒(HBV)复制及其抗原表达的抑制作用。方法1)以HBV前基因组mRNA为靶基因,体外筛选出HDV核酶有效作用位点,构建HDV核酶并进行体外测活;2)分别选用tRNA-Val、U6和hCMV 3种真核启动子,重组构建HDV核酶真核表达载体ptVHRz、pSURz和pcDHRz,分别用3种载体转染HepG2.2.15细胞;3)用点杂交、ELISA和实时荧光定量PCR方法分别检测核酶在细胞内的表达及对HBV的抑制作用。结果在HBV C基因区筛选到一位点,所构建的HDV核酶在体外条件下对该位点能产生有效切割。3种核酶表达载体在细胞内均能高效表达,在转染48 h后,ptVHRz和pcDHRz对HBeAg的表达产生了明显的抑制作用,而对HBsAg没有抑制作用。三者对HBV的复制均未产生明显影响。结论HDV核酶在细胞内对HBV抗原的表达能产生特异性抑制作用,但未能有效抑制HBV的复制,对其原因需进一步深入研究。     

乙型肝炎病毒基因组C区启动子肝富集转录因子结合位点突变对HBx增强乙型肝炎病毒复制的影响

目的:构建乙型肝炎病毒（HBV）C启动子近端肝富集转录因子结合位点突变的重组HBV复制型质粒,以期阐明其在HBx增强HBV复制中的作用。方法:利用定点突变技术在野生型HBV复制型质粒和HBx表达缺失的HBV复制型质粒基础上构建HBV C启动子近端肝富集转录因子结合位点突变的重组质粒。随后在HBV肝癌细胞复制模型和小鼠复...     

丁型肝炎

丁型肝炎病毒基因组RNA包埋锤头状核酶的活性研究——李晓娟等（广东深圳市东湖医院、深圳市肝病研究所518020）：《中华实验和临床病毒学杂志》，2005，19（1）：12-15[目的：探讨用丁型肝炎病毒（HDV）基因组来包埋HBV靶向性核酶对核酶体内外活性产生的影响。方法：用和HBV靶基因体外转录产物在不同反应条件下温育对HDV-核酶重组体的体外切割活性定量分析：     

rAAV载体介导的HDV核酶对HBV基因表达的抑制作用

目的探讨重组腺相关病毒介导的HDV核酶在细胞内抑制乙型肝炎病毒基因表达的作用。方法将针对HBV基因序列C区的反式HDVR z与U6启动子和绿色荧光蛋白基因EGFP及其启动子CMV共同插入腺相关病毒载体pSNAV中并取代其原有CMV启动子区域,构建为pSNAV-CR z重组载体。并将pSNAV-CR z、pSNAV及pLEGFP质粒转染HepG2.2.15培养细胞,荧光显微镜下观察绿色荧光,对转染后培养细胞内蛋白进行HBeAg和HBsAg的ELISA分析。结果所构建的重组载体经双酶切及PCR验证与实验设计一致。重组载体转染培养细胞后,荧光显微计数表明,pSNAV-CR z的转染效率为30%。HBeAg和HBsAg的ELISA检测显示,pSNAV-CR z重组载体对HepG2.2.15细胞中HBV病毒的HBeAg和HBsAg表达抑制率分别为63.5%和50.07%。结论细胞水平试验证明,重组腺相关病毒载体介导的反式HDVR z在体外培养细胞水平对HBV的复制起到一定的抑制作用。     

以乙型肝炎病毒为载体的基因治疗研究

目的 探讨乙型肝炎病毒(HBV)作为肝靶向性基因治疗载体的可能性。方法 用外源报告基因绿色荧光蛋白(GFP)取代HBV S基因读码框构建重组HBV载体,通过脂质体转染HepG2细胞,荧光显微镜下观察外源基因的表达,半巢式聚合酶链反应(PCR)检测细胞核内HBV 共价闭合环状DNA构型,常规PCR和Southern杂交检测上清液重组病毒DNA。结累 携带外源基因GFP的重组HBV载体能够在肝细胞内表达外源蛋白,此重组载体为复制缺损型,单独转染后不能在肝细胞包装与复制,在缺失包装信号ε的辅助HBV质粒下可被包装成携带外源基因的成熟重组HBV颗粒并分泌到胞外。结论 HBV可被改造成肝靶向性基因治疗载体。     

乙型肝炎病毒表达载体pHY106在筛选抗病毒药物中的意义

目的应用新的HBV表达载体,建立体外筛选临床抗HBV药物的方法。方法克隆对拉米夫定耐药的CHB患者体内HBV全基因组,然后将其亚克隆到HBV真核表达载体pHY106,体外转染Huh7细胞,检测转染后不同时间HBsAg、HBeAg、HBV DNA及HBV复制中间体水平。分析拉米夫定和阿德福韦对HBV基因表达和复制的抑制作用,指导临床用药。结果成功构建全部8个HBV临床分离株全基因组真核表达质粒,HBV聚合酶基因YMDD有5个产生YVDD突变,3个产生YIDD突变。该质粒上HBV基因能在Huh7细胞中进行复制和表达,拉米夫定不能体外抑制HBV复制,阿德福韦抑制了HBV在Huh7细胞中的复制,抑制程度与药物浓度相关。阿德福韦在患者体内也抑制了HBV的复制。结论新建立的体外筛选抗HBV药物的方法能用于临床快速筛选抗HBV药物,对CHB的治疗用药具有指导意义。     

不同启动子驱动HDV核酶的逆转录病毒载体构建

目的分别构建CMV、H1、tRNA、U2、U3和U6启动子驱动反式丁型肝炎病毒核酶（HDV核酶）的逆转录病毒表达载体。在这些载体中,HDV核酶设计为靶向HBV基因序列PreS2和C区。方法用PCR技术分别扩增CMV、U2和U3启动子,并连入pMD18-T载体。合成靶向PreS2和C区HDV核酶并利用SalⅠ和H indⅢ的酶切位点分别连入逆转录病毒表达载体pLEGFP（pLEGFP-R z）。然后利用BamHⅠ和SalⅠ的酶切位点分别把CMV、H1、tRNA、U2、U3和U6启动子连入重组载体pLEGFP-R z。所有的重组载体经PCR和酶切的方法验证。结果成功地构建了分别含有6种启动子驱动HDV核酶的逆转录病毒载体。结论这些重组载体的构建为筛选高效表达核酶的启动子奠定基础。同时这些重组载体也可用于进一步研究HDV核酶抑制HBV复制的效率。     

MxA基因真核表达载体构建及体外抗HBV作用研究

目的克隆人类MxA基因,探索其细胞内直接抗HBV作用,以便寻求HBV及其他病毒感染的新的基因治疗靶点。方法以pHMG—MxA质粒载体为基础,构建人类MxA基因表达质粒,采用人HBV—DNA转染的2．2．15细胞株作为研究对象,以不同浓度的MxA基因转染进行干预培养,lamivudine（3TC）阳性对照,同时设立空白对照,观察对HBV表达和复制的影响。结果经过酶切鉴定证明重组MxA基因表达质粒pcDNA—MxA构建正确,转染2．2．15细胞后呈现出明显抑制HBV复制和表达作用,且与转染剂量有关;3TC组也见MxA的表达增高,HBV—DNA复制受到明显抑制。结论抗病毒基因MxA具有细胞内抗HBV的复制及抑制病毒抗原基因的表达作用。     

1．2倍基因组长度C基因型乙型肝炎病毒重组体构建及其在HepG2细胞中表达和复制

目的构建基于pBlueBac4．5质粒的1．2倍基因组长度C基因型乙型肝炎病毒（HBV）重组体，并研究其在HepG2细胞中的表达和复制。方法以重组质粒pWT上的1．2倍基因组长度C基因型HBVDNA序列和pBB4．5HBV1．3（D基因型）上的pBlueBac4．5载体序列为模板，构建重组质粒pBB4．5HBV1．2（C基因型）。用FuGENEHD瞬时转染法，将pBB4．5HBV1．2导人HepG2细胞。用化学发光免疫分析法、Southern印迹杂交法、荧光定量PCR法，分别检测转染后不同时间点HBsAg和HBeAg、HBV复制中间体及HBVDNA水平。此外，对转染时重组质粒用量进行优化。结果酶切和序列分析证实，pBB4．5HBV1．2重组质粒构建成功。初步转染实验证实，在转染细胞培养上清中可检测到HBsAg和HBeAg。优化后转染条件为：使用60mm细胞培养皿，8～11tLgpBB4．5HBV1．2，质粒与转染试剂5：9（μg：μl）。在此条件下，5d实验周期内可检测到HBsAg和HBeAg持续表达（峰值一般出现在转染后第3天）、HBVDNA持续复制（10^6～10^8拷贝／ml）及HBVDNA复制中间体形成。结论在HepG2细胞中，建立了以杆状病毒转移载体pBlueBac4．5为基础的1．2倍基因组长度C基因型HBV体外培养体系，有望为研究HBV耐药、筛选新抗病毒药物等提供新技术平台。     

Perspectives for a Vaccine against Hepatitis Delta Virus

Hepatitis delta virus (HDV) causes severe hepatitis in carriers of hepatitis B virus (HBV). In ~90% of patients, HDV persists together with HBV and causes early development of cirrhosis and liver carcinoma. Worldwide ~15 million people are coinfected with HBV-HDV. Specific defects in the immune response causing persistence of the virus have not been identified. Several approaches to develop a vaccine to prevent superinfection in the preclinical model of the woodchuck have failed. Recent findings show that a DNA prime and viral vectors boost immunization regimen can induce a HDV specific CD8 T cell response and can prevent HDV infection in simultaneous infection of woodchuck hepatitis virus-HDV. The vaccine-induced specific CD8 T cell response is effective in preventing HDV replication and spread in the liver. However, the perspectives for a HDV vaccine against genotype-1 to prevent superinfection are much less promising. The T-cell response induced by the current DNA prime and viral vector boost immunization in the preclinical woodchuck model seems insufficient to prevent the spread of HDV in chronic HBV carriers. A more potent vaccine and repeated vaccinations are necessary to induce a HDV-specific T-cell response, which may prevent superinfection in HBsAg carriers.     

Cell Culture Models for the Study of Hepatitis D Virus Entry and Infection

Chronic hepatitis D is one of the most severe and aggressive forms of chronic viral hepatitis with a high risk of developing hepatocellular carcinoma (HCC). It results from the co-infection of the liver with the hepatitis B virus (HBV) and its satellite, the hepatitis D virus (HDV). Although current therapies can control HBV infection, no treatment that efficiently eliminates HDV is available and novel therapeutic strategies are needed. Although the HDV cycle is well described, the lack of simple experimental models has restricted the study of host–virus interactions, even if they represent relevant therapeutic targets. In the last few years, the discovery of the sodium taurocholate co-transporting polypeptide (NTCP) as a key cellular entry factor for HBV and HDV has allowed the development of new cell culture models susceptible to HBV and HDV infection. In this review, we summarize the main in vitro model systems used for the study of HDV entry and infection, discuss their benefits and limitations and highlight perspectives for future developments.     

Hepatitis D Virus and Hepatocellular Carcinoma

Hepatitis D virus (HDV) is a small, defective RNA virus that depends on hepatitis B virus (HBV) for virion assembly and transmission. It replicates within the nucleus of hepatocytes and interacts with several cellular proteins. Chronic hepatitis D is a severe and progressive disease, leading to cirrhosis in up to 80% of cases. A high proportion of patients die of liver decompensation or hepatocellular carcinoma (HCC), but the lack of large prospective studies has made it difficult to precisely define the rate of these long-term complications. In particular, the question of whether HDV is an oncogenic virus has been a matter of debate. Studies conducted over the past decade provided evidence that HDV is associated with a significantly higher risk of developing HCC compared to HBV monoinfection. However, the mechanisms whereby HDV promotes liver cancer remain elusive. Recent data have demonstrated that the molecular profile of HCC-HDV is unique and distinct from that of HBV-HCC, with an enrichment of upregulated genes involved in cell-cycle/DNA replication, and DNA damage and repair, which point to genome instability as an important mechanism of HDV hepatocarcinogenesis. These data suggest that HBV and HDV promote carcinogenesis by distinct molecular mechanisms despite the obligatory dependence of HDV on HBV.     

Variable In Vivo Hepatitis D Virus (HDV) RNA Editing Rates According to the HDV Genotype

Human hepatitis delta virus (HDV) is a small defective RNA satellite virus that requires hepatitis B virus (HBV) envelope proteins to form its own virions. The HDV genome possesses a single coding open reading frame (ORF), located on a replicative intermediate, the antigenome, encoding the small (s) and the large (L) isoforms of the delta antigen (s-HDAg and L-HDAg). The latter is produced following an editing process, changing the amber/stop codon on the s-HDAg-ORF into a tryptophan codon, allowing L-HDAg synthesis by the addition of 19 (or 20) C-terminal amino acids. The two delta proteins play different roles in the viral cell cycle: s-HDAg activates genome replication, while L-HDAg blocks replication and favors virion morphogenesis and propagation. L-HDAg has also been involved in HDV pathogenicity. Understanding the kinetics of viral editing rates in vivo is key to unravel the biology of the virus and understand its spread and natural history. We developed and validated a new assay based on next-generation sequencing and aimed at quantifying HDV RNA editing in plasma. We analyzed plasma samples from 219 patients infected with different HDV genotypes and showed that HDV editing capacity strongly depends on the genotype of the strain.     

Treatment Options for Hepatitis Delta Virus Infection

The hepatitis D virus (HDV), the smallest virus known to infect man, causes the most severe form of chronic viral hepatitis, hepatitis delta. It is estimated that about 15 to 20 million people are suffering from chronic HDV infection. HDV is a defective satellite virus depending on the hepatitis B surface antigen (HBsAg) for transmission. Chronic hepatitis delta is associated with a rapid progression of liver fibrosis and a high prevalence of liver cirrhosis, even in younger patients. Immunization against hepatitis B virus (HBV) protects from HDV infection, but there is no specific vaccine against HDV available for HBsAg-positive individuals. Treatment options for hepatitis delta patients are limited. So far, only interferon-alpha has shown an antiviral efficacy against HDV. Recent trials showed sustained virological response rates concerning HDV in 25 %–30 % of patients treated with pegylated interferons. HDV is dominant over HBV in the majority of cases, but HBV DNA-positive subjects should be treated with HBV polymerase inhibitors. Combination therapy of pegylated interferon-alpha and adefovir showed a more pronounced HBsAg decline, but the exact role of combination therapies in hepatitis delta requires further investigation. Alternative future treatment strategies may include prenylation inhibitors and HBV entry inhibitors, which are in early clinical development.     

Single (B or C), dual (BC or BD) and triple (BCD) viral hepatitis in HIV-infected patients in Madrid, Spain

INTRODUCTION: There are very limited data about the prevalence of multiple hepatitis virus infections in HIV infected individuals. In HIV uninfected individuals with triple BCD hepatitis, hepatitis D virus (HDV) appears to be the dominant virus. However, in HIV infected patients with triple hepatitis it is not known if HDV replication inhibits hepatitis B virus (HBV) and/or hepatitis C virus (HCV) replication. METHODS: We calculated the prevalence of single (B or C), dual (BC) and triple (BCD) hepatitis in 423 HIV-infected patients with positive HCV serum antibodies and/or positive serum HBsAg. In patients with multiple infections we performed an evaluation of serum markers of HBV, HCV and HDV replication. RESULTS: The prevalence of multiple hepatitis was 4.7% (95% confidence interval, 2.7-6.7%). Multiple hepatitis occurred only among patients who acquired HIV through injection drug use. The most common multiple hepatitis was triple BCD. Patients with hepatitis BC and past or chronic hepatitis D were significantly more likely to have cirrhosis and a negative serum HBeAg and HCV PCR than patients with single hepatitis B or hepatitis C. Patients with chronic hepatitis D showed uniform suppression of HBV and HCV replication markers. CONCLUSIONS: In our geographic area approximately 5% of HIV infected patients with hepatitis suffer multiple hepatitis virus infection. In patients with triple hepatitis BCD virus infection, HDV appears to be the dominant virus causing inhibition of both HBV and HCV replication.     

Prevalence of Hepatitis D Virus Infection Among Patients With Chronic Hepatitis B Attending Birjand Hepatitis Clinic (East of Iran) in 2012

Background

Hepatitis delta virus (HDV) is a defective RNA virus dependent on Hepatitis B virus (HBV) infection for its replication and expression. All patients with HBV infection should be tested for the presence of HDV infection. It is estimated that approximately 5% of hepatitis B surface antigen (HbsAg) carriers in the world are HDV infected patients. HBV-HDV co-infection may lead to more severe acute disease and higher risks of fulminant hepatitis, cirrhosis, and hepatocellular carcinoma than those having HBV infection alone. Also, HBV infected patients with HDV super-infection have a higher rate of progression to chronic disease and serious complications.

Objectives

Our aim was to determine the prevalence of HDV infection among chronic hepatitis B (CHB) patients attending Birjand Hepatitis Clinic, East of Iran.

Materials and Methods

A cross-sectional analytical study was conducted on 413 CHB patients in 2012. Serology test for anti-HDV was measured by ELISA in these patients. CHB patients had positive hepatitis B surface antigen for at least 6 months before the study entrance.

Results

The mean age of CHB patients was 38.5± 11.9 years and 55.9% of them (231 patients) were male. There were 13 cases (3.1%) with HDV infection. There was no association between positive anti-HDV serology and factors such as age, gender, carrier state, liver enzymes, and positive hepatitis B e antigen (HBeAg) serology.

Conclusions

Although HDV had a low prevalence in our area, it is important for healthcare providers and policy makers to plan preventive strategies for HDV spread as well as HBV prevention programs among high risk population.     

Management of Hepatitis B Virus Coinfection: HIV, Hepatitis C Virus, Hepatitis D Virus

Coinfection of hepatitis B virus (HBV) with HIV, hepatitis C virus (HCV) and hepatitis D virus (HDV) is common because of shared modes of transmission. Increasing prevalence of high risk sexual behavior and intra venous drug use (IVDU) contributes to a majority of the cases with coinfection. Occult HBV or prior HBV infection is frequently encountered in patients coinfected with HIV or HCV. Although HBV is a preventable disease, failure to screen and inadequate vaccination in the high risk individuals account for vast under-recognition of the cases with HBV infection. Chronic liver disease from viral hepatitis B and C has emerged as the major cause of morbidity and mortality worldwide as well as in the United States. This is especially true in cases coinfected with HIV. The potential long term risks of untreated hepatitis include cirrhosis and hepatocellular carcinoma. There have been several advancements in the understanding of natural history and management options of chronic viral hepatitis. This article discusses and reviews the natural history, epidemiology, and management of HBV patients coinfected with HIV, HCV, or HDV. It includes an updated summary of the outcomes with liver transplantation and post transplant recurrence in the coinfected population with HBV. It also discusses the role of occult HBV in HIV and HCV coinfection respectively.     

Characterization of a hepatitis B and hepatitis delta virus receptor binding site

Insights into the early infection events of the human hepatitis B (HBV) and hepatitis delta virus (HDV) have been limited because of the lack of a cell culture system supporting the full replication cycle for these important pathogens. The human hepatoma cell line HepaRG allows the experimental induction of a differentiated state, thereby gaining susceptibility toward HBV and HDV infection. We recently identified HBV envelope protein-derived lipopeptides comprising amino acids 2 though 48 of the preS-domain of the L-surface protein, which block infection already at picomolar concentrations. To map the responsible sequence for the peptides' activity we describe an Escherichia coli expression system that permits myristoylation and investigated recombinant HBVpreS-GST fusion proteins with deletion- and point-mutations for their ability to prevent HBV and HDV infection. We found that (1) a myristoylated HBVpreS/2-48-GST fusion protein efficiently interferes with HBV infection of HepaRG cells; (2) deletions and point mutations in the highly conserved preS1 sequence between amino acids 11 through 21 result in the loss of infection inhibition activity; (3) hepatitis B viruses carrying single amino acid exchanges within this region lose infectivity; and (4) HDV infection of HepaRG cells can be inhibited by myristoylated HBVpreS peptides with the same specificity. In conclusion, HBV and HDV use at least one common step to enter hepatocytes and require a highly conserved preS1-sequence within the L-protein. This step is exceptionally sensitive toward inactivation by acylated HBVpreS1 peptides, which therefore represent a novel group of entry inhibitors that could be used for the treatment of hepatitis B and D.