HBV prec/c shRNA慢病毒真核表达载体的构建和鉴定

目的构建针对HBV prec/c区的shRNA真核表达载体psiHBV,感染HepG2 2.15细胞后观察其对HBeAg表达的抑制作用,为探讨防治HBV感染的新措施提供实验依据。方法针对HBV prec/c基因序列,构建shRNA表达载体psiHBV1、psiHBV2和无关序列psiHBVc。psiHBV与慢病毒辅助系统质粒共转染293T细胞组装慢病毒颗粒后,感染HepG2 2.15细胞,RT-PCR检测prec/c mRNA的转录,微粒子化学发光分析仪(MEIA)检测细胞上清和细胞裂解液中HBeAg表达。结果重组质粒双酶切和测序鉴定与预期结果相符合;组装慢病毒颗粒感染HepG2 2.15细胞后,prec/c mRNA转录降低;与对照组比较,HBeAg的表达水平也显著降低,病毒颗粒对HBeAg表达的抑制作用差异有统计学意义(P<0.01)。结论成功构建针对HBVprec/c的慢病毒载体psiHBV1、siHBV2,慢病毒介导的RNA i能抑制HBV表达,为应用RNA干扰技术治疗乙型肝炎提供了实验依据。     

反义前C／C基因转移表达抗乙型肝炎病毒作用的研究

为了观察逆转录病毒载体包装细胞系统介导反义基因转移表达的抗乙型肝炎病毒（HBV）作用,将HBVayw前C／C基因（preC／C）片段反向插入逆转录病毒载体质粒。将重组体转染逆转录病毒包装细胞PA317后,获得重组逆转录病毒。用重组逆转录病毒感染2．2．15细胞后发现,感染后第3天,细胞培养上清HBV表面抗原（HBsAg）和e抗原（HBeAg）表达量即明显减少,抑制作用于感染后第5天达到高峰,其中对HBsAg表达的抑制率为27．0％,对HBeAg表达的抑制率为59.5％。反义基因重组逆转录病毒感染2.2．15细胞对HBV抗原表达的抑制作用至少可以持续到转导后的第11天。空载及正义基因重组逆转录病毒感染对2．215细胞HBV抗原表达无明显抑制作用。此外,反义基因重组逆转录病毒感染对2.2.15细胞HBVDNA复制也有抑制作用．无细胞毒性。     

绿色荧光蛋白分裂肽基因重组乙型肝炎病毒复制子模型的建立

为构建一种重组乙型肝炎病毒(hepatitis B virus, HBV)复制子模型,使其能够在病毒感染的细胞中表达可视化报告基因蛋白,本研究删除HBV基因组核心蛋白(HBV core, HBc)编码区部分序列,构建HBV1.1-ΔHBc113复制子载体。利用内含肽(intein)介导蛋白拼接的特性,选取加强绿色荧光蛋白(enhanced green fluorescent protein, EGFP)和超级折叠绿色荧光蛋白(super folder green fluorescent protein, sfGFP)作为外显肽,建立EGFP^N1-8/EGFP^C9-11和sfGFP^N1-10/sfGFP^C11蛋白分裂系统。基于ΔHBc113载体,分别构建EGFP^C9-11和sfGFP^C11重组HBV复制子;应用DNA印迹法(Southern blotting)验证两种rHBV载体的细胞内复制能力。结果显示,构建的HBV1.1-ΔHBc113复制子载体能够在HBc反式互补条件下在转染细胞中形成病毒复制。构建的EGFP^C9-11和sfGFP^C11重组HBV复制子能够支持HBc互补条件下的细胞内病毒复制,并产生子代病毒颗粒;HBV重组复制子表达的EGFP^C9-11或sfGFP^C11蛋白在共表达氮端蛋白EGFP^N/sfGFP^N细胞中,通过intein介导的蛋白质高效拼接,能够形成完整的、有功能的GFP。结果表明,构建的荧光蛋白重组HBV复制子系统能够为HBV高通量药物筛选和HBV易感性研究提供实验工具,具有重要的病毒学意义和应用前景。     

高嗜肝性8型重组腺相关病毒体内转导法制备乙型肝炎病毒持续感染小鼠模型

用高嗜肝性的重组8型腺相关病毒(Recombinant adeno-associated virus type8,rAAV8)载体携带1.3拷贝乙型肝炎病毒(Hepatitis B virus,HBV)基因组(ayw亚型)体内转导法,建立持续表达HBV抗原的C57BL/6小鼠模型。首先,制备并纯化了携带1.3拷贝HBV基因组(ayw亚型)的重组8型腺相关病毒(rAAV8-1.3HBV);将rAAV8-1.3HBV以剂量2×10e11vg/只注射C57BL/6小鼠(Viralgenome,vg);在不同时间点实施尾静脉采血,采用ELISA方法监测血清中HBsAg和HBeAg的水平及动力学变化;10周后处死小鼠,取血液、肝组织样本,提取基因组DNA,荧光定量PCR检测HBVDNA拷贝数;利用鉴定HBVDNA环化形式的特异性引物进行PCR扩增以检测肝组织中环化的HBVDNA,并检测HBV抗原特异性的免疫组化和肝脏病理变化。结果显示,注射rAAV8-1.3HBV的3只C57BL/6小鼠第1周开始在血液中检测到HBsAg和HBeAg的表达,并持续至第10周均为阳性,其中HBsAg的表达水平经历了一个上升-下降-再上升的过程(注射后第4周时最低,第6周后维持较高水平),而HBeAg表达水平则持续阳性且比较稳定。荧光定量PCR结果显示,3只小鼠10周后血清中HBV DNA的拷贝数分别为4.2×103、3.6×103、2.5×103copies/mL,肝脏中则分别为8.0×106、5.7×106、2.6×106copies/g肝组织。在3只小鼠肝组织中均检测到环化HBV DNA,提示AAV8载体携带的线性HBV DNA成功回复成环化HB VDNA。免疫组化分析显示3只小鼠肝脏中均存在HBsAg和HBcAg表达;体内转染10周后肝脏组织切片的HE染色分析显示未见明显的炎性细胞浸润及组织结构异常。结果表明,本研究利用高嗜肝性重组8型腺相关病毒载体携带1.3拷贝乙型肝炎病毒基因组(ayw亚型)体内转导C57BL/6小鼠,成功地建立了HBV病毒在肝内稳定复制并持续表达HBV抗原的小鼠模型,为进一步研究HBV慢性持续感染的机制与应用于药物以及疫苗评价打下了基础。     

改造HBV作为基因治疗载体

HBV具备改造作为肝靶向性基因治疗载体的基本条件---天然嗜肝特异性,能够在肝细胞内持续复制、反复感染,病毒本身对细胞没有明显的细胞毒性;能够携带外源基因并被包装成病毒颗粒;能够介导外源基因的转移和表达。但由于基因结构复杂,目前改造的HBV载体均存在载容量小、复制包装效率低及安全性差等缺点。就近年相关研究进展进行综述。     

用rAAV8-1.3HBV制备两种品系小鼠乙型肝炎病毒感染模型的比较研究

我们先前用rAAV8-1.3HBV静脉注射C57BL/6小鼠成功地制备了慢性乙型肝炎病毒(Hepatitis B virus,HBV)感染模型。为了探讨不同品系的小鼠对rAAV8-1.3HBV静脉注射是否具有不同反应,本研究比较了C57BL/6和BALB/c小鼠静脉注射重组病毒后外周血中HBV抗原和抗体水平、病毒载量和肝脏组织HBcAg表达情况,以及不同剂量重组病毒注射与这些指标的关系。将低(4×109 Viral genome,vg)、中(4×1010vg)和高(4×1011vg)三种剂量的rAAV8-1.3HBV通过尾静脉注射至C57BL/6和BALB/c小鼠,分别利用ELISA和荧光定量PCR方法检测血清中的HBV抗原、抗体水平以及HBV DNA,利用免疫组化检测肝脏组织HBcAg的表达。结果发现,对于C57BL/6小鼠,三种不同剂量rAAV8-1.3HBV注射均可造成100%小鼠出现HBV持续感染;血清HBsAg、HBeAg和HBV DNA以及肝组织HBcAg稳定表达超过8个月,其表达水平随重组病毒注射剂量的增加而升高,高剂量注射时可造成超过40%的肝细胞感染HBV,血清中HBV DNA可达105 IU/mL以上;未检测到针对HBV的抗体。对于BALB/c小鼠,三种不同剂量rAAV8-1.3HBV注射也可造成100%小鼠出现HBV持续感染;血清HBeAg和HBV DNA以及肝组织HBcAg稳定表达超过8个月,但是血清HBsAg在重组病毒注射2周之后显著下降甚至消失;在中剂量注射组的BALB/c小鼠血清中检测到低水平的Anti-HBs;血清HBeAg和肝组织HBcAg的表达水平随重组病毒注射剂量的增加而增高,并且各剂量组表达水平均高于C57BL/6小鼠,高剂量注射时可造成超过50%的肝细胞感染HBV。本研究表明,低至4×109 vg剂量的rAAV8-1.3HBV注射即可造成C57BL/6和BALB/c两种品系小鼠出现HBV持续感染,并且HBV复制水平随重组病毒注射剂量增加而增高;BALB/c小鼠对HBV的免疫反应强于C57BL/6小鼠,可以产生针对HBsAg的体液免疫反应而使血清HBsAg转阴,但无法清除携带HBV的肝细胞。     

反义前S/S基因转移表达抗乙型肝炎病毒的研究

为了观察反义基因转录表达抗乙型肝炎病毒(HBV)的作用,将HBV ayw前S/S基因(preS/S)片段反向插入逆转录病毒载体质粒,构建preS/S反义基因重组体,经转染PA317细胞后,获得重组逆转录病毒颗粒.用重组病毒转导2.2.15细胞后,第3天即可见细胞培养上清HBV表面抗原(HBsAg)和e抗原(HBeAg)表达量减少,到转导后第5天,细胞培养上清中的HBsAg和HBeAg表达量降到最低水平,HBsAg抑制率为71%,HBeAg抑制率为27%,抑制作用至少可持续到转导后第11天.空载及正向插入基因的重组逆转录病毒转导对2.2.15细胞内HBV抗原表达无抑制作用.     

乙型肝炎病毒感染Babl/c乳鼠动物模型的研究

目的:目前HBV感染动物模型各有局限,无法全面研究HBV。拟建立人HBV血清感染Babl/c乳鼠的动物模型,以便于研究HBV感染与乳鼠免疫力低下的相关性。方法:将20只Babl/c乳鼠随机分为实验组、对照组、PBS组及空白组,通过高压水动力尾静脉注射法将人HBV血清、正常人血清、PBS注入各组乳鼠体内,记录接种后乳鼠体温及体质量。于接种后第7、15、30 d采集血清标本,应用ELISA检测HBs Ag、HBe Ag的表达情况,实时荧光定量PCR检测HBV DNA浓度。结果:接种后各组小鼠体温及体质量均无明显变化。实验组中共4只乳鼠可检测到HBs Ag为阳性且维持时间长达30 d,但HBe Ag均为阴性,HBV DNA浓度均未达500 IU/ml;余下各组检测HBs Ag、HBe Ag均为阴性。结论:通过高压水动力尾静脉注射法接种人HBV血清,可成功使Babl/c乳鼠感染HBV。本实验证实乳鼠免疫力低下,HBV血清进入体内未能有效清除,对HBV存在易感性,为建立HBV感染动物模型提供实验依据,可用于研究HBV对免疫状态的影响。     

靶向HBs基因的shRNA表达载体的构建及其抑制HepG2.2.15表达HBVsAg的作用

探索用PGenesil-1(Pg)构建的靶向乙型肝炎病毒表面抗原(HBsAg)基因的shRNA表达载体PGenesil-1-HBs(简称Pgs),对体外培养HepG2.2.15细胞中的HBV基因及其抗原表达的抑制作用.设计、合成靶向HBV S区的3对DNA序列,分别插入PGenesil-1中构建3个siRNA表达载体Pgs1、Pgs2、Pgs3,经限制性内切酶,DNA序列测定等技术鉴定确认.筛选并确定最佳细胞接种量及重组质粒转染量后,分别或按不同组合转染HepG-2.2.15细胞,48 h后采用半定量RT-PCR检测HBVsmRNA转录水平,免疫细胞化学技术检测HBsAg表达水平,MEIA分别检测细胞裂解液和培养上清中HBsAg和HBeAg的表达水平.结果表明,HBV真核表达载体Pgs1、Pgs2、Pgs3均能不同程度地抑制HepG2.2.15细胞中的HBsAg、HBeAg合成和HBs-mRNA转录.成功构建的HBV真核表达载体Pgs1、Pgs2、Pgs3,其中PgS3能显著抑制HBsAg表达(P＜0.01).多种表达载体联合对抗原表达的抑制作用效率不同.     

乙型肝炎病毒X基因真核表达载体的构建及表达

目的:构建含有天然完整的乙型肝炎病毒(HBV)X基因序列的真核表达载体,观察其在肝癌细胞株中的表达。方法:设计并合成HBV X基因的引物,用PCR方法从含完整HBV全基因的HepG2细胞中扩增X基因序列,并将其连接到真核表达载体pVAX-1上,酶切、PCR鉴定;用Triton X-114去除质粒内毒素后,采用电穿孔法将重组质粒pVAX-HBV X和空质粒pVAX-1分别转染SMMC-7721细胞,RT-PCR法检测HBV X基因mRNA的表达,Western印迹鉴定HBV X蛋白(HBx)的表达。结果:酶切和PCR鉴定证实pVAX-HBV X载体中包含完整的HBVX基因片段,该重组质粒转染的SMMC-7721细胞中HBV X基因mRNA及HBx蛋白的表达稳定。结论:构建了HBV X基因的真核表达载体,为X基因及其编码蛋白的生物学功能的研究提供了可靠的基因材料。     

miR-29c targets TNFAIP3, inhibits cell proliferation and induces apoptosis in hepatitis B virus-related hepatocellular carcinoma

Recent studies have revealed that microRNA-29c (miR-29c) is involved in a variety of biological processes including carcinogenesis. Here, we report that miR-29c was significantly downregulated in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) cell lines as well as in clinical tissues compared with their corresponding controls. Tumor necrosis factor alpha-induced protein 3 (TNFAIP3), a key regulator in inflammation and immunity, was found to be inversely correlated with miR-29c levels and was identified as a target of miR-29c. Overexpression of miR-29c in HepG2.2.15 cells effectively suppressed TNFAIP3 expression and HBV DNA replication as well as inhibited cell proliferation and induced apoptosis. We conclude that miR-29c may play an important role as a tumor suppressive microRNA in the development and progression of HBV-related HCC by targeting TNFAIP3. Thus miR-29c and TNFAIP3 represent key diagnostic markers and potential therapeutic targets for the prevention and treatment of HBV infection.     

Antiviral Effect of Interferon-Induced Guanylate Binding Protein-1 against Coxsackie Virus and Hepatitis B Virus B3 in Vitro

Guanylate binding protein-1(GBP-1) is an interferon-induced protein. To observe its antiviral effect against Hepatitis B virus (HBV) and Coxsackie virus B3 (CVB3), we constructed an eukaryotic expression vector of human GBP-1(hGBP-1). Full-length encoding sequence of hGBP-1 was amplified by long chain RT-PCR and inserted into a pCR2.1 vector, then subcloned into a pCDNA3.1(-) vector. Recombinant hGBP-1 plasmids and pHBV1.3 carrying 1.3-fold genome of HBV were contransfected into HepG2 cells, and inhibition effect of hGBP-1 against HBV replication was observed. Hela cells transfected with recombinant hGBP-1 plasmids were challenged with CVB3, and viral yield in cultures were detected. The results indicated that recombinant eukaryotic expression plasmid of hGBP-1 was constructed successfully and the hGBP-1 gene carried in this plasmid could be efficiently expressed in HepG2 cells and Hela cells. hGBP-1 inhibit CVB3 but not HBV replication in vitro. These results demonstrate that hGBP-1 mediates an antiviral effect against CVB3 but not HBV and perhaps plays an important role in the interferon-mediated antiviral response against CVB3.     

Antiviral Effect of Interferon-Induced Guanylate Binding Protein-1 against Coxsackie Virus and Hepatitis B Virus B3 in Vitro

Guanylate binding protein-1(GBP-1)is an interferon-induced protein.To observe its antiviral effect against Hepatitis B virus(HBV)and Coxsackie virus B3(CVB3),we constructed an eukaryotic expression vector of human GBP-1(hGBP-1).Full-length encoding sequence of hGBP-1 was amplified by long chain RT-PCR and inserted into a pCR2.1 vector,then subcloned into a pCDNA3.1(-)vector.Recombinant hGBP-1 plasmids and pHBV1.3 carrying 1.3-fold genome of HBV were contransfected into HepG2 cells,and inhibition effect of hGBP-1 against HBV replication was observed.Hela cells transfected with recombinant hGBP-1 plasmids were challenged with CVB3,and viral yield in cultures were detected.The results indicated that recombinant eukaryotic expression plasmid of hGBP-1 was constructed successfully and the hGBP-1 gene carried in this plasmid could be efficiently expressed in HepG2 cells and Hela cells.hGBP-1 inhibit CVB3 but not HBV replication in vitro.These results demonstrate that hGBP-1 mediates an antiviral effect against CVB3 but not HBV and perhaps plays an important role in the interferon-mediated antiviral response against CVB3.     

CRL4在增殖的肝细胞系中上调乙型肝炎病毒抗原的分泌表达

乙型肝炎病毒（hepatitis B virus,HBV）编码的X蛋白（hepatitis B virus X protein,HBx）对HBV感染的起始和维持至关重要。HBx可能作为病毒来源的接头分子,介导Cullin-RING E3泛素连接酶4（cullin-RING ubiquitin E3 ligase 4,CRL4）复合物对染色体外DNA限制因子SMC5/6的降解。最近研究发现CRL4接头分子DNA损伤结合蛋白1（DNA damage-binding protein 1,DDB1）可不依赖与HBx的相互作用而直接上调病毒的表达和复制。本研究基于HBx基因删除（X-null）的HBV重组cccDNA（recombinant covalently closed circular DNA,rcccDNA）模型系统,在多种体外培养肝细胞系中证实上述发现。有意思的是,CRL4刺激rcccDNA^X-null转染细胞抗原分泌表达的效应能被血清饥饿实验抵消。应用尾静脉高压注射小鼠模型,同样发现CRL4并不上调rcccDNA^X-null在非增殖小鼠肝脏细胞中的表达。以上结果提示,细胞增殖特征与CRL4不依赖HBx上调病毒抗原表达的效应密切相关,有助于HBx生物学意义的准确分析和理解。     

Antiviral effect of interferon-induced guanylate binding protein-1 against Coxsackie virus and Hepatitis B virus B3 <Emphasis Type="Italic">in Vitro</Emphasis>

Guanylate binding protein-1(GBP-1) is an interferon-induced protein. To observe its antiviral effect against Hepatitis B virus (HBV) and Coxsackie virus B3 (CVB3), we constructed an eukaryotic expression vector of human GBP-1(hGBP-1). Full-length encoding sequence of hGBP-1 was amplified by long chain RT-PCR and inserted into a pCR2.1 vector, then subcloned into a pCDNA3.1(−) vector. Recombinant hGBP-1 plasmids and pHBV1.3 carrying 1.3-fold genome of HBV were contransfected into HepG2 cells, and inhibition effect of hGBP-1 against HBV replication was observed. Hela cells transfected with recombinant hGBP-1 plasmids were challenged with CVB3, and viral yield in cultures were detected. The results indicated that recombinant eukaryotic expression plasmid of hGBP-1 was constructed successfully and the hGBP-1 gene carried in this plasmid could be efficiently expressed in HepG2 cells and Hela cells. hGBP-1 inhibit CVB3 but not HBV replication in vitro. These results demonstrate that hGBP-1 mediates an antiviral effect against CVB3 but not HBV and perhaps plays an important role in the interferon-mediated antiviral response against CVB3. Foundation item: National Natural Science Foundation (No.30271170, No.30170889).     

The “Trojan horse” model-delivery of anti-HBV small interfering RNAs by a recombinant HBV vector

Hepatitis B virus (HBV) is a small virus that infects the liver. The major obstacle in applying the RNA interference method as an anti-HBV weapon is the challenge to deliver the small interfering RNA molecules to the liver efficiently and specifically. Here we show that HBV-specific short hairpin RNAs (shRNAs) are efficiently expressed from a recombinant HBV into which an shRNA-expressing cassette was inserted, resulting in a significant knock-down of HBV gene expression. Notably, this recombinant HBV still expresses the HBV Core protein, which is targeted by the shRNAs produced by the same vector. Our results set the stage for further use of this recombinant HBV virus with the potential to function as a “Trojan horse”; one that specifically targets the liver and uses the resident virus as an helper for its own propagation, and at the same time eliminate itself and the resident HBV by knocking-down their gene expression.