Inhibition of hepatitis C virus infection and expression in vitro and in vivo by recombinant adenovirus expressing short hairpin RNA

Background and Aim:  We have reported previously that synthetic small interfering RNA (siRNA) and DNA-based siRNA expression vectors efficiently and specifically suppress hepatitis C virus (HCV) replication in vitro . In this study, we investigated the effects of the siRNA targeting HCV-RNA in vivo .
Methods:  We constructed recombinant retrovirus and adenovirus expressing short hairpin RNA (shRNA), and transfected into replicon-expressing cells in vitro and transgenic mice in vivo .
Results:  Retroviral transduction of Huh7 cells to express shRNA and subsequent transfection of an HCV replicon into the cells showed that the cells had acquired resistance to HCV replication. Infection of cells expressing the HCV replicon with an adenovirus expressing shRNA resulted in efficient vector delivery and expression of shRNA, leading to suppression of the replicon in the cells by ∼10⁻³. Intravenous delivery of the adenovirus expressing shRNA into transgenic mice that can be induced to express HCV structural proteins by the Cre/ lox P switching system resulted in specific suppression of virus protein synthesis in the liver.
Conclusion:  Taken together, our results support the feasibility of utilizing gene targeting therapy based on siRNA and/or shRNA expression to counteract HCV replication, which might prove valuable in the treatment of hepatitis C.     

干扰Fas受体表达的串联shRNA表达载体的构建

目的:利用pEGFP6-1和pGenesil-1质粒构建针对Fas的2个短发夹RNA(short hairpin RNA,shRNA)串联表达的栽体．方法:设计表达2个shRNA结构的互补DNA序列,经退火成双链,分别克隆至带有U6启动子的质粒载体pEGFP6-1和pGenesil-1中,构建重组质粒,转化大肠杆菌DH5α菌株,扩增,提取质粒,酶切鉴定后测序分析．分别用SacI SalI双酶切重组质粒,胶回收酶切pEGFP6- 1-siFas1大片段和酶切pGenesil-1-siFas2小片段,T4 DNA Ligase连接酶切大、小片段,得到pEGFP6-1-siFas1 siFas2重组质粒．转化感受态细胞DH5α,扩增,提取串联重组质粒进行酶切鉴定．结果:成功构建靶向Fas的2个shRNA串联重组质粒载体pEGFP6-1-siFas1 siFas2．酶切鉴定和测序分析重组质粒,shRNA编码序列与设计的片段完全一致,经酶切凝胶电泳证实载体构建成功．结论:表达2个靶向Fas的shRNA表达框成功构建在一个重组质粒载体上．     

Inhibition of hepatitis B virus surface antigen expression by small hairpin RNA in vitro

AIM: To explore the anti-hepatitis B virus effect of RNA interference (RNAi) using small hairpin RNA (shRNA) expression vector. METHODS: Hepatitis B virus surface antigen green fluorescent protein (HBs-GFP) fusion vector and shRNA expression vectors were constructed and cotransfected transiently into HepG2 cells. mRNAs extracted from HepG2 cells were detected by real-time PCR. Fluorescence of HBs-GFP protein was detected by fluorescence-activated cell sorting (FACS). The effective shRNA expression vector was transfected into HepG2.2.15 cells. HBsAg and HBeAg in HepG2.2.15 cells were analyzed by radioimmunoassay (RIA) method. RESULTS: FACS revealed that shRNA targeting at HBsAg reduced the GFP signal by 56% compared to the control. Real-time PCR showed that HBs-GFP mRNA extracted from HepG2 cells cotransfected with pAVU6+27 and HBs-GFP expression plasmids decreased by 90% compared to the empty vector control. The expressions of HBsAg and HBeAg were also inhibited by 43% and 64%, respectively. CONCLUSION: RNAi using shRNA expression vector can inhibit the expression of HBsAg, providing a fresh approach to screening the efficient small interfering RNAs (siRNAs).     

针对HBV S基因发夹状siRNAs表达载体的构建及其在HepG2215细胞中对HBV基因表达的抑制作用

目的探讨通过载体在体外培养的细胞中表达发夹状siRNAs对HBV基因表达的抑制作用。方法构建表达针对HBV S基因mRNA的发夹状siRNAs的质粒pSilencer 2.1-U6-S,并与ayw亚型HBV全基因组表达质粒共转染体外培养的HepG2215细胞,用半定量RT-PCR分析目标mRNA表达丰度的变化,用ELISA法观察HBsAg表达的变化。结果siRNA处理组细胞上清中HbsAg和HBeAg含量分别比空白对照组降低了63.4%和68.0%,细胞中的2.1kb的信使RNA降低了75.2%。结论siRNA在体外培养的细胞中能有效地抑制HBV基因的表达。     

RNA干扰对乙型肝炎病毒复制的体外影响

目的:通过一种能够在细胞内表达短发卡RNA的逆转录病毒载体来研究RNA干扰对乙型肝炎病毒复制的影响.方法:首先针对HBV基因组Pol基因RT区寻找RNAi的靶位,并设计相对应的寡核苷酸链.然后再将一对碱基配对寡核苷酸链退火后连接入载体形成重组的质粒,并进行鉴定.在Huh-7细胞中,将通过鉴定的干扰质粒与HBV复制型质粒pHBV3.8共转染,分别应用ELISA方法来检测HBV相关的抗原,应用Northern印迹检测HBV RNA,以及应用实时荧光定量PCR和Southern印迹检测HBV核心颗粒DNA.结果:研究通过计算机方法协助寻找了3条RNAi靶位,并且构建了相应的基于逆转录病毒载体的RNA干扰质粒154i、312i和734i.结果发现312i对pHBV3.8表达有明显的抑制,HBsAg和HBeAg分别为阴性对照组的39%和41%,差异均有显著性(P=0.001,P=0.000).定量荧光PCR结果显示312i组核心颗粒DNA水平显著低于阴性对照组(21.3%±1.1%vs 100.0%±10.6%,P=0.0046).Southern blot和Northern blot结果均显示,312i组病毒复制及mRNA转录水平最低(10.5%,12.0%).结论:在HBV基因组RT区找到了一个可用于RNAi的靶位,并且构建了相对应的干扰质粒,此质粒可成功地抑制HBV复制型质粒在细胞中的复制和表达.     

敲低ABCG1慢病毒表达载体的构建及功能检测

目的为探讨人急性单核细胞白血病细胞系(THP-1)中胆固醇转运相关的ABCG1基因的表达对动脉粥样硬化发生发展的作用,构建ABCG1慢病毒干扰载体,并验证干扰效果、进行功能检测。方法针对人ABCG1的cDNA序列,设计两个RNA干扰的寡核苷酸单链DNA。将其插入到慢病毒表达载体上;将构建的载体和包装质粒共转染293T细胞;通过实时荧光定量PCR及蛋白质免疫印迹检测干扰载体对ABCG1表达水平的影响;通过检测外流率进行功能验证。结果构建的ABCG1基因的小干扰RNA慢病毒表达载体感染THP-1细胞可以有效地抑制ABCG1 mRNA和蛋白表达水平,且减少ABCG1介导的胆固醇外流,感染组外流率小于对照组(23.87%±0.45%比30.57%±1.00%,P<0.001)。结论慢病毒表达载体成功敲低THP-1细胞的ABCG1,并为后续的ABCG1在巨噬细胞中生物学作用的研究创造条件。     

CXCR4-shRNA重组腺病毒表达载体的构建及鉴定

目的选择性构建CXC趋化因子受体4（CXCR4）的特异RNA干扰载体。方法在GenBank中获取CXCR4基因的核苷酸序列,设计并合成3条短发夹RNA（shRNA）的DNA序列,并克隆到PL—Dest腺病毒骨架载体（shpAd／PL—Dest）中,组成人趋化因子受体重组腺病毒基因沉默子（shpAd—hCXCR4-eGFP）,采用酶切、PCR和DNA测序方法验证。将验证后3种沉默子经酶切后转染至HEK293A细胞包装病毒,得到CXCR4的腺病毒表达载体。结果构建的shRNA—Ad—hCXCR4-eGFP3种基因沉默子序列正确并成功克隆到腺病毒表达载体上。结论成功构建CXCR4-shRNA腺病毒表达载体。     

Inhibition of hepatitis B virus expression and replication by RNA interference in HepG2.2.15

INTRODUCTION Hepatitis B is a severe infectious disease threatening peoples’ health all over the world. There is still no efficient therapy to control HBV persistent replication, which may lead to the development of liver cirrhosis and hepatocellualar ca…     

RNA干扰抑制乙型肝炎病毒复制的实验研究

目的 以乙型肝炎病毒(HBV)核心区为靶位，构建表达小干扰RNA(siRNA)的质粒载体pSilencer3．1-Hlhygro，体外观察siRNA抗HBV的效果。方法 以HepG2 2．2．15细胞为靶细胞，利用脂质体Metafectene与表达siRNA的质粒载体pSilencer3．1-Hlhygro共转染，用定量聚合酶链反应检测细胞上清液中DNA，用逆转录聚合酶链反应检测HBV C-mRNA。结果 成功构建了表达siRNA的转录质粒载体，两条siRNA均可抑制HBV的复制，而且与siRNA浓度成正相关。结论 靶向HBV核心区的siRNA能抑制HBV的复制。     

Thermodynamic stability of small hairpin RNAs highly influences the loading process of different mammalian Argonautes

MicroRNAs and siRNAs interact with target sequences in mRNAs, inducing cleavage- and non-cleavage-based gene repression through the RNA-induced silencing complex (RISC) that consists of one of four mammalian Argonaute proteins, Ago1-Ago4. The process of how Dicer substrate small hairpin RNAs (shRNAs) are loaded into different mammalian Agos in vivo is not well established. Here we report that shRNAs are loaded into mammalian Agos in two stepwise processes, physical association and activation, with the latter being the rate-limiting step with noncleaving RISC. We establish that, although RNA duplexes processed from shRNAs bind to Agos in cells with similar affinity, the degree by which the complexes are activated (coupled with the removal of the passenger strand) correlates with the thermodynamic instability of RNA duplexes being loaded rather than the structure of the RNA, as was previously demonstrated in Drosophila. Interestingly, Ago loading of siRNAs is less sensitive to thermostability than that of their shRNA equivalents. These results may have important implications for the future design of RNAi-based therapeutics.     

Hepatitis B virus inhibition in mice by lentiviral vector mediated short hairpin RNA

Background  

Chronic hepatitis B virus (HBV) infection is an important cause of cirrhosis and hepatocellular carcinoma. The major challenges for current therapies are the low efficacy of current drugs and the occurrence of drug resistant HBV mutations. RNA interference (RNAi) of virus-specific genes offers the possibility of developing a new anti-HBV therapy. Recent reports have shown that lentiviral vectors based on HIV-1 are promising gene delivery vehicles due to their ability to integrate transgenes into non-dividing cells. Herein, a lentivirus-based RNAi system was developed to drive expression and delivery of HBV-specific short hairpin RNA (shRNA) in a mouse model for HBV replication.     

高表达乙型肝炎病毒转基因小鼠的制备

目的 制备高表达乙型肝炎病毒（ＨＢＶ）转基因小鼠,为乙型肝炎研究提供较理想动物模型。方法 构建、筛选高表达ＨＢＶ质粒载体。用显微注射法导入昆明鼠受精卵雄性原核,用ＰＣＲ、Ｓｏｕｔｈｅｒｎ杂交、放射免疫、免疫组织化学等方法分析ＨＢＶ基因在小鼠体内的整合、表达情况。结果 显微注射１４５６枚卵,产仔１１８只,整合阳性２５只,１１只血清ＨＢＶ ＤＮＡ、ＨＢｓＡｇ阳性,其中２只血清中ＨＢｓＡｇ含量高于１０００ｎｇ／ｍｌ,且子代鼠中达到９００ｎｇ／ｍｌ。肝组织免疫组化分析发现有ＨＢｓＡｇ、ＨＢｃＡｇ表达,未见明显病理学改变。结论 已初步获得高表达ＨＢＶ转基因小鼠。     

逆转录病毒介导双靶区反义RNA在转基因小鼠肝细胞中的表达及对HBV DNA复制的影响

目的:探讨逆转录病毒介导的乙型肝炎病毒(HBV)X,P单、双靶区的反义RNA在乙型肝炎转基因小鼠肝细胞中HBV复制的影响．方法:构建表达HBV X,P双靶区正、反义RNA的重组载体质粒,与脂质体混合,注入小鼠体内,第8周时取小鼠肝脏,提取肝组织总RNA,进行逆转录,将逆转录后的cDNA用PCR扩增,琼脂凝胶电泳和DNA测序定性,荧光聚合酶链反应定量:提取肝组织基因组DNA,利用荧光聚合酶链反应定量测定HBV DNA含量.结果:经过PCR扩增,琼脂凝胶电泳和DNA测序定性,荧光聚合酶链反应定量等方法检测到小鼠肝脏内反义RNA得到高效表达;8 wk后,对HBV DNA(×105 copies／g)的作用:与对照组相比(7．24±1．62),空质粒组(9．49±3．34)及正义RNA组(6．52±1．53)之间无明显差异,单(2．60±1．13,2．83±1．67)、双靶区反义RNA组(3．24±0．45)与对照组之间有明显差异(P<0．05),但单、双靶区反义RNA组间无明显差异(P>0．05)．结论:将脂质体包裹逆转录病毒载体(质粒)介导的单、双靶区乙肝病毒反义RNA经iv导入转基因小鼠细胞的方法可行;反义RNA对乙型肝炎病毒转基因小鼠有显著抗HBV复制作用;对转基因小鼠肝脏中HBV DNA的复制有明显的抑制作用,但单、双靶区反义RNA组间无明显差异．     

Inhibition of hepatitis B virus by retroviral vectors expressing antisense RNA

Two retroviral vectors carrying an antisense gene from the hepatitis B virus (HBV) preS/S or preC/C were constructed and used to infect the human hepatoblastoma cell line 2.2.15, which expresses HBV surface antigen (HBsAg), HBV e antigen (HBeAg) and releases HBV particles. The results showed that the inhibitory effects of antisense gene transfer, mediated by retroviral vectors on the expression of HBV antigens, appeared as early as day 3 after transduction, reached a maximum on day 5 and persisted for at least 11 days. Our data indicate that, on day 5 after introduction, antisense preS/S inhibited HBsAg and HBeAg expression by 71% and 23%, and the antisense preC/C inhibited HBsAg and HBeAg expression by 23% and 59%. HBV DNA production, in the supernatant of the 2.2.15 cells transduced with either antisense preS/S or preC/C, was also reduced on day 5, but the viability of the 2.2.15 cells was not affected. Our results demonstrate that the replication and expression of HBV can be inhibited through antisense gene transfer mediated by retroviral vectors and that the antisense-preC/C or antisense-preS/S may be potentially useful for clinical gene therapy against HBV.     

Clearance of replicating hepatitis C virus replicon RNAs in cell culture by small interfering RNAs

RNA interference is a cellular process of gene silencing in which small duplexes of RNA specifically target a homologous sequence for cleavage by cellular ribonucleases. The introduction of approximately 22-nt small interfering RNAs (siRNAs) into mammalian cells can specifically silence cellular mRNAs without induction of the nonspecific IFN responses that are activated by longer RNA duplexes. We investigate in this article whether siRNAs can also silence the expression of the cytoplasmically replicating hepatitis C virus (HCV) RNAs by using a replicon system that supports robust HCV replication, but not the production of infectious virions. We report the efficient silencing of both cellular lamin AC and HCV RNAs in Huh-7 hepatoma cell lines supporting HCV replication. Silencing of HCV RNAs was dose dependent and specific, inasmuch as two HCV variants that differ by 3 nt within the target sequence were only silenced by the exact homologous sequence for each. siRNAs designed to target HCV RNA triggered an exponential decrease in HCV RNA, resulting in an 80-fold decrease in HCV RNA after 4 days. The introduction of siRNAs into cells with established HCV replication cured >98% of these cells of detectable HCV antigen and replication-competent HCV RNAs. These data support the principle of siRNA-based HCV antiviral therapy.     

Inhibition of hepatitis B virus gene expression and replication by artificial microRNA

AIM： To investigate the inhibitory effects of hepatitis B virus （HBV） replication and expression by transfecting artificial microRNA （amiRNA） into HepG2.2.15 cells. METHODS： Three amiRNA-HBV plasmids were constructed and transfected into HepG2.2.15 cells. HBV antigen secretion was detected in the cells with transient and stable transfection by time-resolved fluoroimmunoassays （TRFIA）. HBV DNA replication was examined by ？ uorescence quantitative PCR, and the level of HBV S mRNA was measured by semi- quantitative RT-PCR. RESULTS： The efficiency of transient transfection of the vectors into 2.2.15 cells was 55%-60%. All the vectors had significant inhibition effects on HBsAg and HBeAg at 72 h and 96 h after transfection （P 〈 0.01 for all）. The secretion of HBsAg and HBeAg into the supernatant was inhibited by 49.8% ± 4.7% and 39.9% ± 6.7%, respectively, at 72 h in amiRNA- HBV-S608 plasmid transfection group. The copy of HBV DNA within culture supernatant was also significantly decreased at 72 h and 96 h after transfection （P 〈0.01 for all）. In the cells with stable transfection, the secretion of HBsAg and HBeAg into the supernatant was significantly inhibited in all three transfection groups （P 〈 0.01 for all, vs negative control）. The copies of HBV DNA were inhibited by 33.4% ± 3.0%, 60.8% ± 2.3% and 70.1% ± 3.3%, respectively. CONCLUSION： In HepG2.2.15 cells, HBV replication and expression could be inhibited by artif icial microRNA targeting the HBV S coding region. Vector-based artificial microRNA could be a promising therapeutic approach for chronic HBV infection.     

RNA interference-mediated control of hepatitis B virus and emergence of resistant mutant

BACKGROUND & AIMS: Present therapy for chronic hepatitis B attains control only in limited proportions. Small interfering RNA (siRNA) offers a new tool with potential therapeutic applications for hepatitis B virus (HBV). Given the importance of sequence identity in the effectiveness of siRNA and the heterogeneity of HBV sequences among different isolates, a short hairpin RNA (shRNA)-expressing plasmid, pSuper/HBVS1, was developed to target a region conserved among major HBV genotypes and assess its effectiveness control of HBV. METHODS: HBV replication-competent plasmid was cotransfected with pSuper/HBVS1 to HuH-7 cells or to mice. The levels of viral proteins, RNA, and DNA were examined in transfected cells and animals. The effects of pSuper/HBVS1 on clinical isolates with genotypes B and C were also determined. RESULTS: pSuper/HBVS1 significantly decreased levels of viral proteins, RNA, and DNA for HBV genotype A in cell culture and in mice. Comparable suppressive effects were observed on clinical isolates of genotypes B and C. A clone with a silent mutation in the target region was identified from a patient with genotype C. This mutant revealed diminished sensitivity to pSuper/HBVS1 and could be selected out in the presence of pSuper/HBVS1 in cell culture. CONCLUSIONS: These findings indicated that shRNA could suppress HBV expression and replication for genotypes A, B, and C, promising an advance in treatment of HBV. However, the emergence of resistant mutants in HBV quasispecies should be considered.