靶向C区基因的M1GS RNA核酶胞内抗乙型肝炎病毒的实验研究

目的探讨靶向作用于乙型肝炎病毒C区基因的M1GS RNA核酶胞内抗乙型肝炎病毒的作用。方法设计并应用PCR技术合成M1RNA核酶，应用pEGFP-C1载体构建M1GSRNA核酶的真核表达质粒，应用脂质体Lipofectamine TM 2000转染HepG2．2．15细胞，以ELISA法检测细胞培养液中病毒抗原，以反转录-聚合酶链反应法（RT-PCR）检测细胞内病毒mRNA，以荧光定量PCR法检测分泌入培养液的HBVDNA含量，用MTT法检测核酶对细胞增殖活性的影响。结果质粒载体表达的M1GS RNA核酶能明显抑制细胞培养液中HBeAg的表达及病毒mRNA的表达，抑制率分别为31．58％，32．5％。但M1GS RNA核酶对培养液中的HBV DNA含量无明显影响，亦不影响HepG2．2．15细胞的增殖活性。结论M1GS RNA核酶能特异性抑制HepG2．2．15细胞内HBV C区基因表达，是一种很有潜力的抗HBV基因治疗方法。     

蒌蒿乙酸乙酯部位体外抗乙型肝炎病毒的实验研究

目的:研究蒌蒿乙酸乙酯部位体外抗乙型肝炎病毒(HBV)的作用。方法:蒌蒿药材用95%乙醇提取后,用乙酸乙酯萃取获得有效部位,作用于HBV-DNA转染的Hep G2.2.15细胞上。采用MTT法检测乙酸乙酯部位对Hep G2.2.15细胞的半数抑制浓度(IC50),用ELISA法观察乙酸乙酯部位对Hep G2.2.15细胞分泌HBs Ag和HBe Ag表达的抑制作用。结果:蒌蒿乙酸乙酯部位对Hep G2.2.15细胞有一定的细胞抑制作用,对Hep G2.2.15细胞分泌HBs Ag和HBe Ag表达有不同程度的抗原抑制作用。结论:蒌蒿乙酸乙酯部位有较强的抗乙型肝炎病毒作用。     

靶向X区的siRNA抑制乙型肝炎病毒基因的表达和复制

目的构建针对乙型肝炎病毒（HBV）X基因的siRNA表达载体，观察其对HBV基因表达和复制的影响。方法设计并合成针对HBVX区基因的siRNA寡核苷酸，经退火形成双链后克隆人pSUPER载体，构建成功的siRNA表达载体与pTK-Hyg质粒共转染稳定表达HBV的HepG22．2．15细胞，潮霉素抗性筛选获得稳定细胞克隆，对所得细胞培养上清液中的HBsAg和HBeAg进行定量检测，逆转录-聚合酶链反应（RT-PCR）检测靶基因mRNA的抑制效果，荧光定量PCR检测HBVDNA。结果成功构建了针对HBVX基因的siRNA表达载体pSUPER-X1和pSUPER-X2，两种siRNA均能明显抑制HepG22．2．15细胞的HBsAg和HBeAg分泌，抑制率分别为97％和88％，RT-PCR结果显示HBV的mRNA表达降低，荧光定量PCR结果证实siRNA能降低HBVDNA拷贝数2个数量级。结论载体产生的针对HBVX基因的siRNA能高效、特异地抑制HBV基因的表达和复制。     

Low in vivo toxicity of a novel cisplatin-ursodeoxycholic derivative (Bamet-UD2) with enhanced cytostatic activity versus liver tumors

Cisplatin-bile acid derivatives belonging to the Bamet-family maintain both liver organotropism and cytostatic activity. "In vivo" toxicity and usefulness as chemotherapeutic agent versus liver tumors of a novel drug, Bamet-UD2 [cis-diamminechlorocholylglycinate platinum (II)], with enhanced "in vitro" cytostatic activity was investigated. Using orthotopically implanted mouse Hepa 1-6 hepatoma in the liver of Nude mice, the antitumor effect of Bamet-UD2 was compared with that of a previously characterized compound of this family, Bamet-R2 [cis-diamminebis-ursodeoxycholate platinum(II)], and cisplatin. Life span was significantly prolonged in mice treated with both Bamets (Bamet-UD2 > Bamet-R2), compared with animals receiving saline or cisplatin. All these drugs inhibit tumor growth (Bamet-UD2 = cisplatin > Bamet-R2). However, toxicity-related deaths only occurred under cisplatin treatment. Using rats maintained in metabolic cages, organ-specific toxicity and drug accumulation in tissues were investigated. The amount of both Bamets in the liver was severalfold higher than that of cisplatin. By contrast, a significantly higher amount of cisplatin in kidney and nerve was found. In lung, heart, muscle, brain, and bone marrow the amount of drug was small and also significantly lower in animals receiving Bamets. Signs of neurotoxicity (altered nerve conduction velocity), nephrotoxicity (increased serum urea and creatinine concentrations and decreased creatinine clearance), and bone marrow toxicity (decreased platelet and white blood counts) in animals treated with cisplatin but not with the Bamets were found. These results indicate that, owing to strong antitumor activity together with absence of side effects, Bamet-UD2 may be useful in the treatment of liver tumors.     

Long-term suppression of hepatitis B virus replication by short hairpin RNA expression using the scaffold/matrix attachment region-based replicating vector system pEPI-1

Since the emergence of viral resistance of hepatitis B virus (HBV) during treatment is becoming an important issue even with newer drugs, there is a need for alternative treatment options such as, for example, RNA interference (RNAi) technology. While short-term suppression of HBV replication is easily achieved with small interfering RNA oligonucleotides, this is not the case for long-term suppression due to the lack of an optimal vector system. Based on the nonviral scaffold/matrix attachment region (S/MAR)-based vector system pEPI-1, which is free of common side effects and is stably retained as an episome even in the absence of selection, we designed a short hairpin RNA (shRNA) expression vector called pEPI-RNAi for HBV suppression. HBV-replicating HepG2.2.15 cells were transfected with pEPI-RNAi, and the intracellular status of the plasmid was followed by PCR and Southern analysis. HBV replication was measured on the DNA, RNA, and protein level. HBV RNA expression was reduced by almost 85% 3 months posttransfection with pEPI-RNAi. At 8 months posttransfection in the absence of antibiotic selection pressure, the suppression level was still 70% and the vector was retained as an episome. The reduction of total intracellular HBV DNA at this point was 77%, showing a marked suppression of HBV DNA replication. At a comparable level, secretion of viral antigens, as well as progeny HBV virions, was inhibited. The S/MAR-based vector system pEPI-1 allows long-term suppression of HBV replication by the expression of suitable shRNAs. Due to its unique properties compared to commonly used vectors, it provides an interesting option for the treatment of chronically HBV-infected individuals.     

Strong and selective inhibitors of hepatitis B virus replication among novel N4-hydroxy- and 5-methyl-beta-L-deoxycytidine analogues

Novel N(4)-hydroxy- and 5-methyl-modified beta-L-deoxycytidine analogues were synthesized and evaluated as anti-hepatitis B virus (HBV) agents. Their in vitro efficiencies were investigated in HepG2.2.15 cells stably transfected with HBV. beta-L-2',3'-Didehydro-2',3'-dideoxy-N(4)-hydroxycytidine (beta-L-Hyd4C) was most effective in reducing secreted HBV DNA (50% effective concentration [EC(50)], 0.03 microM), followed by beta-L-2',3'-dideoxy-3'-thia-N(4)-hydroxycytidine (EC(50), 0.51 microM), beta-L-2',3'-dideoxy-N(4)-hydroxycytidine (EC(50), 0.55 microM), and beta-L-5-methyl-2'-deoxycytidine (EC(50), 0.9 microM). The inhibition of the presumed target, the HBV DNA polymerase, by the triphosphates of some of the beta-L-cytidine derivatives was also assessed. In accordance with the cell culture data, beta-L-Hyd4C triphosphate was the most active inhibitor, with a 50% inhibitory concentration of 0.21 microM. The cytotoxicities of some of the 4-NHOH-modified beta-L-nucleosides were dramatically lower than those of the corresponding cytidine analogues with the unmodified 4-NH(2) group. The 50% cytotoxic concentrations for beta-L-Hyd4C in HepG2 and HL-60 cells were 2,500 microM and 3,500 microM, respectively. In summary, our results demonstrate that at least beta-L-Hyd4C can be recommended as a highly efficient and extremely selective inhibitor of HBV replication for further investigations.     

Identification of BMS-200475 as a potent and selective inhibitor of hepatitis B virus.

BMS-200475 is a novel carbocyclic 2'-deoxyguanosine analog found to possess potent and selective anti-hepatitis B virus (anti-HBV) activity. BMS-200475 is distinguished from guanosine by replacement of the natural furanose oxygen on the sugar moiety with an exo carbon-carbon double bond. In the HepG2 stably transfected cell line 2.2.15, BMS-200475 had a 50% effective concentration (EC50) of 3.75 nM against HBV, as determined by analysis of secreted HBV DNA. Structurally related compounds with adenine, iodouracil, or thymine base substitutions were significantly less potent or were inactive. Direct comparison of the antiviral activities of BMS-200475 with those of a variety of other nucleoside analogs, including lamivudine (EC50 = 116.26 nM), demonstrated the clearly superior in vitro potency of BMS-200475 in 2.2.15 cells. Intracellular HBV replicative intermediates were uniformly reduced when cells were treated with BMS-200475, but rebounded after treatment was terminated. The concentration of BMS-200475 causing 50% cytotoxicity in 2.2.15 cell cultures was 30 microM, approximately 8,000-fold greater than the concentration required to inhibit HBV replication in the same cell line. Treatment with BMS-200475 resulted in no apparent inhibitory effects on mitochondrial DNA content.     

The short hairpin RNA driven by polymerase II suppresses both wild-type and lamivudine-resistant hepatitis B virus strains

BACKGROUND: Chronic infection with hepatitis B virus (HBV) is widespread because of the limited availability of therapeutic treatments. Although previous reports have suggested that RNA interference has promise as a treatment for HBV infection, further studies of long-term and off-target drug effects on HBV, especially on drug-resistant strains of HBV, are needed. Therefore, seven vectors that express short hairpin RNAs (shRNAs), driven by the polymerase II promoter, pSilencer4.1/HBV, were constructed to target open reading frames (ORFs) of the HBV C and S genes from wild-type and drug-resistant strains. Treatment efficiency was also assessed. METHODS: The pSilencer4.1/HBV vectors were investigated in HepG2.2.15 cells and transgenic mice that consistently produce wild-type HBV. Additionally, vectors that produce a lamivudine-resistant strain of HBV were developed and cotransfected, along with pSilencer/HBV, into both HepG2 cells and mice. The effects of polymerase-II-driven pSilencer4.1/HBV were compared with those of polymerase-III-driven pSilencer3.1/HBV at both the gene and protein level. RESULTS: pSilencer4.1/HBV inhibited the expression of viral protein, DNA and HBV subtype ayw mRNA in both HepG2.2.15 cells and transgenic mice. Toxicity, as well as off-target effects, did not occur after a short- to medium-term examination. Moreover, an HBV strain resistant to lamivudine, subtype adr, was suppressed by shRNA in both HepG2 cells and mice. In contrast to polymerase III, vectors that used polymerase II could drive efficient silencing without off-target effects. CONCLUSIONS: Silencing by shRNA dramatically inhibited HBV expression and replication regardless of strain type. ShRNA could therefore be a promising treatment for HBV infection.     

实时荧光定量RT-PCR技术检测siRNA对HBV复制的干扰效果

目的 运用实时荧光定量RT-PCR的方法,检测小RNA分子（small interfering RNAs,siRNA）对乙型肝炎病毒（hepatitis B virus,HBV）复制的抑制作用.方法 在HepG2.2.15细胞内导入筛选的三条特异抗HBV的siRNA分子,用实时荧光定量RT-PCR的方法,检测干扰后HBV的mRNA表达水平.结果 导入特异siRNA分子的细胞中HBV的mRNA表达量明显降低.结论 实时荧光定量RT-PCR技术能准确可靠的检测mRNA的表达水平,对siRNA分子干扰效果的评价有很好的应用价值.     

A substituted tetrahydro-tetrazolo-pyrimidine is a specific and novel inhibitor of hepatitis B virus surface antigen secretion

The high levels of hepatitis B virus (HBV) surface antigen (HBsAg)-bearing subviral particles in the serum of chronically infected individuals are thought to play a role in suppressing the HBV-specific immune response. Current therapeutics are not directed at reducing this viral antigenemia; thus, our group has focused on identifying inhibitors of HBsAg secretion. By using the HBV-expressing cell line HepG2.2.15, high-throughput screening of an 80,288-compound synthetic small-molecule library identified HBF-0259, an aromatically substituted tetrahydro-tetrazolo-(1, 5-a)-pyrimidine. Following resynthesis, HBF-0259 had a 50% effective concentration of approximately 1.5 microM in a secondary, HBV-expressing cell line, with a concentration that exhibited 50% cytotoxicity of >50 microM. The equilibrium concentration of HBF-0259 in aqueous solution at physiological pH was 15 to 16 microM; the selective index was thus >9. As intended by our screening paradigm, HBF-0259 is a selective, potent inhibitor of secretion of both subviral and DNA-containing viral particles, while the secretion of alpha-1-acid glycoprotein and alpha-1-antitrypsin was unaffected. The HBV e antigen, which is not a constituent of HBV particles, was also unaffected, suggesting that the secretion of particles bearing HBV structural glycoproteins is targeted directly. Inhibitory activity was also confirmed by transfection of HBsAg, indicating that the action of the compound is independent of those of other viral proteins. HBF-0259 had no effect on HBV DNA synthesis, demonstrating that inhibition is independent of viral genomic replication. Finally, HBF-0259 had little or no effect on the cell-to-cell spread of two unrelated viruses, suggesting that it is a specific inhibitor of secretion of HBsAg. Possible mechanisms of action and the implications for its development are discussed.     

Antiviral activity of a conjugate of adenine-9-beta-D-arabinofuranoside 5'-monophosphate and a 9 kDa fragment of arabinogalactan

An arabinogalactan conjugate containing a 9 kDa fragment of arabinogalactan and adenine-9-beta-D-arabinofuranoside 5'-monophosphate (araAMP), denoted AG(9 kDa)-araAMP, has been synthesized and characterized. In 2.2.15 (human hepatoblastoma) cells, the attachment of araAMP to AG(9 kDa), a ligand of the asialoglycoprotein receptor, decreased the effective concentration for inhibiting extracellular hepatitis B virus (HBV) production by 90% (EC90) from 17 to 0.9 microM adenine arabinoside (araA) equivalents, and increased the cytotoxic concentration (CC50) from 188 to > 17 300 microM araA equivalents. Hence, the selectivity index (CC50/EC90) of araA was improved from 11 (188/17) to > 19200 (17 300/0.9) by conjugation with the 9 kDa fragment of arabinogalactan. AG(9 kDa)-araAMP did not affect the production of viral RNA or viral proteins. In the woodchuck hepatitis model, AG(9 kDa)-araAMP inhibited woodchuck hepatitis virus (WHV) DNA replication at a dose of 0.3 mg of araA equivalents per kg; in this case, AG(9 kDa)-araAMP was 20-30 times more potent than was unconjugated araA. AG(9 kDa)-araAMP was effective by intramuscular or subcutaneous administration. The reduction in HBV DNA levels obtained in 2.2.15 cells and of WHV DNA levels in woodchucks was sustained after treatment with AG(9 kDa)-araAMP ceased. In both cases, viral DNA gradually returned to pre-treatment levels.     

The Anti-hepatitis B Virus Activity of Boehmeria nivea Extract in HBV-viremia SCID Mice

Boehmeria nivea extract (BNE) is widely used in southern Taiwan as a folk medicine for hepato-protection and hepatitis treatment. In previous studies, we demonstrated that BNE could reduce the supernatant hepatitis B virus (HBV) DNA in HBV-producing HepG2 2.2.15 cells. In the present study, we established an animal model of HBV viremia and used it to validate the efficacy of BNE in vivo. In this animal model, serum HBV DNA and HBsAg were elevated in accordance with tumor growth. To evaluate the anti-HBV activity of BNE, HBV-viremia mice were built up after one subcutaneous inoculation of HepG2 2.2.15 tumor cells in severe combined immunodeficiency mice over 13 days. The levels of serum HBV DNA were elevated around 10(5)-10(6) copies per milliliter. Both oral and intraperitoneal administration of BNE were effective at inhibiting the production of HBsAg and HBV DNA, whereas tumor growth was not affected by all test articles. Intraperitoneal administration of BNE appeared to have greater potential to inhibit serum HBV DNA levels compared with oral administration under the same dosage. Notably, reduced natural killer cell activity was also observed after high dosage of BNE administration, and this correlated with reduced serum HBV DNA. In conclusion, BNE exhibited potential anti-HBV activity in an animal model of HBV viremia.     

Penciclovir is a selective inhibitor of hepatitis B virus replication in cultured human hepatoblastoma cells.

Penciclovir [9-(4-hydroxy-3-hydroxymethylbut-1-yI)guanine], an effective antiherpesvirus agent, was found to be a potent and selective antiviral agent against intracellular hepatitis B virus (HBV) replication (drug concentration at which a 10-fold decrease in HBV DNA from the average level in an untreated culture was observed [EC90], 1.6 microM) and extracellular virion release (EC90, 0.7 microM) by cultured human hepatoblastoma (2.2.15) cells. Acyclovir and three other related 9-alkoxypurines with activity against either herpesviruses or human immunodeficiency virus were uniformly inactive against HBV. The activity of penciclovir is discussed in relation to recent findings related to its mode of action against HBV.     

In vitro antiviral activity of three enantiomeric sesquiterpene lactones from Senecio species against hepatitis B virus

Three enantiomeric sesquiterpene lactones were isolated under the bioguidance of the suppression of hepatitis B virus (HBV) surface antigen (HBsAg) from Senecio species, a widely distributed Chinese medicinal herb traditionally used for the treatment of hepatitis B, dermatosis and inflammation. The anti-HBV activity of the purified compounds was measured; all of them showed suppressive activity on the expression of HBsAg and HBV e antigen (HBeAg) in the HepG2.2.15 cell line. Real-time quantitative PCR analysis showed that the studied compounds decreased the number of infectious virions released, but did not inhibit the intracellular HBV DNA. The results suggest that enantiomeric sesquiterpene lactones may possess the potential to work synergistically with other antiviral compounds for the treatment of HBV infection.     

壁虎粉提取物作用于乙型肝炎病毒侵袭的HepG2和HL-7702细胞的实验研究

目的探讨壁虎粉提取物对乙型肝炎病毒侵袭过的人肝癌细胞（HepG2）和人肝细胞（HL-7702）中乙型肝炎病毒的复制能力和细胞生长状况的影响。方法实验分壁虎粉干预组、干扰素干预组、乙肝对照组和正常对照组四组,除正常对照组,其他三组以终浓度为1×107IU/mL含HBV-DNA的患者血清侵袭2小时后,再以一定浓度壁虎粉提取物或干扰素分别作用于上述两种细胞,收集各时段的培养液上清和（或）细胞,检测培养液上清AST、ALT、r-GT和LDH含量;采用荧光定量PCR法检测HBV-DNA;AO/EB进行细胞凋亡染色。结果两种细胞不同组别（除正常对照组外）培养6天、9天较培养3天AST显著增高（P〈0.01）,以两个干预组增高更为明显;HepG2干预组各时间段LDH含量高于HL-7702干预组（P〈0.01）,以壁虎粉干预HepG2组增高最为明显,同时凋亡细胞增多也较明显;两干预组细胞HBV-DNA含量较乙肝对照组低约1个数量级。结论壁虎粉提取物和干扰素对HBV复制具有抑制作用,对HL-7702细胞作用更为明显;壁虎粉提取物可诱导肝癌HepG2细胞早期凋亡、坏死。     

High-capacity in vitro assessment of anti-hepatitis B virus compound selectivity by a virion-specific polymerase chain reaction assay.

An integrated assessment system specific for hepatitis B virus (HBV) Dane particle DNA was developed to examine the activity of potential anti-HBV compounds in chronic HBV-producing HepG2-derived 2.2.15 cells. Cell culture, immunoaffinity purification, polymerase chain reaction, and hybrid-capture detection were performed in the microtiter format to facilitate increased throughput by automation. The high sensitivity afforded by the assay provided quantitative detection of less than 0.5 fg of extracellular HBV DNA from 25 microliters of cell culture supernatants, and drug-induced reductions in HBV titers greater than 100-fold were easily measured. Fluorometric determination of total cellular DNA from the same 96-well proliferating cell cultures allowed simultaneous evaluation of inhibition of cell growth, thus providing the ability to assess the overall selectivities of candidate compounds in a single experiment. The potent activities of three anti-HBV compounds, the (+) and (-) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxythiolane-5-yl]cytosine (FTC) and D-carbocyclic-2'-deoxyguanosine (CDG), were confirmed by this method. (-)-FTC was more active than its (+) enantiomer (50% inhibitory concentrations, 0.033 +/- 0.006 and 0.723 +/- 0.160 microM [standard error of the mean; SEM], respectively), while both enantiomers demonstrated a lack of cytotoxicity at 200 microM. CDG was more potent (50% inhibitory concentration, 0.0063 +/- 0.0007 microM [SEM]) but was also significantly more toxic, inhibiting cell growth by 50% at 32 +/- 6 microM (SEM). These results demonstrate the usefulness of this immunoaffinity-based, quantitative polymerase chain reaction system as a high-capacity in vitro tool for assessment of anti-HBV compound selectivity.