Effect of various pyrimidines possessing the 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl] moiety, able to mimic natural 2'-deoxyribose, on wild-type and mutant hepatitis B virus replication

Hepatitis B virus (HBV) is the most common cause of chronic liver disease worldwide. Development of drug resistance against clinical anti-HBV drug lamivudine due to long-term use and rebound of viral DNA after cessation of treatment has been a major setback of the current therapy. We have synthesized a series of pyrimidine nucleosides possessing a variety of substituents at the C-5 position, and a 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl] flexible acyclic glycosyl moiety at the N-1 position, that have the ability to mimic the natural 2'-deoxyribosyl moiety. Some of these potential antiviral compounds included variations at both C-5 and C-6 positions of the uracil base. Other variations of the uracil derivatives were the 6-aza congeners. 4-Amino and 4-methoxy pyrimidine derivatives were also made. Compounds in which the base moiety was substituted by 5-chloro- (25), 5-(2-bromovinyl)- (32), or 5-bromo-6-methyl- (37) groups possess significant activity against duck-HBV, wild-type human HBV (2.2.15 cells), and lamivudine-resistant HBV containing single and double mutations. No cytotoxicity was seen in host HepG2 and Vero cells, up to the highest concentration tested. The anti-HBV activity exhibited by compounds 25, 32, and 37 was superior for human HBV and comparable for DHBV to that of the corresponding purine nucleoside, ganciclovir. Further, they were only 10-15-fold less inhibitory against human HBV in 2.2.15 cells than the reference drug, lamivudine. Other compounds in the series were moderately inhibitory against DHBV and wild-type human HBV. The size of the halogen and the electronegativity of the substituents at the 5- and 6-positions are important for antiviral activity toward HBV. These compounds were also evaluated for their antiviral activity for West Nile virus, respiratory syncytial virus, SARS-coronavirus, and hepatitis C virus. They were generally inactive in these antiviral assay systems (at concentrations up to 100 microg/mL). 1-[(2-Hydroxy-1-(hydroxymethyl) ethoxy)methyl]-5-fluorocytosine (34) showed some inhibitory activity against hepatitis C virus. Taken together, these data support our previous observations that the 5-substituted pyrimidine nucleosides containing acyclic glycosyl moieties have potential to serve as a new generation of potent, selective, and nontoxic anti-HBV agents for wild-type and lamivudine-resistant mutant HBV.     

HBV-前C区基因变异与乙肝病毒复制的相关性

目的 研究乙型肝炎病毒(HBV)前C区G1896A变异与乙肝病毒复制的相关性.方法 选取38例慢性轻度,57例慢性中度,29例慢性重度的乙型肝炎患者为研究对象.采用突变特异PCR技术检测HBV前C基因nt1896位点突变情况,并对血清中HBVDNA进行测序.同时检测乙型肝炎病毒HBeAg/抗-Hbe、HBVDNA定量、肝纤维化指标.结果 (1)抗Hbe阳性者在单纯变异株感染的慢性乙型肝炎患者中所占的比例(84.61%)高于单纯野生株感染者(24.32%).(2)随着变异株感染率的增加,HBVDNA的含量增高.(3)随着变异株感染率增加,肝脏纤维化分期的逐渐加重.结论 前C区G1896A变异与乙肝病毒的复制程度相关.     

硼替佐米对转基因小鼠原代肝细胞HBV的抑制作用

目的利用HBV转基因小鼠原代肝细胞评价蛋白酶体抑制剂硼替佐米的抗病毒效果。方法采用改良的两步灌流法分离HBV转基因小鼠原代肝细胞;分别采用ELISA和荧光定量PCR法检测HBsAg和HBV-DNA的水平;采用MTT法观察不同浓度的硼替佐米对HBV转基因小鼠原代肝细胞和HepG2.2.15细胞的毒性,观察其作用24 h后细胞培养上清中病毒学指标的变化。结果分离的原代肝细胞纯化后活细胞占0.90,HBsAg和HBV-DNA在5 d内均能稳定表达。药物作用24 h后,MTT结果显示260μmol·L-1及以下浓度的硼替佐米对原代肝细胞无明显毒性,但对HepG2.2.15细胞显示较强的细胞毒性,其最大无毒浓度为12.5 nmol·L-1。药物在0.026μmol·L-1～26μmol·L-1的浓度范围内对转基因小鼠原代肝细胞HBsAg和HBV-DNA有明显抑制作用。结论硼替佐米在体外对HBV有抑制作用;HBV转基因小鼠原代肝细胞可用于抗肿瘤药物的抗HBV活性研究。     

Inhibition of human hepatitis B virus (HBV) by a novel non-nucleosidic compound in a transgenic mouse model

BAY 41-4109 is a member of a class of heteroaryl-pyrimidines that was recently identified as potent inhibitors of human hepatitis B virus (HBV) replication. We have investigated the antiviral activity of BAY 41-4109 (methyl (R)-4-(2-chloro-4-fluorophenyl)-2-(3,5-difluoro-2-pyridinyl)-6-methyl-1,4-dihydro-pyrimidine-5-carboxylate) in HBV-transgenic mice (Tg [HBV1.3 fsX(-)3'5']). Bay 41-4109 was administered per os using different schedules (b.i.d. or t.i.d. for up to 28 days) and dosages ranging from 3 to 30 mg/kg. The compound reduced viral DNA in the liver and in the plasma dose-dependently with efficacy comparable to 3TC. In contrast to 3TC-treated mice, we found a reduction of cytoplasmic hepatitis B virus core antigen (HBcAg) in liver sections of BAY 41-4109-treated mice, which indicated a different mode of action. Pharmacokinetic studies in mice have shown rapid absorption, a bioavailability of 30% and dose-proportional plasma concentrations. We conclude that BAY 41-4109 is a new anti-HBV drug candidate.     

The main hepatitis B virus (HBV) mutants resistant to nucleoside analogs are susceptible in vitro to non-nucleoside inhibitors of HBV replication

Long-term treatment of chronic hepatitis B with nucleos(t)ide analogs can lead to the emergence of HBV resistant mutants of the polymerase gene. The development of drugs with a different mode of action is warranted to prevent antiviral drug resistance. Only a few non-nucleosidic molecules belonging to the family of phenylpropenamides (AT-61 & AT-130) and heteroaryldihydropyrimidines (BAY41-4109) can prevent RNA encapsidation or destabilize nucleocapsids, respectively. The sensitivity of the main nucleos(t)ide analog- resistant mutants to these inhibitors was evaluated in vitro. HepG2 stable cell lines permanently expressing wild type (WT) HBV or the main HBV mutants resistant to lamivudine and/or adefovir (rtL180M + rtM204V, rtV173L + rtL180M + rtM204V, rtM204I, rtL180M + rtM204I, rtN236T, rtA181V, rtA181V + rtN236T, rtA181T, rtA181T + rtN236T) were treated with AT-61, AT-130 or BAY-41 4109. Analysis of intracellular encapsidated viral DNA showed that all mutants were almost as sensitive to these molecules as WT HBV; indeed, the fold-resistance ranged between 0.7 and 2.3. Furthermore, the effect of a combination of either AT-61 or AT-130 with BAY41-4109, and the combination of these compounds with tenofovir was studied on wild type HBV as well as on a lamivudine and an adefovir-resistant mutant (rtL180M + M204V and rtN236T, respectively). These combinations of compounds resulted in inhibition of viral replication but showed slight antagonistic effects on the three HBV species. Based on this in vitro study, BAY-41 4109, AT-61 and AT-130 molecules that interfere with capsid morphogenesis are active against the main lamivudine- and adefovir-resistant mutants. These results suggest that targeting nucleocapsid functions may represent an interesting approach to the development of novel HBV inhibitors to prevent and combat drug resistance.     

Neutralization of hepatitis B virus (HBV) by human monoclonal antibody against HBV surface antigen (HBsAg) in chimpanzees

The virus neutralizing efficacy of HB-C7A, a human monoclonal antibody raised against the surface antigen of hepatitis B virus (HBsAg), was proved using hepatitis B virus (HBV)-na?ve chimpanzees. One control chimpanzee which received 100CID(50) of HBV, subtype adw, without HB-C7A antibody became infected by HBV as evidenced by the appearance of HBV DNA on week 10 and subsequent appearance of HBsAg, anti-HBc and anti-HBs in the serum. Two experimental chimpanzees were inoculated intravenously with same dose of HBV as the control chimpanzee, which was previously incubated with 0.1mg and 10mg of HB-C7A antibody prior to inoculation. HBV infection was not observed in the antibody-treated chimpanzees during 12 months of follow-up, exhibiting neither detectable HBsAg nor anti-HBc antibody. This work demonstrates the neutralization of HBV by HB-C7A monoclonal antibody and shows the possibility of prevention of HBV infection using this antibody in liver transplantation and exposure to HBV.     

Effect of cantharidin, cephalotaxine and homoharringtonine on "in vitro" models of hepatitis B virus (HBV) and bovine viral diarrhoea virus (BVDV) replication

The effect as antiviral agents versus viral hepatitis B and C of three compounds purified from natural products commonly used as remedies in traditional Chinese medicine, cantharidin, cephalotaxine and homoharingtonine, was investigated. To assess the activity of these compounds against flavivirus, we used bovine viral diarrhoea virus (BVDV) as a surrogate for hepatitis C virus (HCV). Anti-BVDV activity was determined by reduction in BVDV-RNA production and protection of infected embryonic bovine trachea (EBTr) cells against the cytopathic effect of BVDV. The effect versus hepatitis B virus (HBV) was investigated by measuring HBsAg and HBV-DNA release from hepatoblastoma HepG2 2.2.15 cells infected with HBV. As positive control we used the standard anti-HBV and anti-HCV drugs, lamivudine and ribavirin, respectively. Up to 100 microM lamivudine and ribavirin did not induce cell toxicity, whereas they induced dose-dependent anti-HBV and anti-BVDV effects, respectively. In the same range, cantharidin, cephalotaxine and homoharringtonine induced toxicity in EBTr cells and had no protective effect against BVDV. In contrast, they were able to inhibit HBV production at concentrations 10- to 100-fold lower than those inducing cell toxicity, which suggests that they are useless for the treatment of infection by flaviviruses, but potentially useful in combined therapy against hepatitis B.     

针对HBVX基因的反义核酸抑制HBV表达的体外研究

目的筛选反义脱氧寡核苷酸 (ASON)抗乙型肝炎病毒 (HBV)的有效靶向位点。方法设计合成针对HBVX翻译起始位点的ASON即序列Ⅰ ,并设非互补序列作对照即序列Ⅱ ,以人肝癌细胞系 (2 .2 .15 )为细胞模型 ,应用ELISA动态观察不同浓度 (1、5、10 μmol/L)ASON一次性用药对HBV基因表达的抑制作用 ,用MTT比色法观察ASON对细胞代谢的影响 ,以苔盼蓝染色计数观察ASON对细胞活性的影响。结果ASON可有效地抑制HBV基因的表达 ,在 1、5、10 μmol/L浓度时对HBsAg的抑制率分别为 6 3%、45 %和 5 7% ,对HBeAg的抑制率分别为 38%、41%和 5 6 % ;而对照序列Ⅱ对HBsAg和HBeAg的抑制率均低于 12 %。MTT法表明ASON对 2 .2 .15细胞代谢无影响(P >0 .0 5 ) ,苔盼蓝染色计数表明ASON对 2 .2 .15细胞活性无影响 (P >0 .0 5 )。结论HBVX翻译起始区是ASON抗HBV复制表达的有效靶向位点     

Thiazolides as novel antiviral agents. 1. Inhibition of hepatitis B virus replication

We report the syntheses and activities of a wide range of thiazolides [viz., 2-hydroxyaroyl-N-(thiazol-2-yl)amides] against hepatitis B virus replication, with QSAR analysis of our results. The prototypical thiazolide, nitazoxanide [2-hydroxybenzoyl-N-(5-nitrothiazol-2-yl)amide, NTZ] 1 is a broad spectrum antiinfective agent effective against anaerobic bacteria, viruses, and parasites. By contrast, 2-hydroxybenzoyl-N-(5-chlorothiazol-2-yl)amide 3 is a novel, potent, and selective inhibitor of hepatitis B replication (EC(50) = 0.33 μm) but is inactive against anaerobes. Several 4'- and 5'-substituted thiazolides show good activity against HBV; by contrast, some related salicyloylanilides show a narrower spectrum of activity. The ADME properties of 3 are similar to 1; viz., the O-acetate is an effective prodrug, and the O-aryl glucuronide is a major metabolite. The QSAR study shows a good correlation of observed EC(90) for intracellular virions with thiazolide structural parameters. Finally we discuss the mechanism of action of thiazolides in relation to the present results.     

HBV病毒复制机制及慢性乙型肝炎药物靶点

乙型肝炎病毒(HBV)感染是一种严重影响公共卫生与人体健康的全球性流行性疾病,尽管乙肝防治已有很大提高,但仍缺乏高效的药物与手段。研究表明,肝损伤、肝衰竭程度与HBV及宿主免疫系统相互作用存在复杂关系。因而详细地探明HBV生命周期和感染过程,为研究HBV药物靶点和制定新的抗病毒策略提供前期坚实的基础,意义重大。该文详细介绍HBV病毒复制机制,并系统地阐述近年来新发现的和潜在的药物靶点,为制备新型的抗HBV药物提供参考。     

亚硒酸钠对乙型肝炎病毒的体外抑制作用

目的探讨亚硒酸钠在体外对乙型肝炎病毒(HBV)蛋白合成、DNA复制的影响及机制。方法将不同浓度的亚硒酸钠作用于HepG2.2.15细胞系,通过检测细胞培养上清液中乙型肝炎表面抗原(HBsAg)、乙型肝炎e抗原(HBeAg)水平、乙型肝炎核心抗原(HBcAg)和HBV DNA水平来评价HBV复制情况;免疫组织化学检测HepG2.2.15细胞p53蛋白的表达情况。结果亚硒酸钠对HBV复制具有抑制作用,随着亚硒酸钠浓度的升高,对HBsAg和HBeAg的抑制率逐渐上升,但对HBsAg的抑制作用要小于HBeAg。细胞内HBV DNA复制水平也逐渐下降(P<0.01)。p53蛋白的分布也发生了改变。结论亚硒酸钠对HepG2.2.15细胞HBsAg、HBeAg和HBcAg表达、HBV DNA复制均有抑制作用,作用机制与其干扰p53蛋白的表达有关。     

核苷类药物对HBV复制的抑制机制和HBV对核苷类药物的耐药机制

乙型肝炎病毒(HBV)仍然是全世界面临的对人类危害最大的病原体之一.核苷(酸)类似物药物可以有效抑制HBV的复制,目前已成为治疗HBV感染的首选药物.患者长期用药会导致对耐核苷(酸)类似物的HBV突变体的选择,影响药物的继续使用.本文参考近年来国内外有关研究进展,对核苷(酸)类似物的作用机制和HBV对其的耐药机制作一综述.     

拉米呋啶治疗后病人HBV DNA载量及血清标志物的变化

目的观察拉米呋啶治疗慢性乙肝病人1年期间,血清HBV DNA,ALT水平及乙肝标志物变化的关系。方法拉米呋啶治疗60例乙肝患者后,在3,6,9和12个月时检测其HBV DNA含量和ALT水平及乙肝标志物的变化。结果用药6和12个月后HBV DNA含量分别为2.47×106,1.43×105,显著低于治疗前(P<0.01)。随治疗时间的延长,HBV DNA阴转率逐渐增加,ALT水平逐渐降低。治疗12个月时60名患者中有5名HBeAg转阴,3名患者发生血清转换(HBeAg转为HBeAb)。结论拉米呋啶治疗乙肝病毒患者疗效显著,血清HbeAg转为HbeAb的转换可以作为停药的标准。如出现YMDD变异,应停药或联合用药。