甲型H1N1流感重组病毒模型的建立及应用北大核心CSCD

目的:针对流感病毒感染宿主机体的作用机制,建立以甲型H1N1流感A/California/04/2009(H1N1)为靶点的重组病毒模型,并对其应用进行探索。方法:通过将表达流感病毒血凝素蛋白HA、神经氨酸酶NA及敲除外壳基因、复制基因并带有荧光素酶报告基因的HIV^(-1)质粒共转染至293T包装细胞,产生以HA[A/California/04/2009(H1N1)]和NA[A/California/04/2009(H1N1)]为膜蛋白,HIV^(-1)(p NL4-3.Luc.R-E-)为核心的重组病毒。通过该重组流感病毒模型评价阳性对照化合物(奥斯他韦、奥斯他韦酸)、中和血清以及板蓝根药材提取液对重组病毒活性的抑制作用。结果:奥司他韦、奥司他韦酸抑制重组病毒p NL+HA04+NA04的IC50为1.07×10-8 mol·L^(-1)和1.82×10-9 mol·L^(-1);中和血清的IC50为1∶320~1∶640;中药板蓝根提取液的IC50为1.91×10-5 g·m L^(-1)。结论:奥斯他韦、奥斯他韦酸、中和血清及板蓝根提取液对于重组病毒的活性有抑制作用,提示所构建的重组病毒模型可用于上述作用机制药物的筛选和评价。     

一种新型流感病毒神经氨酸酶抑制剂的设计、合成及活性研究

本研究以H5N1亚型流感病毒神经氨酸酶(NA)活性位点旁的150-空穴为靶标,采用半柔性分子对接计算机模拟技术,设计并合成了一种绿原酸的结构类似物——4-(咖啡酰基)氨基丁酸,计算机模拟结果显示该化合物能够插入到N1150-空穴中并和Arg156侧链以氢键的方式结合,与N1的最佳结合自由能为-7.70 kcal.mol-1,与奥司他韦相当。同时,利用以H5N1假病毒体系为基础建立的NA抑制剂筛选模型,测定了奥司他韦、绿原酸和4-(咖啡酰基)氨基丁酸对NA的抑制作用,发现与绿原酸相比,4-(咖啡酰基)氨基丁酸显著增强了对N1型神经氨酸酶的抑制作用,但与奥司他韦仍有一定的差距。本实验初步探索了150-空穴作为新型神经氨酸酶抑制剂靶标的可能性,为开发新型神经氨酸酶抑制剂提供了新的思路。     

表达甲型H5N1禽流感病毒结构蛋白的重组痘苗病毒的构建与鉴定

目的  构建表达甲型H5N1禽流感病毒（H5N1 avian influenza A virus,H5N1 AIAV）NIBRG14株结构蛋白的重组痘苗病毒,为研制新型人用流感疫苗奠定基础。方法  通过反转录PCR扩增H5N1 AIAV NIBRG14株的血凝素（hemagglutinin,HA）和神经氨酸酶（neuraminidase,NA）编码基因,并将改造的HA、NA基因克隆至痘苗病毒穿梭质粒 pSCCK。在重组质粒与痘苗病毒天坛株（vaccinia virus Tiantan,VTT）于Vero细胞中发生同源重组后,筛选同时表达HA和NA的重组痘苗病毒（rVTT-HA/NA）,并对其进行鉴定。结果  反转录PCR扩增的HA和NA基因大小约分别为1 700和1 400 bp,与预期相同。DNA测序证实,改造的HA和NA序列正确。对获得的rVTT-HA/NA进行PCR及测序表明,HA和NA基因正确插入VTT。蛋白质印迹显示,rVTT-HA/NA感染的Vero细胞表达的HA和NA能与相应的抗体发生反应。表达的HA具有血凝活性,血凝滴度为1∶32。结论  重组痘苗病毒rVTT-HA/NA可稳定表达H5N1 AIAV NIBRG14株的HA和NA。     

流行性感冒和禽流感的抗病毒治疗

早期抗病毒治疗是改善流行性感冒和禽流感患者预后的关键。目前临床用于抗流感病毒的药物按作用机制可大致分为两类,一类作用于病毒表面的糖蛋白神经氨酸酶,另一类作用于离子通道M2蛋白。我国目前常用的抗流感病毒药物主要有奥司他韦、扎那米韦、金刚烷胺和金刚乙胺。抗流感病毒治疗应在发病后48h内尽早进行;在缺乏耐药检测结果的情况下,甲型流感病毒可选用奥司他韦、扎那米韦、金刚烷胺或金刚乙胺进行治疗,乙型流感病毒选用奥司他韦或扎那米韦治疗。耐药分析表明,对于甲型H1N1型流感、H5N1型禽流感和H7N9型禽流感应首选神经氨酸酶抑制剂治疗,疗程通常为5d,对重症患者可增加药物剂量并延长治疗时间。流感病毒耐药性的出现给抗流感病毒治疗带来了挑战,可考虑采用具有不同作用机制的抗流感病毒药物联合治疗耐药流感病毒感染。     

奥司他韦安全性再聚焦——研发者视角

奥司他韦（达菲）是瑞士巴塞尔豪夫迈一罗氏制药有限公司（罗氏公司）研发的一种有效、稳定和选择性的甲型和乙型流感病毒神经氨酸酶抑制剂,口服用于治疗和预防流行性感冒（流感）。达菲口服后经肝脏和肠道酯酶迅速催化转化为其活性代谢物奥司他韦羧酸盐。奥司他韦羧酸盐能选择性结合和抑制流感病毒神经氨酸酶,阻止病毒颗粒从被感染细胞中释放,从而减少甲型和乙型流感病毒的播散和减轻病毒负荷。     

磷酸奥司他韦颗粒的临床应用观察

磷酸奥司他韦是一种前体药物,在体内代谢产生奥司他韦羧酸盐,此盐是选择性的流感病毒神经氨酸酶抑制剂。神经氨酸酶是病毒表面的一种糖蛋白酶,其活性对新形成的病毒颗粒从被感染细胞中释放和感染性病毒在人体进一步播撒至关重要。磷酸奥司他韦的活性代谢产物可抑制甲型和乙型流感病毒的神经氨酸酶活性。在体外对病毒神经氨酸酶活性的半数抑制浓度低至纳克水平。在体外观察到活性代谢产物抑制流感病毒生长,在体内也观察到其抑制流感病毒的复制和致病性［1］。该药通过抑制病毒从被感染的细胞中释放,从而减少了甲型或乙型流感病毒的播散。     

截短型H1N1神经氨酸酶基因的克隆及其在毕赤酵母中的表达

将密码子优化的截短型H1N1神经氨酸酶基因克隆到载体pPICZαA中,以构建重组质粒pPICZαA-NAS.将线性化的重组质粒pPICZαA-NAS转化毕赤酵母SMD1168,获得了能够分泌表达截短型H1N1神经氨酸酶的重组菌株.结果表明,重组菌株能够分泌表达具有生物活性的截短型神经氨酸酶,该酶受两种已知的神经氨酸酶抑制剂(奥司他韦和扎那米韦)的显著抑制,可用于构建新型神经氨酸酶抑制剂的高通量筛选模型.     

应用假病毒模型寻找H5NI高致病流感病毒侵入抑制剂

目的：建立不同亚型流感病毒侵入环节的细胞水平重组病毒药理筛选模型,并应用该模型筛选流感病毒侵入抑制剂。方法：将表达流感病毒外壳蛋白（hemagglutinin,HA）质粒和HIV-1核心基因共转染至病毒生成细胞,生成由HA包装HIV核心的重组病毒颗粒,简称HA／HIV模型,HIV-1核心基因上携带的报告基因的表达水平可以反映感染水平。在筛选过程中,以VSVG／HIV模型作为特异性对照模型,以HA抗体作为阳性对照。结果：成功构建了两种H5N1亚型和-种H5N2亚型的流感病毒侵入为靶标的药理筛选模型,HA抗体可以成功抑制HA／HIV假病毒颗粒的侵入。应用以上模型筛选了2000余个化合物,其中发现三个海洋来源的化合物YCUA-6、YC-72、GC-29可以剂量依赖性抑制三种不同亚型流感病毒HA介导的侵入,其IC50均在1～10μM之间。结论：目前针对流感病毒的侵入环节尚无有效的药物,本研究首次建立了以流感病毒侵入环节为靶标的药物筛选模型,发现三个海洋来源化合物单体YCUA-6、YC-72、GC-29可有效抑制H5N1高致病流感病毒的侵入,本研究提供了流感病毒侵入抑制剂的先导化合物,为研发新靶点和新结构类型的流感病毒抑制剂建立了筛选和物质平台。     

黄酮类化合物的神经氨酸酶抑制活性及构效关系研究进展

神经氨酸酶(neuraminidase,NA)为A型和B型流感病毒表面的一种糖蛋白,是抗流感病毒药物的靶点之一。近年来,国内外研究者发现一些黄酮类化合物具有很好的NA抑制活性,其结构骨架不同于已上市NA抑制剂奥司他韦和扎那米韦,有望解决流感病毒耐药性和当前药物NA亚型依赖性等问题。有些黄酮类化合物与奥司他韦联用能显著增强后者对不同亚型NA的抑制活性,因此该类药物的研发上市将为临床治疗方案提供新的选择。现综述不同结构类型黄酮类化合物的NA抑制活性及构效关系研究进展,为新型黄酮类NA抑制剂先导化合物的发现和结构改造提供参考。     

奥司他韦致结膜炎1例及文献复习

奥司他韦(oseltamivir)是一种神经氨酸酶抑制剂,通过抑制病毒从被感染细胞中释放,从而减少甲型或乙型流感病毒的播散,用于治疗成人和1岁以上儿童的甲型和乙型流感,以及用于预防成人和13岁及以上青少年的甲型和乙型流感[1].奥司他韦常见的不良反应主要有胃肠系统损害(呕吐、恶心、腹泻、腹痛)、神经系统紊乱(睡眠障碍、...     

Assessment of the efficacy of the neuraminidase inhibitor oseltamivir against 2009 pandemic H1N1 influenza virus in ferrets

Pandemic 2009 influenza A (H1N1) virus (H1N1pdm) is different from contemporary seasonal human viruses in that it can cause infection deep in the lungs of critical care patients. Here we establish a mammalian animal model and assessed the efficacy of the neuraminidase (NA) inhibitor oseltamivir treatment against H1N1pdm virus infection. Oseltamivir (25 mg/kg/day twice daily for 5 days) was orally administered to groups of ferrets, starting either 2 or 24 h after inoculation with 10⁶ PFU of A/California/04/2009 (H1N1) influenza virus. We determined that virus replication was restricted to 1 or 2 of 4 lung lobes in oseltamivir-treated animals, while virus was consistently isolated from 4 of 4 lung lobes in control animals (1.5-3.8 log₁₀ PFU/g). Analysis of arterial blood oxygenation revealed less pronounced changes in partial oxygen and carbon dioxide pressure in oseltamivir-treated ferrets, and histologic examination confirmed reduced pneumonia. Treated animals had significantly decreased inflammatory responses in the upper respiratory tract (P < 0.05), less fever and weight loss, and less reduction of activity. Virus titers in the nasal washes of treated and control ferrets did not differ significantly. NA sequencing and fluorescence-based phenotypic assays identified no oseltamivir-resistant variants. Overall, oseltamivir treatment decreases the signs of infection and reduced the spread of H1N1pdm influenza virus in the lungs of ferrets and therefore impeded the development of viral pneumonia.     

The hydrophobic side chain of oseltamivir influences type A subtype selectivity of neuraminidase inhibitors

Neuraminidase, which plays a critical role in the influenza virus life cycle, is a target for new therapeutic agents. The study of structure–activity relationships revealed that the C‐5 position amino group of oseltamivir was pointed to 150‐cavity of the neuraminidase in group 1. This cavity is important for selectivity of inhibitors against N1 versus N2 NA. A serial of influenza neuraminidase inhibitors with the oseltamivir scaffold containing lipophilic side chains at the C‐5 position have been synthesized and evaluated for their influenza neuraminidase inhibitory activity and selectivity. The results indicated that compound 13o (H5N1 IC₅₀ = 0.1 ± 0.04 μm , H3N2 IC₅₀ = 0.26 ± 0.18 μm ) showed better inhibitory activity and selectivity against the group 1 neuraminidase. This study may provide a clue to design of better group 1 neuraminidase inhibitors.     

The H274Y mutation in the influenza A/H1N1 neuraminidase active site following oseltamivir phosphate treatment leave virus severely compromised both in vitro and in vivo

Oseltamivir carboxylate is a potent and specific inhibitor of influenza A and B neuraminidase (NA). Oseltamivir phosphate, the ethyl ester prodrug of oseltamivir carboxylate, is the first orally active NA inhibitor available for the prophylaxis and treatment of influenza A and B. It offers an improvement over amantadine and rimantadine which are active only against influenza A and rapidly generate resistant virus. The emergence of virus resistant to oseltamivir carboxylate in the treatment of naturally acquired influenza infection is low (about 1%). The types of NA mutation to arise are sub-type specific and largely predicted from in vitro drug selection studies. A substitution of the conserved histidine at position 274 for tyrosine in the NA active site has been selected via site directed mutagenesis, serial passage in culture under drug pressure in H1N1 and during the treatment of experimental H1N1 infection in man. Virus carrying H274Y NA enzyme selected in vivo has reduced sensitivity to oseltamivir carboxylate. The replicative ability in cell culture was reduced up to 3 logs, as was infectivity in animal models of influenza virus infection. Additionally, pathogenicity of the mutant virus is significantly compromised in ferret, compared to the corresponding wild type virus. Virus carrying a H274Y mutation is unlikely to be of clinical consequence in man.     

Anti-influenza virus activity of peramivir in mice with single intramuscular injection

In the event of an influenza outbreak, antivirals including the neuraminidase (NA) inhibitors, peramivir, oseltamivir, and zanamivir may provide valuable benefit when vaccine production is delayed, limited, or cannot be used. Here we demonstrate the efficacy of a single intramuscular injection of peramivir in the mouse influenza model. Peramivir potently inhibits the neuraminidase enzyme N9 from H1N9 virus in vitro with a 50% inhibitory concentration (IC(50)) of 1.3+/-0.4 nM. On-site dissociation studies indicate that peramivir remains tightly bound to N9 NA (t(1/2)>24h), whereas, zanamivir and oseltamivir carboxylate dissociated rapidly from the enzyme (t(1/2)=1.25 h). A single intramuscular injection of peramivir (10mg/kg) significantly reduces weight loss and mortality in mice infected with influenza A/H1N1, while oseltamivir demonstrates no efficacy by the same treatment regimen. This may be due to tight binding of peramivir to the N1 NA enzymes similar to that observed for N9 enzyme. Additional efficacy studies indicate that a single injection of peramivir (2-20mg/kg) was comparable to a q.d.x 5 day course of orally administered oseltamivir (2-20mg/kg/day) in preventing lethality in H3N2 and H1N1 influenza models. A single intramuscular injection of peramivir may successfully treat influenza infections and provide an alternate option to oseltamivir during an influenza outbreak.     

Docking study on chlorogenic acid as a potential H5N1 influenza A virus neuraminidase inhibitor

Docking simulation between chlorogenic acid and H5N1 influenza virus neuraminidase (NA) was performed and the binding free energies of the best pose and average for the best three different poses of H5N1 NA–chlorogenic acid complex are −9.71 and −9.27 kcal/mol, respectively, which is lower than those of H5N1 NA–oseltamivir complex (−7.13 and −6.39 kcal/mol) by using ArgusLab docking method. The hydrogen bonds could be formed between chlorogenic acid and the H5N1 NA amino acid residues Arg156 and Thr439. Arg152 from the 150-cavity makes polar contact with the –COOH group in chlorogenic acid. Chlorogenic acid could be a potential H5N1 influenza A virus NA inhibitor.     

Susceptibility of human influenza viruses from Australasia and South East Asia to the neuraminidase inhibitors zanamivir and oseltamivir

Human influenza viruses isolated from Australasia (Australia and New Zealand) and South East Asia were analysed to determine their sensitivity to the NA inhibitor drugs, zanamivir and oseltamivir. A total of 532 strains isolated between 1998 and 2002 were tested using a fluorescence-based assay to measure the relative inhibition of NA activity over a range of drug concentrations. Based on median IC50 values, influenza A viruses (with neuraminidase subtypes N1 and N2) were more sensitive to both the NA inhibitors than were influenza B strains. Influenza A viruses with a N1 subtype and influenza B strains both demonstrated a greater sensitivity to zanamivir than to oseltamivir carboxylate, whereas influenza A strains with a N2 subtype were more susceptible to oseltamivir carboxylate. For each of the neuraminidase types, IC50 values for viruses from Australasia and South East Asia were found to be comparable. Based on the data prior to and following the licensing of the drugs into the respective regions, the use of the NA inhibitors did not appear to have a significant impact on the susceptibility of the viruses tested to zanamivir or oseltamivir carboxylate.     

In vitro generation and characterisation of an influenza B variant with reduced sensitivity to neuraminidase inhibitors

A contemporary influenza type B virus was passaged in vitro in the presence of increasing concentrations of the neuraminidase inhibitors, zanamivir and oseltamivir carboxylate (0.1-1000 microM over nine passages). After the fifth passage in the presence of zanamivir (10 microM), the virus acquired a Glu 119 Asp neuraminidase mutation (influenza A N2 subtype numbering) in the enzyme active site. After a further three passages, in which growth occurred in 100 microM of zanamivir, a Gln 218 Lys mutation (A (H3) numbering) in the HA1 domain of the haemagglutinin was found. In a fluorescence-based neuraminidase inhibition assay, viruses with the Glu 119 Asp NA mutation had a 32,000-fold reduction in sensitivity to the NA inhibitor zanamivir compared to the wild-type virus, while the mutation resulted in a 105-fold reduction in sensitivity to oseltamivir carboxylate. Viruses grown in the presence of 1000 microM oseltamivir carboxylate did not acquire any neuraminidase mutations but did have a His 103 Gln substitution (A (H3) numbering) in the HA1 region of the haemagglutinin which was demonstrated to significantly reduce receptor binding strength in vitro. Tissue culture assays demonstrated that the HA mutation caused a seven-fold reduction in sensitivity to oseltamivir carboxylate, and a 90-fold reduction in sensitivity to zanamivir.     

雌二醇在人、比格犬和大鼠的肝微粒体中体外代谢比较研究

采用体外肝微粒体孵育体系, 研究雌二醇在大鼠、比格犬和人肝微粒体中酶代谢动力学及代谢产物差异。通过对雌二醇浓度、肝微粒体蛋白含量和孵育时间等条件的考察, 优化雌二醇与肝微粒体的反应体系; 应用LC-MS/MS定量检测孵育体系中的雌二醇及代谢产物, 分析比较雌二醇在3个种属、不同性别肝微粒体中代谢产物种类和生成量的差异, 计算并比较相应的动力学参数。在3个种属肝微粒体中均发现9个I相代谢产物, 且百分比有种属差异。结果表明, 3个种属的肝微粒体对雌二醇I相代谢途径基本相同, 但是代谢产物的生成量及雌二醇的药物代谢动力学性质存在一定的差异。     

Characterization of drug-resistant recombinant influenza A/H1N1 viruses selected in vitro with peramivir and zanamivir

There is a limited information with regard to the neuraminidase (NA) mutations conferring resistance to peramivir and zanamivir in the influenza N1 background. In this study, an influenza A/WSN/33 (H1N1) recombinant virus was passaged under peramivir or zanamivir pressure. The peramivir-selected variant had a H274Y mutation in the neuraminidase (NA) gene conferring resistance to peramivir and oseltamivir but susceptibility to zanamivir. The zanamivir-selected variant had a massive deletion in the region encoding the NA active center and an A200T hemagglutinin mutation. This variant exhibited reduced susceptibility to zanamivir with a drug-dependent phenotype.     

噻吩诺啡在人、比格犬和大鼠肝微粒体中体外代谢比较

采用体外肝微粒体孵育体系, 研究噻吩诺啡在大鼠、比格犬和人肝微粒体中酶代谢动力学及代谢产物差异。通过对噻吩诺啡浓度、微粒体蛋白含量和孵育时间等条件的考察优化噻吩诺啡与肝微粒体的反应体系; 应用LC-MS/MS定量检测孵育体系中的噻吩诺啡及代谢产物, 分析比较噻吩诺啡在3种肝微粒体中代谢产物种类和生成量的差异, 计算并比较相应的动力学参数。噻吩诺啡在人肝微粒体中代谢转化最慢, 其相应的动力学参数K_m = (4.00 ± 0.59) µmol·L⁻¹、V_max = (0.21 ± 0.06) µmol·L⁻¹·min⁻¹、T_1/2 = (223 ± 6.10) min、CL_int = (117 ± 3.19) mL·min⁻¹·kg⁻¹; 比格犬和大鼠肝微粒体中相应的参数K_m、V_max、T_1/2和CL_int分别为 (3.57 ± 0.69) 和 (3.28 ± 0.50) µmol·L⁻¹、(0.18 ± 0.04) 和 (0.14 ± 0.04) µmol·L⁻¹·min⁻¹、(244 ± 1.21) 和 (70.7 ± 1.05) min、(213 ± 1.06) 和    (527 ± 7.79) mL·min⁻¹·kg⁻¹。在3个种属肝微粒体中均观察到噻吩诺啡的6个I相代谢产物, 但6个产物的相对生成百分比在不同种属肝微粒体中有一定差异。实验结果表明, 噻吩诺啡在体外人、比格犬和大鼠肝微粒体中主要的I相代谢途径相同, 但是代谢产物的生成量及噻吩诺啡的代谢动力学性质存在着一定的差异。