抗肠道病毒71型感染药物的研究进展

肠道病毒71型(enterovirus 71,EV71)是引起手足口病(hand foot mouth disease,HFMD)的主要病原体,临床表现为手、足、口腔等部位的疱疹及中枢神经系统并发症[1].5岁以下的儿童感染后易发生严重的并发症,如无菌性脑炎、脑膜脑炎、脑干脑炎、脊髓灰质炎样麻痹、心肌炎和肺水肿等,这些并发症可导致死亡或永久性麻痹[2].至今,在全球许多国家发生了EV71感染的暴发,造成病例大量死亡[3-4].目前对于EV71感染既无有效的疫苗,也无明确有效的抗病毒药物[5-6].该病毒的复制周期包括吸附、穿入、脱壳、生物合成、装配与释放,这些过程都可能成为抗病毒药物设计的靶点,按照作用的靶点不同将目前研究的抗EV71药物分为以下几个方面进行综述.     

应用枯草芽孢杆菌表达系统制备肠道病毒71型VP1蛋白

目的利用枯草芽孢杆菌系统表达肠道病毒71型（EV71）病毒VPl蛋白。方法使用基因特异性引物扩增VPl开放读码框（ORF）,构建包含VP1完整开放读码框的pSac—VPl穿梭载体。根据枯草芽孢杆菌表达系统双交叉同源重组的特点,将EV71的结构抗原基因VPl整合在枯草芽孢杆菌sacA染色体,并经测序鉴定。使用VPl特异性抗体,通过蛋白印记（Western—Blot）鉴定枯草芽孢杆菌中VPl蛋白的表达情况。结果成功克隆EV71的VPl基因,长度1361bp,并将其克隆入穿梭载体pSae—Kan。测序结果显示VPl基因成功整合如sacA染色体。Western．Blot证实VPl抗原在枯草芽孢杆菌的成功表达,相对分子质量约35×10^3。结论利用枯草芽孢杆菌表达系统成功制备EV71病毒VPl抗原,为后续EV71诊断试剂、疫苗研发奠定基础。     

肠道病毒71型与脊髓灰质炎病毒抗体交叉反应性研究

通过临床血清样本研究及实验动物验证,探讨肠道病毒71型(EV71)与脊髓灰质炎病毒(PV)之间的抗体交叉反应性。以酶联免疫吸附试验(ELISA)分别检测健康儿童血清中IgG型抗体与EV71及PV的反应性;用原核表达与亲和纯化等方法分别获得EV71和PV的衣壳蛋白VP1及非结构蛋白3C;将PV-VP1、EV71-VP1、EV71灭活疫苗及PV灭活疫苗(IPV)分别经皮下免疫BALB/c小鼠制得免疫血清,以蛋白免疫印迹实验分别研究PV-VP1或EV71-VP1小鼠阳性血清与EV71-VP1和PV-VP1的反应情况,进一步以竞争ELISA试验分别研究EV71-VP1对PV-VP1与其特异性免疫血清特异结合的影响。微量中和试验研究PV阳性抗血清对EV71的体外中和效应。结果:已接种PV疫苗但未曾感染EV71的健康儿童的IgG抗体与EV71有较高的反应性,且针对EV71及PV两种病毒的IgG抗体的相对含量成正相关;蛋白免疫印迹实验显示PV-VP1与EV71-VP1免疫的小鼠抗血清中存在交叉抗体,竞争ELISA试验进一步表明EV71-VP1蛋白能明显抑制PV-VP1与其特异性免疫血清抗体的结合,反之亦然。但中和实验揭示PV阳性血清在体外不能中和EV71病毒。PV之间存在大量交叉反应性抗体,但PV免疫后产生的与EV71交叉反应的抗体是非中和性质抗体。非中和抗体可能通过免疫调理效应在EV71病毒的致病的过程中发挥重要作用。     

肠道病毒EV71及CA16在不同细胞系中细胞病变作用的研究

目的研究CA16和EV71在4种细胞系中细胞病变作用的差异.方法随机选择滴度相似的EV71轻症、EV71重症和CA16轻症毒株各1株,分别感染RD、Vero、U251和SY5Y细胞,比较3株病毒在细胞病变的形态及程度、感染后的细胞存活率、病毒在细胞中的复制水平和病毒所致凋亡蛋白相关mRNA的表达水平等方面的差别.结果3株病毒的感染在同一细胞系中表现相似.镜下从形态学上无法对三株病毒加以区别;感染后病毒载量均表现为从高到低依次为Vero、RD、SY5Y细胞到U251细胞的顺序;病毒感染后细胞存活率的顺序与细胞内复制水平与相反,两者之间存在类似负相关的趋势.3株病毒的感染在3种细胞系中均有凋亡蛋白caspase-8、9和3相关mRNA的表达,提示可能3种细胞系中凋亡启动的途径相同.结论细胞水平的感染,提示这两种病毒感染所致临床表现的差异性并非单独由病毒所决定.     

江苏省肠道病毒71型分离株的分子遗传演化特征

肠道病毒71型(EV71)是小RNA病毒科肠道病毒属成员,其感染主要引起患者手足口病(handfoot-mouth disease,HFMD),个别患者可引起无菌性脑膜脑炎等并发症.自1998年EV71在中国台湾暴发以来,EV71病毒在亚洲的流行呈上升趋势.流行病学资料表明,不同地区不同症状的EV71病毒性疾病的暴发可能与毒株间的差异等因素有关[1].为了解EV71病毒的遗传和变异特征,本实验室对2009年在江苏手足口病流行地区分离到的一株EV71型病毒株(Jiangsu01,GenBank:FJ600325.1)的基因组核苷酸序列进行了遗传进化分析,从分子水平为EV71病毒的流行以及所致疾病的防控提供理论基础.     

肠道病毒71型3D蛋白关键氨基酸突变对病毒增殖的影响

目的:研究肠道病毒71型(enterovirus 71, EV71)中3D蛋白关键氨基酸突变对病毒增殖的影响,并根据3D三级结构模型推断突变影响病毒增殖能力的可能机制。方法:以强毒株SDLY107构建的质粒pMD19T-SDLY107-EGFP为模板,利用定点突变和反向遗传学技术构建病毒突变株,对突变株增殖特性进行测定...     

利巴韦林注射液在细胞水平上抑制EV71病毒复制的初步研究

目的 通过体外实验,观察利巴韦林注射液对肠道病毒71型(EV71)病毒在横纹肌肉瘤传代细胞(RD-A细胞)复制的抑制作用和体外灭活作用.方法 使用在2008年4月安徽阜阳疫情中分离到的EV71病毒,通过三种体外细胞实验:药物在细胞中抑制EV71病毒复制的药效测定实验;药物对细胞的保护作用实验;药物体外对EV71病毒的灭活作用的药效测定实验.观察利巴韦林注射液对EV71病毒感染横纹肌肉瘤传代细胞(RD-A细胞)中所起的作用.结果 在利巴韦林注射液在细胞中抑制EV71病毒复制的药效测定实验中,1:640利巴韦林注射液稀释度组较病毒对照组延迟病变出现2 d,细胞生长未受到影响.在药物对细胞的保护作用实验中,1:8利巴韦林稀释度组较病毒对照组延迟病变出现4 d.在利巴韦林注射液药物体外对EV71病毒的灭活作用的药效测定研究中,1:40稀释度组较病毒对照组延迟病变出现2 d,而细胞生长未受到影响.结论 利巴韦林注射液在体外有抑制EV71病毒复制和部分灭活病毒的作用;并有一定的保护细胞抑制EV71病毒感染的作用.本研究对于临床上EV71感染的早期预防和治疗具有一定的指导意义.     

人前列腺LRIG1蛋白三维结构同源模建及其小分子激动剂的虚拟筛选

目的 LRIG1(tandem leucine-rich repeat sand immunoglobulin-like domains 1,LRIG1)是新近发现的抑癌基因,在前列腺癌中表达下降,通过对人前列腺LRIG1蛋白的三维结构进行同源模建,虚拟筛选出LRIG1的功能蛋白,试图为前列腺癌新靶点治疗提供新思路.方法 以LRIG1的同源蛋白LRRC4 C蛋白的晶体结构(PDB号3 ZYJ)为模型,通过MODELLER软件搭建LRIG1蛋白的三维空间结构;采用柔性对接的虚拟筛选技术,以荷兰SPECS公司的202490个化合物进行对接和打分,挑选出排名靠前的10个小分子化合物;通过AMBER软件分别进行20 ns的分子动力学模拟,并分析这10个小分子的结合模式、 动力学轨迹的RMSD、RMSF、 结合口袋的氢键以及它们的结合能量.结果 10个小分子化合物都具有一致的结合模式,而且都具有激活LRIG1活性的潜在能力.结论 发现与人LRIG1具有潜在特异结合能力的激动剂,可以为前列腺癌治疗新靶点的确立及开发具有药理活性的先导化合物提供理论依据.     

3C蛋白酶及抑制剂研究进展

3C蛋白酶是催化小RNA病毒前体蛋白中非结构蛋白部分裂解的关键蛋白酶,对病毒的复制有着重要作用,是当前抗病毒研究的一个重要靶点.本文简要概述了3C蛋白酶的结构、功能和抑制剂的研究进展,对该酶的抑制研究和相关病毒的治疗有积极意义.     

自噬抑制剂3-MA抑制EV71病毒颗粒的产生与释放

目的 通过研究肠道病毒71型（Enterovirus 71,EV71）感染引起细胞的自噬及抑制自噬对病毒滴度的影响,为进一步明确EV71的致病机制提供基础.方法 利用Western Blot检测EV71感染后RD-A细胞内源性LC3的型别转换和P62的降解来指示细胞发生自噬的水平,通过测定染毒细胞培养上清中EV71病毒CCID50来观察抑制自噬后细胞释放EV71感染性病毒颗粒的变化.结果 EV71的感染促进了细胞LC3的型别转换和F62的降解,诱导了细胞发生自噬;3-MA抑制细胞自噬后,EV71染毒细胞产生的感染性EV71病毒颗粒数量减少.结论 EV71可以诱导细胞发生自噬,细胞自噬可能促进EV71感染性病毒颗粒的产生和释放.     

VP1-Binding Protein Glucose-regulated protein 78 as an important mediator for Enterovirus 71 infecting Human Brain Microvascular Endothelial Cells

Purpose: Enterovirus 71 (EV71) is one of the main pathogens causing hand, foot and mouth disease, which could even induce severe brain damage in some patients. As the underlying mechanism of the invasion and replication process still remains largely unknown, we investigated the role of candidate proteins expressed during EV71 invasion in human brain microvascular endothelial cells (HBMECs) to delineate the pathophysiological mechanism of EV-71 infection. Materials and Methods: Ninety-one candidate EV71-associated proteins which could bind the major capsid protein (viral protein 1 [VP1]) of EV71 on the HBMEC were identified by applying an analysis of glutathione-S-transferase pull-down coupling with liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). Seventy-eight kDa glucose-regulated protein 78 (GRP78) binding to the VP1 protein was further validated by co-immunoprecipitation, immunofluorescence and western blot analysis. To explore the role of GRP78 in EV71 infection, GRP78 was knocked down and overexpressed in HBMEC and was verified by TCID50 assay. Results: LC-ESI-MS/MS-identified 91 proteins were subjected to gene ontology analysis, and on molecular and biological function analysis revealed GRP78 act as an important binding protein in mediating EV71 infection. In addition, immunofluorescence demonstrated the co-localisation of GRP78 and VP1 in cytoplasm of the infected HBMEC. The TCID50 assay showed that knockdown of GRP78 could attenuate the replication capacity of EV71 in HBMEC, and the overexpression could increase the virus titre in HBEMC at 24 h post-infection suggesting that GRP78 was associated with the replication capacity of EV71 in HBMEC. Conclusion: These findings provided evidence that GRP78 plays an important role during the progression of EV71 infection as a mediator in HBMEC.     

The VP1 structural protein of enterovirus 71 interacts with human ornithine decarboxylase and gene trap ankyrin repeat

Enterovirus 71 (EV71) is a major etiological agent of hand, foot and mouth disease (HFMD). Several outbreaks in East Asia were associated with neurological complications and numerous deaths. EV71 possesses four structural proteins VP1-VP4 that are necessary in the formation of the pentameric icosahedral capsid. The viral capsid contributes to virulence, and VP1 is a prime target for EV71 vaccine development. Using yeast two-hybrid analysis, we demonstrated binding affinity between VP1 and three human proteins, i.e. ornithine decarboxylase (ODC1), gene trap ankyrin repeat (GTAR), and KIAA0697 expressed in brain tissue. These interactions were authenticated by co-immunoprecipitation experiments, and by indirect immunofluorescent confocal microscopy of transfected and EV71-infected Vero cells. The significant interaction between VP1 and ODC1 may compromise the latter's activity, and interfere with polyamine biosynthesis, growth and proliferation of EV71-infected cells. The interaction between VP1 and GTAR is noteworthy, since ankyrin proteins are associated with certain neural cell adhesion molecules and with the CRASH neurological syndrome. Given that VP1 is synthesized in large amounts during productive infection, these viral-host protein interactions may provide insights into the role of VP1 in the pathogenesis of EV71 disease and its neurological complications such as acute flaccid paralysis and encephalitis.     

In vitro and in vivo protection against enterovirus 71 by an antisense phosphorothioate oligonucleotide

Enterovirus 71 (EV71) is a highly infectious virus that is a major cause of hand, foot, and mouth disease (HFMD), which can lead to severe neurological complications. Currently, there is no effective therapy against EV71. Five antisense oligodeoxynucleotides targeting the 5′-terminal conserved domain of the viral genome were designed using a method based on multiple predicted target mRNA structures. They were then screened for anti-EV71 activity in vitro based on their ability to inhibit an EV71-induced cytopathic effect (CPE). A novel antisense oligonucleotide (EV5) was tested both in rhabdomyosarcoma (RD) cells and in vivo using a mouse model, with a random oligonucleotide (EV5R) of EV5 as a control. EV5 was identified as having significant anti-EV71 activity in vitro and in vivo without significant cytotoxicity. Treatment of RD and Vero cells with antisense oligodeoxynucleotide EV5 significantly and specifically alleviated the cytopathic effect of EV71 in vitro. The inhibitory effect was dose dependent and specific, with a corresponding decrease in viral RNA and viral protein levels. In vivo, EV5 was specifically effective against EV71 virus in preventing death, decreasing weight reduction and reducing the viral RNA copy number and the level of viral proteins in the lungs, intestines and muscles. These results demonstrate the potential and feasibility of using antisense oligodeoxynucleotides specific for the 5′-terminal conserved domain of the viral genome as an antiviral therapy for EV71 disease.     

以乙肝病毒核心蛋白为载体制备肠道病毒71 型非结构蛋白3D 单克隆抗体

目的：预测肠道病毒71型（EV71）非结构蛋白3D的表位,以HBc蛋白为载体展示多肽,制备并鉴定抗EV71-3D的特异性单克隆抗体（mAb）。方法：应用生物信息学方法分析预测出EV71-3D蛋白亲水性和免疫原性指数较高的多肽片段,并运用HBc颗粒型蛋白载体展示肽段,构建多肽融合蛋白,免疫BALB/c雌鼠,通过杂交瘤技术和亲和层析技术制备和纯化抗EV71-3D蛋白的特异性mAb,用间接ELISA、ELISPOT、IFA和IHC对mAb的性质进行初步鉴定。结果：构建表达分别嵌合3D蛋白34~43位氨基酸残基、 61~76位氨基酸残基、151~164位氨基酸残基的HBc重组蛋白,免疫并经过多轮克隆化筛选,获得抗EV71-3D单克隆抗体3E1,其亚类为IgG2a;免疫荧光试验、ELISPOT法和免疫组织化学染色结果显示其可与EV71特异性结合。结论：成功制备可特异性识别EV71的单克隆抗体3E1,为病毒的检测及进一步研究3D蛋白的功能奠定了基础,同时还验证了生物信息学技术与HBc颗粒型载体展示多肽技术相结合可快速高效地制备单克隆抗体。     

人源抗EV71病毒基因工程抗体的研究

目的 研制人源抗EV71病毒基因工程抗体.方法 采集多个患儿外周血淋巴细胞,构建人源抗EV71单链（scFv）噬菌体抗体基因文库.用纯化的EV71 VPI蛋白对抗体库进行筛选,将筛出抗体的轻链和重链通过序列测定确定抗体轻重链型别后分别克隆入全抗体表达载体pAC-LCH3R后转染昆虫Sf9细胞,利用杆状病毒/昆虫细胞系统实现全抗体的分泌型表达.结果 成功地获得了1株抗EV71病毒VPI蛋白的人源单克隆抗体,利用ELISA、IFA对所获人源单克隆抗体的功能特性进行鉴定,表达成分泌型IgG全抗体在体外与A型及C4亚型EV71病毒的中和反应结果 显示为阴性.结论 从免疫库中获得了1株人源非中和单抗,为EV71病毒引起的手足口病的鉴别诊断奠定了基础.     

Enterovirus 71 contains a type I IRES element that functions when eukaryotic initiation factor eIF4G is cleaved

Human enterovirus 71 (EV71) is a member of the Enterovirus genus of the Picornaviridae family. Other members of this family utilize an unusual mechanism of translation initiation whereby ribosomes are recruited internally to the viral RNA by an internal ribosome site (IRES) located in their 5' noncoding regions (5' NCR). Using dicistronic reporter constructs, we demonstrate that the 5' NCRs of the 7423/MS/87 and BrCr strains of EV71 function as an IRES both in extracts and in cultured cells. Preincubation of translation extracts with purified coxsackievirus 2A protease cleaved elF4G, a component of the cap binding complex, resulting in a significant decrease in translation of capped mRNAs. In contrast, the translational efficiency of the EV71 IRES was enhanced under this condition, demonstrating that the EV71 IRES functions similar to other enterovirus IRES elements when components of the cap binding protein complex are cleaved. Finally, insertion of an upstream, out-of-frame start codon in the 5' NCR of the EV71 genome inhibited IRES activity, suggesting that EV71 can be classified as a type I IRES, in which ribosomes first bind upstream of the initiation codon and then scan the mRNA until an appropriate downstream AUG start codon is encountered and protein synthesis commences.     

Identification of Novel Compounds against an R294K Substitution of Influenza A (H7N9) Virus Using Ensemble Based Drug Virtual Screening

Influenza virus H7N9 foremost emerged in China in 2013 and killed hundreds of people in Asia since they possessed all mutations that enable them to resist to all existing influenza drugs, resulting in high mortality to human. In the effort to identify novel inhibitors combat resistant strains of influenza virus H7N9; we performed virtual screening targeting the Neuraminidase (NA) protein against natural compounds of traditional Chinese medicine database (TCM) and ZINC natural products. Compounds expressed high binding affinity to the target protein was then evaluated for molecular properties to determine drug-like molecules. 4 compounds showed their binding energy less than -11Kcal/mol were selected for molecular dynamics (MD) simulation to capture intermolecular interactions of ligand-protein complexes. The molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) method was utilized to estimate binding free energy of the complex. In term of stability, NA-7181 (IUPAC namely {9-Hydroxy-10-[3-(trifluoromrthyl) cyclohexyl]-4.8-diazatricyclo [6.4.0.02,6]dodec-4-yl}(perhydro-1H-inden-5-yl)formaldehyde) achieved stable conformation after 20ns and 27ns for ligand and protein root mean square deviation, respectively. In term of binding free energy, 7181 gave the negative value of -30.031 (KJ/mol) indicating the compound obtained a favourable state in the active site of the protein.