可调控表达甲型流感病毒M2蛋白的哺乳动物细胞系的建立与鉴定

甲型流感病毒M2蛋白是一种具有离子通道功能的跨膜蛋白,其氨基酸序列非常保守,可用于流感通用疫苗的研究。为了构建可调控的稳定表达甲型流感病毒M2蛋白的哺乳动物细胞系,首先应用PCR方法从含有流感病毒PR8株第七节段全长基因的质粒中扩增得到M2基因。将该片段亚克隆到真核表达载体pcDNA5/FRT/TO上,用BamHⅠ和NotⅠ双酶切鉴定正确后将重组质粒与表达Flp重组酶的pOG44质粒共转染Flp-In T-REx-293细胞,使目的基因整合到宿主细胞染色体。筛选具有Hygromycin B抗性的细胞株。在该细胞的培养基中加入四环素以诱导目的基因表达,48 h后通过间接免疫荧光方法检测到M2蛋白的表达。共得到16株高表达M2蛋白的重组细胞株,这些细胞株在传10代后仍能稳定表达目的蛋白。未加四环素诱导的细胞没有检测到M2蛋白,说明四环素调控系统严格控制着目的基因的表达。今后,该细胞系可用于流感病毒M2蛋白的功能研究、流感候选疫苗的免疫学评价以及流感病毒减毒活疫苗的研制。     

流感病毒NS1蛋白稳定表达的A549细胞系建立

A型流感病毒的NS1(Nonstructurol 1 protein,NS1)蛋白是病毒复制、毒力等的重要调节蛋白.运用RT-PCR方法扩增A/Beijing/501/2009(H1N1)流感病毒NS1基因,克隆至真核表达载体pCMV-HA,用Lipofectamine2000将线性化pCMV-HA-NS1与neo基因共同转染A549细胞,通过G418筛选获得阳性重组细胞,并采用PCR、RT-PCR、Western blot技术检测重组细胞中NS1蛋白的表达,通过免疫荧光技术观察NS1蛋白在细胞中的定位.PCR、RT-PCR检测显示NS1基因成功整合进入细胞基因组,并转录为mRNA;Western blot检测显示重组细胞系稳定表达NS1蛋白,免疫荧光显示NS1蛋白定位于细胞核内.表明通过G418筛选,成功构建稳定表达NS1蛋白的重组A549-HA-NS1细胞系,且NS1蛋白定位于细胞核内,为进一步研究NS1蛋白的生物学功能奠定基础.     

流感病毒基质蛋白DNA疫苗的免疫保护作用研究

流感病毒基质蛋白(matrix protein,M)在病毒复制和毒力方面有重要作用.编码基质蛋白的M1基因和M2基因胞外域序列是A型流感病毒的保守序列,是研究具有交叉保护能力流感疫苗的候选基因.我们构建了真核表达质粒pCAGGSP7/M1和pCAGGSP7/M2,用质粒DNA免疫小鼠以观察其免疫原性.分别在M1DNA免疫2、3、4、5、6次或M2 DNA免疫4、5、6次7 d后,用致死量同源流感病毒A/PR/8攻击小鼠,通过检测小鼠血清抗体滴度、肺部病毒量和小鼠存活率来观察质粒DNA的保护效果.结果表明,随着免疫次数增加,M1 DNA免疫组在病毒攻击后小鼠存活率增高,而M2 DNA免疫组小鼠攻毒后全部死亡.说明M1 DNA多次免疫后能提供抗流感病毒的部分保护,M2 DNA没有免疫保护作用.     

利用慢病毒载体快速建立表达外源基因的哺乳动物细胞系

建立稳定表达外源基因的哺乳动物细胞系是一项重要的生物技术,介绍了联合使用慢病毒载体和流式细胞仪分选技术来建立稳定表达绿色荧光蛋白的293T细胞系.结果表明,在1个月左右的时间里即可获得表达绿色荧光蛋白的293T细胞系,阳性细胞率高达96.5％,而且建立的细胞系能够稳定传代.因此,联合慢病毒载体和流式细胞仪分选技术的策略对于建立稳定表达外源基因的哺乳动物细胞系快捷和可靠.     

哺乳动物细胞系(株)的应用

哺乳动物细胞系(株)已在细胞遗传学、分子遗传学和生物医学等方面得到越来越广泛的应用。其已被用于基因定位、检测理化因素的毒性和细胞因子活性、生产单克隆抗体、制备组织工程化人工器官和转基因动物等方面,更是研究发育生物学、肿瘤发生学、肿瘤治疗等不可或缺的材料。综述了哺乳动物细胞系(株)的建立方法及其在以上各方面的应用。     

重组甲型流感病毒基质蛋白1和2通过ERK信号因子诱导小鼠气管上皮细胞产生IFN-γ

探讨重组甲型流感病毒基质蛋白1和2(rM1和rM2)通过细胞外信号调节蛋白激酶(Extracellular signal regulated kinase,ERK)诱导小鼠气管上皮细胞产生γ-干扰素(Interferon-γ,IFN-γ)作用及机制。以原代小鼠气管上皮细胞为实验模型,实验分为6组(rM1组、rM2组、甲型流感病毒(Influenza A virus,IAV)组、rM1+IAV组、rM2+IAV组和正常对照组)。在各组分干预细胞4h、8h、24h时,采用半定量RT-PCR法检测各组细胞中IFN-γmRNA的表达和免疫印迹法检测各组细胞中IFN-γ、ERK、磷酸化ERK(phospho-ERK,p-ERK)蛋白的表达;用抑制剂阻断ERK信号因子信号传导,观察对各组分诱导小鼠气管上皮细胞产生IFN-γ的影响。各组分干预细胞4h、8h、24h,rM1组、rM2组、IAV组、rM1+IAV组、rM2+IAV组细胞的IFN-γmRNA和IFN-γ蛋白表达水平高于正常对照组(P0.01或P0.05);rM1+IAV组、rM2+IAV组细胞的IFN-γmRNA和IFN-γ蛋白表达水平高于IAV组(P0.01或P0.05)。在干预细胞4h,仅rM2组细胞中ERK磷酸化水平显著高于正常对照组(P0.01),在干预细胞8h、24h,rM1组、rM2组、IAV组、rM1+IAV组、rM2+IAV组细胞中ERK磷酸化水平均显著高于正常对照组(P0.01或P0.05)。加入ERK抑制剂,rM1组、rM2组、rM1+IAV组、rM2+IAV组细胞的IFN-γmRNA和IFN-γ蛋白表达水平显著低于非抑制剂组。本研究数据表明rM1和rM2可通过上调ERK信号因子的磷酸化水平诱导小鼠气管上皮细胞中产生IFN-γ,该诱导作用在干预4h即显著表现,并维持至少24h。     

稳定表达人SidT2基因细胞系的建立及其dsRNA转运功能的研究

目的:构建稳定表达人SidT2基因的BHK及MDCK细胞系,探讨SidT2基因过表达与细胞转运双链RNA(dsRNA)能力的关系。方法:根据人SidT2基因序列设计引物,克隆其编码区序列,经双酶切后与pEGFP-N3载体连接,构建其真核表达载体,分别瞬时转染BHK及MDCK细胞,并使用G418筛选稳定表达细胞系;在此基础上,体外转录合成绿色荧光蛋白(GFP)dsRNA,以GFP基因为报告基因,进一步分析过表达人SidT2基因对BHK及MDCK细胞转运dsRNA能力的影响。结果:经基因克隆、酶切、连接后,构建了人SidT2基因真核表达载体pEGFP-SidT2;经瞬时转染及G418筛选,获得稳定过表达人SidT2基因的BHK及MDCK细胞系,实时荧光定量RT-PCR分析表明,其SidT2基因转录水平分别提高71、64.5倍;稳定表达SidT2基因后,在培养液中添加GFP dsRNA,GFP荧光强度较对照细胞分别降低88.1%、73.7%,表明稳定表达SidT2基因的BHK、MDCK细胞转运dsRNA的能力显著增强。结论:构建了稳定表达人SidT2基因的BHK及MDCK细胞系,SidT2基因过表达可显著提高外源性dsRNA的转运能力。     

流感病毒在Vero细胞系与MDCK细胞系增殖条件的比较

目的研究流感病毒H1N1及其他亚型在Vero细胞系和MDCK细胞系高效增殖的最适条件,比较两种细胞系对流感病毒的敏感性差异及影响敏感性差异的条件。方法在培养好的Vero细胞系与MDCK细胞系用不同的病毒感染复数(M.O.I)、胰酶浓度、病毒吸附时间、病毒维持液血清质量浓度等条件进行流感病毒在细胞上的增殖。结果在M.O.I为0.01接种流感病毒,吸附时间为1 h,胰酶质量浓度2μg/mL,血清质量浓度为8%时,流感病毒血凝素在MDCK细胞系可获得较高的滴度。结论 MDCK细胞系是适于流感病毒培养的细胞,它作为生产新型流感病毒疫苗的主要细胞基质需要进一步的研究。     

稳定表达HLA-A33蛋白细胞系的建立

旨在构建能稳定表达HLA-A33蛋白的细胞系,并观察其在细胞中的表达水平.首先克隆取得HLA-A33基因,并将其插入慢病毒载体,经酶切和测序鉴定,确定载体构建正确.通过慢病毒系统感染正常RD细胞,将HLA-A33基因整合进RD细胞的基因组.提取构建细胞系的基因组做PCR鉴定,并通过免疫荧光和蛋白免疫印迹法检测,结果显示,HLA-A33基因成功整合入RD细胞基因组中,且在重组细胞系中成功表达.该细胞系可为A33等位基因与HBV感染后的慢性化以及EV71感染的相关研究提供试验参考.     

选择适合表达 HBsAg 的哺乳动物细胞系

将含有重组ＨＢｓＡｇ的ｐＭＥＰ４表达性质粒转染ＨｅｐＧ２,ＣＨＯ,Ｃ１２７和ＣＶ１细胞,并用ＥＬＩＳＡ检测表达量,结果在ＨｅｐＧ２细胞中的表达量较高,在Ｃ１２７和ＣＶ１细胞中的表达量偏低,而在ＣＨＯ细胞中没有表达。     

狂犬病病毒糖蛋白哺乳动物细胞稳定表达细胞系建立

试验首先根据GenBank上所发表的狂犬病病毒CVS-24株糖蛋白基因序列,设计并合成一对特异性引物,通过反转录 聚合酶链式反应（RT-PCR）,获得糖蛋白全长cDNA,连接在pMD18-T载体上,测序证明克隆的正确性后,将其插入真核表达载体pIRES1neo,构建了糖蛋白单一表达载体pICG,表达质粒通过脂质体转染BHK-21细胞,在G418抗性压力下出现细胞克隆,通过PCR检测,确定启动子与糖蛋白基因在细胞基因组中共同整合。借助Western blot检测,证明所表达的糖蛋白与狂犬病抗血清有特异的反应性。采用间接ELISA法,筛选出3株高效表达糖蛋白的细胞株,分别命名为ICG1、ICG2、ICG3。     

Toxicity of Influenza A Virus Matrix Protein 2 for Mammalian Cells is Associated with its Intrinsic Proton-Channeling Activity

Molecules of influenza matrix protein 2 (M2) are organized in tetramers that constitute a well-conserved virion component and also form proton channels in the plasma membrane of infected cells. In this report we demonstrate that influenza M2 protein is cytopathic in vitro for mammalian cells. An M2 point-mutant (M2pm) protein was constructed that contained amino acid changes designed to block the proton channel via introduction of large hydrophobic residues. This mutant was significantly less toxic upon transient transfection in vitro than the wild-type M2 (M2wt). To assess the possible correlation between M2 cytotoxicity and its proton channel activity, we monitored changes in mitochondria membrane potential induced by M2wt and M2pm. M2wt rapidly decreased mitochondria membrane potential reflecting the transmembrane proton gradient, while M2pm was markedly less efficient. Thus, M2 is cytotoxic for mammalian cells, likely via its proton channel activity and may therefore contribute to influenza pathogenesis through this previously unknown mechanism.     

Association of Influenza Virus Matrix Protein with Ribonucleoproteins

To characterize the sites and nature of binding of influenza A virus matrix protein (M1) to ribonucleoprotein (RNP), M1 of A/WSN/33 was altered by deletion or site-directed mutagenesis, expressed in vitro, and allowed to attach to RNP under a variety of conditions. Approximately 70% of the wild-type (Wt) M1 bound to RNP at pH 7.0, but less than 5% of M1 associated with RNP at pH 5.0. Increasing the concentration of NaCl reduced M1 binding, but even at a high salt concentration (0.6 M NaCl), approximately 20% of the input M1 was capable of binding to RNP. Mutations altering potential M1 RNA-binding regions (basic amino acids 101RKLKR105 and the zinc finger motif at amino acids 148 to 162) had varied effect: mutations of amino acids 101 to 105 reduced RNP binding compared to the Wt M1, but mutations of zinc finger motif did not. Treatment of RNP with RNase reduced M1 binding by approximately half, but even M1 mutants lacking RNA-binding regions had residual binding to RNase-treated RNP provided that the N-terminal 76 amino acids of M1 (containing two hydrophobic domains) were intact. Addition of detergent to the reaction mixture further reduced binding related to the N-terminal 76 amino acids and showed the greatest effect for mutations affecting the RNA-binding regions of basic amino acids. The data suggest that M1 interacts with both the RNA and protein components of RNP in assembly and disassembly of influenza A viruses.     

Establishment of Epstein-Barr Virus Growth-transformed Lymphoblastoid Cell Lines

Infection of B cells with Epstein-Barr virus (EBV) leads to proliferation and subsequent immortalization, resulting in establishment of lymphoblastoid cell lines (LCL) in vitro. Since LCL are latently infected with EBV, they provide a model system to investigate EBV latency and virus-driven B cell proliferation and tumorigenesis¹. LCL have been used to present antigens in a variety of immunologic assays^{2, 3}. In addition, LCL can be used to generate human monoclonal antibodies^{4, 5} and provide a potentially unlimited source when access to primary biologic materials is limited^{6, 7}.A variety of methods have been described to generate LCL. Earlier methods have included the use of mitogens such as phytohemagglutinin, lipopolysaccharide⁸, and pokeweed mitogen⁹ to increase the efficiency of EBV-mediated immortalization. More recently, others have used immunosuppressive agents such as cyclosporin A to inhibit T cell-mediated killing of infected B cells^{7, 10-12}.The considerable length of time from EBV infection to establishment of cell lines drives the requirement for quicker and more reliable methods for EBV-driven B cell growth transformation. Using a combination of high titer EBV and an immunosuppressive agent, we are able to consistently infect, transform, and generate LCL from B cells in peripheral blood. This method uses a small amount of peripheral blood mononuclear cells that are infected in vitroclusters of cells can be demonstrated. The presence of CD23 with EBV in the presence of FK506, a T cell immunosuppressant. Traditionally, outgrowth of proliferating B cells is monitored by visualization of microscopic clusters of cells about a week after infection with EBV. Clumps of LCL can be seen by the naked eye after several weeks. We describe an assay to determine early if EBV-mediated growth transformation is successful even before microscopic clusters of cells can be demonstrated. The presence of CD23^hiCD58⁺ cells observed as early as three days post-infection indicates a successful outcome.     

登革2型病毒衣壳蛋白在哺乳动物细胞中的表达与鉴定

从构建的重组质粒pLEX—C中高保真PCR获得编码登革2型病毒43株C基／E／（D2C）DNA片段,通过基因重组的方法将其克隆入真核表达载体pcDNA6／V5-His获得了重组真核表达载体pc／D2C。经电穿孔的方法转染BHK21细胞后,分别通过RT—PCR、免疫荧光和western印迹鉴定表达的蛋白。结果重组蛋白在BHK21细胞中获得表达,表达的蛋自主要存在于胞浆中,并具有较好的抗原性,能够被抗登革病毒衣壳蛋白单克隆抗体特异识别。此研究为深入了解登革病毒衣壳蛋白在病毒复制及组装过程中的生物学功能奠定了基础。     

用于重组蛋白生产的哺乳动物细胞表达新技术

近年来,用于重组蛋白生产的哺乳动物细胞表达领域涌现出一系列革命性的新技术。优化的工程细胞为表达重组蛋白提供了优良的宿主;基于荧光的筛选方法可以快捷地得到高表达细胞株;高通量的培养工艺能够预测适合外源蛋白表达的细胞培养条件;可抛弃式生物反应器为大规模细胞培养提供了更多的选择;大规模瞬时表达技术节省了重组蛋白的生产时间。这些新技术提高了重组蛋白的研发和生产效率,加快了蛋白药物的工业化进程。     

在哺乳动物细胞中稳定表达丙型肝炎病毒E2糖蛋白

利用ＤＮＡ重组技术,将Ⅲ型中国株ＨＣＶＥ２／ＮＳ１基因片段插入真核表达载体,然后转染哺乳动物细胞ＮＩＨ３Ｔ３以表达Ｅ２糖蛋白．检测显示来自３月以上培养的细胞克隆中表达产物分子量为７０ｋＤ,经Ｗｅｓｔｅｒｎｂｌｏｔ证实该表达产物能与抗ＨＣＶ阳性血清进行特异性反应．以上表明首次在哺乳动物细胞中成功表达Ⅲ型中国株ＨＣＶ的Ｅ２糖蛋白,并建立相应的稳定表达细胞系．     

Proton Channel Activity of Influenza A Virus Matrix Protein 2 Contributes to Autophagy Arrest

Influenza A virus infection can arrest autophagy, as evidenced by autophagosome accumulation in infected cells. Here, we report that this autophagosome accumulation can be inhibited by amantadine, an antiviral proton channel inhibitor, in amantadine-sensitive virus infected cells or cells expressing influenza A virus matrix protein 2 (M2). Thus, M2 proton channel activity plays a role in blocking the fusion of autophagosomes with lysosomes, which might be a key mechanism for arresting autophagy.