Bac-to-Bac杆状病毒表达系统在BHK细胞表达鼠IL-2蛋白的研究

目的:利用Bac-to-Bac杆状病毒表达系统在BHK细胞表达重组鼠白细胞介素(IL)-2蛋白。方法:用Flag标记鼠IL-2并加入真核细胞启动子CMV,构建重组质粒pFB-CMV-IL-2并予酶切和PCR鉴定;将鼠IL-2克隆入杆状病毒表达载体pFastBacDual中,将pFB-CMV-IL-2转化到含杆状病毒穿梭载体Bacmid的DH10Bac感受态菌中,筛选阳性克隆,获得重组杆状病毒载体Bacmid-pFB-CMV-IL-2,抽提质粒;用脂质体转染法将Bacmid-pFB-CMV-IL-2转染Sf9昆虫细胞包装病毒,收获重组杆状病毒,将构建病毒转导BHK细胞培养,用Western blot检测IL-2蛋白。结果:通过杆状病毒表达系统,在BHK细胞成功表达重组的鼠IL-2蛋白。结论:重组杆状病毒在真核细胞中成功表达重组鼠IL-2蛋白。     

SARS-3CL蛋白酶基因在杆状病毒载体中的构建及其转染

目的:构建SARS冠状病毒3CL蛋白酶基因的杆状病毒重组供体质粒,包装重组3CL蛋白酶的杆状病毒,感染昆虫细胞进行表达.方法:首先扩增含3cl-Teagy和pFagtBac HTh的转化菌,用酶切连接法构建重组转座质粒pFB HTb-3cl.将该质粒转化E.coli DH10Bac感受态菌,在菌体内进行重组,并经三重抗性和蓝白斑筛选,得到杆状病毒重组质粒Bacmid-HTb-3cl,对重组质粒Bacmid-HTB-3cl进行纯化并转染St9昆虫细胞包装杆状病毒,利用病毒感染St9昆虫细胞并进行蛋白表达.利用SDS-PAGE检测蛋白表达情况.结果:成功构建了重组表达载体并得到了重组杆状病毒,SDS-PAGE检测到有3CL蛋白酶表达.结论:3CL蛋白酶在昆虫细胞中的表达为蛋白活性的检测及抑制剂的筛选奠定了基础.     

重组杆状病毒——哺乳动物细胞基因送递载体

杆状病毒表达系统可广泛用于重组蛋白在昆虫细胞中的表达.最近,利用哺乳动物细胞启动子构建的重组杆状病毒载体成功地将外源基因运送到哺乳动物细胞内.试验证明,经修饰的重组杆状病毒可在体内送递基因.与其他常用的病毒载体相反,杆状病毒仅在昆虫细胞中繁殖,在哺乳动物细胞中则表现为无病毒产生的不完全复制.重组杆状病毒易于操纵,可大量插入外源DNA,具有较好的生物安全性.     

人降钙素在昆虫细胞中的表达

目的：利用昆虫细胞杆状病毒系统表达重组人降钙素(recombinant human Calcitonin，rhCT)，探索一条真核生物表达生物活性rhCT的新途径。方法：将人降钙素基因重组到pFastBac杆状病毒穿梭载体(baculovirus shuttle vector，Bacmid)中，构建重组人降钙素杆状病毒表达载体即rhCT Bacmid，并将其转染昆虫细胞Sf9，表达目的蛋白。并对表达产物进行分子量及免疫反应性鉴定，在初步纯化后对人降钙素表达产物进行大鼠体内低血钙活性检测。结果：证实目的基因在昆虫细胞中获得了表达，表达产物经大鼠体内低血钙活性测定具有生物活性。结论：成功构建了rhCT Bacmid并在昆虫细胞中表达出了具有生物活性的rhCT。     

HIV-1 Gag-gp120嵌合基因在重组杆状病毒系统中的嵌合表达

将中国株HIV-1B亚型gag基因序列克隆到杆状病毒表达载体pFASTBAC1中,将gp120基因以相同的读框克隆到gag基因的3／端下游,构建了重组表达质粒pFge,利用大肠杆菌埃希菌杆状病毒表达系统筛选重组杆状病毒,在昆虫细胞sf9中表达了HIV-1的Gag-gp120嵌合蛋白。     

人骨形态发生蛋白—2基因的真核表达载体构建

目的;利用杆状病毒载体,构建可直接转染昆虫细胞Sf9的含人骨形态发生蛋白-2（hBMP-2)基因的重组穿梭载体（bacmidDNA),最终获得重组蛋白。方法：将编码包含hBMP-2 N-端信号肽,中间前肽以及C－端成熟肽共1188bp的cDNA片断,插入真核表达载体pFastBacl的多克隆位点,受控于pPolh启动子,构建成pFastBacl/hBMP-2重组转移载体。重组子转化大肠杆菌DH10Bac。转座后、挑选阳性菌落,提取bacmid DNA,经PCR鉴定后,以重组bacmidDNA转染Sf9细胞。收集重组病毒,扩大转染Sf9,表达产物行SDS－PAGE初步鉴定。结果：获得了含hBMP-2全长cDNA片段的重组bacmid DNA和重组病毒,经SDS－PAGE证实在昆虫细胞中表达了分泌型hBMP-2蛋白,经激光密度扫描仪扫描显示分泌性蛋白表达量占细胞蛋白总量的35．6％。结论：利用杆状病毒载体成功构建了可用于直接转染昆虫细胞而无需同源重组的重组bacmidDNA,并在昆虫细胞中表达了分泌型hBMP-2蛋白。     

重组杆状病毒—哺乳动物细胞基因送递载体

杆状病毒表达系统可广泛用于重组蛋白在昆虫细胞中表达。最近，利用哺乳动物细胞启动子构建的杆状病毒载体成功地将外源基因运送到哺乳动物细胞内，试验证明，经修饰的重组杆状病毒可在体内送递基因，与其他常用的病毒载体相反，杆状病毒仅在昆虫细胞中繁殖，在哺乳动物细胞中则表现为无病毒产生的不完全复制，生组杆状病毒易于操纵，可大量插入外源DNA，具有较好的生物安全性。     

在Sf9昆虫细胞-杆状病毒系统中表达毒蕈碱型M_2及M_5受体重组突变体

目的为乙酰胆碱毒蕈碱(M)受体亚型特异性的变构调节剂及基因工程的研究提供实验平台。方法用PCR及搭桥PCR法对乙酰胆碱M2及M5受体作以下突变:①将N-糖基化位点Asp突变为Asn;②删除对蛋白酶敏感的M受体的第三个细胞内环;③在C端添加凝血酶识别位点(CMV)和6-His标记。将PCR扩增出重组嵌合蛋白基因亚克隆到杆状病毒转移载体,制备重组杆状病毒并感染昆虫细胞表达M2/M5受体蛋白。Western印迹及放射性配体受体结合实验验证受体的正确表达及功能。结果通过搭桥PCR,成功扩增出1018 bp的重组M2受体和1041 bp重组M5受体核酸序列;使用pUC/M13的扩增引物成功构建M2/M5重组转移载体。将重组载体质粒与线性化病毒DNA共转染昆虫细胞Sf9,制备重组杆状病毒并感染昆虫细胞,见细胞空泡样病变。Western印迹分析确定重组杆状病毒感染昆虫细胞M2/M5蛋白表达,放射性配体受体饱和实验结果表明,表达的重组受体蛋白与[3H]N-甲基-东莨菪碱具有特异性结合能力。结论 Sf9昆虫细胞能够表达M2及M5重组受体蛋白,M2及M5重组受体蛋白的病毒样颗粒可用于M受体的新药研究。     

人磷酸二酯酶同工酶3A在昆虫杆状病毒系统中的表达

目的利用杆状病毒表达系统探讨人磷酸二酯酶同工酶3A(HPDE3A)在Tn细胞中的表达。方法用重组HPDE3A杆状病毒感染昆虫Tn细胞进行蛋白表达，通过RT-PCR，SDS-PAGE和Western blotting技术检测HPDE3A表达情况。结果重组杆状病毒在感染Tn细胞后形态变化明显，获得表达产物,RT-PCR扩增结果证实了Tn细胞中HPDE3A的mRNA水平增高，Tn细胞能够表达出与HPDE3A多克隆抗体结合的蛋白，蛋白分子质量约为120 kD。结论HPDE3A在昆虫杆状病毒表达系统中可以稳定表达，为进一步研究HPDE3A的生物学活性及筛选HPDE3A抑制剂奠定了基础。     

人甲状腺过氧化物酶膜外区基因的克隆及其杆状病毒表达载体的构建

摘要 目的：尝试克隆人甲状腺过氧化物酶（hTPO）膜外区基因并构建其杆状病毒表达载体,为其在昆虫细胞中的表达打好基础。方法：PCR扩增hTPO膜外区基因,并将其先后重组入pGEM3zf(+)质粒和pFastBac1质粒,以hTPO-pFastBAC1质粒转染E.coli DH10Bac大肠杆菌,获得重组hTPO杆状病毒表达载体（hTPO-Bacmid）,分别以多种方法鉴定其正确性。结果：经PCR及酶切、基因测序等方法证实得到的重组hTPO-pGEM3zf(+)质粒、hTPO-pFastBAC1质粒和hTPO-Bacmid均与预期相符。结论：成功的克隆了hTPO膜外区基因,并将其正确重组入pGEM3zf(+)质粒和pFastBac1质粒,后者经位点特异性转座整合至Bacmid,成功的构建了重组hTPO杆状病毒表达载体,为进一步实现hTPO在昆虫细胞中的真核表达作好了准备。     

BacMam technology and its application to drug discovery

The recombinant baculovirus/insect cell system was firmly established as a leading method for recombinant protein production when a new potential use for these viruses was revealed in 1995. It was reported that engineered recombinant baculoviruses could deliver functional expression cassettes to mammalian cell types; a system which has come to be known as BacMam gene delivery. In the field of high-throughput screening the failure of many common transient gene delivery methods in reproducibility and cell survival has caused investigators to routinely apply stable cell lines in support of cell-based assays. The ease of use, versatility, safety and economics of the BacMam system makes transient gene delivery a viable option in the high-throughput screening setting and in most instances circumvents many of the limitations of stable cell lines. Although a few pharmaceutical companies have embraced the technology, its use is poised to become more widespread with increased familiarity and the emergence of enabling products based on the BacMam system.     

重组人乳头瘤病毒58型L1蛋白在Sf9细胞中的表达条件优化

目的 采用昆虫细胞-杆状病毒表达系统扩增人乳头瘤病毒(human papillomavirus,HPV)58型L1蛋白基因,确定L1蛋白表达的最佳条件.方法 取处于埘数生长期的S19细胞以不同的感染复数(MOI)值扩增病毒,用噬斑试验检测病毒滴度,确定扩增重组病毒的最适条件;用间接免疫荧光法判断目的蛋白表达情况;通过蛋白印迹法测定不同的表达时间和MOI值条件下目的蛋白表达量,确定目的蛋白的最佳表达条件.结果 处于对数生长期的细胞以MOI值为0.5表达48 h条件下扩增含HPV58 LI基因的重组杆状病毒,滴度最高,可达5×108pfu/ml;以MOI值为5.0表达72 h获得最佳的目的蛋白表达量.结论 确定了扩增病毒和表达相应目的蛋白的最佳条件.     

红光熊蜂蜂毒蛋白酶的基因克隆和表达

目的克隆表达序列标签(ESTs)中筛选出的红光熊蜂蜂毒蛋白酶(BiVP)基因,在草地夜蛾(Spodoptera frugiperda)细胞Sf-9中进行表达。方法利用ESTs从红光熊蜂cDNA文库中获得BiVP基因,以PCR技术扩增出BiVP的完整cDNA,并构建病毒表达载体PBac1-BiVP,通过昆虫杆状病毒表达系统,在Sf-9昆虫细胞中进行表达,表达产物用快速蛋白液相色谱(FPLC)系统进行纯化。结果成功克隆BiVP基因并在Sf-9昆虫细胞中得到表达,表达产物纯化后经SDS-PAGE检查为单一条带。结论首次在红光熊蜂中克隆到蜂毒蛋白酶基因,在昆虫杆状病毒表达系统中进行了表达,并对表达产物进行了纯化,为深入研究BiVP的生物活性奠定了基础。     

Application of baculovirus-insect cell expression system for human therapy

A major advantage of recombinant DNA technology is its flexibility allowing for "on demand" production of specific proteins with theurapeutic value in heterologous expression systems. Gene expression vectors based on baculovirus, insect virus attacking mostly lepidopteran species, are frequently used for relatively inexpensive and fast production of such proteins. This expression system is recognized as one of the most powerful technologies for commercial synthesis of glycoproteins originating from vertebrate themselves or from vertebrate viruses. Glycosylation pathways utilized by insects are not identical, though they are similar to vertebrate glycosylation pathways. In the review special attention is given to the development of new virus-like particles (VLPs) potential vaccines which represent a novel class of subunit vaccines that are able to stimulate efficiently cellular and humoral immune responses against viral agents. Apart from production of vertebrate proteins or VLPs "on demand " in insect cells, a new exciting field of using baculovirus as gene delivery system to vertebrate cells was recently open which has a great potential for future uses of baculovirus as effective gene therapy vector.     

Viral-mediated gene delivery for cell-based assays in drug discovery

Background: Adenovirus, retrovirus and lentivirus-based vectors, originally engineered and optimized for in vivo and ex vivo gene therapy, have become increasingly useful for viral-mediated gene delivery to support in vitro cell-based assays. Viral vectors underpin functional genomics screening of cDNA, shRNA and aptamer libraries, are used for a variety of target validation studies and importantly, for high-throughput cell-based drug discovery and compound profiling assays. The baculovirus/insect cell expression system had gained prevalence as a tool for recombinant protein production when it was observed that recombinant baculovirus vectors too could serve as efficient gene delivery vehicles for a wide range of mammalian cells. Although the use of baculovirus vectors in vivo has lagged behind retroviral, adenoviral and lentiviral vectors, they have gained prominence for development of in vitro cell-based assays due to the ease of generation, broad host range and excellent biosafety profile. There is an increasing emphasis on cell-based assays in high-throughput automated drug discovery laboratories and a variety of commercially available viral-vectors can be used for supporting these assays. Objective: We compare and contrast the current viral-mediated gene delivery vector systems and highlight their suitability for cell-based drug discovery assays. Conclusion: Viral-mediated gene delivery is increasingly being used in support of genome scale target validation studies and cell-based assay development for specific drug target genes such as ion channels, G protein-coupled receptors and intracellular enzymes. The choice of a delivery system over another for a particular application is largely dictated by the cell types and cell lines in use, virus cellular tropism, assay throughput, safety requirements and ease/cost of reagent generation.     

Baculovirus expression vectors for insect and mammalian cells

Functional expression of recombinant proteins has become a routine, but critical tool in modern molecular biology. Since their introduction, the use of baculovirus vectors to produce proteins for purification has become one of the most widely-used viral gene delivery systems as expression levels obtained are difficult to match with any other eukaryotic expression system. Extensive engineering to simplify and accelerate the process of recombinant virus construction has made this system accessible to virtually any modern biological laboratory. The utility of baculoviruses has been broadened with the discovery that appropriately modified virus can mediate gene expression in a wide variety of mammalian cell lines, and thus can function as a flexible cell-based assay development tool. The wide range of applications and potential for commercialization of products leads to consideration of a number of aspects of the system.     

Baculovirus vectors: novel mammalian cell gene-delivery vehicles and their applications

Various methods have been developed to transfer and express genes in mammalian cells. Each method, whether virally, non-virally, or physically-based, has unique favorable features, but also drawbacks with respect to meeting desired and specific needs. Baculoviruses have been used since 1983 to express recombinant genes controlled by strong insect-virus promoters in their natural host (insect) cells. Today this is a well-established and easy to handle system for producing large quantities of recombinant proteins for numerous purposes. In 1995 it was first published that recombinant baculoviruses are able to deliver genes into mammalian cells. These genes are expressed provided that they are controlled by a promoter which is active in mammalian cells. Since then, various vector variants have been developed and numerous potential and meaningful applications have been described. It is not surprising that the use of baculovirus vectors as mammalian cell gene delivery vectors is constantly increasing and that the system is undergoing permanent improvements. Based on the convenience of the system to transfer genes into mammalian cells, baculoviruses can be applied in cell-based assays for drug screening to overcome the long periods of time required to generate stable cell lines. Baculovirus vectors are able to deliver very large DNA sequences into mammalian cells and vectors for toxic gene products can also be generated. In addition, baculoviruses are valuable tools for launching viral infection in cases where there is no appropriate cell culture system. Moreover, recent research has shown that the vectors can be applied in vivo. Depending on the design of the study, baculovirus vectors allow for sustained gene expression or are able to induce an immune response directed against the delivered and/or displayed gene product. The latter offers the opportunity to generate monoclonal antibodies against certain proteins that have failed by other means. In addition, it points to the potential usefulness of baculovirus vectors as new kinds of vaccines. Baculovirus vectors are therefore considered an enabling technology for various product opportunities.