基于人免疫缺陷病毒-1的慢病毒载体系统研究进展

慢病毒能够感染分裂细胞和非分裂细胞,因而被发展成为重要的转基因载体。慢病毒载体已经发展到了第三代,其安全性已经大为提高。经过结构优化的慢病毒载体已经用于转基因动物生产和基因治疗研究,而稳定包装细胞系的建立使得慢病毒的生产更为简便。     

Mouse Transplant Models for Evaluating the Oncogenic Risk of a Self-Inactivating XSCID Lentiviral Vector

Hematopoietic stem cell gene therapy requires the use of integrating retroviral vectors in order to stably transmit a therapeutic gene to mature blood cells. Human clinical trials have shown that some vector integration events lead to disrupted regulation of proto-oncogenes resulting in disordered hematopoiesis including T-cell leukemia. Newer vectors have been designed to decrease the incidence of these adverse events but require appropriate pre-clinical assays to demonstrate safety. We have used two distinct mouse serial transplant assays to evaluate the safety of a self-inactivating lentiviral vector intended for use in X-linked severe combined immunodeficiency (XSCID) gene therapy trials. These experiments entailed 28 months of total follow-up and included 386 mice. There were no cases in which the XSCID lentiviral vector clearly caused hematopoietic malignancies, although a single case of B cell malignancy was observed that contained the lentiviral vector as a likely passenger event. In contrast, a SFFV-DsRed γ-retroviral vector resulted in clonal transformation events in multiple secondary recipients. Non-specific pathology not related to vector insertions was noted including T cell leukemias arising from irradiated recipient cells. Overall, this comprehensive study of mouse transplant safety assays demonstrate the relative safety of the XSCID lentiviral vector but also highlight the limitations of these assays.     

可分泌性GLP-1重组慢病毒的构建

目的:为了探讨使用基因治疗在体内分泌表达胰高血糖素样肽-1(GLP-1)方法治疗糖尿病的可行性,构建可分泌表达GLP-1的重组慢病毒.方法:1.将已构建成功的NT4-GLP-1融合基因插入慢病毒包装质粒pLenti6V5D-TOPO中,构建pLenti6V5D-TOPO/NT4-GLP-1重组慢病毒包装质粒.2.用慢病毒包装辅助质粒plp1、plp2、plp/VSVG,及重组慢病毒包装质粒pLenti6V5D-TOPO/NT4-GLP-1,四质粒磷酸钙共沉淀法转染80%融合的293细胞系,包装慢病毒.3.通过免疫组化法染色确定重组慢病毒效应.结果:重组质粒经BamHI和XhoI联合酶切,10g/L琼脂糖凝胶电泳可见在342bp处有一目的片段.该值与NT4-GLP-1融合基因片段的大小一致,说明NT4-GIP-1融合基因已经成功重组于慢病毒包装质粒pLenti6V5D-TOPO内.免疫组化结果显示,实验组细胞内出现大量棕黄色颗粒,阳性细胞达到70%以上,对照组中没有阳性细胞,所以说明NT4-GLP-1重组慢病毒在细胞中可以正确地分泌表达GLP-1.结论:NT4-GLP-1重组慢病毒包装质粒构建正确,病毒包装成功.     

Doxycycline-Dependent Inducible and Reversible RNA Interference Mediated by a Single Lentivirus Vector

Most fermented milk prepared by strains of Lactobacillus helveticus showed significant antihypertensive effect in spontaneously hypertensive rats (SHR) by oral administration. However, milk fermented by other species of lactic acid bacteria did not show significant antihypertensive effects. Most of the whey fractions of the milk fermented by L. helveticus or Lactobacillus delbrueckii subsp. bulgaricus showed higher angiotensin I-converting enzyme (ACE) inhibitory activity than the activity of milk fermented by other species. Proteolytic activity in cell wall and peptide content of the fermented milk were higher in L. helveticus strains than other species.     

Minimal Requirement for a Lentivirus Vector Based on Human Immunodeficiency Virus Type 1

The use of human immunodeficiency virus vectors for gene therapy is hampered by concern over their safety. This concern might be ameliorated, in part, if the viral accessory genes and proteins could be eliminated from the vector genomes and particles. Here we describe a minimal vector system that is capable of transducing nondividing cells and which does not contain tat, vif, vpr, vpu, and nef.     

携带三种报告基因慢病毒载体的构建及其实验研究

慢病毒是逆转录病毒科的一个属.它具有可以感染分裂期及非分裂期细胞、容纳外源性目的基因片段大、目的基因表达时间较长、免疫反应小等诸多优点,因此成为运载目的基因的理想载体而得到广泛的应用.构建了带有3种报告基因即红色荧光蛋白(mCherry)、荧光素酶基因(luciferase)及绿色荧光蛋白(eGFP)的慢病毒载体,其中...     

miR-455慢病毒表达载体的构建与鉴定

目的：构建人源microRNA-455（miR-455）慢病毒载体,并鉴定成熟has-miR-455在细胞内的表达水平。方法：提取siHa细胞中的人基因组DNA,设计并合成人miR-455的上下游引物,PCR扩增目的基因,将其中表达miR-455的结构经酶切后插入慢病毒转移质粒pWPT-GFP,构建成pWPT-GFP-pri-miR-455,在293T细胞中与pMD2G、pSPAX2包装产生慢病毒,并用含慢病毒的上清感染SiHa细胞。结果：测序结果证明插入质粒载体中的miR-455前体序列完全正确,慢病毒载体构建成功并获得相应的慢病毒;重组慢病毒质粒pWPT-GFP-pri-miR-455感染SiHa细胞后上调miR-455的表达近40倍。结论：构建了miR-455的慢病毒载体,并能在293T细胞中表达,产生的慢病毒能成功感染SiHa细胞。为进一步研究miR-455的功能,以及利用慢病毒进行基因治疗奠定了基础。     

KLF4siRNA慢病毒载体构建和鉴定

目的:构建上皮锌指蛋白4(Krüppel-like factor 4,KLF4)siRNA慢病毒载体并进行初步鉴定,为研究KLF4在宫颈细胞癌中的分子机制奠定基础。方法:利用公用网站中提供的RNA干扰序列设计原则,设计4个RNA干扰靶点序列,合成含干扰序列的单链DNA oligo,然后退火配对产生双链,再通过其两端所含酶切位点直接连入酶切后的RNAi慢病毒载体上;将连接产物转入制备好的细菌感受态细胞,PCR鉴定阳性重组子后,送测序验证,测序结果经比对确认正确的克隆,制备编码慢病毒颗粒的重组病毒质粒及其两种辅助包装原件载体质粒,共转染293T细胞,收集富含慢病毒颗粒上清液,对其浓缩后得到高滴度的慢病毒浓缩液,在293T细胞中测定并标定病毒滴度。收集上清液感染宫颈癌He La细胞,通过q RT-PCR及Western Blot鉴定KLF4 siRNA慢病毒干扰效果。结果:成功构建KLF4 siRNA慢病毒载体。KLF4 siRNA慢病毒感染He La细胞后,q RT-PCR及Western Blot测定结果显示,KLF4表达明显降低。结论:KLF4 siRNA慢病毒载体构建及包装成功,可有效抑制KLF4表达,为研究KLF4生物学功能奠定基础。     

小鼠ameloblastin基因重组慢性病毒表达载体的构建及表达

目的：构建表达小鼠ameloblastin基因的慢性病毒表达载体,生产有感染及表达能力的病毒,为进一步研究ameloblastin基因在牙釉质形成中的功能奠定基础。方法：利用RT．PCR的方法从出生后1d钟状期小鼠牙胚组织totalRNA中扩增ameloblastin编码区cDNA,并克隆到pCRII-TOPO载体中,再亚克隆到pNL-IRES2-EGFP中。将病毒三质粒系统转染293T细胞,收集病毒,并鉴定病毒感染及表达能力。结果：通过酶切和PCR的方法鉴定ameloblastin基因已成功的构建入慢性病毒表达载体pNL-IRES2-EGFP中,经293T细胞生产的病毒感染人牙髓干细胞（DPSCs）,DPSCs有较强荧光发出,并可稳定表达ameloblastin基因。结论：成功的构建了慢性病毒表达载体,并获得有感染及表达能力的病毒。     

慢病毒载体介导的层黏连蛋白受体稳定抑制细胞株的建立

目的:构建靶向层黏连蛋白受体(LR)基因的小发卡RNA(sh RNA)慢病毒表达载体,鉴定其对LR的抑制效果,并筛选LR稳定抑制的He La细胞株。方法:设计针对LR的sh RNA序列,将此序列和H1启动子克隆入含有EGFP报告基因的p Lenti6/v5慢病毒表达载体,通过病毒包装、细胞感染、抗生素筛选获得稳定细胞株,用real-time PCR和Western印迹检测筛选得到的稳定细胞株中LR的表达水平。结果和结论:构建了含有LR靶向sh RNA的慢病毒表达载体,包装成病毒后感染He La细胞,经抗生素筛选后获得了稳定抑制LR的细胞株;筛选后的细胞均可观察到报告基因EGFP的表达;经m RNA和蛋白水平检测,LR-sh6和LR-sh7均可显著抑制He La细胞株中LR的表达。     

Contributions of Viral Splice Sites and cis-Regulatory Elements to Lentivirus Vector Function

The mobile transgene constructs of most human immunodeficiency virus (HIV)-based lentivirus vectors currently in use contain viral long terminal repeats, a 5' untranslated region, gag sequences, and env sequences that include the Rev-responsive element (RRE). In this study, we examined the possibility of deleting HIV splice sites and gag and env sequences from an HIV type 1 recombinant vector established in our laboratory as part of our ongoing efforts to improve this vector system. Mutations in the major splice donor site (SD) markedly reduced viral RNA expression but had little effect on vector titer. Deletion of gag or env sequences, excluding RRE, led to a moderate reduction in vector titer. Interestingly, deletion of RRE slightly reduced viral RNA expression but markedly impaired vector function. Combined deletions of RRE, gag (except for the first 40 nucleotides), env, and the SD mutation resulted in a twofold increase in cytoplasmic viral RNA expression and a recovery of vector efficiency to approximately 50% of the wild-type level. This increase in cytoplasmic RNA levels is likely to be due, at least in part, to effects of the TE671 host cells, a human rhabdomyosarcoma cell line used for vector production in our system, on the cytoplasmic distribution of spliced and unspliced viral RNA. These results show that optimal lentivirus vector function can be maintained in the absence of multiple essential viral elements.     

Development of a Lentivirus Vector-Based Assay for Non-Destructive Monitoring of Cell Fusion Activity

Cell-to-cell fusion can be quantified by endowing acceptor and donor cells with latent reporter genes/proteins and activators of these genes/proteins, respectively. One way to accomplish this goal is by using a bipartite lentivirus vector (LV)-based cell fusion assay system in which the cellular fusion partners are transduced with a flippase-activatable Photinus pyralis luciferase (PpLuc) expression unit (acceptor cells) or with a recombinant gene encoding FLPe^NLS+, a nuclear-targeted and molecularly evolved version of flippase (donor cells). Fusion of both cell populations will lead to the FLPe-dependent generation of a functional PpLuc gene. PpLuc activity is typically measured in cell lysates, precluding consecutive analysis of one cell culture. Therefore, in this study the PpLuc-coding sequence was replaced by that of Gaussia princeps luciferase (GpLuc), a secretory protein allowing repeated analysis of the same cell culture. In myotubes the spread of FLPe^NLS+ may be limited due to its nuclear localization signal (NLS) causing low signal outputs. To test this hypothesis, myoblasts were transduced with LVs encoding either FLPe^NLS+ or an NLS-less version of FLPe (FLPe^NLS−) and subsequently co-cultured in different ratios with myoblasts containing the FLPe-activatable GpLuc expression cassette. At different times after induction of cell-to-cell fusion the GpLuc activity in the culture medium was determined. FLPe^NLS+ and FLPe^NLS− both activated the latent GpLuc gene but when the percentage of FLPe-expressing myoblasts was limiting, FLPe^NLS+ generally yielded slightly higher signals than FLPe^NLS− while at low acceptor-to-donor cell ratios FLPe^NLS− was usually superior. The ability of FLPe^NLS+ to spread through myofibers and to induce reporter gene expression is thus not limited by its NLS. However, at high FLPe concentrations the presence of the NLS negatively affected reporter gene expression. In summary, a rapid and simple chemiluminescence assay for quantifying cell-to-cell fusion progression based on GpLuc has been developed.     

表达人尿激酶原突变体的重组山羊乳腺特异性表达慢病毒载体的构建

目的：构建山羊乳腺特异性表达尿激酶原突变体的重组慢病毒载体,证明其表达的有效性。方法：将劳氏肉瘤病毒增强子／启动子、复制缺陷型人免疫缺陷病毒（HIV-1）的5′端长重复序列（LTR）、HIV-1ψ包装信号、HIVRev反应元件、山羊β-酪蛋白调控序列、尿激酶原M13cDNA、AU3／3′LTR、牛生长激素（BGH）基因poly（A）依次连接,构建乳腺特异性表达的慢病毒载体,通过体外转染人乳腺癌细胞系MCF-7、中国仓鼠卵巢细胞及泌乳山羊乳腺注射证明其表达有效性。结果：酶切鉴定证实山羊乳腺特异性表达载体构建正确;将该载体转染细胞,采用溶圈法和Western印迹检测证实了其表达的有效性;慢病毒载体注射到泌乳山羊的乳腺,在乳汁中也检测到了尿激酶原的表达。结论：为在转基因动物乳腺中表达尿激酶原突变体奠定了基础。     

含EGFP报告基因的慢病毒载体的构建及有感染能力病毒的制备

目的:构建含EGFP报告基因的慢病毒表达载体,包装成病毒并测定病毒感染效率。方法:以pEGFP-C1为模板扩增EGFP基因,经PstⅠ和XhoⅠ酶切后与载体连接,得到慢病毒表达载体pLenti6/v5-EGFP;将此载体与包装质粒共转染包装细胞制备病毒,测定不同感染复数(MOI)下病毒的感染效率。结果与结论:构建了含EGFP报告基因的慢病毒表达载体,制备了有感染能力的慢病毒。     

慢病毒介导的HTRA1 基因稳定过表达人脑血管平滑肌细胞株的建立

目的:构建并包装针对HTRA1基因以及其1091TC突变基因(HTRA1-Mut)的过表达慢病毒载体,以及建立稳定表达HTRA1及HTRA1-Mut基因的人脑血管平滑肌细胞(HBVSMC)株。方法:采用RT-PCR方法扩增HTRA1及HTRA1-Mut基因片段并将其连接于GV287载体质粒,采用慢病毒包装三质粒系统(GV287/p Helper 1.0/p Helper 2.0)转染293T细胞,收集富含慢病毒颗粒的细胞上清液并标定病毒滴度,慢病毒感染经培养和鉴定的HBVSMC细胞株。结果:成功构建含HTRA1及HTRA1-Mut基因的慢病毒重组载体,PCR鉴定阳性的克隆进行测序和BLAST比对分析显示与源基因序列一致,并能够有效的感染并在293T细胞中表达。表达载体包装后测定病毒滴度为:2E+8 TU/mL。过表达慢病毒感染后HBVSMC有荧光表达,并且荧光率达80%以上,细胞生长良好传后细胞几乎无死亡现象。结论:成功构建了过表达HTRA1及HTRA1-Mut基因的慢病毒表达载体,得到了较高滴度的病毒悬液,建成了稳定表达HTRA1及HTRA1-Mut基因的HBVSMC细胞株,为进一步探讨HTRA1基因及突变后细胞的功能变化提供了良好的研究工具。     

Advances in Lentivirus Purification

Lentiviral vectors (LVs) have been increasingly used as a tool for gene and cell therapies since they can stably integrate the genome in dividing and nondividing cells. LV production and purification processes have evolved substantially over the last decades. However, the increasing demands for higher quantities with more restrictive purity requirements are stimulating the development of novel materials and strategies to supply the market with LV in a cost-effective manner. A detailed review of each downstream process unit operation is performed, limitations, strengths, and potential outcomes being covered. Currently, the majority of large-scale LV manufacturing processes are still based on adherent cell culture, although it is known that the industry is migrating fast to suspension cultures. Regarding the purification strategy, it consists of batch chromatography and membrane technology. Nevertheless, new solutions are being created to improve the current production schemes and expand its clinical use.