通用型腺病毒伴随病毒载体的构建

目的构建含腺病毒伴随病毒（ＡＡＶ）基因组两端的反向重复序列（ＩＴＲｓ）和表达必须元件如启动子、多克隆位点和ＰｏｌｙＡ信号的通用型载体质粒ｐＡＣＲ－Ｎｅｏ，并获得重组ＡＡＶ（ｒＶＶ／ＡＣＲ－Ｎｅｏ）。方法通过ＤＮＡ重组技术，将ＳＶ４０ＰｏｌｙＡ、Ｎｅｏ基因、ＣＭＶ－ＩＥ启动子和多克隆位点组成表达盒子，取代含ＡＡＶ全基因组质粒ｐＳＳＶ９中ＡＡＶ结构基因部分，构建成质粒ｐＡＣＲ－Ｎｅｏ。用ｐＡＣＲ－Ｎｅｏ转染５型腺病毒（Ａｄ５）感染的重组ＡＡＶ包装细胞系ＡＥ１２０１，能获得重组病毒ｒＡＡＶ／ＡＣＲ－Ｎｅｏ。提取ｒＡＡＶ／ＡＣＲ－Ｎｅｏ感染细胞的染色体，用Ｓｏｕｔｈｅｍ杂交分析重组病毒基因组在感染细胞中的存在情况。结果质粒ｐＡＣＲ－Ｎｅｏ转染包装细胞系后所得ｒＡＡＶ／ＡＣＲ－Ｎｅｏ滴度为４．２×１０５ＣＦＵ／ｍｌ，并且ｒＡＡＶ／ＡＣＲ－Ｎｅｏ能在转导细胞内实现其基因组与细胞染色体的整合。结论成功地构建了通用型ＡＡＶ载体，为今后的ＡＡＶ载体研究、基因治疗和临床应用打下了基础     

β—半乳糖苷酶基因的腺伴随病毒（AAV—2）载体的构建及其在…

以野生型２型人类腺伴随病毒（ＡＡＶ－２）全基因组载体（ｐＳＳＶ９和ｐＳＳＶ９－ｉｎｔ＾－）为基础，构建了重组ＡＡＶ载体ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（＋）和ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（－），制备ＡＡＶ重组病毒，感染宿主细胞后表达了β－半乳糖苷酶基因。此外，用脂质体转染法将载体导入２９３细胞和Ａ５４９细胞，进行了ＬａｃＺ基因瞬时表达研究。结果显示，重组ＡＡＶ载体（ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（＋））     

应用痘苗病毒载体表达猴轮状病毒VP4抗原基因

把编码猴轮状病毒（Ｒｈｅｓｕｓｒｏｔａｖｉｒｕｓ，ＲＲＶ）Ｖｐ４抗原的第４基因片段插入到痘苗病毒表达载体ｐＪＳＡ１１７５的Ｐ７．５启动子下游，构建成在痘苗病毒Ｐ７．５启动子调控下表达猴轮状病毒Ｖｐ４抗原基因的重组质粒ＰＪＳＡ１１７５－ＶＰ４。应用磷酸钙沉淀技术将ＰＪＳＡ１１７５－ＶＰ４ＤＮＡ转入ＴＫ－１４３细胞，在ＢＵＤＲ和Ｘ－ｇａｌ存在下筛选蓝色蚀斑。经３代以上纯化和病毒增殖，获重组病毒Ｒ－ＶＪＳＡ１１７５－Ｖｐ４。蚀斑滴定其满度达到１５×１０１１ＰＦＵ／Ｌ。经核酸杂交试验证明所获得的重组痘苗病毒带有猴轮状病毒Ｖｐ４抗原基因。用重组病毒感染ＴＫ－１４３细胞（或Ｖｅｒｏ细胞），在感染后４８ｈ，用酶免疫法（ＥＩＡ）检测受染细胞上清液和细胞裂解液中表达的猴轮状病毒Ｖｐ４抗原基因均呈阳性反应。本试验为本研究室轮状病毒基因工程疫苗的一部分，为深入了解轮状病毒基因结构及其功能在方法学上奠定了必要的基础。     

应用痘苗病毒体表达猴轮状病毒VP4抗原基因

把编码猴轮状病毒Ｖｐ４抗原的第４基因片段插入到痘苗病毒表达载体ｐＪＳＡ１１７５的Ｐ７．５启动子下游，构建成在痘苗病毒Ｐ７．５启动子调控下表达猴轮状病毒Ｖｐ４抗原基因的重组质粒ｐＪＳＡ１１７５－Ｖｐ４。应用磷酸钙沉淀技术将ｐＪＳＡ１１７５－Ｖｐ４ＤＮＡ转入ＴＫ－１４３细胞，在ＢＵＤＲ和Ｘ－ｇａｌ 存在下筛选蓝色蚀斑。     

我国登革2型病毒prM基因与甲病毒载体重组RNA的构建

目的 将我国登革２型病毒的ｐｒＭ（Ｄ２－ｐｒＭ）基因导入甲病毒载体（ＰＳｆＶ）,研究该基因及其编码蛋白介导的抗病毒作用。方法 首先将扩增的病毒ｐｒＭ基因导入ｐＳｆＶ的Ｓｐ６启动子下游并进行核苷酸序列测定。用ＳｐｅⅠ酸将ｐＳｆＶ－ｐｒＭ重组ＤＮＡ线形化,再将其体外转录成５’末端含帽子结构的重组ＲＮＡ。然后通过电穿孔法将此重组ＲＮＡ转染ＢＨＫ－２１／１３细胞。采用Ｘ－Ｇａｌ原位染色和免疫荧光法对转染细     

重组HIV-1腺病毒伴随病毒的构建及表达

目的 构建带有ＨＩＶ－１ ｇａｇ或ｇｐ１２０基因的重组腺病毒伴随病毒ＡＡＶ－ＨＩＶ ｇａｐ或ＡＡＶ－ＨＩＶ ｇｐ１２０。方法 共转染法获取重组ＡＡＶ－ＨＩＶ;免疫酶法检测病毒滴度。结果 测定制备的重组腺病毒伴随病毒ＡＡＶｇａｇ４２,ＡＡＶＧＰ４２,ＡＡＶｇｒＲｊ６,病毒滴度在１０＾４～１０＾５范围。结论 构建了带有ｇａｇ和ｇｐ１２０基因的重组ＡＡＶ－ＨＩＶ,可以感染真核细胞并有较高的表达,可以用于做靶细胞,为发展新型的ＨＩＶ－１重组ＡＡＶ病毒载体活疫苗打下基础。     

β－半乳糖苷酶基因的腺伴随病毒（AAV－2）载体的构建及其在哺乳类细胞中的表达

以野生型２型人类腺伴随病毒（ＡＡＶ－２）全基因组载体（ｐＳＳＶ９和ｐＳＳＶ９－ｉｎｔ－）为基础，构建了重组ＡＡＶ载体ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（＋）和ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（－），制备ＡＡＶ重组病毒，感染宿主细胞后表达了β－半乳糖苷酶基因。此外，用脂质体转染法将载体导入２９３细胞和Ａ５４９细胞，进行了ＬａｃＺ基因瞬时表达研究。结果显示，重组ＡＡＶ载体（ＰＳＳＶ９／Ｐ４０－ＬａｃＺ（＋））ＬａｃＺ基因表达的动态变化特点是，转染后表达较早（１２～２４ｈ）出现，并迅速达到高峰值（经２４ｈ），随后较快下降（经４８～７２ｈ）并维持在较低水平。将启动子附近ｉｔｒ结构有差别的上述两载体转染宿主细胞７２ｈ后做表达水平比较，结果ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（－）在２９３细胞和Ａ５４９细胞中，ＬａｃＺ表达水平均高于ｐＳＳＶ９／Ｐ４０－ＬａｃＺ（＋）（１．２倍～１．４倍），提示启动子附近ＡＡＶｉｔｒ结构的变异对表达有一定的影响。     

复制缺陷型人IL-2重组腺病毒的制备与鉴定

目的将人ＩＬ－２的重组腺病毒载体与Ａｄ５腺病毒ＤＮＡ末端肽复合物同源重组，高效制备人ＩＬ－２的复制缺陷型重组腺病毒，并进行体外表达和活性检测。方法将含全部编码序列的人ＩＬ－２ｃＤＮＡ置于真核表达载体ｐＣＩｃｃ的ＣＭＶ启动子下游，切出含ＣＭＶ启动子、人ＩＬ－２ｃＤＮＡ和ＳＶ４０ｐｏｌｙＡ信号肽序列的ＣｌａＩ片段，插入Ｅ１区替代的腺病毒载体ｐＡｘｌｏｗ，选择左向转录的人ＩＬ－２重组腺病毒载体ｐＡｘｌｃｗ．ＣＩｈＩＬ－２与经ＥｃｏＴ２２Ⅰ酶切的Ａｄ５腺病毒ＤＮＡ－末端肽复合物共转染２９３细胞；通过同源重组获得人ＩＬ－２的复制缺陷型重组腺病毒；体外转染人宫颈癌ＨｅＬａ细胞、人Ｔ细胞淋巴瘤Ｈｕｔ７８细胞和原代人皮肤成纤维细胞。结果扩增到的病毒滴度达２．１×１０９ＰＦＵ／ｍｌ；体外转染的人肿瘤细胞均检测到ＩＬ－２的表达（４００～２６００Ｕ／１０６细胞／２４小时）。结论所制备的复制缺陷型重组腺病毒能有效介导人ＩＬ－２的基因转移，可望用于肿瘤基因治疗的临床研究。     

腺病毒载体,腺病毒相关病毒载体与基因治疗

近年来，腺病毒载体（ＡＶ），腺病毒相关病毒载体（ＡＡＶ）已经成为继反转录病毒载体（ＲＶ）以来最重要的病毒载体。与反转录病毒载体相比较，ＡＶ有其独特的优点，构建带有目的基因的腺病毒载体通过２９３辅助细胞产生重组腺病毒颗粒，用于活体基因转移及靶细胞感染。目前已利用ＡＶ研究了ｎｅｏ，ｌａｃＺ，ＨＢｓＡｇ及ＣＦＴＲ等基因在不用组织中的表达，其中人们已利用ＣＦＴＲ基因通过ＡＶ介导对囊性纤维化进行基因治疗临床     

重组rAAV-LMP诱导的特异性细胞毒T细胞对LMP阳性靶细胞的识别与杀伤

在正常个体中Ｅｐｓｔｅｉｎ－Ｂａｒ（ＥＢ）病毒是由病毒特异性细胞毒Ｔ淋巴细胞（ＣＴＬ）所控制，虽不能清除病毒，却对于控制细胞处于潜伏感染状态是必需的。抽取病人血分离淋巴细胞，在实验室制备ＥＢ病毒特异性ＣＴＬ，然后回输到病人体内，具有预防和治疗ＥＢ病毒相关疾病的意义。我们将ＥＢ病毒潜伏感染膜蛋白（ＬＭＰ）基因重组到腺病毒伴随病毒载体ｐＡＣＰ中去，与包装质粒Ａｄ８共转染已感染了Ⅱ型腺病毒的２９３细胞，获得重组病毒ｒＡＡＶ－ＬＭＰ，用此病毒感染淋巴细胞并表达ＬＭＰ，用高能Ｘ线照射灭活，与自体淋巴细胞共培养产生特异性ＣＴＬ。以ＥＢ病毒转化的类淋巴母细胞作靶细胞与ＣＴＬ反应，用ＢＬＴ活性法测定ＣＴＬ活性。结果表明，４株ＣＴＬ均能够识别和杀伤对应的靶细胞，并且随着ＣＴＬ数量的增加和反应时间的延长，上清中ＢＬＴ活性也增强。     

Inverted terminal repeat sequences of adeno-associated virus enhance the antibody and CD8(+) responses to a HIV-1 p55Gag/LAMP DNA vaccine chimera

The immune responses to an HIV-1 p55Gag vaccine encoded as a DNA chimera with the lysosomal associated membrane protein-1 (LAMP) have been examined for the effect of the addition of the inverted terminal repeat (ITR) sequences of the adeno-associated virus (AAV) to the DNA plasmid construct, and of packaging the LAMP/gag gene as a recombinant AAV vector (rAAV). DNA plasmids encoding Gag and the LAMP/Gag protein chimera were constructed in two vectors, the pcDNA3.1 and a corresponding plasmid containing the ITR sequences (pITR) flanking the expression elements of the plasmid, and the pITR LAMP/gag DNA plasmid was encapsidated in the rAAV vector. Human 293 cells transfected in vitro with LAMP/gag plasmids either in pcDNA3.1 or pITR produced much Gag protein in cell extracts (1.6 and 2.2 ng of Gag/mg of protein, respectively). The immune responses of mice to immunization with these constructs were examined under three protocols: DNA prime/DNA boost, DNA prime/rAAV boost, and a single rAAV immunization. The results demonstrated that under DNA prime/DNA boost protocol, the "naked" DNA vaccines encoding the LAMP/gag chimera, either as pcDNA3.1 or pITR DNA plasmid constructs, elicited strong CD4(+) T cell responses. In contrast, significantly higher levels of CD8(+) and antibody responses were observed with the pITR-DNA constructs. Immunization with the rAAV vector under the DNA prime/rAAV boost protocol resulted in sustained T cell responses and a markedly increased antibody response, predominantly of the IgG(1) isotype resulting from the activation of the Th2 subset of CD4(+) T cells, that was sustained for at least 5 months after immunization.     

Optimization of recombinant adeno-associated virus production using an herpes simplex virus amplicon system.

A major limitation of adeno-associated virus (AAV) based vectors for clinical applications to date is the production of high-titer recombinant AAV vector stocks. Despite recent improvements, the amount of recombinant adeno-associated virus vectors (rAAV) particles produced per cell continues to be significantly lower than that of wild-type AAV. In this study, an HSV-based system for rAAV production was used to examine the influence of different parameters including transfection conditions (vector-to-packaging plasmid ratio, amount of total transfected DNA, cell confluency) and multiplicity of infection of herpes helper virus on the resulting titre of rAAV stocks. For herpes helper virus, time-course experiments were carried out to analyse the effect on rAAV yields up to 72 h postinfection and to determine the ideal harvesting time. Taken together, the optimized production scheme consistently yields more than 3x10(3) transducing units per producer cell.     

小鼠pdx-1基因真核表达载体的构建及其在胚胎干细胞中的表达

目的： 克隆小鼠pdx-1基因，构建其真核表达载体，并在小鼠胚胎干细胞中表达，为糖尿病的细胞移植治疗奠定基础。方法： PCR扩增小鼠胰腺pdx-1基因 cDNA，酶切后和携带绿色荧光蛋白报告基因的真核表达载体pEGFP-N1重组，将pdx-1基因 cDNA片段连接到pEGFP-N1载体的多克隆位点，形成重组载体pEGFP/pdx-1，转化大肠杆菌DH5α菌株，构建成pdx-1基因真核表达载体质粒。扩增DH5α后抽提质粒DNA，Hind Ⅲ 和BamHⅠ酶切，电泳，DNA测序鉴定。鉴定正确的质粒DNA用脂质体包裹后转染小鼠胚胎干细胞MESPU13。结果： 从小鼠胰腺cDNA扩增出876 bp的DNA片段并成功重组到pEGFP-N1载体中。经酶切和DNA测序验证，插入载体的DNA片段为pdx-1基因，插入方向正确。重组质粒经脂质体转染胚胎干细胞MESPU13，24 h 后观察到绿色荧光蛋白报告基因和目的基因的pdx-1表达。结论： 小鼠pdx-1基因的克隆和真核表达载体构建获得成功，为进一步研究其功能奠定了基础。     

人LIGHT基因的克隆及其重组腺病毒载体的构建

目的 克隆人LIGHT基因，构建其重组腺病毒载体，以研究LIGHT过表达与腺病毒感染对细胞生长的影响。方法 用RT-PCR法从人外周血单个核细胞（PBMC）中克隆人的LIGHT全长基因。将LIGHT cDNA克隆到穿棱载体pAdTrack-CMV-LIGHT重组质粒中，经酶切线性化后，将重组质粒pAdTrack-CMV-LIGHT和骨架质粒pAdEasy-1，以电穿孔法共转染大肠杆菌BJ5183，获得重组腺病毒质粒。最后，将线性化的重组腺病毒质粒转染293细胞包装获得重组腺病毒，用荧光显微镜、PCR及Western blot分析LIGHT基因的表达。结果 用RT－PCR法从人的PBMC中，扩增出723bp的cDNA，测序证实为人LIGHT基因。荧光显微镜、PCR及Western blot证实，LIGHT重组腺病毒可感染293细胞，并在293细胞内进行有效的复制。结论 成功地克隆了人LIGHT基因，并构建了其重组腺病毒载体，为进一步研究LIGHT基因的功能提供了条件。     

Evaluation of risks related to the use of adeno-associated virus-based vectors

Recombinant AAV efficacy has been demonstrated in numerous gene therapy preclinical studies. As this vector is increasingly applied to human clinical trials, it is a priority to evaluate the risks of its use for workers involved in research and clinical trials as well as for the patients and their descendants. At high multiplicity of infection, wild-type AAV integrates into human chromosome 19 in approximately 60% of latently infected cell lines. However, it has been recently demonstrated that only approximately 1 out of 1000 infectious units can integrate. The mechanism of this site-specific integration involves AAV Rep proteins which are absent in vectors. Accordingly, recombinant AAV (rAAV) do not integrate site-specifically. Random integration of vector sequences has been demonstrated in established cell lines but only in some cases and at low frequency in primary cultures and in vivo. In contrast, episomal concatemers predominate.Therefore, the risks of insertional mutagenesis and activation of oncogenes are considered low. Biodistribution studies in non-human primates after intramuscular, intrabronchial, hepatic artery and subretinal administration showed low and transient levels of vector DNA in body fluids and distal organs. Analysis of patients body fluids revealed rAAV sequences in urine, saliva and serum at short-term. Transient shedding into the semen has been observed after delivery to the hepatic artery. However, motile germ cells seemed refractory to rAAV infection even when directly exposed to the viral particles, suggesting that the risk of insertion of new genetic material into the germ line is absent or extremely low. Risks related to viral capsid-induced inflammation also seem to be absent since immune response is restricted to generation of antibodies. In contrast, transgene products can elicit both cellular and humoral immune responses, depending on the nature of the expressed protein and of the route of vector administration. Finally, a correlation between early abortion as well as male infertility and the presence of wt AAV DNA in the genital tract has been suggested. Although no causal relationship has been established, this issue stresses the importance of using rAAV stocks devoid of contaminating replication-competent AAV. This review comprehensively examines virus integration, biodistribution, immune interactions, and other safety concerns regarding the wild-type AAV and recombinant AAV vectors.     

腺相关病毒介导胰岛素样生长因子I对高糖诱导神经元凋亡的保护作用

目的研究重组腺相关病毒（AAV）载体介导胰岛素样生长因子I（IGFI）在体外神经元表达的情况,及其对高糖诱导神经元凋亡的保护作用。方法利用分子克隆技术将大鼠IGFI基因克隆到pSNAV2．0质粒上,构建包含重组质粒pSNAV2．0-IGFI的杂合型重组AAV载体rAAV2／1-IGFI。将人神经母细胞瘤SH—SY5Y细胞分为正常组（A组）、无血清组（B组）、无血清高糖组（C组）,无血清高糖＋rAAV2／1-IGFI组（D组）,其中A组不做任何处理;B组使用无血清培养基培养;C组用含100mmol／LD．葡萄糖的无血清培养基培养;D组则先用rAAV2／1-IGFI病毒载体感染后再用含100mmol／LD．葡萄糖的无血清培养基处理。干预24h后应用RT—PCR和Western免疫印迹检测各组IGFI基因和蛋白的表达情况;应用Hoechst 33342荧光染色法、AnnexinV—FITC／PI双染法流式细胞仪检测细胞凋亡。观察rAAV2／1-IGFI感染后对高糖诱导SH—SY5Y细胞凋亡的保护作用。结果成功构建rAAV2／1-IGFI重组AAV载体。感染SH-SY5Y细胞后,RT—PCR显示SHSY5Y能表达大鼠IGFI基因;Western免疫印迹检测发现D组IGFI蛋白的表达水平（0．44±0．04）显著高于其他3组（A组0．29±0．02,B组0．17±0．02,C组0．08±0．02,均P〈0．05）。rAAV2／1-IGFI能明显降低高糖诱导细胞凋亡的凋亡率：Hoechst33342荧光染色检测总凋亡率分别为A组（2．71±1．03）％,B组（9．17±1．72）％,C组（25．63±1．81）％,D组（14．50±2．27）％,各组间差异均有统计学意义（P〈0．05）;流式细胞仪分析结果表明Annexin V-FITC^＊／PI^-的早期凋亡细胞加上Annexin V—FITC^＊／PI^＊的晚期凋亡细胞的总细胞凋亡率A组为（5．01±1．17）％,B组为（9．87±1．38）％,C组为（27．56±2．25）％,D组为（17．34±2．08）％,各组间差异均有统计学意义（P〈0．05）。结论rAAV2／1-IGFI感染体外神经元SH—SY5Y细胞能     

Long-term expression of a transferred gene in Epstein-Barr virus transformed human B cells

Delivering a gene into the Epstein-Barr virus (EBV)-transformed B cells is useful in studying effects of the gene on B-cell functions. However, although people have been able to efficiently transfer genes into and get them expressed in B-lympho blastoid cells for a time probably long enough to kill the cells using vectors harbouring oriP, the expression time of the delivered gene is not long enough in order to study the gene function in B cells. To solve this problem, we constructed an adeno-associated virus (AAV) plasmid pAGX(+) based on plasmids pSub201 and pRc/CMV. We developed and packaged recombinant AAV (rAAV) expression vectors containing an antisense or a sense DNA fragment of 6A8 cDNA encoding a human alpha-mannosidase, or an antisense fragment of 5D4 cDNA encoding a human cell membrane protein, or EYFP DNA. EBV-transformed B cell SKW6 and 3D5 were transduced with those rAAV or the mock. Transduction with the rAAV-EYFP showed an infection frequency of 64 +/- 3.5% and 58 +/- 6.2% for SKW6 and 3D5 cell, respectively. Genomic polymerase chain reaction (PCR) for neoR gene indicated an integration of the transferred gene into the host DNA. After being cultured and propagated for over 12 months, the cells were detected for the expression of the transferred gene. The RT-PCR, enzymatic assay and Con A binding test demonstrated an inhibition of 6A8 alpha-mannosidase in both SKW6 and 3D5 cells transduced with the antisense 6A8 DNA. Immunofluorescence staining with monoclonal antibodies (MoAb) 5D4 showed a reduction of the 5D4 protein expression on both the cells transduced with the antisense 5D4 DNA. The DNA fragmentation assay showed a resistance of the cells with 6A8 alpha-mannosidase inhibition to apoptosis induction by anti-Fas antibody. The data indicate that the AAV vector pAGX(+) can efficiently introduce genes into EBV-transformed B cells and the delivered gene can be expressed in the cells for more than 12 months which may be long enough for the study of gene functions in B cells.     

miRNA let-7a1真核表达载体的构建及对肺癌细胞增殖的影响

目的： 构建miRNA let-7a1真核表达载体,研究其在肺癌A549细胞株的表达及对A549细胞增殖的影响。方法：以人肺癌细胞A549的总RNA为模板,RT-PCR扩增miRNA pre-let-7a1基因序列, 将miRNA pre-let-7a1基因克隆到真核表达载体pSilencerTM4.1-CMV neo中,构建成pSilencerTM 4.1-let-7a1重组体。将pSilencerTM 4.1-let-7a1表达载体瞬时转染肺癌A549细胞,RT-PCR法检测miRNA let-7a1在转录水平的表达。根据miRBase Targets数据库,查hsa-let-7a1靶序列,构建 let-7a1靶序列-报道基因融合质粒pMIR-report-let-7a1T,与pSilencerTM 4.1-let-7a1表达载体共转染A549细胞,通过荧光素酶活性检测pSilencerTM 4.1-let-7a1质粒对其靶序列的作用。MTT法检测pSilencerTM 4.1-let-7a1转染A549细胞后,对细胞增殖的影响。结果：pSilencerTM 4.1-let-7a1真核表达栽体和let-7a1靶序列-报道基因融合质粒经酶切及测序鉴定正确。pSilencerTM 4.1-let-7a1转染 A549细胞后,经RT-PCR证明能有效表达miRNA let-7a1。 pSilencerTM 4.1-let-7a1 质粒和pMIR-report-let-7a1T质粒共转染A549细胞后,通过报告基因检测,相对荧光素酶活性明显降低,表明pSilencerTM 4.1-let-7a1转染A549细胞后,可表达let-7a1并具有生物学活性。MTT检测结果显示：pSilencerTM 4.1-let-7a1 转染后的A549活细胞数目明显减少。结论：成功构建了真核表达载体pSilencerTM 4.1-let-7a1,转染肺腺癌A549细胞后能有效表达,miRNA let-7a1基因过表达抑制A549细胞的增殖。     

Adeno-associated viral vectors as gene delivery vehicles

Adeno-associated virus (AAV), a non-pathogenic human parvovirus, is gaining attention for its potential use as a human gene therapy vector. One of the most attractive features of recombinant AAV vectors is the ability to be stably maintained in host cells as integrated proviruses. This property is particularly desireable for therapies requiring long-term correction of a genetic defect. This review highlights recent advances made in the AAV field and will discuss some limitations of rAAV vector integration. A novel method for enhancing the integration efficiency of these vectors will be presented.