DNA疫苗的运送载体——减毒霍乱沙门氏菌

霍乱沙门氏菌是人兽共患病原菌,遗传背景清楚,利用它作为载体表达外源抗原基因已得到较广泛的研究并取得了一定的效果。本文从沙门氏菌的侵入途径、减毒重组菌对基因疫苗的呈递及诱发免疫应答的机制、作为载体的优势以及免疫存在的问题等方面就减毒霍乱沙门氏菌作为运送DNA疫苗的载体作简要概述。     

双顺反子载体构建及其在基因联合免疫中的应用

目的 为了便于多价DNA疫苗的制备和基因表达的研究.方法 以pcDNA3.0为基础构建了pcDNA3.0BA双顺反子载体,将HBV preS2S与HCV pc154基因插入pcDNA3.0BA构建了单价和双价质粒.质粒转染Cos-7细胞瞬时表达,并经肌肉免疫BALB/c小鼠测定抗体应答和淋巴细胞增殖能力.结果 pcDNA3.0BA全长为6.4kb,具有两个外源基因表达单元,其调控元件均为CMV启动子和BGH pol A;两个表达单元中多克隆位点单酶切分别为：MCS1为EcoRⅤ、Not Ⅰ、Xho Ⅰ;MCS2为：Kpn Ⅰ、BamHⅠ、EcoRⅠ.双价质粒在Cos-7细胞中preS2S与HCV pc154两个基因都同时表达,诱导小鼠产生了抗HBs和HCV核心蛋白抗体,抗体效价和淋巴细胞对抗原刺激的增殖能力单价和双价质粒相比差异不显著.结论 pcDNA3.0BA双顺反子载体可以共表达多个基因,并诱导产生免疫应答.     

A nucleoprotein complex mediates the integration of retroviral DNA

The integration of viral DNA into the host genome is an essential step in the retrovirus life cycle. To understand this process better, we have examined the native state of viral DNA in cells acutely infected by murine leukemia virus (MLV), using both a physical assay for viral DNA and a functional assay for integration activity (Brown et al. 1987). The viral DNA and integration activity copurify during velocity sedimentation, gel filtration, and density equilibrium centrifugation, indicating that viral DNA is in a large (approximately 160S) nucleoprotein complex that includes all functions required for integration activity in vitro. Analysis by immunoprecipitation shows that the viral capsid protein is part of the active nucleoprotein complex, but recognition of the complex by only a subset of anti-capsid sera implies that the protein is constrained conformationally. The viral DNA within this structure is accessible to nucleases; the effects of nucleases on the integrity of the complex suggest that the integration-competent particle is derived from and similar to the core of extracellular virions.     

A novel retroviral vector that allows the magnetic selection of infected cells

Retroviral vectors are used widely in research and are also being designed for use in gene therapy trials. In practice, these vectors usually contain a marker gene, which is often a drug selection gene. In this report, a novel retroviral vector has been constructed which contains a gene that allows selection for infected cells by a magnet. This gene is a single-chain antibody (sFv) to a specific hapten molecule 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one (phOx). sFv specific for phOx is displayed on the surface of infected cells. This feature allows binding to phOx-BSA coated magnetic beads which are used to isolate the infected cells.     

NDRG2基因反转录病毒载体的构建及表达

背景：NDRG2(N-Myc Downstream Regulated Gene 2)是一个新的抑癌基因,既可以增强经典抑癌通路的抗肿瘤效应,又可以对正常细胞的癌变起到监控。有关NDRG2在骨髓瘤发生中的功能和作用至今还未见报道。 目的：构建NDRG2基因反转录病毒表达载体,利用包装的病毒感染人骨髓瘤细胞系U266,检测NDRG2的表达情况。 方法：设计与合成引物,提取U266细胞的RNA,反转录和PCR扩增,经BamHⅠ和TaqⅠ双酶切,琼脂糖凝胶电泳,切胶回收进行连接转化,并再次酶切鉴定;并将构建的载体包装为反转录病毒,感染U266细胞,筛选出稳定表达NDRG2的U266细胞(U266-NDRG2)克隆扩大培养,利用Western blot实验检测筛选到的U266细胞中NDRG2的表达。 结果与结论：成功构建了携带NDRG2基因表达的重组载体pBaba-puro-NDRG2,并包装为反转录病毒,筛选到的U266细胞(U266-NDRG2)中NDRG2蛋白表达明显高于U266-cherry细胞和U266细胞。结果可见利用反转录病毒载体基因重组技术成功构建出携带相应基因的反转录病毒,为研究NDRG2在人骨髓瘤中的作用奠定了实验基础。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

The retroviral vector family: something for everyone

After 30 years of retroviral vector research it became clear that the parental viruses can be both friend and foe. Especially human immunodeficiency virus sparked a global pandemic, but could be converted into a versatile tool for cell therapy. For all retroviral genera, the way from virus to vector was similar resulting in split-vector systems based on the separation of the genes needed for vector particle formation and transgene expression. The first gene therapy trials, although clinically effective, revealed the genotoxicity of retroviral vectors caused by insertional mutagenesis. This issue was solved using self-inactivating vectors carrying weaker cellular promoters. Further fine-tuning was able to generate inducible systems. The current toolbox also contains vectors for the generation of induced pluripotent stem cells or efficient RNA interference. More recently the application of CRISPR-Cas9-mediated gene editing led to the development of genome-wide small guide RNA libraries targeting all human genes and single lentiviral vectors for an easy delivery of Cas9.     

Structural biology of retroviral DNA integration

Three-dimensional macromolecular structures shed critical light on biological mechanism and facilitate development of small molecule inhibitors. Clinical success of raltegravir, a potent inhibitor of HIV-1 integrase, demonstrated the utility of this viral DNA recombinase as an antiviral target. A variety of partial integrase structures reported in the past 16 years have been instrumental and very informative to the field. Nonetheless, because integrase protein fragments are unable to functionally engage the viral DNA substrate critical for strand transfer inhibitor binding, the early structures did little to materially impact drug development efforts. However, recent results based on prototype foamy virus integrase have fully reversed this trend, as a number of X-ray crystal structures of active integrase-DNA complexes revealed key mechanistic details and moreover established the foundation of HIV-1 integrase strand transfer inhibitor action. In this review we discuss the landmarks in the progress of integrase structural biology during the past 17 years.     

A non-replicating adenoviral vector as a potential HIV vaccine

HIV-specific T cell immune responses will play an important role in any HIV vaccine paradigm. Studies in rhesus monkeys have shown that significant and persistent virus-specific T cell responses can be elicited with vaccines incorporating viral genetic sequences and that these responses are primarily mediated by CD8 T cells. Benefits such as stable CD4 levels and viral control have resulted. Two vaccine candidates developed by Merck and Co., Inc., including a non-replicating adenoviral vector, have been studied in animals and are now being studied in Phase I clinical trials in humans. Important considerations include cross-clade reactivity (effectiveness in diverse HIV-infected populations), tolerability, and durability of response. Ongoing studies are looking at responses in both uninfected and infected individuals. Optimal vaccine combinations as well as the development and testing of vaccines with multiple genetic targets are part of future plans investigating this vaccine strategy.     

DNA vaccine

DNA vaccine involves the injection of plasmid DNA encoding an antigen under the control of an eukaryotic promoter, and results in cellular and humoral immune responses to the plasmid DNA-encoded antigen. The immune response induced by DNA vaccine usually has a T-helper-1(Th1) bias through a potent Th1-promoting adjuvant effect of immunostimulatory DNA sequences with CpG motifs present in plasmid DNA. It has been demonstrated that volunteers who were vaccinated with plasmid DNA encoding a malaria protein or a human immunodeficiency virus protein developed antigen-specific, human leukocyte antigen(HLA)-restricted, CD8+ cytotoxic T lymphocytes(CTLs) The demonstration in humans of the induction of CD8+ CTLs by DNA vaccines, including CTLs, provides a foundation for further clinical application of this potentially revolutionary vaccine technology.     

携带mIL-12基因逆转录病毒载体的构建与表达

目的：构建携带小鼠IL-12（ mouse IL-12, mIL-12）基因逆转录病毒表达载体pLXmIL-12SN并检测其在B16F10细胞中的表达。 方法： 应用限制性内切酶从载体pGCp35-IRES-p40SN中酶切p35-IRES-p40（mIL-12基因片段）及将逆转录病毒载体pLXSN切开，通过连接酶连接，通过序列测定确定p35-IRES-p40基因片段正向插入载体pLXSN中的重组子，将阳性重组子转染B16F10细胞并通过RT-PCR方法检测mIL-12基因在B16F10细胞中表达。 结果： 成功地构建表达载体pLXmIL-12SN并可在mRNA水平检测到mIL-12基因在B16F10细胞中表达。 结论： 载体pLXmIL-12SN的构建成功及可在B16F10细胞中表达，为mIL-12基因治疗眼部疾病的研究奠定了基础和提供了借鉴。     

神经生长因子基因重组逆转录病毒载体的构建与鉴定

目的构建神经生长因子(NGF)基因重组逆转录病毒表达载体,研究NGF在神经干细胞(NSC)中的表达情况。方法从大鼠海马组织提取总RNA,利用RT-PCR的方法获得编码大鼠β-NGF的基因片段,应用基因重组技术,将大鼠β-NGF基因片段克隆到逆转录病毒表达载体pLEGFP-N1中,通过脂质体Lipofectamine2000转染包装细胞PT67,经G418筛选后,收集阳性克隆病毒上清,用于感染神经干细胞(NSC),观察该NSC表达的NGF对PC12细胞突起生长的作用。结果限制性内切酶酶切分析鉴定表明为正确重组子,β-NGF基因在NSC中获得表达,该NSC的培养上清液可以促进PC12细胞突起生长。结论重组逆转录病毒表达载体pLEGFP-NGF构建成功,β-NGF基因可在NSC中表达并具有生物学活性。     

含人组织型纤溶酶原激活剂cDNA重组逆转录病毒的制备及鉴定

将人组织型纤溶酶原激活剂ｃＤＮＡ与逆转录病毒载体ＬＮＳＸ重组后转染病毒包装细胞ＰＡ３１７，形成完整的重组病毒颗粒，电镜下重组病毒呈散在分布，球形，直径９０～１８０ｎｍ，由囊膜、外壳和核心三部分组成。重组病毒颗粒感染ＮＩＨ３Ｔ３细胞，在含Ｇ４１８培养基中筛选培养２周后计数阳性细胞克隆数，结果达６×１０８ＣＦＵ／Ｌ；被感染的受体细胞ＮＩＨ３Ｔ３高效表达具有纤溶活性的重组人组织型纤溶酶原激活剂。     

Magnetic concentration of a retroviral vector using magnetite cationic liposomes

For tissue engineering purposes, retroviral vectors represent an efficient method of delivering exogenous genes such as growth factors to injured tissues because gene-transduced cells can produce stable and constant levels of the gene product. However, retroviral vector technology suffers from low yields. In the present study, we used magnetite nanoparticles and magnetic force to concentrate the retroviral vectors to enhance the transduction efficiency and to enable their magnetic manipulation. Magnetite nanoparticles modified with cationic liposomes were added to a solution containing a retroviral vector pseudotyped with vesicular stomatitis virus glycoprotein. The magnetic particles that captured the viral vectors were collected using a magnetic force and seeded into mouse neuroblastoma Neuro2a cells. The viral titer was up to 55 times greater (up to 3 x 10(8) infectious units/mL). Additionally, the magnetically labeled retroviral vectors can be directed to the desired regions for infection by applying magnetic fields, and micro-patterns of gene-transduced cell regions could be created on a cellular monolayer using micro-patterned magnetic concentrators. These results suggest that this technique provides a promising approach to capturing and concentrating viral vectors, thus achieving high transduction efficiency and the ability to deliver genes to a specific injured site by applying a magnetic field.     

Construction of SARS-CoV-2 spike-pseudotyped retroviral vector inducing syncytia formation

Virus Genes - Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is handled in biosafety level 3 (BSL-3) facilities, whereas the antiviral screening of pseudotype virus is conducted in...     

Microplate-based DNA hybridization assays for detection of human retroviral gene sequences.

Nonisotopic, microwell-based DNA hybridization assays for the specific detection of human immunodeficiency virus type 1 (HIV-1) gag, human T-cell lymphotropic virus type I (HTLV-I) pol, and HTLV-II pol DNA sequences were evaluated. The performances of these detection kits (Gene Detective enzyme oligonucleotide assays; Cellular Products, Inc., Buffalo, N.Y.) were assessed by using clinical samples whose infection status were established by amplification by PCR and then liquid hybridization detection by using virus-specific probes. Peripheral blood mononuclear cell lysates from 59 HIV-1-, 35 HTLV-I-, and 19 HTLV-II-infected individuals and from 15 healthy blood donors were used as substrates for PCR amplification. The results of the study demonstrated a clinical sensitivity of 100%. In addition, the enzyme oligonucleotide assays were able to detect 1 to 10 proviral copies subsequent to PCR amplification, indicating an analytical sensitivity comparable to that of liquid hybridization.     

含人组织型纤溶酶原激活剂cDNA重组逆转录病毒的制备…

A recombinant retroviral vector containing tissue-type plasminogen activator (t-PA) cDNA was constructed and transfected into PA317 viral packaging cells, forming intact virus particles. Under electron microscope the recombinant retroviral particles were composed of envelope, capsid and core. These viral particles were spherical with a diameter of 90-180nm, and spread dispersely in the cells. NIH3T3 cell infected by retrovirus particles were screened with G418. The virus titer of 6 x 10(8) CFU/L was verified by counting the positive clones two weeks after screening. The expression of t-PA was demonstrated in the NIH3T3 cells infected with the recombinant virus.     

逆转录病毒载体介导的人白细胞介素10在大鼠心肌细胞的表达

目的：建立一个在大鼠心肌细胞表达人白细胞介素１０（ＨｕｍａｎＩｎｔｅｒｌｅｕｋｉｎ１０,ｈＩＬ１０）的重组逆转录病毒载体基因转移系统,为下一步的研究工作做准备。方法：将构建的表达人白细胞介素１０的逆转录病毒重组体ｐＬＸ（ｈＩＬ１０）ＳＮ经ＰＡ３１７细胞包装,Ｇ４１８筛选,ＮＩＨ３Ｔ３细胞进行病毒滴度测定,选滴度最高的克隆（６×１０５ＣＦＵ／ｍｌ）作为感染大鼠心肌细胞的感染细胞;用重组逆转录病毒感染大鼠心肌细胞,应用聚合酶链反应（ＰＣＲ）及反转录聚合酶链反应（ＲＴＰＣＲ）检测转染大鼠心肌细胞ＤＮＡ及ｍＲＮＡ,应用ＥＬＩＳＡ测定ｈＩＬ１０在心肌细胞的表达。结果：外源性ｈＩＬ１０基因已整合到心肌细胞染色体ＤＮＡ并有效地转录和翻译,表达水平最高达１７５５ｎｇ／（１０６ｃｅｌｓ·２４ｈ）。结论：外源性ｈＩＬ１０基因可以转移到大鼠心肌细胞并稳定表达,为今后研究ｈＩＬ１０的作用机制及在治疗疾病中的应用打下了基础。     

腺病毒为载体的新型结核病疫苗Ad5Ag85A

结核病是一个在全球范围内严重威胁人类健康的呼吸道传染性疾病.据世界卫生组织(WHO)估计,世界上约有1/3的人口受到结核分枝杆菌(Mycobacterium tuberculosis)的感染,其中1/10的人可能会最终患上结核病.全球每年的新病例超过900万,约200万人死于结核病[1].结核病负担最重的地区主要是东南亚(占总报告病例的35％)、非洲(24％)和西太平洋地区(22％).中国的结核病年发病患者数约为130万,占全球发病的14.3％,是世界第二大结核病高发国家(仅次于印度)[2].