Epitope specificity is critical for high and moderate avidity cytotoxic T lymphocytes associated with control of viral load and clinical disease in horses with equine infectious anemia virus

Equine infectious anemia virus (EIAV) is a lentivirus that causes persistent infections in horses. We hypothesized that high-avidity CTL specific for nonvariable epitopes might be associated with low viral load and minimal disease in EIAV-infected horses. To test this hypothesis, memory CTL (CTLm) responses were analyzed in two infected horses with high plasma viral loads and recurrent disease (progressors), and in two infected horses with low-to-undetectable viral loads and mild disease (nonprogressors). High-avidity CTLm in one progressor recognized an envelope gp90 epitope, and the data documented for the first time in EIAV that viral variation led to CTL escape. Each of the nonprogressors had high-to-moderate avidity CTLm directed against epitopes within Rev, including the nuclear export and nuclear localization domains. These results suggested that the epitope specificity of high- and moderate-avidity CTLm was an important determinant for disease outcome in the EIAV-infected horses examined.     

大鼠CRH基因RNA干扰慢病毒载体的构建与鉴定

目的：构建针对大鼠促肾上腺皮质激素释放激素（CRH）基因的RNA干扰（RNAi）慢病毒表达载体并进行鉴定。方法针对CRH基因设计4个RNAi靶点并分别构建入慢病毒骨架载体,测序鉴定。过表达质粒和RNAi质粒共转染293T工具细胞后,用Western blot进行外源筛靶以确定有效靶序列。有效RNAi病毒质粒与辅助质粒通过Lipofectamine 2000共转染293T细胞,培养48 h后,收集细胞培养上清液,将其浓缩后用孔稀释法测定病毒滴度。结果 Western blot外源筛靶显示3个靶点能有效敲减目的基因的表达。测定浓缩病毒悬液的滴度为1．5×109 T U／ml。结论成功构建了CRH基因的RNAi慢病毒载体,可用于CRH在应激反应中作用的研究。     

Characteristics of a thyroid hormone responsive reporter gene transduced into a Xenopus laevis cell line using lentivirus vector

We introduced a self-inactivation (SIN) lentivirus vector (LV) into Xenopus laevis cell lines and established a permanent cell line expressing a reporter gene in a 3,5,3'-l-triiodothyronine (T(3)) dependent manner. The SIN LV contained the luciferase gene downstream from the X. laevis T(3)-response elements (TREs) and the SV40 promoter, and the enhanced green fluorescent protein (EGFP) gene downstream from the cytomegalovirus (CMV) promoter. It was integrated into the genome of X. laevis XL58, XTC2, and KR cells. The SIN LV transduced the X. laevis cells as efficiently as mammalian cells; however, the expression of EGFP in the transgene decreased with increasing culture time. A cell clone exhibiting the highest TH-dependent luciferase gene expression (XL58-TRE-Luc clone) was isolated from the EGFP-positive XL58 cell pool and characterized. The minimum effective concentration of T(3) that significantly induced the luciferase gene expression was 10(-11)M in the XL58-TRE-Luc clone. The application of the luciferase gene assay using the permanent XL58-TRE-Luc clone for the screening of thyroid-disrupting chemicals revealed that tetrachlorobisphenol A, at 10(-6)M, had a weak T(3)-agonist activity, whereas trichlorobisphenol A, at 10(-8) - 10(-6)M had a weak T(3)-antagonist activity. Our results indicated that the permanent X. laevis cell line containing a T(3)-response transgene could be used as a bioassay, with small intra-assay variation, for the rapid screening, identification, and characterization of the thyroid-disrupting chemicals.     

Lentivirus-based RNA Silencing of Nemo-like Kinase (NLK) Inhibits the CAL 27 Human Adenosquamos Carcinoma Cells Proliferation and Blocks G0/G1 Phase to S Phase

Background: The Nemo-like kinase (NLK) is a serine/threonine-protein kinase that involved in a number of signaling pathways regulating cell fate. Variation of NLK has been shown to be associated with the risk of cancer. However, the function of NLK in oral adenosquamous carcinoma cells line CAL-27 is unknown.Methods: In this study, we evaluated the function of NLK in CAL-27 cells by using lentivirus-mediated RNA silence. The targeted gene expression, cell proliferation and cell cycle are investigated by RT-PCR, western-blot, MTT method, colony forming assay and flow cytometry analysis respectively.Results: After NLK silencing, the number of colonies was significantly reduced (54±5 colonies/well compared with 262±18 colonies/well in non-infected or 226±4 colonies/well in negative control group (sequence not related to NLK sequence with mismatched bases). Using crystal violet staining, we also found that the cell number per colony was dramatically reduced. The RNA silencing of NLK blocks the G0/G1 phase to S phase progression during the cell cycle.Conclusions: These results suggest that NLK silencing by lentivirus-mediated RNA interference would be a potential therapeutic method to control oral squamous carcinoma growth.     

GRHL2沉默对肺癌A549细胞增殖及凋亡的影响

目的探讨GRHL2沉默对肺癌A549细胞的增殖、凋亡的影响。方法利用RNA干扰技术,构建GRHL2沉默慢病毒表达载体,将肺癌A549细胞分为3个组,实验组:GRHL2沉默慢病毒感染的A549细胞系;阴性对照组:空载慢病毒感染的A549细胞系;空白对照组:不给予任何处理的A549细胞系。采用倒置荧光显微镜观察细胞绿色荧光蛋白的强度,通过实时定量聚合酶链式反应和蛋白质印迹法检测肺癌A549细胞中GRHL2 mRNA和蛋白质表达水平。采用细胞计数试剂盒检测GRHL2沉默对A549细胞增殖的影响。采用Annexin V-APC/PI细胞凋亡检测试剂盒及流式细胞术分析GRHL2沉默对A549细胞凋亡的影响。结果实验组中GRHL2 mRNA及蛋白质表达水平均较空白对照组及阴性对照组显著降低(F=48.13、42.57,P值均<0.05),A549细胞的增殖能力明显下降(F=65.64,P<0.05),凋亡显著增强(F=56.76,P<0.05)。结论靶向沉默GRHL2能显著抑制肺癌A549细胞的增殖并促进其凋亡,GRHL2有望成为临床肺癌靶向治疗的新靶点。     

体外利用慢病毒介导BMP-2基因诱导兔滑膜间充质干细胞向软骨细胞分化

目的使用慢病毒介导兔BMP-2基因转染兔滑膜间充质于细胞（SMSCs）,检测其安全性,并在体外定向诱导至软骨细胞。方法通过构建包含BMP-2基因的慢病毒载体,转染SMSCs后行安全性分析;各项检测和MicroRNA分析判断转染后的SMSCs是否进入软骨细胞分化谱系。结果贴块法获得的SMSCs在经分离纯化后,表现出间充质干细胞应有的结构和表面标志物,具有多向分化潜能。增殖动力学、核型分析、致瘤型分析等证实被慢病毒转染的SMSCs安全。Westernblot、免疫荧光等证实且能稳定表达BMP-2蛋白。14d后,免疫组化、MicroRNA检测等证实在不需外加外源性BMP-2的体外环境下SMSCs可自发向软骨细胞分化。结论经重组慢病毒载体感染的兔SMSCs足够安全,能稳定表达BMP-2,体外能自发向软骨细胞分化。     

Compartmentalization of small ruminant lentivirus between blood and colostrum in infected goats

The compartmentalization of small ruminant lentivirus (SRLV) subtype A (Maedi-Visna virus) and B (caprine arthritis-encephalitis virus) variants was analyzed in colostrum and peripheral blood mononuclear cells of four naturally infected goats. Sequence analysis of DNA and RNA encompassing the V4-V5 env regions showed a differential distribution of SRLV variants between the two compartments. Tissue-specific compartmentalization was demonstrated by phylogenetic analysis in three of the four cases. In these animals colostrum proviral sequences were clustered relative to the blood viral sequences. In one goat, the blood and colostrum-derived provirus sequences were intermingled, suggesting trafficking of virus between the two tissues or mirroring a recent infection. Surprisingly, the pattern of free virus variants in the colostrum of all animals corresponded only partially to that of the proviral form, suggesting that free viruses might not derive from infected colostral cells. The compartmentalization of SRLV between peripheral blood and colostrum indicates that lactogenic transmission may involve specific viruses not present in the proviral populations circulating in the blood.     

基因工程化分泌神经营养因子-3的鼠胚神经干细胞实验研究

目的：探索以Lentivirus为载体,构建同时表达绿色荧光蛋白（GFP）和神经营养因子-3（NT-3）的基因工程化鼠胚神经干细胞（NSC）的可行性.方法：体外分离培养鼠胚NSC,用同时携带NT-3和GFP的lentivirus转染构建工程化NSC：用荧光显微镜、鼠胚背根神经结培养（Dorsal Root Ganglion,DRG）、Western blot等方法检测基因工程NSC的转基因表达.结果：荧光显微镜观察到几乎100%的工程化NSC表达GFP;DRG培养和Western blot检测到基因工程化NSC能高效分泌NT-3蛋白.结论：以Lentivirus为载体,构建同时携带并稳定表达GFP和NT-3的基因工程化鼠胚NSC是可行的,可为脊髓损伤基础研究提供有价值的细胞资源.     

mmu_circ_0001033过表达慢病毒载体的构建与鉴定

目的构建环状RNA mmu_circ_0001033慢病毒表达载体,作为在低氧性肺动脉高压功能学实验研究的基础。 方法首先设计引物将目的基因片段从原质粒上扩增下来,通过引物两端所含无缝克隆识别位点将其重组到酶切后的过表达载体上;将连接产物转入制备好的细菌感受态细胞,而后将其单克隆菌落送测序公司进行测序鉴定。其次通过PCR产物跑胶和测序验证成环情况。最后用构建的重组表达载体和包装质粒共同转染293T细胞,包装慢病毒,收集病毒原液,超滤浓缩,并测定滴度。 结果经过比对,重组克隆中插入片段序列与目的片段序列完全一致,表明质粒构建成功。PCR产物后经sanger测序确认环化位点处序列完全正确。将构建的过表达载体测序结果和质粒构建方案基因比对,重组克隆中插入片段序列与目的片段序列与预期完全一致,可实现转染质粒后目的基因的表达,PCR产物跑胶和测序结果表明mmu_circ_0001033成环成功。PCR产物跑胶和测序结果表明mmu_circ_0001033成环成功。最后通过比较RT-qPCR测定病毒滴度值为2.09×10⁸ TU/ml。 结论成功构建环状RNA mmu_circ_0001033慢病毒表达载体,能稳定转染293T细胞,可用于后续细胞实验。