Hsp70-NP融合蛋白增强诱导HTNV NP特异性CTL的实验研究

本文采用纯化蛋白Hsp70-NP,NP,Hsp70分别免疫C57/BL6小鼠,取各组小鼠脾淋巴细胞进行淋巴细胞增殖试验和细胞毒试验。此外,为了获得细胞毒实验的靶细胞,本文还采用脂质体介导质粒pcDNA3.1/S转染黑色素瘤细胞B16,通过G418筛选稳定克隆,并用RT-PCR,Westernblots以及免疫荧光染色证实N蛋白在胞浆中表达。淋巴细胞增殖实验表明,Hsp70-NP,NP组小鼠脾淋巴细胞均能够对体外抗原刺激产生增殖反应,而Hsp70-NP组的增殖指数明显高于NP免疫组。细胞毒实验结果表明,LDH的释放具有效应细胞依赖性,Hsp70-NP,NP免疫组脾淋巴细胞均可以特异性杀伤靶细胞B16-N,而Hsp70-NP免疫组的杀伤率显著高于NP免疫组。实验结果显示,Hsp70可以增强NP诱导产生特异性CTL的能力。本研究结果为进一步设计基于NP的合成肽疫苗或基因疫苗提供了重要实验依据。     

Hsp70与汉滩病毒S基因融合蛋白的原核表达及免疫小鼠的初步研究

本文构建了hsp70与S基因的原核融合表达载体pGEX-4T-1/hsp70-S,在大肠杆菌中表达,并通过GSTrapFF柱进行了纯化.同时制备了NP和Hsp70两种纯化蛋白.分别用这三种纯化蛋白免疫BALB/c小鼠,结果表明纯化的NP和Hsp70-NP两种蛋白均可同时诱导产生抗汉滩病毒核蛋白(NP)抗体,且后者刺激产生的抗体效价明显高于前者.淋巴细胞增殖实验表明,两组免疫小鼠的脾细胞均能够对体外抗原刺激产生增殖反应,而Hsp70-NP组免疫小鼠脾细胞对NP的增殖指数明显高于NP组免疫组.结果显示,与单独用NP免疫小鼠相比,Hsp70-NP纯化蛋白可以刺激机体产生更强的抗汉滩病毒体液免疫应答和特异性淋巴细胞增殖反应.     

Hsp70与汉滩病毒S基因融合蛋白的原核表达及免疫小鼠的初步研究

本文构建了hsp70与S基因的原核融合表达载体pGEX-4T-1/hsp70-S,在大肠杆菌中表达,并通过GSTrapFF柱进行了纯化。同时制备了NP和Hsp70两种纯化蛋白。分别用这三种纯化蛋白免疫BALB/c小鼠,结果表明纯化的NP和Hsp70-NP两种蛋白均可同时诱导产生抗汉滩病毒核蛋白(NP)抗体,且后者刺激产生的抗体效价明显高于前者。淋巴细胞增殖实验表明,两组免疫小鼠的脾细胞均能够对体外抗原刺激产生增殖反应,而Hsp70-NP组免疫小鼠脾细胞对NP的增殖指数明显高于NP组免疫组。结果显示,与单独用NP免疫小鼠相比,Hsp70-NP纯化蛋白可以刺激机体产生更强的抗汉滩病毒体液免疫应答和特异性淋巴细胞增殖反应。     

Hsp65与IL-2融合蛋白诱导小鼠细胞免疫应答及保护力

目的研究Hsp65与hIL-2的融合蛋白在小鼠体内诱导的免疫应答及保护力。方法在大肠杆菌中诱导表达Hsp65与hIL-2的融合蛋白,通过Ni-NTA亲合柱纯化后的蛋白经鉴定后,与佐剂DDA和MPL联合免疫小鼠,连续免疫3次,每次间隔2周,最后一次免疫结束后两周,分离5只小鼠脾淋巴细胞,测定淋巴细胞增殖指数,IFN-γ和IL-2水平,以及特异性淋巴细胞杀伤功能,其余5只免疫小鼠用于MTB毒株攻击实验。结果获得融合蛋白可分别与抗Hsp65和抗hIL-2的单抗发生特异性反应。融合蛋白免疫小鼠后,小鼠脾淋巴细胞被有效活化,诱导产生的-γIFN和IL-2的水平以及CTL杀伤功能均显著高于BCG和单纯Hsp65免疫组（P〈0.05）。融合蛋白免疫组可有效抵抗MTB毒株攻击,脾脏细菌数显著减少（4.36±0.48）,提供的保护力与BCG相当（4.30±0.53）。结论Hsp65与hIL-2的融合蛋白是一种有效的亚单位疫苗,可用于TB的预防。     

肿瘤细胞混合肽诱导特异性抗肿瘤免疫应答

采用细胞冻融、加热沉淀及酸处理等基本生化技术, 从肿瘤细胞中获取混合 肽; 将热休克蛋白70与肽体外结合, 观察热休克蛋白70-肽复合物对小鼠脾淋巴细胞的激活增殖作用以及增殖的淋巴细胞对瘤细胞的特异性杀伤作用, 并运用流式细胞仪分析增殖的淋巴细胞类型; 分别通过对腹腔和腿部肌肉接种了H22肝癌细胞的BALB/c小鼠进行热休克蛋白70-H22抗原肽复合物免疫注射, 观察小鼠肿瘤的抑制和荷瘤小鼠的生存期情况. 另外, 对免疫的小鼠采血进行肝、肾功能检测. 结果显示, 获取的混合肽中含有肿瘤特异的抗原肽, 其经热休克蛋白提呈后, 体外可刺激淋巴细胞活化增殖, 增殖的淋巴细胞为T淋巴细胞, 对肿瘤细胞有特异性细胞毒效应, 体内对腹水型和实体瘤型肿瘤的生长均可产生显著抑制作用, 同时延长荷瘤小鼠的生存期, 并且这种体内免疫对小鼠肝肾功能不产生影响, 不会引发自身免疫反应.     

单纯疱疹病毒2gD-Hsp70融合蛋白基因的构建及表达

构建并原核表达Hsp70-HSV2gD融合蛋白。将Hsp70和HSV-2gD蛋白基因分别克隆到原核表达载体pGEX-4T-1,构建成重组质粒pGEX-4T-Hsp70-gD,并测序鉴定。重组质粒pGEX-4T-Hsp70-gD转化大肠杆菌DH5α后,IPTG诱导表达并进行SDS-PAGE分析。表达产物纯化后做Westernblot检测。将其肌注免疫BALB/c小鼠,检测融合蛋白对免疫小鼠脾淋巴细胞增殖、γ-干扰素产生以及血清中gDIgG水平的影响。表达产物的SDS-PAGE分析发现,在相对分子量为118kD处有外源蛋白表达,与预期蛋白带一致。用GST柱得到了纯化的Hsp70-HSV2gD融合蛋白。Westernblot证实,表达产物具有良好的活性。GST-Hsp70-gD组蛋白疫苗免疫的小鼠,其脾淋巴细胞刺激指数和脾淋巴细胞培养上清中γ-干扰素的水平高于其它组(P<0.05)。血清单纯疱疹病毒-2gD蛋白的抗体水平高于其它组(P<0.05)。     

新型结核病疫苗AEH/Al/IC在小鼠中的免疫原性研究

目的检测重组结核分枝杆菌(Mycobacterium tuberculosis,Mtb)融合蛋白Ag85B-ESAT6(Antigen 85 B,6-kDa early secretory antigenic target,AE)和热休克蛋白X(heat shock protein X,Hsp X)与氢氧化铝和聚肌胞苷酸(Polyinosinic-polycytidylic acid,poly I∶C)构建的新型结核病亚单位疫苗AEH/Al/IC在小鼠中的免疫原性。方法用疫苗(AEH/Al/IC)和佐剂(Al/Poly I∶C)分别免疫雌性BALB/c小鼠3剂次,每剂次间隔10 d。末次免疫后第10天,经ELISA检测小鼠血清中抗原特异性Ig G、Ig G1和Ig G2a的抗体效价,经酶联免疫斑点试验(enzyme-linked immunospot,ELISPOT)检测小鼠脾细胞分泌抗原特异性IFN-γ和IL-2的细胞频数,经ELISA检测小鼠脾细胞抗原特异性IFN-γ、IL-2和TNF-α的分泌量。结果与佐剂组相比,疫苗组诱导小鼠产生了高水平的AE和Hsp X特异性抗体;疫苗组诱导小鼠产生的AE和Hsp X特异性IFN-γ和IL-2阳性脾淋巴细胞(斑点形成细胞spot forming cells,SFC)均高于佐剂组,差异有统计学意义(IFN-γ:P0.05; IL-2:P0.05);疫苗组小鼠脾细胞AE特异性IFN-γ、IL-2和TNF-α分泌量明显较佐剂组高,差异均有统计学意义(P0.05),Hsp X特异性IFN-γ和TNF-α分泌量比佐剂组稍高,但差异均无统计学意义(P0.05)。结论结核病亚单位疫苗AEH/Al/IC具有良好的免疫原性,有希望成为一种新型的结核病预防候选疫苗。     

趋化因子基因对HIV-1外膜蛋白基因疫苗诱导的免疫应答的影响

研究趋化因子基因对HIV-1外膜蛋白基因疫苗诱导免疫应答的影响,以探求防治HIV的新策略.将pVAX1GP120联合RANTES、MIP-1α基因或者pVAX1GP120单独免疫Balb/c小鼠,采用ELISA检测免疫小鼠的特异性抗体和IFN-γ水平,用MTT比色法检测免疫小鼠脾淋巴细胞的增殖,用乳酸脱氢酶(LDH)试验检测小鼠特异性细胞毒性T淋巴细胞(CTL)的应答.与pVAX1GP120免疫组比较,pVAX1GP120联合RANTES、MIP-1d基因免疫组小鼠血清的抗HIV-1gp120抗体滴度升高,有显著性差异(p＜0.01);与pVAX1GP120免疫组比较,pVAX1GP120联合RANTES、MIP-1d基因免疫组小鼠血清的IFN-γ升高,有显著性差异(p＜0.01);pVAX1GP120联合RANTES、MIP-1α基因免疫组小鼠的脾淋巴细胞增殖实验刺激指数(SI)以及特异性CTL活性均高于pVAX1GP120免疫组,有显著性差异(p＜0.01).RANTES、MIP-1α基因联合HIV-1外膜蛋白基因疫苗免疫小鼠,可能增强HIV特异性Th1细胞和CTL反应,RANTES、MIP-1α基因对体液免疫有加强作用.因此,RANTES、MIP- 1α基因对于HIV-1外膜蛋白基因疫苗具有较好应用前景的免疫佐剂.     

SDF-1基因对HIV-1核酸疫苗诱导的免疫应答

研究SDF-1基因对HIV-1核酸疫苗诱导免疫应答的影响,以探求治疗性HIV-1核酸疫苗的新策略. 将pCI-neoGAG联合SDF-1基因或者pCI-neoGAG单独免疫Balb/c小鼠,采用ELISA检测免疫小鼠的特异性抗体和IFN-γ水平,用MTT比色法检测免疫小鼠脾淋巴细胞的增殖,用乳酸脱氢酶(LDH)试验检测小鼠特异性细胞毒性T淋巴细胞(CTL)的应答.研究结果提示 与pCI-neoGAG免疫组比较,pCI-neoGAG联合SDF-1基因免疫组小鼠血清的抗HIV-1p24抗体滴度降低,有显著性差异(p<0.01);而与pCI-neoGAG免疫组比较,pCI-neoGAG联合SDF-1基因免疫组小鼠血清的IFN-γ升高,差异显著(p<0.01);pCI-neoGAG联合SDF-1基因免疫组小鼠的脾淋巴细胞增殖实验刺激指数(SI)以及特异性CTL活性均高于pCI-neoGAG免疫组,有显著性差异(p<0.01).因此,SDF-1基因联合HIV-1核酸疫苗免疫小鼠,可能增强特异性Th1细胞和CTL反应,SDF-1基因对体液免疫有抑制作用.SDF-1基因对于治疗性HIV-1核酸疫苗是具有较好应用前景的免疫佐剂.     

佐剂CpG-ODN与重组HBsAg疫苗联合免疫乙型肝炎病毒转基因小鼠的免疫应答研究

目的 以CpG-ODN为佐剂与重组HBsAg(rHBsAg)疫苗合用,研究其对乙型肝炎病毒转基因(HBV Tg)小鼠模型的免疫应答效果.方法 40只HBV Tg小鼠随机分为4组,每组小鼠分别注射rHBsAg疫苗(单用rHBsAg组)、rHBsAg疫苗+CpG-ODN(试验组)、rIFNα-2b(IFN组)、生理盐水(对照组).经多次免疫HBV转基因小鼠,于免疫前、后不同时间采血,动态观察各组小鼠血清中HBsAg量、抗-HBs阳性率和HBV DNA的变化,检测肝组织中HBsAg的表达.检测免疫小鼠的外周血T淋巴细胞亚群和白细胞介素2(IL-2)、IL-12(p70)以及γ干扰素(IFN-γ)的含量,分别检测免疫小鼠的脾细胞增殖和细胞毒性T淋巴细胞(CTL)杀伤功能并计算各组小鼠肝组织活性指数(HAI).结果 rHBsAg组和rHBsAg+CpG组在免疫小鼠后2周100%诱导抗-HBs;rHBsAg+CpG组能显著降低血清中的HBsAg量或使HBsAg转阴,rHBsAg+CpG组肝组织中HBsAg的表达量与血清中一样降低,并降低血清中HBV DNA的拷贝数.rHBsAg组的CD3+、CD4+、CD8+细胞在T细胞中所占百分比,IL-2、IL-12(p70)和IFN-γ的含量以及淋巴细胞特异性增殖和杀伤效应均明显高于对照组(P＜0.05).rHBsAg+CpG组与rHBsAg组比较,免疫小鼠产生更强的HBV特异性细胞应答(P＜0.05),且以Th1型细胞免疫应答为主.在rHBsAg+CpG组肝组织中出现大量淋巴细胞,肝脏的HAI在4个组中最高.结论 CpG-ODN作为佐剂可以增强重组HBsAg疫苗诱导HBV转基因小鼠产生抗病毒免疫应答,重组HBsAg疫苗辅以CpG ODN可作为免疫治疗慢性HBV感染的可行性途经.     

Symmetric primary and tertiary structure mutations within a symmetric superfold: a solution, not a constraint, to achieve a foldable polypeptide

In previous studies designed to increase the primary structure symmetry within the hydrophobic core of human acidic fibroblast growth factor (FGF-1) a combination of five mutations were accommodated, resulting in structure, stability and folding kinetic properties similar to wild-type (despite the symmetric constraint upon the set of core residues). A sixth mutation in the core, involving a highly conserved Met residue at position 67, appeared intolerant to substitution. Structural analysis suggested that the local packing environment of position 67 involved two regions of apparent insertions that distorted the tertiary structure symmetry inherent in the beta-trefoil architecture. It was postulated that a symmetric constraint upon the primary structure within the core could only be achieved after these insertions had been deleted (concomitantly increasing the tertiary structure symmetry). The deletion of these insertions is now shown to permit mutation of position 67, thereby increasing the primary structure symmetry relationship within the core. Furthermore, despite the imposed symmetric constraint upon both the primary and tertiary structure, the resulting mutant form of FGF-1 is substantially more stable. The apparent inserted regions are shown to be associated with heparin-binding functionality; however, despite a marked reduction in heparin-binding affinity the mutant form of FGF-1 is surprisingly approximately 70 times more potent in 3T3 fibroblast mitogenic assays. The results support the hypothesis that primary structure symmetry within a symmetric protein superfold represents a possible solution, rather than a constraint, to achieving a foldable polypeptide.     

Integrating statistical pair potentials into protein complex prediction

The biophysical study of protein-protein interactions and docking has important implications in our understanding of most complex cellular signaling processes. Most computational approaches to protein docking involve a tradeoff between the level of detail incorporated into the model and computational power required to properly handle that level of detail. In this work, we seek to optimize that balance by showing that we can reduce the complexity of model representation and thus make the computation tractable with minimal loss of predictive performance. We also introduce a pair-wise statistical potential suitable for docking that builds on previous work and show that this potential can be incorporated into our fast fourier transform-based docking algorithm ZDOCK. We use the Protein Docking Benchmark to illustrate the improved performance of this potential compared with less detailed other scoring functions. Furthermore, we show that the new potential performs well on antibody-antigen complexes, with most predictions clustering around the Complementarity Determining Regions of antibodies without any manual intervention.     

The heat capacity of proteins

The heat capacity plays a major role in the determination of the energetics of protein folding and molecular recognition. As such, a better understanding of this thermodynamic parameter and its structural origin will provide new insights for the development of better molecular design strategies. In this paper we have analyzed the absolute heat capacity of proteins in different conformations. The results of these studies indicate that three major terms account for the absolute heat capacity of a protein: (1) one term that depends only on the primary or covalent structure of a protein and contains contributions from vibrational frequencies arising from the stretching and bending modes of each valence bond and internal rotations; (2) a term that contains the contributions of noncovalent interactions arising from secondary and tertiary structure; and (3) a term that contains the contributions of hydration. For a typical globular protein in solution the bulk of the heat capacity at 25°C is given by the covalent structure term (close to 85% of the total). The hydration term contributes about 15 and 40% to the total heat capacity of the native and unfolded states, respectively. The contribution of non-covalent structure to the total heat capacity of the native state is positive but very small and does not amount to more than 3% at 25°C. The change in heat capacity upon unfolding is primarily given by the increase in the hydration term (about 95%) and to a much lesser extent by the loss of noncovalent interactions (up to ～5%). It is demonstrated that a single universal mathematical function can be used to represent the partial molar heat capacity of the native and unfolded states of proteins in solution. This function can be experimentally written in terms of the molecular weight, the polar and apolar solvent accessible surface areas, and the total area buried from the solvent. This unique function accurately predicts the different magnitude and temperature dependences of the heat capacity of both the native and unfolded states, and therefore of the heat capacity changes associated with folding/unfolding transitions. © 1995 Wiley-Liss, Inc.     

Protein microarrays as a discovery tool for studying protein–protein interactions

Exploring the function of the genome and the encoded proteins has emerged as a new and exciting challenge in the postgenomic era. Novel technologies come into view that promise to be valuable for the investigation not only of single proteins, but of entire protein networks. Protein microarrays are the innovative assay platform for highly parallel in vitro studies of protein–protein interactions. Due to their flexibility and multiplexing capacity, protein microarrays benefit basic research, diagnosis and biomedicine. This review provides an overview on the basic principles of protein microarrays and their potential to multiplex protein–protein interaction studies.     

Lethal mutations in the major homology region and their suppressors act by modulating the dimerization of the rous sarcoma virus capsid protein C‐terminal domain

An infective retrovirus requires a mature capsid shell around the viral replication complex. This shell is formed by about 1500 capsid protein monomers, organized into hexamer and pentamer rings that are linked to each other by the dimerization of the C‐terminal domain (CTD). The major homology region (MHR), the most highly conserved protein sequence across retroviral genomes, is part of the CTD. Several mutations in the MHR appear to block infectivity by preventing capsid formation. Suppressor mutations have been identified that are distant in sequence and structure from the MHR and restore capsid formation. The effects of two lethal and two suppressor mutations on the stability and function of the CTD were examined. No correlation with infectivity was found for the stability of the lethal mutations (D155Y‐CTD, F167Y‐CTD) and suppressor mutations (R185W‐CTD, I190V‐CTD). The stabilities of three double mutant proteins (D155Y/R185W‐CTD, F167Y/R185W‐CTD, and F167Y/I190V‐CTD) were additive. However, the dimerization affinity of the mutant proteins correlated strongly with biological function. The CTD proteins with lethal mutations did not dimerize, while those with suppressor mutations had greater dimerization affinity than WT‐CTD. The suppressor mutations were able to partially correct the dimerization defect caused by the lethal MHR mutations in double mutant proteins. Despite their dramatic effects on dimerization, none of these residues participate directly in the proposed dimerization interface in a mature capsid. These findings suggest that the conserved sequence of the MHR has critical roles in the conformation(s) of the CTD that are required for dimerization and correct capsid maturation. Proteins 2013. © 2012 Wiley Periodicals, Inc.     

A large scale test of computational protein design: folding and stability of nine completely redesigned globular proteins

A previously developed computer program for protein design, RosettaDesign, was used to predict low free energy sequences for nine naturally occurring protein backbones. RosettaDesign had no knowledge of the naturally occurring sequences and on average 65% of the residues in the designed sequences differ from wild-type. Synthetic genes for ten completely redesigned proteins were generated, and the proteins were expressed, purified, and then characterized using circular dichroism, chemical and temperature denaturation and NMR experiments. Although high-resolution structures have not yet been determined, eight of these proteins appear to be folded and their circular dichroism spectra are similar to those of their wild-type counterparts. Six of the proteins have stabilities equal to or up to 7kcal/mol greater than their wild-type counterparts, and four of the proteins have NMR spectra consistent with a well-packed, rigid structure. These encouraging results indicate that the computational protein design methods can, with significant reliability, identify amino acid sequences compatible with a target protein backbone.     

蛋白质相互作用研究的新技术与新方法

目前,蛋白质相互作用已成为蛋白质组学研究的热点. 新方法的建立及对已有技术的改进标志着蛋白质相互作用研究的不断发展和完善．在技术改进方面,本文介绍了弥补酵母双杂交的蛋白定位受限等缺陷的细菌双杂交系统;根据目标蛋白特性设计和修饰TAP标签来满足复合体研究要求的串联亲和纯化技术,以及在双分子荧光互补基础上发展的动态检测多个蛋白质间瞬时、弱相互作用的多分子荧光互补技术．还综述了近两年建立的新方法：与免疫共沉淀相比,寡沉淀技术直接研究具有活性的蛋白质复合体;减量式定量免疫沉淀方法排除了蛋白质复合体中非特异性相互作用的干扰;原位操作的多表位－配基绘图法避免了样品间差异的影响,以及利用多点吸附和交联加固研究弱蛋白质相互作用的固相蛋白质组学方法.     

Improvement of protein stability in protein microarrays

Protein stability in microarrays was improved using protein stabilizers. PEG 200 at 30% (w/v) was the most efficient stabilizer giving over 4-fold improvement in protein stability compared to without the stabilizer. PEG 200 above 10% (w/v) in the array solution prevented the evaporation of water in the sample and thereby improved protein stability in the microarray. When the streptavidin-biotin binding reaction was performed under optimized conditions, biotin-BSA-fluorescein isothiocyanate (FITC) was detected from 1 ng ml^–1 to 5 g ml^–1 by fluorescence analysis.     

A solubility-enhancement tag (SET) for NMR studies of poorly behaving proteins

Protein-fusion constructs have been used with great success for enhancing expression of soluble recombinant protein and as tags for affinity purification. Unfortunately the most popular tags, such as GST and MBP, are large, which hinders direct NMR studies of the fusion proteins. Cleavage of the fusion proteins often re-introduces problems with solubility and stability. Here we describe the use of N-terminally fused protein G (B1 domain) as a non-cleavable solubility-enhancement tag (SET) for structure determination of a dimeric protein complex. The SET enhances the solubility and stability of the fusion product dramatically while not interacting directly with the protein of interest. This approach can be used for structural characterization of poorly behaving protein systems, and would be especially useful for structural genomics studies.