重叠延伸PCR合成风疹病毒E1蛋白抗原肽基因及其表达

目的:利用重叠延伸PCR合成风疹病毒E1基因的抗原肽段,构建其原核表达载体并表达蛋白,为进一步获得高质量的rE1重组抗原肽奠定基础。方法:利用软件对风疹病毒E1基因进行生物信息学分析,根据大肠杆菌密码子偏爱性对其密码子进行优化;设计多对寡核苷酸引物,以重叠延伸PCR法合成相应抗原肽段,克隆后测序鉴定。再以酶切连接的方法将合成的抗原肽序列克隆导入原核表达载体pET32a;利用IPTG诱导抗原肽段的表达,SDS-PAGE和West-ern blot法分析表达产物。结果:经过6轮重叠延伸PCR扩增,成功获得与预期目的序列一致的风疹病毒E1基因抗原肽并构建获得重组质粒pET32-rE1;在37℃下分别以终浓度为1 mmol/L和0.5 mmol/L的IPTG诱导抗原肽表达,SDS-PAGE和Western blot法检测到预期的蛋白条带;且以IPTG终浓度为1 mmol/L诱导6 h后表达量最高。结论:成功合成了密码子优化的风疹病毒E1基因抗原肽段,构建其原核表达载体pET32-rE1并表达该抗原肽。     

BirA酶基因表达载体的构建、原核表达及表达产物的活性鉴定

目的:构建生物素-蛋白连接酶(BirA酶)基因的表达载体,并在大肠杆菌BL-21(DE3)中表达具有生物学活性的BirA酶。方法:用PCR法扩增BirA酶基因。将PCR产物克隆入pGEX-4T-2中构建BirA酶-GST融合蛋白基因的重组表达载体pGEX-BirA。经测序验证后,在大肠杆菌BL-21(DE3)中诱导表达,表达产物采用谷胱苷肽-琼脂糖层析柱进行纯化。以带有生物素酶底物肽(BirAsubstratepeptide,BSP)的HLA-A2-肽复合物为底物,用ELISA和Westernblot鉴定表达产物的生物素化活性。结果:构建了pGEX-BirA原核表达质粒,并在大肠杆菌BL-21(DE3)中诱导表达Mr为61300的BirA酶-GST融合蛋白,表达产物经谷胱苷肽-琼脂糖层析柱纯化后,得到N端带有GST标签的BirA酶蛋白。ELISA和Westernblot的结果显示,表达产物能使HLA-A2-肽复合物生物素化。结论:成功地制备了具有生物学活性的Bi-rA酶,为研究蛋白质分子的相互作用提供了有效的制剂。     

HIV核心抗原p24原核系统的高效表达、纯化及活性鉴定

目的　在原核表达系统中对HIVp2 4抗原基因进行克隆和高效表达、纯化并鉴定其活性。方法　利用PCR技术从HIV-1全基因质粒 (B2N)中扩增p2 4抗原基因 ,并克隆入T载体中。通过酶切消化后连接到表达载体pRSET上 ,用此连接产物转化大肠埃希菌BL2 1,经IPTG诱导 ,表达p2 4抗原。利用固定化金属离子 (Ni2 )配体亲和层析技术从表达蛋白中纯化目的蛋白。并运用双酶切技术、SDS-PAGE电泳、WesternBlot(WB)及ELISA法分别对插入基因片段的正确性、表达产物的活性及特异性进行检测。结果　PCR产物约为 6 90bp ,与预期p2 4抗原全基因片段大小一致。重组质粒T-p2 4和pRSET-p2 4经BamHⅠ和HindⅢ双酶切 ,其插入的外源基因片段均为 6 90bp。将纯化前与纯化后的蛋白作SDS PAGE电泳 ,均可见一条约 2 4× 10 3的外源基因表达带 ,与计算的相对分子质量相符。经WB和ELISA试验 ,证明基因工程表达的p2 4抗原具有较高的特异性及活性。结论　成功构建了HIVp2 4表达载体pRSET-p2 4 ,并在原核细胞中高效表达 ,其表达产物具有良好的特异性及活性     

蓝藻抗病毒蛋白-N在大肠杆菌中的表达及其抗体的制备

目的:构建抗病毒蓝藻蛋白-N(Cyanovirin-N,CV-N)表达载体并在大肠杆菌中稳定表达,并进一步制备用于检测转CV-N基因表达产物的特异抗体.方法:以已构建的pMD(CV-N)为模板,设计引物,利用PCR技术扩增出CV-N基因,将成熟CV-N的编码框序列构建到原核表达载体pET-His中,氨苄青霉素平板筛选及PCR、酶切鉴定,挑选出阳性克隆进行扩增,DNA测序正确后,转化大肠杆菌BL21(DE3)进行IPTG诱导表达.SDS-PAGE以及MALDI-TOF/MS分析鉴定,采用透析法重折叠复性,亲和层析分离纯化得到分子量为12 700的带有组氨酸标签的重组CV-N融合蛋白.用亲和层析分离纯化后的CV-N融合蛋白作为抗原,采用皮下多点注射免疫的方法免疫昆明小鼠,经过31天的免疫,获得抗CV-N的多克隆抗体.结果:成功地获得了CV-N基因,并且以包涵体的形式表达于大肠杆菌中,表达量高达42.0%.用间接酶联免疫吸附(ELISA)方法,测得抗体效价超过1∶8 000,Western blot检测结果显示,该抗体能特异性地与CV-N抗原产生明显免疫亲和反应.结论:建立原核高效稳定表达CV-N系统,获得具有生物学活性的CV-N蛋白,所制备的抗体具有很好的灵敏性和特异性,为进一步研究其功能奠定基础.     

鼠抗寻常性天疱疮抗原噬菌体抗体库的构建与筛选

目的 :应用重组噬菌体抗体库技术制备抗寻常性天疱疮抗原 (PVA)的单链抗体。方法 :用PVA免疫小鼠 6w后 ,抽取小鼠脾脏细胞RNA ,逆转录为cDNA。设计针对小鼠抗体重链可变区 (VH)和轻链可变区 (VL)的特异性引物 ,PCR扩增出VH 和VL 片段。用带有VH3′端、连接肽和VL5′端序列的引物修饰VL 得VL′后 ,与VH 进行重叠延伸拼接 (splicingbyoverlapex tension ,SOE) ,连接成VH—Linker—VL(ScFv) ,并大量扩增。此ScFv经限制性内切酶Sfi1和Not1酶切后 ,以噬粒pCANTAB 5E为载体 ,构建重组质粒 ,转导TG1 感受态菌 ,建成库容为 1 5× 10 6 的噬菌体抗体库 ,用PVA筛库。结果 :构建了抗PVA的特异性单链抗体库 ,筛选出一高丰度表达单链抗PVA抗体的细胞株。结论 :从小鼠噬菌体抗体库中获得特异性的、单克隆的、单链抗PVA噬菌体抗体     

SV40TAg真核表达载体的设计与构建

目的 设计并构建SV40TAg真核表达载体。方法 采用重叠延伸拼接法从pUC19-SV40载体中克隆切除了内含子的SV40LT基因全长，在其5’端连上loxP位点，EcoR I、BamH I双酶切，同时采用重叠延伸拼接法从pEGFP-N1真核表达载体中克隆EGFP基因全长，并在3’端连上loxP位点，两个酶切产物连接后定向克隆至pEGFP-N1真核表达载体，DNA序列分析鉴定重组质粒。结果 SV40LT基因和两个loxP位点成功克隆至pEGFP-N1真核表达载体中。结论 本实验构建的SV40LT重组质粒为利用SV40T抗原进行黑素细胞发育、分化，黑素生成以及黑素瘤发生等研究提供了新的分子工具。     

人β防御素4基因的合成及克隆载体的构建

目的：合成人β防御素4（HBD4）基因并构建其克隆载体.方法：根据GenBank中HBD4结构基因的序列, 设计合成了6条长度为32 ～60 bp的寡聚核苷酸片段, 用重叠延伸PCR法扩增合成HBD4 cDNA全长.PCR产物经双酶切后, 克隆入载体pMD18-T中, 并导入细菌中进行扩增.结果：HBD4基因的PCR产物和重组载体经凝胶电泳和酶切鉴定、 测序分析证实, 合成的目的基因与设计的HBD4 cDNA的序列相一致, 并成功地克隆入克隆载体pMD18-T中.结论：用重叠延伸PCR法能方便、 准确地获得目的基因片段.重组克隆载体pMD18-T-HBD4 的获得, 为构建HBD4基因的表达载体并表达奠定了基础.     

构建重组人pET-32a-瘦素高效的表达载体

背景：瘦素的功能是作为脂肪细胞体脂量的信号来认识的,作为体内的能量平衡信号反馈到下丘脑,与其中各部位神经元的受体结合后参与调节进食、饮水、能量代谢。 目的：构建原核重组表达载体pET-32a-瘦素并检测其在大肠杆菌BL21中的高效表达。 方法：取人脂肪组织,RT-PCR法制备瘦素目的基因,采用DNA重组技术将其克隆至pMD18T与pET-32a原核表达载体,双酶切及测序鉴定,转化大肠杆菌BL21株诱导其表达,SDS-PAGE电泳分离鉴定,表达产物变性复性后,间接酶联免疫吸附法检测抗原反应原性。 结果与结论：实验成功扩增出520 bp的瘦素目的基因并构建了原核重组表达载体pET-32a-瘦素;测序结果与GenBank收录序列相一致;目的蛋白pET-32a-瘦素呈极高效表达,占总蛋白的50%以上;变性复性后抗原反应原性较复性前明显提高(P < 0.01)。结果证实,实验成功构建原核重组高效表达的载体pET-32a-瘦素,并提高其抗原反应原性。     

降钙素基因相关肽表达载体的构建

背景：为研究降钙素基因相关肽基因治疗在骨质疏松中的应用,首先要建立高效的降钙素基因相关肽基因载体。 目的：构建降钙素基因相关肽真核表达载体pBaBb-puro-CGRP。 方法：设计引物并通过PCR扩增出降钙素基因相关肽,酶切后用T4 DNA连接酶将其与pBaBb-puro进行连接,经过转化、阳性克隆筛选后,进行酶切和测序鉴定。 结果与结论：经PCR扩增获得了含430 bp的降钙素基因相关肽基因编码序列,经过酶切、连接、转化后,挑选10个菌落进行PCR检测,筛查到8个菌落含有重组质粒,进一步行酶切和测序鉴定,结果与理论预期完全相符。提示实验成功构建了pBaBb-puro-CGRP真核表达载体。     

肝癌抗原肽(EPVTKAEML)与人HSP70融合基因的构建及原核表达

目的:构建及原核表达肝癌抗原肽(EPVTKAEML)与人热休克蛋白70(HSP70)的融合基因.方法:采用加端PCR方法,将EPVTKAEML的基因序列融合到人HSP70基因的3′端;将融合基因克隆入原核表达载体pET-28a( )中,构建重组质粒pET-28a( )/EPVTKAEML-HSP70.经限制性内切酶BamH I、Xho I双酶切鉴定及序列测定后,转化E.coli BL21(DE3),经IPTG诱导表达融合蛋白,SDS-PAGE检测表达结果.结果:应用加端PCR方法扩增出约2.0 kb的目的片段,序列测定结果证实,EPVTKAEML的基因序列成功地融合到人HSP70基因的3′端.经BamH I、Xho I酶切鉴定证实,融合基因成功地克隆到原核表达载体pET-28a( )上;转入重组质粒的E.coli BL21(DE3)经IPTG诱导后,SDS-PAGE分析发现在相对分子质量(Mr)约72 000处有表达量明显增多的蛋白条带.结论:成功地构建并表达了肝癌抗原肽(EPVTKAEML)与人HSP70的融合基因.     

TRAIL和EGFR配体寡肽与力达霉素辅基蛋白融合蛋白制备过程的优化

目的对以包涵体形式表达的TRAIL和EGFR配体寡肽与力达霉素辅基蛋白融合蛋白Ec-LDP-TRAIL的制备过程进行优化。方法对大肠杆菌原核表达Ec-LDP-TRAIL目的蛋白的温度、诱导物浓度、起始菌体密度及时间等条件进行优化;在Ni2+亲和层析纯化蛋白过程中对样品预处理以及纯化缓冲液成分进行优化;对纯化后蛋白的分步透析复性过程进行一系列优化,并通过基于ELISA的结合活性实验分析Ec-LDP-TRAIL与肿瘤细胞的结合能力。结果经过工艺优化后,纯化后的融合蛋白Ec-LDP-TRAIL纯度达95%以上,复性后LB培养基活性蛋白收率约为2.2 mg/L,与初始复性条件相比提高近2倍。复性后融合蛋白Ec-LDP-TRAIL显示出能够与人表皮癌A431和人大细胞肺癌H460细胞的结合活性。结论融合蛋白Ec-LDP-TRAIL制备过程的优化为后续研发和生产奠定了实验基础,同时也为其他以包涵体形式表达的基于TRAIL的抗肿瘤蛋白药物的制备提供借鉴。     

Relationship of epidermal growth factor receptor detectability with the A, B, H blood group antigens. Emphasis on normal and neoplastic urothelium.

The epidermal growth factor receptor (EGFR) is a glycoprotein that carries on its extracellular domains oligosaccharide chains, some of which are similar to blood group determinants. The author examined the expression of the EGFR using immunohistochemistry and three anti-EGFR antibodies with different fine specificities. These were applied to frozen sections from 120 tissue biopsies, including normal and neoplastic urothelium. The expression of blood group A, B, H determinants was also evaluated in the same tissues. Significant differences were noted, depending on the fine specificity of the anti-EGFR antibody, cellular differentiation, and the tissue donor's blood group. The most interesting finding was a reciprocal relationship between the reaction patterns obtained using antibodies with carbohydrate specificity and those with peptide specificity. These patterns were characteristic of cellular differentiation and suggested that the EGFR peptide determinants are detected in excess in immature and malignant cells that, however, appear deficient in oligosaccharide determinants. The combination of 'loss' of blood group antigen and an apparent overexpression of EGFR peptide determinants is indicative of invasive growth in transitional cell carcinomas.     

重组表达的着丝粒蛋白-B N-端抗原在抗着丝粒自身免疫病血清检测中的应用

目的 分析重组表达的CENP-B抗原对抗着丝粒自身免疫病血清的鉴定结果，探讨其作为临床诊断指标的可行性。方法 通过构建原核表达载体，在大肠杆菌中高效表达CENP-B-N端300个氨基酸的1段多肽；纯化包涵体，制备重组表达的CENP-B抗原，并利用ELISA、Western blot的方法对临床诊断为阳性的ACA血清进行鉴定。结果 重组表达的CENP-B N-端抗原对ACA血清的ELISA阳性检出率为99％，Western blot阳性检出准确率为97％。结论 重组表达的CENP-B抗原可以作为抗着丝粒自身免疫病血清临床诊断的1个指标。     

Secretion of the mycobacterial 19-kilodalton protein by Escherichia coli, a novel method for the purification of recombinant mycobacterial antigens.

We have reported previously (R.G. Hewinson and W.P. Russell, J. Gen. Microbiol. 139:1253-1259, 1993) the secretion by Escherichia coli of a recombinant form of the immunogenic protein MPB70 of Mycobacterium bovis when the protein is translated from its native initiation codon. N-terminal sequence analysis of the purified protein revealed that the signal peptide of MPB70 was cleaved by an endopeptidase of E. coli at the same cleavage site as reported for the protein in M. bovis. Since both the B- and T-cell antigenicities of the purified recombinant protein were similar to that of the native protein, the 19-kDa antigen of M. bovis was used as a model to test whether the signal peptide of MPB70 could direct the secretion of heterologous proteins in E. coli and whether antigen produced in this way retained antigenicity superior to that of recombinant protein produced as a fusion to glutathione-S-transferase. A chimeric protein was produced in which the signal peptide of MPB70 was fused to the 19-kDa antigen of M. bovis at amino acid residue 23. This chimeric protein was found to be secreted into the periplasm and culture medium of recombinant E. coli, and the signal peptide was cleaved by an endopeptidase of E. coli during secretion. Secretion of the 19-kDa antigen facilitated purification of the antigen by two-stage preparative electrophoresis which gave yields of 2.5 mg of purified, soluble 19-kDa antigen from 2.5 g (wet weight) of E. coli. Antigen purified in this way retained both B- and T-cell antigenicities. Moreover, the nonspecific mitogenic activity of the purified 19-kDa antigen was low, while the magnitude of the T-cell response induced by the purified antigen was considerably higher than that observed with purified antigen produced as a fusion protein with glutathione-S-transferase.     

EGF receptor variant III as a target antigen for tumor immunotherapy

The EGF receptor (EGFR) is the first tyrosine kinase receptor ever cloned and remains at the forefront of targeted therapies against cancer. Currently, there are four US FDA-approved drugs and several more in Phase III studies that target the EGFR. These drugs, while resulting in some dramatic remissions, have not resulted in strong nor consistent improvements in survival. EGFR variant III (EGFRvIII) is the most common variant of the EGFR and is present in many different cancer types but not in normal tissue. It results from the fusion of exon 1 to exon 8 of the EGFR gene, which results in a novel glycine at the junction. This mutant receptor is constitutively active in these tumors and can lead directly to cancer phenotypes due to its oncogenic properties. EGFRvIII is an attractive target antigen for cancer immunotherapy because it is not expressed in normal tissue and because cells producing EGFRvIII have an enhanced capacity for dysregulated growth, survival, invasion and angiogenesis. In this review, we will discuss preclinical and clinical data from studies using EGFRvIII as the target antigen for immunotherapy, with a focus on the potential for greatly improved survival for patients diagnosed with glioblastoma multiforme.     

非小细胞肺癌患者ALK,EGFR及KRAS基因的检测及临床病理特征

目的:研究汉族非小细胞肺癌患者中间变性淋巴瘤激酶(anaplastic lymphoma kinase,ALK)、表皮生长因子受体(epidermal growth factor receptor,EGFR)及Kirsten鼠肉瘤基因(Kirstenrat sarcoma,KRAS)突变的阳性率及其与临床病理特征的关系.方法:采用免疫组织化学(immunohistochemistry,IHC)的方法检测ALK融合基因异常表达,采用PCR检测EGFR基因和KRAS基因突变,采用x2检验及Fisher精确概率法进行数据分析.结果:共2 267例进行了ALK融合基因检测,其中1 655例同时进行了EGFR突变检测,951例同时进行了KRAS检测.ALK融合基因、EGFR基因及KRAS基因突变阳性率分别为7.28％(165/2 267)、48.58％(804/1 655)、11.40％(108/947).ALK基因突变多见于年轻、腺癌患者;EGFR基因突变多见于女性、腺癌患者;KRAS基因突变多见于老年、男性、腺癌患者.1 655例同时进行了ALK与EGFR检测的病例中,共6例存在双基因突变(0.36％);947例同时进行了ALK与KRAS检测,共4例存在双基因突变(0.42％);943例同时进行了EGFR与KRAS突变检测,未发现双突变病例.结论:非小细胞肺癌患者ALK,EGFR和KRAS基因的突变与患者的年龄、性别、组织学类型均存在相应的联系,个别病例可以出现ALK融合基因与EGFR或KRAS突变共存.     

肺鳞状细胞癌EGFR/ALK的基因状态

目的:探讨肺鳞状细胞癌各亚型中EGFR和ALK的基因状态.方法:应用ARMS方法检测肺鳞状细胞癌石蜡组织中EGFR基因突变和ALK融合基因情况.结果:218例肺鳞状细胞癌样本中,E GFR基因突变率为4.59％(10/218),19del和L858R各为2.29％(5/218).ALK融合基因阳性率为6.14％(7/114).结论:肺鳞状细胞癌存在一定比例EGFR基因突变和ALK融合基因阳性,肺鳞状细胞癌EGFR基因和ALK融合基因常规检测不可忽视.     

异种表皮生长因子受体胞外段的表达及其抗肿瘤效果研究

目的:构建异种EGFR蛋白疫苗并研究其抗肿瘤效果.方法:用PCR方法获得鸡EGFR胞外片段, 与pGEX- 4T-2载体连接, 并在E.coli BL21(DE3)中表达鸡的EGFR胞外片段与GST的融合蛋白, 融合蛋白经Ni2 亲和层析柱纯化、复性后, 免疫小鼠, 免疫3次后, 接种小鼠Lewis细胞, 观测肿瘤生长情况, ELISA检测小鼠血清中抗EGFR蛋白的抗体效价.结果:成功构建了EGFR胞外段基因的原核表达载体; SDS-PAGE显示成功表达了目的融合蛋白; 融合蛋白免疫小鼠后, ELISA法检测到特异性抗EGFR抗体; 实验组与对照组肿瘤体积的比较结果显示, 融合蛋白疫苗能够在一定程度上抑制肿瘤的生长.结论:异种EGFR蛋白能够克服免疫耐受问题, 诱导机体产生抗体, 有一定的抗肿瘤效果, 为后续的肿瘤疫苗研究打下了基础.     

Design and construction of a new recombinant fusion protein (2b2t+EPC1) and its assessment for serodiagnosis of cystic echinococcosis

The immunodiagnostic tests for cystic echinococcosis (CE) are mostly serological tests based on ELISA that use hydatid cyst antigens for primary screening because of its simple preparation and availability. The challenge to develop new serological methods (as compared to those based on the hydatid cyst fluid antigens) to meet the gold standard remains. Appropriate sources of antigenic material are necessary for application to improve the efficacy of immunodiagnostic tests at a population level. In the current study, a fusion protein containing the coding sequence of antigen B2t and two sequences of EPC1 antigen with some modifications was reconstructed. Using bioinformatics tools, these sequences were joined together by applying the sequence of a rigid α‐helix‐forming linker to obtain an appropriate structure of a fusion protein. Synthetic recombinant fusion protein was expressed using pET28a as a vector and evaluated by indirect ELISA test for sera from patients with hepatic CE and other parasitic infections. The sensitivity of the fusion protein was lower (88.46%) than the available ELISA kit (96.15%). However, the differences in sensitivity were not statistically significant as compared to the recombinant fusion peptide with the commercial kit (p = 0.269). The specificity of the recombinant fusion protein (95.45%) was not significantly lower than the commercial kit (96.59%; p = 1.000). Moreover, surprisingly there was no difference in the cross‐reactivity values of performance between the recombinant‐ELISA and commercial kit. The positive and negative predictive values of the recombinant antigen were achieved as 92% and 93.33%, respectively, while for the commercial kit, they were obtained as 94.33% and 97.70%, respectively. In conclusion, as an early evaluation of these antigens the performance of our recombinant fusion protein in ELISA is relatively promising. Although, it seemed that this peptide with specific antigenic epitopes might be more appropriate for the serological evaluation of CE by use of bioinformatics tools, our findings showed that cross‐reactions and a negative reaction could occur in clinical performance. This fusion protein may have utility for diagnosis in humans, but further evaluation is needed using the WHO ultrasound classification for CE.     

A hemagglutinin-based multipeptide construct elicits enhanced protective immune response in mice against influenza A virus infection

Multipeptide constructs, comprising adjacent sequences of the 317–341 intersubunit region of immature influenza A hemagglutinin (H1N1), were designed and the functional properties of these branched peptides were compared to that of the corresponding linear peptides. In vivo studies revealed that the immunogenicity of the peptides was dependent on the presence of the hydrophobic fusion peptide (comprised in FP3), encompassing the N-terminal 1–13 sequence of the HA2 subunit. Antibody and T cell recognition, however, was directed against the 317–329 HA1 sequence, comprised in the P4 peptide. Multiple copies of P4, covalently linked by branched lysine residues, significantly enhanced the efficiency of antibody binding and the capacity of peptides to elicit B- and T-cell responses. A fraction of peptide induced antibodies reacted with immature or with proteolitically cleaved hemagglutinin (HA) molecules pretreated at low pH. Immunization with a multipeptide construct, (P4)₄–FP3, not only resulted in elevated antibody and T cell responses but conferred enhanced protection against lethal A/PR/8/34 (H1N1) infection as compared to its subunit peptides. The beneficial functional properties of this artificial peptide antigen may be acquired by multiple properties including: (i) stabilized peptide conformation which promotes strong, polyvalent binding to both antibodies and MHC class II molecules; (ii) appropriate P4 conformation for antibody recognition stabilized by the covalently coupled fusion peptide, resulting in the production of virus cross reactive antibodies which inhibit the fusion activity of the virus; (iii) activation of peptide specific B cells which potentiate antigen presentation and peptide specific T cell responses; and (iv) generation of helper T cells which secrete lymphokines active in the resolution of infection.