噬菌体随机肽库的应用现状

简要介绍了噬菌体肽库的构建原理及筛选方法，并分析了噬菌体肽库在寻找未知的抗原表位，疾病检测，疫苗研究、多肽药物筛选等领域的应用。     

噬菌体随机肽库的应用现状

简要介绍了噬菌体肽库的构建原理及筛选方法 ,并分析了噬菌体肽库在寻找未知的抗原表位、疾病检测、疫苗研究、多肽药物筛选等领域的应用     

大肠杆菌表面CS3菌毛展示随机肽库的构建

目的:在肠毒素性大肠杆菌CS3菌毛表面构建 10肽随机肽库．方法:首先将原有的单酶切CS3菌毛呈现载体改造为双酶切载体,并证实改造后的载体能正确形成CS3菌毛．同时设计合成2条寡核苷酸序列,链1含有1个10肽随机编码序列(NNS)10, 链2可与链1的3′端互补．两条链经过退火、延伸、酶切和回收与经过同样酶切的呈现载体连接,连接产物纯化后分多次电击转化,获得随机肽库．随机挑选10个克隆进行测序并对测序结果进行分析．结果:获得1个库容量为1．8×106大小的随机肽库．测序结果显示,所构建肽库的基本框架与预期设计相符,4个寡核苷酸出现的频率也与理论值相接近．结论:在肠毒素性大肠杆菌CS3菌毛表面成功构建库容量为1．8×106大小的10肽随机肽库．为下一步利用肽库进行筛选奠定了基础．     

噬菌体展示肽库技术及其应用研究现状

噬菌体展示技术是将随机多肽文库表达于丝状噬菌体的表面，筛选功能性多肽的一种生物技术.该技术在抗原表位定位、免疫学诊断、疫苗研制、药物筛选等方面具有重要用途。     

利用噬菌体肽库筛选特异性哇巴因结合肽

目的 寻找与哇巴因特异性结合的多肽，为实现阻断或拮抗哇巴因与钠泵的作用，减少EO致高血压作用奠定实验及理论基础。方法 采用噬菌体随机肽库表面呈现技术筛选出哇巴因特异性结合肽，通过测序，获得氨基酸序列，进行同源性分析，合成筛选出的12肽，采用放射性配基受体结合法检测哇巴因结合肽与哇巴因的结合能力。结果 从噬菌体12肽库中筛选出三种多肽，肽A（12肽的筛选一致率达到66．7％（8／12）；肽B（8肽，插入片段中出现终止子）筛选一致率为16．7％（2／12），肽C（12肽）的筛选一致率达到66．7％（8／12），肽B（8肽，插入片段中出现终止子）筛选一致率为16．7％（2／12）；肽C／（12肽）为8．3％（1／12），仅1例未见插入的多肽片段。Genbamk中蛋白质同源性分析结果：肽A，B，C均未见同源蛋白。结论 哇巴因特异性结合肽蛋白质序列的获得，为哇巴因的研究提供了实验基础。     

用噬菌体肽库筛选配体及其用途

外源多肽能够在丝状噬菌体表面表达,是Smith等人于1980年第一次报道的。当把外源多肽核酸序列插入到丝状噬菌体外壳P3或P8基因中后,感染宿主菌,P3或P8蛋白氨基端就可以表达出多肽,并且该噬菌体依然具有侵染宿主菌的能力。在此后的二十年里此项研究已发展成为噬菌体肽库的表达,克隆好的噬菌粒经转化进入宿主     

利用噬菌体肽库筛选特异性哇巴因结合肽

目的寻找与哇巴因特异性结合的多肽,为实现阻断或拮抗哇巴因与钠泵的作用,减少EO致高血压作用奠定实验及理论基础.方法采用噬菌体随机肽库表面呈现技术筛选出哇巴因特异性结合肽,通过测序,获得氨基酸序列,进行同源性分析,合成筛选出的12肽,采用放射性配基受体结合法检测哇巴因结合肽与哇巴因的结合能力.结果从噬菌体12肽库中筛选出三种多肽,肽A(12肽)的筛选一致率达到66.7%(8/12);肽B(8肽,插入片段中出现终止子) 筛选一致率为16.7%(2/12);肽C(12肽)为8.3%(1/12);仅1例未见插入的多肽片段.Genbamk中蛋白质同源性分析结果肽A、B、C均未见同源蛋白.结论哇巴因特异性结合肽蛋白质序列的获得,为哇巴因的研究提供了实验基础.     

噬菌体抗体库技术的应用现状

噬菌体抗体库技术是抗体组合文库技术和噬菌体表面展示技术相结合形成的一项新技术,是继多克隆抗体、单克隆抗体之后兴起的第三代基因工程抗体技术,在生物科学领域极具潜力,本文就其应用现状和发展前景作一综述。     

噬菌体随机环7肽库筛选恶性疟原虫EBA-175的结合肽

目的从噬菌体随机环7肽库中筛选恶性疟原虫EBA175抗原的结合肽。方法以EBA175重组蛋白为靶筛选噬菌体随机环7肽库,通过ELISA、竞争抑制试验、Westernblot等方法鉴定获得的噬菌体短肽与EBA175之间的结合特性。对阳性克隆进行DNA序列测定,推导其氨基酸序列并与GPA氨基酸全序列进行了同源性比较。结果获得9株可与EBA175结合的阳性噬菌体克隆,序列分析显示为3种氨基酸序列,P1(MLLITIR)、P2(TRKLPRT)、P3(KRLMPLK)。其中出现频率最高的P1序列中LLI与EBA175的受体GPA的108110位氨基酸同源。竞争性ELISA显示展示序列P1的噬菌体能竞争抑制EBA175与其单抗的结合。结论获得了可与EBA175特异结合的阳性噬菌体短肽,·LLI··几位氨基酸可能对EBA175与GPA的结合起重要作用。     

噬菌体展示肽库在乳腺癌血清肿瘤标志物筛选中的应用

目的用噬菌体随机12肽库对乳腺癌患者的血清进行差异性筛选,以获得乳腺癌特异性的新的肿瘤标志物。方法对噬菌体随机12肽库进行三轮差异性筛选,用ELISA法测定噬菌体克隆对乳腺癌患者血清结合的特异性。结果经过三轮筛选,噬菌体富集率逐轮递增,经47例乳腺癌患者和正常人血清的ELISA法检测验证,获得一株与乳腺癌患者血清特异较好的噬菌体,经DNA测序和推导,其短肽序列为短肽(QVSAEHKVQGFW)。结论成功筛选到能与乳腺癌患者血清高亲和力特异结合的12肽序列,为今后研究乳腺癌肿瘤标志物奠定了基础。     

结肠癌患者淋巴结构建抗结肠癌噬菌体Fab抗体库

目的　构建 2个结肠癌患者自然致敏淋巴结抗体Fab段噬菌体呈现库。方法　取 2个结肠癌患者转移淋巴结 ,提取淋巴结总RNA ,逆转录PCR扩增重链Fd和κ轻链cDNA。依次将PCR产物插入载体 pComb3的相应部位 ,噬菌体VCSM13辅助感染。以点印迹检测噬菌体表面Fab的表达。 结果　所选 2种Ig亚类的重链Fd片段、2种κ轻链cDNA得到扩增。Fd片段和κ轻链均插入 pComb3的重组率为 40 %,Fab噬菌体表达库容量达 1.48× 10 6。噬菌体悬液的点印迹免疫染色显示有Fab表达。结论　构建了 2个结肠癌患者自然致敏淋巴结抗体Fab段噬菌体呈现库 ,为筛选结肠癌相关抗体奠定了基础。     

人源性抗结核分枝杆菌噬菌体展示单链抗体文库的构建

目的 构建人源抗结核分枝杆菌噬菌体展示单链抗体文库,为结核特异性单链抗体的筛选奠定基础. 方法 从抗结核分枝杆菌抗体阳性患者淋巴细胞中提取总RNA,逆转录成cDNA,PCR扩增获得抗体的重、轻链可变区基因,然后拼接装配成单链抗体基因,重组于噬菌粒载体pCANTAB5S,转化大肠埃希菌E.coli TG1,以辅助噬菌体拯救后,构建人源性抗结核分枝杆菌噬菌体展示单链抗体库. 结果 成功构建人源性抗结核分枝杆菌噬菌体展示单链抗体文库,库容量达107. 结论 以结核患者淋巴细胞免疫球蛋白可变区基因片段和噬菌粒展示载体pCANTAB5S为基础,成功构建人源性抗结核分枝杆菌噬菌体展示单链抗体库,并达到建库标准,可进一步从中筛选获得结核特异性单链抗体.     

微小隐孢子虫T7噬菌体展示文库的构建

目的为筛选微小隐孢子虫保护性抗原基因,构建了微小隐孢子虫T7噬菌体展示文库。方法用Trizol试剂提取微小隐孢子虫总RNA,分离纯化mRNA,经反转录合成双链cDNA。在双链cDNA末端加上定向EcoRⅠ/HindⅢ接头,用EcoRⅠ和HindⅢ消化接头,使形成两端分别带有EcoRⅠ和HindⅢ粘性末端的双链cDNA。经Mini Column纯化,收集400bp以上的双链cDNA片段,将其连接于带有EcoRⅠ和HindⅢ末端的T7Select 10-3b载体,经体外包装后,以BLT5403为受体菌构建T7噬菌体展示文库。结果经测定,库容量为1.2×107pfu/mL,重组率为96.7%,扩增后文库滴度为2.4×1010pfu/mL。对随机挑取的100个噬菌斑进行PCR鉴定,92%的插入片段大于400bp。结论成功构建了微小隐孢子虫T7噬菌体展示文库。     

Affinity peptide developed by phage display selection for targeting gastric cancer

AIM: To develop an affinity peptide that binds to gastric cancer used for the detection of early gastric cancer.METHODS: A peptide screen was performed by biopanning the PhD-12 phage display library, clearing non-specific binders against tumor-adjacent normal appearing gastric mucosa and obtaining selective binding against freshly harvested gastric cancer tissues. Tumor-targeted binding of selected peptides was confirmed by bound phage counts, enzyme-linked immunosorbent assay, competitive inhibition, fluorescence microscopy and semi-quantitative analysis on immunohistochemistry using different types of cancer tissues.RESULTS: Approximately 92.8% of the non-specific phage clones were subtracted from the original phage library after two rounds of biopanning against normal- appearing gastric mucosa. After the third round of positive screening, the peptide sequence AADNAKTKSFPV (AAD) appeared in 25% (12/48) of the analyzed phages. For the control peptide, these values were 6.8 ± 2.3, 5.1 ± 1.7, 3.5 ± 2.1, 4.6 ± 1.9 and 1.1 ± 0.5, respectively. The values for AAD peptide were statistically significant (P < 0.01) for gastric cancer as compared with other histological classifications and control peptide.CONCLUSION: A novel peptide is discovered to have a specific binding activity to gastric cancer, and can be used to distinguish neoplastic from normal gastric mucosa, demonstrating the potential for early cancer detection on endoscopy.     

Identification of targeting peptides for ischemic myocardium by in vivo phage display

Therapies selectively targeting ischemic myocardium could be applied by intravenous injection. Here, we report an approach for ischemic tissue-selective targeting based on in vivo screening of random peptide sequences using phage display. We performed in vivo biopanning using a phage library in a rat model of ischemia-reperfusion and identified three peptide motifs, CSTSMLKAC, CKPGTSSYC, and CPDRSVNNC, that exhibited preferential binding to ischemic heart tissue compared to normal heart as well as other control organs. The CSTSMLKAC sequence was capable of mediating selective homing of phage to ischemic heart tissue. The CSTSMLKAC peptide was then made as a fusion protein with Sumo-mCherry and injected intravenously in a mouse model of myocardial ischemia-reperfusion injury; subsequently, bio-distribution of Sumo-mCherry-CSTSMLKAC was measured with quantitative ELISA. The targeting peptide led to a significant increase in homing to ischemic left ventricle compared to tissues from non-ischemic left ventricle, the right ventricle, lung, liver, spleen, skeletal muscle, and brain (all p < 0.001). These results indicate that the peptide sequence CSTSMLKAC represents a novel molecular tool that may be useful in targeting ischemic tissue and delivering bioengineered proteins into the injured myocardium by systemic intravenous administration.     

人源性大肠癌Fab段噬菌体抗体库的免疫组化鉴定

目的：鉴定基因工程抗体库技术构建的人源性大肠癌自然致敏噬菌体Fab段抗体库与人大肠癌组织及体外培养的大肠癌细胞的特异性结合活性。方法：通过免疫组化的方法检测抗体库对人大肠癌标本及体外培养的大肠癌lovo细胞的结合活性，并取绒毛状腺瘤、胃癌、食管癌及正常肠粘膜组织和体外培养的胃癌、肝癌细胞进行对照研究。结果：30例大肠癌有22例发生了阳性反应；肠息肉、胃癌、食管癌、正常肠粘膜各取20例，发生阳性反应的分别为13例、5例、4例和1例，体外培养的胃癌、肝癌细胞未发生阳性反应。结论：大肠癌噬菌体抗体库能较特异性地与人大肠癌组织及体外培养的大肠癌细胞结合。     

利用噬菌体展示肽库筛选和鉴定沙门氏菌O9抗原的模拟表位

目的　用生物素标记沙门氏菌O9单克隆抗体 (3- 4 7-O)作为分子探针 ,从两个九肽噬菌体展示文库中筛选鉴定该抗体所识别的抗原模拟表位 ,从而为模拟多糖的多肽疫苗或编码该模拟表位的DNA疫苗研制奠定基础。方法与结果　经过三轮的亲和筛选 ,得到了两个能与O9单抗反应的强阳性单克隆扩增物gm6 2和 gm6 8,其序列分别为SHHVRGGGG和YQKWYLPKS。竞争ELISA实验表明 ,10 10转导单位噬菌体 gm6 8对肠炎沙门氏菌与 3- 4 7-O结合的抑制率达到 6 5 % ,而噬菌体 gm6 2的抑制率仅为 2 0 % ,且 gm6 8可以诱导产生针对沙门氏菌O9的抗体 ,而gm6 2则不能。 结论　实验结果显示九肽YQKWYLPKS是具有免疫原性的O9抗原模拟表位。     

噬菌体展示技术筛选日本血吸虫抱雌沟蛋白分子受体

目的筛选日本血吸虫抱雌沟蛋白相互作用分子。方法利用噬菌体展示技术,以融合表达的抱雌沟蛋白为靶标,采用亲和淘洗方法筛选日本血吸虫44d成虫噬菌体展示cDNA文库。结果得到70条有效表达序列标签,对其进行聚类分析、同源性搜索与功能预测等生物信息学分析,获得5个与血吸虫抱雌沟蛋白有相互作用的蛋白或多肽。结论采用筛选噬菌体展示文库的方法成功获得抱雌沟蛋白相互作用分子。     

结核分枝杆菌T7噬菌体展示基因组DNA文库的构建与鉴定

目的 利用T7噬菌体作为载体,构建结核分枝杆菌的基因组DNA文库。方法 提取MTB的基因组DNA,用EcoR I和Hind III进行双酶切,以对基因组DNA进行片段化,并在其末端加上定向的EcoR I和Hind III黏性末端,用DNA片段纯化分离柱除去小于200 bp的片段和多余接头。将DNA片段与T7 10-3b噬菌体连接,经包装蛋白进行包装后转入BLT5403宿主菌以构建T7噬菌体展示基因组DNA文库,并检测文库的滴度和随机性。结果 成功提取到较高质量的MTB基因组DNA;构建的T7噬菌体展示基因组DNA文库的滴度约为6×10⁶ pfu/cm³;用PCR检测结果表明,在随机挑取的16个噬菌斑中,其重组率为100%,且插入片段都介于250~2 000 bp左右。结论 成功构建了MTB T7噬菌体展示基因组DNA文库,为从基因组范围筛选MTB的优势抗原奠定了前期实验基础。     

Human scFv antibody fragments specific for hepatocellular carcinoma selected from a phage display library

AIM: To identify the scFv antibody fragments specific for hepatocellular carcinoma by biopanning from a large human naive scFv phage display library. METHODS: A large human naive scFv phage library was used to search for the specific targets by biopanning with the hepatocellular carcinoma cell line HepG2 for the positive-selecting and the normal liver cell line L02 for the counter-selecting. After three rounds of biopanning, individual scFv phages binding selectively to HepG2 cells were picked out. PCR was carried out for identification of the clones containing scFv gene sequence. The specific scFv phages were selected by ELISA and flow cytometry. DMA sequences of positive clones were analyzed by using Applied Biosystem Automated DNA sequencers 3 730. The expression proteins of the specific scFv antibody fragments in F.coli HB2151 were purified by the affinity chromatography and detected by SDS-PAGE, Western blot and ELISA. The biological effect of the soluble antibody fragments on the HepG2 cells was investigated by observing the cell proliferation. RESULTS: Two different positive clones were obtained and the functional variable sequences were identified. Their DNA sequences of the scFv antibody fragments were submitted to GenBank (accession nos: AY686498 and AY686499). The soluble scFv antibody fragments were successfully expressed in E.coli HB2151. The relative molecular mass of the expression products was about 36 ku, according to its predicted M, value. The two soluble scFv antibody fragments also had specific binding activity and obvious growth inhibition properties to HepG2 cells. CONCLUSION: The phage library biopanning permits identification of specific antibody fragments for hepatocellular carcinoma and affords experiment evidence for its immunotherapy study.