恶性疟原虫感染的红细胞膜表面蛋白1模拟肽的筛选及鉴定

目的 筛选恶性疟原虫感染的红细胞膜表面蛋白1（PfEMP?鄄1）的噬菌体表位模拟肽。 方法 细胞间粘附分子ICAM-1模拟12肽（KLYLIAEGSVAA）能模拟ICAM-1分子与疟原虫感染红细胞结合的功能，以展示该短肽的噬菌体为靶，采用差减筛选法（subtraction method）对噬菌体环7肽库进行3轮筛选，通过ELISA、竞争抑制试验鉴定获得的噬菌体短肽与ICAM-1之间的结合特性。对阳性克隆进行DNA及氨基酸序列分析并与PfEMP-1氨基酸序列进行同源性比较。 结果 ELISA筛选22个克隆有3个为阳性克隆，氨基酸序列分析显示2个克隆的展示的短肽序列为C-ITAVPVR-C，另1为C-DIMGGYN-C。同源性分析未发现2短肽序列与野生型MC株恶性疟原虫PfEMP-1的氨基酸序列有同源性。但竞争抑制试验显示3个阳性克隆均可与15.2单抗间互相竞争抑制与ICAM-1分子的结合。 结论 获得2种PfEMP-1噬菌体构象表位模拟肽，两短肽能与ICAM-1分子特异性结合。     

广谱趋化作用抑制剂的体内筛选及其活性鉴定

目的为抗炎药物的研发提供先导肽。方法利用脂多糖（LPS）刺激SD大鼠建立炎症模型,应用噬菌体展示技术经大鼠体内筛选得到阳性噬菌体克隆,经体内回输实验、趋化抑制实验和竞争结合实验鉴定噬菌体克隆的活性,提取生物活性较好的10个阳性噬菌体克隆的DNA进行测序,据此推导插入的氨基酸序列。结果经过三轮体内筛选,目的噬菌体得到了有效富集。对10个趋化抑制效果较好的阳性噬菌体进行测序,共得到5个序列,其中有2个序列出现的频率均为30％。结论利用噬菌体展示技术体内筛选方法得到了抑制趋化作用的相关肽;该相关肽可作为抗炎药物的先导肽。     

用噬菌体展示随机7肽库筛选血型A抗原模拟肽

目的:通过血型A单克隆抗体从噬菌体展示随机7肽库中筛选血型A抗原的模拟多肽。方法:通过对噬菌体随机7肽库进行3轮亲和筛选,从第三轮筛选后获得的洗脱物中挑选多个噬菌体克隆,采用ELISA方法鉴定阳性克隆,测序并推导噬菌体展示短肽的氨基酸序列,化学合成短肽、红细胞凝集抑制试验鉴定短肽模拟A抗原的能力。结果:三轮筛选后特异性噬菌体被富集了200多倍,对ELISA鉴定信号较强的16个噬菌体克隆DNA测序并推导氨基酸序列的结果显示两个克隆展示相同的序列FSYLPSH。化学合成肽能抑制A型红细胞与抗A的凝集作用。结论:肽FSYLPSH具有模拟血型A抗原表位的作用,具有代替天然血型A抗原在临床中应用的潜能。     

人类白细胞抗原-B*2704/B*2705重链拮抗肽的筛选和初步鉴定

目的 从噬菌体展示随机12肽库筛选人类白细胞抗原(HLA)-B·2704及B·2705重链拮抗肽并做初步鉴定.方法 用HLA-B*2704/B*2705重链胞外区蛋白分别筛选噬菌体展爪随机肽库,酶联免疫吸附试验(ELISA)鉴定阳性克隆,DNA测定确定氨基酸序列,免疫荧光和流式细胞术鉴 ,定噬菌体克隆分别与HLA-B*2704及B*2705细胞株结合的特异性.结果 经3轮筛选,获得12个HLA-B·2704拈抗肽,共有5种序列,分别为HTSFCSTHLCLI(×4),QHCSPTLCQIHR(×5),ARCTITL-CYLSN(×1),YGLCTDWYCHIT(×1),YPLCDAILCRLP(×1);10个B*2705拮抗肽共有4种序列,分别为:①SHCSPHWCALPF(×6);②HLCSNSLCLLPW(×2);③EPMCSWFWCTLP(×1);④WTCSPLLCTWGA(×1).比对分析表明,B*2704与B*2705拮抗肽的序列是基本一致的,均含有CS(T)TXXL(W)CXL表位.展示有B*2704拮抗肽的噬菌体克隆可与HLA-B*2704细胞株结合,阳性率为43.55%;而B*2705拈抗肽噬菌体克隆与HLA-B·2705细胞株的阳性结合率为45.69%.结论 筛选获得的HLA-B27拈抗肽的噬菌体克隆具有一定的亲和力,可与表达于细胞株表面的B*2704和B**2705分子特异性结合,而与正常B细胞不结合,因而表现出一定的结合特异性.     

内皮抑素30肽抑制HepG2细胞侵袭转移的机制

目的探讨RGD修饰的人内皮抑素30肽抑制HepG2细胞侵袭转移的机制。方法以人内皮抑素27肽作为对照,采用细胞增殖实验和Transwell实验分别检测30肽对HepG2细胞增殖和侵袭能力的影响,同时筛选与侵袭作用相关的整合素;免疫荧光检测30肽对HepG2细胞表面αvβ3整合素的聚集作用;RT-PCR及Western印迹检测30肽对细胞诱导型环氧合酶(iCOX-2)、基质金属蛋白酶(MMP)-2和MMP-9 mRNA和蛋白表达的影响。结果 30肽能明显抑制HepG2细胞增殖、侵袭,对侵袭作用的影响与整合素αvβ3相关,同时30肽能下调Hep G2细胞中i Cox-2、MMP-2和MMP-9 mRNA及蛋白表达,30肽加入αvβ3抗体后,上述作用明显增强。结论 30肽可通过整合素αvβ3发挥其抗肿瘤侵袭转移作用。     

日本血吸虫童虫表膜结合多肽的亲和筛选与初步鉴定

目的筛选噬菌体十二肽库中与日本血吸虫(Schistosoma japonicum)童虫表膜特异性结合的多肽并鉴定。方法利用噬菌体十二肽库与日本血吸虫活童虫靶分子之间的亲和力结合,经3轮吸附-洗脱-扩增,从末次回收的结合噬菌体中随机挑取20个克隆进行测序。根据测序结果 ,选取出现次数最多的噬菌体克隆作为目标噬菌体,免疫组化检测目的噬菌体,并回输到已感染日本血吸虫的小鼠体内,2.5h后处死小鼠,回收肝脏和日本血吸虫童虫,分别洗脱与肝脏和童虫结合的噬菌体,进行统计学分析。结果经3轮筛选后,噬菌体回收率从第1轮的0.77×10-8到第3轮的0.75×10-5,说明噬菌体得到了有效富集。DNA测序结果表明,20个噬菌体克隆中的15个克隆呈现QHPRIRKOOOOO序列。免疫组化结果显示,表达该序列的噬菌体能与童虫表膜有效结合;体内回输试验证实,该噬菌体能有效地靶向结合于体内日本血吸虫童虫表膜。结论筛选获得的短肽QHPRIRKOOOOO能有效地靶向结合日本血吸虫童虫表膜。     

从人肝癌细胞cDNA表达文库筛选人肝再生增强因子相互作用蛋白及其活性初步鉴定

目的利用噬菌体表面展示技术筛选人肝再生增强因子(hALR)相互作用蛋白并初步鉴定噬菌体展示肽的生物学活性。方法以hALR为靶蛋白,采用T7噬菌体表面展示技术从人肝癌细胞cDNA表达文库筛选与 hALR相互作用的特异噬菌体克隆;对获得的特异噬菌体克隆cDNA插入片段进行测序及生物信息学分析;利用3H- TdR掺入法测定噬菌体展示肽及联合hALR对QGY肝癌细胞的增殖效应。结果经过四轮生物淘洗,特异噬菌体克隆富集,获得212 bp的噬菌体cDNA插入序列,生物信息学分析与人Citron激酶同源性达100％;该噬菌体展示肽及联合应用hALR对QGY细胞具有促增殖效应。结论利用噬菌体表面展示技术可以筛选出与hALR具有相互作用的多肽,该序列与人Citron激酶完全同源,Citron激酶可能参与了hALR促肝癌细胞增殖的过程。     

日本血吸虫特异性IgE抗体相关肽表位的筛选与免疫学鉴定

目的　从噬菌体表面显示肽库筛选并鉴定日本血吸虫特异性IgE抗体相关表位。 方法用ABC 酶联免疫吸附 (ELISA)法检测日本血吸虫病流行区居民血清 15 0份 ,选择其中 15份具高滴度血吸虫特异性IgE抗体的血清 ,混合后经蛋白G柱亲和层析祛除IgG抗体 ,用于对 12肽的噬菌体表面显示肽库进行 5轮免疫亲和淘筛。从所获噬菌体克隆中挑取 35个克隆 ,经DNA序列测定 ,对各独立肽表位进行免疫学鉴定。结果　经 5轮筛选 ,DNA序列测定显示共有 4个独立噬菌体克隆 ,其中 phage 3和 phage 6有较多重复克隆存在 ,为优势克隆 ;Westernblot分析显示 ,筛库血清中特异性IgE抗体能有效识别各噬菌体克隆。分别用各克隆噬菌体免疫小鼠 ,均能诱导特异性IgE抗体产生。结论　从 12肽噬菌体表面显示肽库中成功筛选到日本血吸虫特异性IgE抗体相关肽表位。     

噬菌体表达短肽模拟旋毛虫抗原表位及其抗血吸虫保护性免疫研究

目的　从噬菌体随机肽库中筛选出模拟旋毛虫特异性抗原表位的短肽分子 ,探讨其抗血吸虫的交叉免疫保护效果。　方法　以纯化的旋毛虫感染鼠血清IgG为配基 ,亲合筛选法富集特异性噬菌体 ,随机挑取噬菌体克隆用ELISA检测其特异性 ;混合噬菌体克隆经皮下免疫小鼠 3次 ,攻击感染后第 4 5天剖杀小鼠 ,观察减虫和减卵效果。　结果　经 3轮筛选 ,特异性噬菌体得到了有效的富集 ,第三轮洗脱噬菌体的产量约为第一轮的 15 0倍。随机挑取 2 4个噬菌体克隆经ELISA测定 ,有 2 1个克隆能与旋毛虫感染鼠血清IgG特异性反应。与对照组相比 ,混合噬菌体克隆免疫小鼠的减虫率与减卵率分别为 4 2 8%与 6 6 3% (P <0 0 0 1)。　结论　利用噬菌体随机肽库技术可获得模拟旋毛虫特异性抗原表位的短肽分子 ,这些短肽分子能诱导明显的抗血吸虫的保护性免疫。     

日本血吸虫雌虫抗原模拟表位的筛选及免疫保护性

目的　筛选日本血吸虫雌虫抗原的模拟表位 ,并探讨其抗日本血吸虫的免疫保护效果。　方法　用日本血吸虫雌虫免疫兔血清IgG作配体对噬菌体随机 12肽库进行 3轮亲和筛选 ,随机挑取 18个噬菌体克隆用Dot ELISA检测其特异性 ,并对其中的 4个阳性克隆进行测序。分别在 0、2、4周用混合噬菌体克隆免疫小鼠 3次 ,第 6周每鼠经腹部感染 40条日本血吸虫尾蚴 ,42d后剖杀冲虫 ,计数虫数和每克肝卵数。　结果　经 3轮筛选 ,特异性噬菌体富集了 2 0 0多倍 ,随机挑取的 18个克隆经Dot ELISA鉴定有 17个能与雌虫抗原免疫兔血清呈阳性反应。DNA自动测序的 4个序列与GenBank的已知序列均无同源性。与对照组相比 ,混合噬菌体克隆免疫小鼠的减虫率为 2 6.5 7% ,减卵率为 65 .3 4%。　结论　采用噬菌体随机肽库技术可获得模拟日本血吸虫雌虫特异性抗原表位的短肽分子 ,这些短肽分子能诱导一定程度的保护性免疫。     

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.     

金黄色葡萄球菌肠毒素SEC3抑制剂的筛选及活性鉴定

目的从噬菌体随机12肽库中筛选出金黄色葡萄球菌SEC3抑制剂并鉴定其活性。方法用纯化的重组的金黄色葡萄球菌SEC3包被酶标板,按吸附-洗脱-扩增的淘洗过程对噬菌体随机12肽库进行3轮筛选;用竞争ELISA法观察单个噬菌体克隆的竞争抑制效应,评价其活性。结果噬菌体3轮筛选的投入产出比逐轮升高,回收率从4.5×10-6升高至6.3×10-4,升高140倍,提示具有良好的富集效果;与阴性对照（未加噬菌体）相比,随机挑选的8个噬菌体克隆（A1~A8）竞争抑制率为10.6%~38.3%,差异有统计学意义（t值为9.0~23.5,P〈0.05）,其中A1平均竞争抑制率最高,为（30.5±7.4）%,A5的平均竞争抑制率最小,为（16.4±4.7）%。以噬菌体滴度对数值为x轴,以克隆噬菌体各滴度对应的平均竞争抑制率为y轴,绘制竞争抑制曲线,其回归方程为Y=2.7943X-4.7733,相关系数r=0.935,决定系数R2=0.8727。在噬菌体滴度在108~1012pfu范围内,随着噬菌体滴度的增高,其抑制率也增高,且克隆噬菌体滴度在1011pf或1012pfu的竞争抑制率最高。结论用纯化的SEC3从噬菌体随机12肽库中筛选的SEC3抑制剂具有一定的竞争抑制活性,而且竞争抑制活性随着噬菌体滴度的增高而增强。     

日本血吸虫辐照尾蚴模拟表位的筛选和初步鉴定

目的从噬菌体表面显示随机肽库中筛选日本血吸虫辐照尾蚴抗原模拟表位。方法用Sepharose4B亲和层析法,从日本血吸虫辐照尾蚴免疫鼠血清中纯化抗体,经正常血吸虫尾蚴抗原吸收后,用于12肽噬菌体随机肽库的免疫筛选。经三轮筛选,随机挑取20个噬菌体克隆,经DNA序列分析后,对各独立表位进行免疫学鉴定。结果DNA序列分析,获得4个有序列重复的噬菌体克隆;Dot-ELISA分析显示,4个克隆均能被辐照尾蚴免疫血清中IgM型抗体识别,反应强度有一定差别;P1和P2克隆还能被IgG型抗体识别。结论从噬菌体随机肽库中成功筛选到日本血吸虫辐照尾蚴抗原模拟表位。     

囊虫抗原模拟表位的筛选和序列分析

目的探讨能否从与兔抗蚯蚓血清免疫球蛋白(EIg)结合后的噬菌体12肽库中筛选囊虫抗原模拟表位。方法噬菌体12肽库经过EIg筛选1轮后,再以囊虫病患者血清免疫球蛋白(CIg)作为靶分子进行3轮吸附-洗脱-扩增,随机挑取24个蓝色噬菌斑扩增;分析其抗原性及诊断囊虫病的价值;并测定核苷酸序列分析同源性。结果24个克隆中有17个克隆可与囊虫病患者混合血清发生免疫反应,其中6个A491值较高的克隆ELISA和囊虫抗原DotELISA的抗体阳性率无显著性差异(P>0.05);与其它寄生虫病的交叉反应率明显低于囊虫抗原(P<0.05),说明所获克隆具有诊断囊虫病的潜在价值。挑选其中2个克隆(C3、C5)测定核苷酸序列,结果显示这两个抗原模拟表位的氨基酸序列具有结构同源性。结论将EIg结合后的肽库作为源肽库经过3轮筛选,得到对囊虫病具有较高潜在诊断价值的抗原模拟表位。     

细胞粘附因子-1与恶性疟原虫感染红细胞结合位点的鉴定

目的　探索恶性疟原虫感染红细胞(PRBCs)与细胞粘附因子1(ICAM1)之间的结合位点,研制治疗脑型疟的抗粘附药物。　方法　以抗ICAM1(I区)的单抗15.2为靶,采用亲和筛选法对噬菌体随机十二肽库进行3轮筛选,通过ELISA、竞争抑制试验、dotELISA及Westernblotting鉴定获得的噬菌体短肽与单抗15.2之间的结合特性。对阳性克隆进行DNA序列测定,推导其十二肽的氨基酸序列并与ICAM1氨基酸全序列进行同源性比较。　结果　经3轮亲和筛选后,结合噬菌体得到良好富集。从第3轮洗脱液铺制的琼脂板中随机挑取30个噬菌体单克隆,ELISA检测有26个为阳性,阳性率达86.7%。竞争性ELISA显示多数阳性噬菌体能竞争抑制ICAM1与15.2单抗结合。DNA及氨基酸序列分析表明半数以上的噬菌体克隆表达十二肽KLYLIAEGSVAA,该短肽中K(XX)L(XXX)GSV与ICAM1的64～73位aa有50%的同源性。　结论　阳性噬菌体表达的短肽是15.2单抗所识别的模拟表位,K··L···GSV几个氨基酸可能对ICAM1与PRBCs的结合起重要作用     

利用噬菌体展示技术筛选日本血吸虫模拟抗原表位

目的　从噬菌体肽库筛选日本血吸虫抗原模拟抗原表位。方法　制备亲和纯化的日本血吸虫病人血清抗体 Ig G,用此 Ig G包被酶标板对 12肽库进行反复淘选 ,对获得的目的噬菌体进行鉴定及免疫原性分析。结果　获得一批阳性噬菌体克隆 ,其中一部分与血吸虫病人血清反应产生较高的吸光值 ,Western blotting分析表明这些噬菌体能被血吸虫病人血清所识别 ,具有类似于血吸虫抗原的免疫原性。结论　获得一批具有模拟日本血吸虫抗原表位的噬菌体克隆 ,为今后进一步研究它们在血吸虫病诊断及疫苗研究中的作用奠定了基础。     

Identification of a peptide directed against the anti-CD34 antibody, 9C5, by phage display and its use in hematopoietic stem cell selection.

A peptide sequence was identified by phage display technology that could be used as an alternative to chymopapain for the release of hematopoietic progenitor cells captured by anti-CD34 monoclonal antibodies. This was achieved by affinity selection screening (biopanning) of a random hexapeptide sequence phage display library. Four rounds of biopanning were performed to enrich for phage clones with specific affinity for anti-CD34 monoclonal antibody, 9C5. DNA sequence analyses of these phage clones revealed an enrichment of two predominant sequences, QQGWFP and TQGSFW. These two clones also shared a consensus sequence motif, QGxF, that exhibited 50% and 67% homology with a region spanning amino acids 14-19 of the mature CD34 antigen. Based on these data, synthetic peptides were generated and assessed for their ability to release 9C5 from CD34+ cells. Using a flow cytometric assay, it was found that the synthetic peptide, 9069N, effectively released 9C5 from the CD34-expressing cell line, KG1a, in a concentration-dependent manner (77% and 99% release of 9C5 at 0.14 and 0.70 mM peptide concentrations, respectively). In the Isolex 300i immunomagnetic selection system, this peptide was shown to be effective at releasing 9C5 sensitized CD34+ hematopoietic progenitors from sheep anti-mouse IgG Dynabeads. Thus, a synthetic peptide, which specifically and efficiently released immunomagnetically selected hematopoietic progenitor cells from paramagnetic beads, was identified. This reagent is a significant advance in the selection of hematopoietic progenitors in that it does not alter cell surface antigens. As such, further phenotypic characterization or immunoselection can be performed.     

Identification of Hitherto Undefined B-Cell Epitopes by Antibodies in the Sera of Vitiligo Patients Using Phage-Display Peptide Library

A random 12 mers phage library was used to screen a pool of immunoglobulin fractions obtained from vitiligo patients. Subsequent to panning experiments, a panel of affinity selected phage from vitiligo patients were obtained. This panel was tested using an ELISA for their reactivity with pooled sera from patients and normal controls. Among the 16 randomly selected clones, two of clones showed distinct positive reactivity with the patient's sera compared with controls. The peptides displayed by these phages expressed the following amino acid sequences: SHMPLANQYQWA and NHVQAWEQFWDS. Thus, screening with phagedisplayed random peptide library of vitiligo sera can reveal peptide sequences that mimic vitiligo-related self-antigen.     

Production of a human single-chain variable fragment antibody against esophageal carcinoma

AIM: To construct a phage display library of human singlechain variable fragment (scFv) antibodies associated with esophageal cancer and to preliminarily screen a scFvantibody against esophageal cancer.METHODS: Total RNA extracted from metastatic lymph nodes of esophageal cancer patients was used to construct a scFv gene library. Rescued by M13K07 helper phage, the scFv phage display library was constructed, esophageal cancer cell line Eca 109 and normal human esophageal epithelial cell line (NHEEC) were used for panning and subtractive panning of the scFv phage display library to obtain positive phage clones. Soluble scFv was expressed in E.coliHB2151 which was transfected with the positive phage clone, then purified by affinity chromatography.Relative molecular mass of soluble scFv was estimated by Western blotting, its bioactivity was detected by cell ELISA assay. Sequence of scFv was determined using the method of dideoxynucleotide sequencing.RESULTS: The size of scFv gene library was approximately 9&#215;10^6 clones. After four rounds of panning with Eca109 and three rounds of subtractive panning with NHEEC cells,25 positive phage clones were obtained. Soluble scFv was found to have a molecular mass of 31 ku and was able to bind to Ecal09 cells, but not to HeLa and NHEEC cells.Variable heavy (VH) gene from one of the positive clones was shown to be derived from the γ chain subgroup IV of immunoglobulin, and variable light (VL) gene from the κ chain subgroup I of immunoglobulin.CONCLUSION: A human scFv phage display library can be constructed from the metastatic lymph nodes of esophageal cancer patients. A whole human scFv against esophageal cancer shows some bioactivity.     

原因不明性肝炎血清蛋白结合蛋白的筛选和鉴定

目的应用噬菌体表面展示技术寻找原因不明性肝炎血清蛋白成分在肝细胞表面的结合蛋白,探讨原因不明性肝炎发病机制。方法将原因不明性肝炎患者血清蛋白作为固相筛选分子,对噬菌体正常人肝细胞T7 cDNA文库进行4轮生物筛选,经噬斑PCR测序,获得原因不明性肝炎血清蛋白结合蛋白的cDNA序列,将其在GenBank中搜索,比对可能与原因不明性肝炎血清蛋白相结合的蛋白。结果筛选出已有功能研究的蛋白9个和未知功能蛋白3个。结论发现了12种可能与原因不明性肝炎血清蛋白结合的肝细胞表面蛋白,为进一步研究原因不明性肝炎的发病机制提供基础。