日本血吸虫童虫早期诊断抗原模拟表位的初步筛选研究

目的：利用噬菌体随机12肽库技术筛选日本血吸虫感染早期诊断抗原。方法：用日本血吸虫感染后21d兔血清从噬菌体12肽库中经3轮筛选,有效地富集与早期感染兔血清有亲和力的噬菌体克隆。随机挑取11个单克隆分别纯化、扩增,随后采用ELISA、DOT-ELISA等检测方法,挑选出与早期感染兔血清有高亲和力的噬菌体克隆。结果：挑选出3个与感染后21d兔血清具有高亲和力的噬菌体单克隆。结论：用感染后21d兔血清从噬菌体随机12肽库中能筛选到日本血吸虫童虫早期诊断抗原模拟表位。     

应用随机肽库筛选展示河豚毒素模拟表位噬菌体

目的利用噬菌体随机肽库筛选展示河豚毒素(TTX)模拟抗原表位的噬菌体,并以其替代毒素建立免疫学检测方法。方法以抗TTX单克隆抗体为靶分子,从以融合蛋白形式表达在丝状噬菌体M13外壳蛋白Ⅲ表面的随机七肽库中进行生物亲和淘选,用ELISA法鉴定阳性克隆。结果通过4轮淘选,获得了7株能与抗TTX单克隆抗体特异性结合的噬菌体,采用间接竞争ELISA,筛选到3株能抑制TTX的阳性克隆。其中以4号噬菌体建立的免疫检测方法,线性范围为1～20ng/ml(TTX毒素浓度),R2=0.9947,检测下限为1ng/ml。结论从噬菌体七肽库筛选到了展示TTX模拟抗原表位的噬菌体,淘选出来的噬菌体粒子可作为毒素的替代品用于免疫学检测。     

幽门螺杆菌基因克隆表达及其抗原表位分析

目的 克隆表达幽门螺杆菌基因hp0410,构建12肽噬菌体展示库,对hp0410的抗原表位进行筛选和分析,为构建多表位嵌合疫苗提供理论依据.方法 从幽门螺杆菌NCTC11639基因组DNA中扩增出hp0410,并克隆入pGEX-4T-1中表达.利用纯化重组蛋白筛选出特异性单抗E018,利用该单抗和M13噬菌体12肽随机肽库,构建HP0410抗原表位的抗原展示库.竞争-抑制实验验证获得的阳性噬菌体并测序,生物信息学分析HP0410的抗原表位.结果 成功构建可高水平分泌型表达HP0410的原核表达系统.对13株阳性噬菌体测序后获得8个表位,其中候选表位1个.HP0410可有效抑制展示该表位的噬菌体与单抗E018结合.分析表明,获得的8个表位与HP0410同源性不高,但处于生物信息学预测的区域.结果 获得8个HP0410高抗原性区域的模拟表位,其中1个为模拟单抗E018特异性结合的抗原决定基的候选表位.     

采用噬菌体展示技术筛选黄曲霉毒素B_1模拟抗原表位

目的从随机肽库中筛选黄曲霉毒素B1模拟抗原表位,以建立无需黄曲霉毒素B1偶联抗原的免疫学检测方法。方法利用噬菌体展示技术,以抗黄曲霉毒素B1单克隆抗体为靶分子,从随机七肽库中进行生物亲和淘选,ELISA鉴定阳性克隆,通过DNA测序对每个阳性克隆进行定性分析。结果通过4轮结合/扩增循环,获得了能与抗黄曲霉毒素B1单克隆抗体结合的肽,采用间接竞争ELISA,筛选到了4株能抑制黄曲霉毒素B1的阳性克隆子,经DNA测序得到HXXDPXH共有序列,其中X为任意氨基酸。以其中P10噬菌体阳性克隆建立竞争ELISA方法,线性范围为500~2000pg/ml,检测下限为50pg/ml。结论利用噬菌体展示技术筛选到了黄曲霉毒素B1模拟抗原表位,并以其代替黄曲霉毒素B1偶联抗原建立了免疫学检测方法。     

生殖支原体黏附素蛋白模拟表位的筛选和鉴定

目的制备兔抗重组生殖支原体粘附素蛋白(rMgPa)的多克隆抗体(pAb),以期筛选MgPa的模拟表位。方法用rMgPa免疫新西兰兔以制备兔抗rMgPa的pAb,以此pAb为靶分子对噬菌体展示随机12肽库进行生物淘洗,随机挑取74个噬菌体克隆进行DNA测序与分析,用ELISA检测噬菌体与pAb结合的特异性。结果制备了兔抗rMgPa的特异性pAb,以此抗体为靶分子对噬菌体展示肽库进行生物淘洗后,特异性噬菌体克隆得到了明显富集。经对74个噬菌体克隆所展示的外源性多肽序列进行比较分析,共可大致分为3组一致性的核心序列:P-S-A-A/V-X-R-F/W-E/S-L-S-P,A-K-I/L-T/Q-X-T-L-X-L和K-S-L-S-R-X-D-X-I。ELISA结果说明36个噬菌体克隆能与pAb发生特异性结合,因此,这三组核心序列可能是MgPa的模拟表位。结论成功制备了兔抗rMg-Pa的pAb,并筛选到MgPa的3个可能的模拟表位,为进一步研究Mg的诊断与预防提供一定的实验依据。     

应用噬菌体展示技术筛选氯胺酮模拟表位的研究

目的应用噬菌体展示技术筛选氯胺酮模拟表位,为建立无毒ELISA检测体系提供基础。方法以抗氯胺酮单克隆抗体为配体,在噬菌体七肽库中淘选氯胺酮的模拟表位。经4轮淘选后,选择可与氯胺酮单克隆抗体有不同程度结合的噬菌体,并进一步以间接竞争ELISA确定与盐酸氯胺酮存在竞争抑制的阳性克隆。结果发现10个噬菌体均可与氯胺酮单克隆抗体不同程度的结合;以间接竞争ELISA确定其中5个阳性克隆与盐酸氯胺酮存在竞争抑制现象;5个阳性克隆测序结果表明,获得了4种不同的氨基酸序列。结论初步判断这4个噬菌体展示了氯胺酮模拟抗原表位。     

脱氧雪腐镰刀菌烯醇七肽模拟表位淘选及应用

目的从噬菌体随机七肽库中淘选脱氧雪腐镰刀菌烯醇（DON）的模似表位，并以之替代人工抗原建立ELISA检测方法。方法利用抗脱氧雪腐镰刀菌烯醇单克隆抗体12D1，从噬菌体随机七肽库中淘选到脱氧雪腐镰刀菌烯醇七肽模似表位，七肽模拟表位氨基酸序列为CMRPWLQ。以含有DON七肽模拟表位的噬菌体替代DON人工抗原建立DON间接竞争ELISA检测方法，检测范围为20-400ng／ml，并应用于小麦、玉米样品中DON含量的检测。结果检删结果与德国r—Biopharm公司DON检测试剂盒差异无统计学意义。结论DON噬菌体模拟表位替代DON人工抗原建立的ELISA检测方法可应用于小麦和玉米样品中DON的检测。     

噬菌体展示肽库筛选赭曲霉毒素A模拟表位的研究

目的从噬菌体随机肽库中筛选模拟赭曲霉毒素A表位的噬菌体粒子,并以其替代毒素建立免疫学检测方法。方法以抗赭曲霉毒素A的单克隆抗体为配基,免疫亲和筛选以融合蛋白形式表达在丝状噬菌体M13外壳蛋白Ⅲ上的随机七肽库,以ELISA方法鉴定阳性克隆,同时进行DNA测序确定插入七肽的氨基酸序列。结果经过4轮淘选,共筛选到11株能与该抗体特异性结合的阳性克隆,且该结合能被赭曲霉毒素A阻断,模拟表位的共有序列为IRPMVXX,X为任意氨基酸。以其中的P2号克隆建立了竞争ELISA检测方法,线性范围为200～8000pgml,检测下限为150pgml。结论噬菌体展示技术可成功筛选到赭曲霉毒素A模拟表位,筛选到的噬菌体粒子可作为毒素的替代品建立免疫学分析方法。     

用M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域表达HIV-1 gp41抗原表位

目的:探讨M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域表达融合蛋白的可行性。方法:以纯化的HIV-1感染者血清多克隆抗体为配体,在噬菌体展示随机十二肽库中进行生物淘洗,经ELISA鉴定阳性克隆,DNA测序,确定优势表位。将优势表位及两个优势表位的串联体分别与M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域连接,克隆入PQE30载体进行蛋白表达,再以表达蛋白为抗原检测HIV-1感染者血清中的抗体。结果:成功筛选到位于HIV-1 gp41蛋白上的3组优势抗原表位(HGPKDAETTAIW;AAFKDNQLLRIW;AAFKDNQLTRIW),3组优势表位及表位串联体(YGPKDAETTAIW-GGGS-SCSAKFTCTTQI)在PQE30载体中实现可溶性融合表达。重组蛋白具有良好的抗原性,能与不同的HIV-1抗体阳性血清呈特异反应。结论:用M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域表达HIV-1 gp41抗原表位是可行的。     

用M13噬菌体P H蛋白Ⅰ-Ⅱ结构域表达HIV-1 gp41抗原表位

目的：探讨M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域表达融合蛋白的可行性.方法：以纯化的HIV-1感染者血清多克隆抗体为配体,在噬菌体展示随机十二肽库中进行生物淘洗,经ELISA鉴定阳性克隆,DNA测序,确定优势表位.将优势表位及两个优势表位的串联体分别与M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域连接,克隆入PQE30载体进行蛋白表达,再以表达蛋白为抗原检测HIV-1感染者血清中的抗体.结果：成功筛选到位于HIV-1 gp41蛋白上的3组优势抗原表位（HGPKDAETTAIW;AAFKDNQLLRIW;AAFKDNQLTRIW）,3组优势表位及表位串联体（YGPKDAETTAIW-GGGS-SCSAKFTCTTQI）在PQE30载体中实现可溶性融合表达.重组蛋白具有良好的抗原性,能与不同的HIV-1抗体阳性血清呈特异反应.结论：用M13噬菌体PⅢ蛋白Ⅰ-Ⅱ结构域表达HIV-1 gp41抗原表位是可行的.     

Mapping the specificity of an anti-feline immunodeficiency virus monoclonal antibody using a filamentous phage displayed peptide library.

Recent developments in peptide technology enable the use of random peptide libraries for identifying linear amino acid sequences (mimotopes) which can mimic conformational epitopes without necessarily exhibiting amino acid sequence homology with the native linear sequence. In this study a 15-mer random peptide library displayed on the surface of a filamentous phage has been used to characterise the conformational epitopes recognised by a monoclonal antibody raised against the envelope protein gp120 of feline immunodeficiency virus (FIV). Three mimotopes were identified that reacted with the selecting antibody in an immunoblot assay. Sequence analysis revealed that, whereas the three mimotopes had several amino acids in common, there was no significant homology with the primary amino acid sequence of gp120 although some amino acids were shared between the variable region (V3) and the three mimotopes. Petide mimtopes of complex retroviral glycoproteins may have potential uses as novel vaccines and for the serological diagnosis of FIV.     

Peptide mimotopes of rabies virus glycoprotein with immunogenic activity

A random constrained hexapeptide phage display library (Cys-6aa-Cys) was screened with purified neutralizing human anti-rabies virus IgG antibodies (hRABVIgG) to identify peptides that correspond to or mimic natural epitopes on rabies virus glycoprotein (RABVG) and to investigate their immunogenicities in vivo. After four rounds of biopanning, 20 phage clones randomly selected for their specificity to hRABVIgG, effectively blocked the binding of the inactive rabies virus (RABV) to hRABVIgG. The phage clones were sequenced and the deduced amino acid sequences were derived (C-KRDSTW-C; C-KYLWSK-C; C-KYWLSR-C; C-KYWWSK-C; C-KYAWSR-C; C-KYSMSK-C). Alignments to the amino acid sequence of RABVG showed good match with the antigenic site III (at 330–338 aa), indicating that the hRABVIgG antibodies most likely recognize preferentially this antigenic site. The selected mimotopes were able to inhibit the interactions of the hRABVIgG antibodies with RABV in a dose-dependent manner. Subcutaneous administration of phageKRDSTW expressing the RABVG site III mimotope induced an RABVG-specific IgG response in BALB/c mice. The results indicated that peptide mimotopes when displayed on phages, are accessible to the mice immune system to trigger a humoral response and to induce IgG production. The RABVG site III mimotope (C-KRDSTW-C) would provide a new and promising concept for the development of rabies vaccine.     

脂多糖结合蛋白与脂多糖结合位点模拟肽的筛选

目的应用噬菌体随机12肽库筛选脂多糖结合蛋白（LBP）与脂多糖结合位点的多肽序列。方法以脂多糖为固相筛选分子,对噬菌体12肽库进行4轮亲合筛选,采用酶联免疫吸附法鉴定筛选后的噬菌体克隆与脂多糖的结合活性．取结合活性较高的克隆进行DNA测序,推导其多肽序列并与LBP序列比对,再进行竞争抑制实验检测筛选噬菌体与LBP竞争结合的效力。结果选取的86个噬菌体克隆中,多数结合实验鉴定阳性,取20个亲和力最高的克隆测序,得到20条不同编码的12肽序列,20条多肽与LBP一级结构有不同程度同源性,均为模拟肽。12个噬菌体克隆有较高的竞争抑制率。结论用噬菌体12肽库成功筛进出LBP与脂多糖结合位点模拟肽为讲一步以技蜱多肽曲鼻导物拼行串向讲什研密撂僻了宴聆依据和结构其础     

Selection of an immunogenic peptide mimic of the capsular polysaccharide of Neisseria meningitidis serogroup A using a peptide display library

The presently available meningococcal vaccine is poorly immunogenic in infants and fails to induce long-lasting immunity in adults. Efforts to convert this TI-2 type vaccine into a T dependent vaccine are being actively pursued and include conjugate vaccine development. Alternatively, the meningococcal polysaccharide can be rendered into a T dependent antigen through the use of peptides which mimic the capsular polysaccharide complexed or conjugated to potent protein carrier molecules. We have previously developed an anti-idiotypic monoclonal antibody (mAb) based peptide mimic of meningococcal group C polysaccharide (MCPS). A direct approach to identification of peptide mimics of antigen is through the use of peptide display libraries. We have utilized a phage library and a mAb with specificity for meningococcal group A polysaccharide (MAPS) to screen for a peptide mimic of MAPS. Six different peptide motifs were selected with the use of the mAb. Thirty-eight of the 60 sequenced phage clones were represented by motif 1 and 2 which differed only in three amino acids at the carboxy terminus. Immunological assays were performed. Phage clones with motif 1 and 2 were capable of binding human hyperimmune sera and inhibiting the binding of human hyperimmune sera to nominal antigen. Immunization with motif 1 peptide complexed to proteosomes resulted in an anti-MAPS antibody response. Priming with the peptide proteosome complex induced an anamnestic response indicating the formation of immunological memory.     

Identification of mimotopes by screening of a bacterially displayed random peptide library and its use in eliciting an immune response to native HBV-preS

Bacterially-displayed peptide libraries have been widely used as an alternative to phage-displayed peptide libraries in screening epitopes or mimotopes of antibodies. Using a protective monoclonal antibody (mAb) 3B9 against hepatitis B virus (HBV) preS protein as target, mimotopes were successfully screened from a FliTrx random peptide library. To monitor the enrichment ratios of each round and to isolate higher affinity clones from the library, a modified procedure was performed in which the titer of eluted bacteria from an antibody-coated well (P value) was compared with that from a non-coated well (N value). After sufficient enrichment of the library, bacterial colonies were randomly picked and identified further by the monoclonal bacterial P/N value assay and Western blotting analysis. Immunization of mice with the selected bacterially-displayed mimotopes, including the enriched populations without clone identification, elicited strong specific immune responses against the recombinant preS protein. The present study provides a potentially rapid and effective strategy for the development of engineered live bacterial vaccines without the need for information about the aetiological agents or their antigens.     

肺吸虫模拟抗原诊断价值及序列分析

目的　探讨噬菌体展示肺吸虫模拟抗原的诊断价值并分析与天然抗原的同源性。方法　建立肺吸虫噬菌体模拟抗原的ELISA ,对肺吸虫病人、日本血吸虫病人、旋毛虫病人及健康者血清进行检测 ,分析其敏感性和特异性 ;提纯噬菌体模拟肽的DNA模板进行序列测定 ,以Blast软件分析其序列同源性。结果　肺吸虫模拟抗原的 6个阳性克隆中P5、P6、P8、P13、P16的阳性、阴性预测值及诊断效率均为 10 0 % ,P7的阳性、阴性预测值及诊断效率分别为 10 0 %、78.9%、86.7%。上述 6个克隆有 2个克隆的DNA序列完全相同 ,即 6个克隆包含了 5种不同的抗原表位 ;Blast分析表明 5个表位与已知的肺吸虫抗原表位无DNA序列的同源性。结论　肺吸虫模拟抗原对肺吸虫病具有一定的诊断价值 ,这 5种表位可能从空间结构上模拟了天然抗原表位。     

A mimotope peptide-based anti-cancer vaccine selected by BAT monoclonal antibody

Combinatorial phage display peptide libraries are employed to identify small molecules which bind with high affinity to receptor molecules and which mimic the interaction with natural ligands. We used a synthetic combinatory phage display peptide library to screen for peptides that bind BAT monoclonal antibody, an immune modulatory and anti-tumor antibody, to serve as the basis for an anti-cancer vaccine. Two distinct mimotopes, peptides A and B, were isolated, with repeated Proline, Arginine, and Isoleucine amino acids. Mimotope binding was determined by direct binding and by inhibition of BAT binding to the peptide bound phages and to Daudi cells. Immunization of mice with the peptides induced cellular and humoral responses. Cellular response was manifested by significant increase in cytolitic activity. Humoral response was manifested by production of specific antibodies. Serum purified IgG fraction contained anti-peptide antibodies that identified BAT binding mimotopes and competed with BAT binding on Daudi cells. These "BAT like" antibodies exhibited similar immune stimulatory properties to BAT. Immunization of mice with the peptides prevented tumor growth. These finding are the basis for the development of an anti-cancer vaccine.