幽门螺杆菌UreB抗原表位预测及其有效表位噬菌体展示的筛选

目的 筛选幽门螺杆菌（Hp）尿素酶B亚单位（UreB）分子中的抗原表位，为研制多抗原肽（MAP）疫苗奠定基础。方法 采用生物信息学技术对UreB的T细胞和B细胞表位进行预测和分析。构建ureB基因原核表达系统，Ni-NTA亲和层析法提纯目的重组表达产物rUreB，常规皮内免疫法制备兔抗血清。选择UreB主要T细胞和B细胞联合表位肽并构建其噬菌体展示系统，PEG／NaCl沉淀法提纯重组噬菌体，SDS-PAGE鉴定目的重组PⅢ蛋白（rPⅢ）。分别以商品化抗跏全菌IsG和rUreB抗血清为一抗，采用Western blot对上述表位肽进行鉴定和筛选。结果 与GenBank中相关序列比较，所克隆的ureB基因核苷酸和氨基酸相似性分别为96％～99．5％和96％～100％。rUreB表达量约为细菌总蛋白的52％，提纯后仅见单一蛋白条带。预测的4个主要表位肽UreB230、UreB322、UreB479和UreB527在M13噬菌体中获得成功表达，采用不同一抗的Westernblot均显示相似的阳性结果，但UreB322和UreB527反应强度明显高于UreB230和UreB479。结论 本研究成功地构建ureB基因高效原核表达系统和UreB主要T细胞和B细胞联合表位肽噬菌体展示系统。所采用的生物信息学技术可有效地预测抗原表位。UreB322和UreB527是UreB有效抗原表位，可作为幽门螺杆菌MAP疫苗的候选表位。     

人类肝素酶B细胞表位的预测和免疫原性鉴定

目的 预测并鉴定肝素酶(heparanase)蛋白B细胞表位免疫原性.方法 以肝素酶蛋白的氨基酸序列为基础,采用DNAStar分析软件以及Bcepred在线二级结构分析工具分析其蛋白二级结构并预测B细胞表位.根据预测结果 ,采用8分支多抗原肽结构合成针对该表位的抗原肽,将后者与通用型T辅助表位人IL-1β线性短肽(VQGEESNDK,氨基酸163～171)联合免疫日本白毛黑眼兔,检测免疫血清效价,鉴定其特异性和免疫原性.结果 软件预测显示,肝素酶蛋白大亚基的第1～15位(MAP1)、第279～293位(MAP2)及175～189位(MAP3)氨基酸序列最可能为其优势B细胞表位.间接酶联免疫吸附试验、免疫印迹及免疫组化分析,证实MAP1、MAP2及MAP3均能诱导机体产生高滴度抗体,但仅MAP1、MAP2抗体具有高特异性,MAP2抗体与肝癌组织的结合力最强.结论 肝素酶大亚基的第1～15位、第279～293位氨基酸为其优势B细胞表位,其中第279～293位氨基酸的免疫原性最强,这为肝素酶多肽抗体及B细胞优势短肽疫苗研制提供了理论依据.     

鼠Mincle蛋白B细胞抗原表位预测及多克隆抗体制备

目的预测鼠Mincle蛋白的B细胞抗原表位及制备其多克隆抗体。方法以鼠Mincle蛋白氨基酸序列为基础,利用signalP3.0和TMHMM Server在线软件分析其信号肽和跨膜结构,利用DNAstar软件预测其二级结构、蛋白骨架区的柔韧性、亲水性、表面可能性及表面抗原性指数;融合表达PET30a(+)/Mincle蛋白并通过镍层析柱纯化后,免疫兔获得Mincle多克隆抗体。结果 Mincel蛋白是一种跨膜蛋白质,N末端第1-22号氨基酸可能位于蛋白的表面并可能为抗原表位;成功构建了重组载体PET30a(+)/Mincle,转化大肠杆菌BL21后表达包涵体融合蛋白,利用镍亲和层析得到了无生物活性的高纯度重组蛋白,纯化蛋白免疫兔,制备了滴度达1:128 000的多克隆抗体;Western-blot检测显示抗体特异性高。结论 Mincle蛋白N端即胞外区的第1-22氨基酸可作为Mincle蛋白的主要抗原表位区以制备Mincle多克隆抗体。     

狂犬病毒核蛋白基因的克隆及核蛋白主要抗原表位分析

目的:克隆狂犬病毒ERA株核蛋白基因并对核蛋白主要抗原表位进行分析.方法:根据GenBank中已发表的RV N基因序列,设计合成了1对特异性引物,对RV ERA株N基因进行了RT-PCR扩增.将PCR产物纯化后与pMD18-T连接得到重组质粒pMD-N,并进行核苷酸序列测定.结果:该基因全长1 353 bp,编码450个氨基酸.RV ERA株与Gen-Bank中RV不同固定毒株和分离毒株N基因相比,核苷酸的同源性为98.0%～99.6%,推导的氨基酸序列的同源性为98.3%～99.60A,.核蛋白主要抗原表位分析表明,ERA株与其他固定毒株和分离毒株相比,仅在BC抗原表位(369～383位氨基酸)和Th抗原表位(394～408位氨基酸)处有1～3个氨基酸的不同,其他表位无差异.但与Iagos bat、Mokola和Duvenhage毒株相比,抗原位点氨基酸组成差异明显.结论:RV ERA株N基因可用于基因工程疫苗研制和核酸检测的靶基因;核蛋白可作为抗原用于狂犬病的检测.     

T细胞表位预测研究进展

T细胞表位是指抗原经过抗原提呈细胞加工后，由MHC分子提呈给T细胞受体的短肽。随着分子生物医学和分子免疫学技术的发展，尤其是计算机在生物学中的广泛应用，对T细胞表位可以进行初步预测。本文就T细胞表位预测的分子基础、CTL抗原表位和Th抗原表位预测研究进展作一简要综述。     

统计学筛选电脑预测的人H5N1毒株核蛋白B细胞表位

目的 预测并筛选人禽流感H5N1毒株核蛋白(NP)的B细胞抗原表位.方法 采用DNAStar Lasergene 7.1软件,进行人禽流感H5N1毒株NP基因核苷酸序列分析.采用Kyte-Doolittle的亲水性方法、Emini方法和Jameson-Wolf抗原指数方法,辅以对NP的二级结构中的柔性区域的分析,采用SPSS13.0进行聚类、相关和四分位数分析,建立一种统计学筛选程序,预测H5N1病毒NP的B细胞表位,并对毒株A/GD/01/06(H5N1)的NP变异进行评价.结果 预测并筛选最有可能的B细胞表位为位于NP的N端317～326、452～457、467～473、367～370、491～498、375～378、171～177、48～53、245～250、76～104肽段等.A/GD/01/06(H5N1)的NP通过氨基酸第370位(N370S)位点置换,增加一个糖基化位点(NES368-370)并改变NP的特性.结论 用多参数预测并统计学筛选H5N1毒株NP的B细胞表位,可以为分子免疫学研究和药物筛选提供依据.A/GD/01/06(H5N1)毒株NP氨基酸第370位(N370S)位点置换改变其抗原性,但抗原表位大小未变(SNEN367-370).     

旋毛虫Ts87抗原单克隆抗体的制备及其识别肽段的研究

将原核系统成功表达的Ts87重组蛋白纯化后免疫动物,利用淋巴细胞杂交瘤技术制备抗Ts87抗原的单克隆抗体.通过ElISA、免疫印迹、免疫组化等方法筛选出能分泌抗Ts87御抗原的抗体的阳性克隆,在1000个融合的杂交瘤细胞中,有3株融合细胞分泌的单克隆抗体(2A2,5A3,6G12)鉴定结果为阳性.这3株融合细胞分泌的抗体均能识别Ts87重组蛋白、旋毛虫成虫和幼虫的Ts87抗原以及旋毛虫幼虫组织切片.获得的抗Ts87抗原的单克隆抗体在将来的研究中可作为旋毛虫病的诊断试剂.为了进一步鉴定抗体识别的相应抗原表位和模拟抗原表位,选择了其中一株单克隆抗体5A3筛选噬菌体十二肽库.噬菌体M7展示的肽段是抗体识别Ts87抗原的线性表位,其他的噬菌体克隆展示的肽段是Ts87抗原的模拟表位.该技术为旋毛虫病多表位疫苗的构建奠定了基础.     

应用噬菌体随机十二肽库筛选旋毛虫Ts87蛋白抗原表位

以抗旋毛虫Ts87蛋白单克隆抗体2A2作为靶标,对噬菌体展示随机十二肽库进行筛选.通过ELISA鉴定筛选克隆的结合特性,并对阳性克隆提取DNA进行测序分析.结果显示,经3轮生物淘洗后,目标噬菌体得到433倍富集.随机挑选20个克隆进行ELISA鉴定,其中有18个噬菌体克隆可以与单抗2A2特异性结合.测序分析发现,这18个克隆带有4种氨基酸序列,分别为:TPHPHIFYREAS、DWKAWTQMLDSY、WQIEYFrLHSLW和VSPHEYWSEL.经比对未发现这4种序列与Ts87蛋白序列有明显同源性.将这4株噬菌体克隆扩增后,经Western-blot鉴定均可被单抗2A2识别.结果表明本次筛选鉴定得到的4个噬菌体展示肽可能是旋毛虫 Ts87蛋白的模拟抗原表位.     

T细胞表位预测研究进展

T细胞表位是指抗原经过抗原提呈细胞加工后 ,由MHC分子提呈给T细胞受体的短肽。随着分子生物医学和分子免疫学技术的发展 ,尤其是计算机在生物学中的广泛应用 ,对T细胞表位可以进行初步预测。本文就T细胞表位预测的分子基础、CTL抗原表位和Th抗原表位预测研究进展作一简要综述。     

肿瘤相关抗原CEA的B细胞表位预测

目的分析癌胚抗原（carcinoembryonic antigen,CEA）的B细胞表位,为肿瘤治疗提供理论基础。方法以CEA的完整氨基酸序列为研究基础,采用Hopp＆Woods的亲水性方案,Emini表面可及性方案和Jameson-Wolf抗原指数方案,辅以CEA的二级结构及其柔性区域分析,预测CEA的B细胞表位。结果预测的B细胞表位可能位于CEA的N端第150～160、168～172、207～211、332～338、372～377、467～472、485～490、507～516、580～584区段。结论应用多参数预测CEA的B细胞表位,可进一步用于CEA相关肿瘤治疗性表位疫苗的分子设计和研究。     

应用RNA干扰技术对旋毛虫Ts87基因功能的初步研究

为研究旋毛虫Ts87基因的功能,通过RNA干扰途径抑制目的基因的表达。针对Ts87基因序列设计并合成特异性dsRNA、siRNA,通过浸泡方式分别将dsRNA、siRNA导入肌幼虫体内,利用实时荧光定量PCR分析Ts87基因及旋毛虫管家基因GAPDH的表达。此外,测定RNA干扰作用下的肌幼虫体外存活率的变化。根据实时荧光定量PCR结果,dsRNA及siRNA均能有效抑制Ts87基因mRNA的表达。此外,两种RNA能够在一定程度上降低肌幼虫体外存活率。实验表明,RNA干扰技术能够有效抑制旋毛虫功能基因Ts87表达,从而为研究旋毛虫基因的功能提供一种新的有效途径。     

旋毛虫Ts87重组蛋白诱导的小鼠黏膜免疫保护性研究

本实验探讨旋毛虫Ts87重组蛋白灌胃免疫小鼠诱导的黏膜免疫保护性作用。实验分对照组、佐剂组(霍乱毒素B亚单位组,CTB)和免疫组(CTB Ts87重组蛋白),灌胃免疫,间隔1周共免疫3次。末次免疫后第7天用400条旋毛虫感染期幼虫攻击,比较3组小鼠肠道成虫数、雌虫生殖力和肌幼虫数。且于末次免疫后第7天刮取肠黏液、取血检测特异性sIgA、IgG抗体水平。结果显示免疫组小鼠成虫减虫率、新生蚴减虫率、肌幼虫减虫率分别是81·34%、67·02%、84·49%;小鼠肠黏液sIgA水平及血清IgG水平显著高于对照组和佐剂组。结果表明Ts87重组蛋白黏膜免疫能够诱导小鼠产生抗旋毛虫的保护性免疫。灌胃免疫能显著提高肠黏液特异性sIgA水平,对促进肠道成虫的排出有明显作用。     

日本血吸虫钙蛋白酶肽链文库的制备及其B细胞表位的筛选

目的 筛选钙蛋白酶（calpain)的B细胞表位，探讨其B细胞表位的免疫原性及其所诱导的免疫应答类型。方法 用Genetyx-MAC9.0分析calpain肽连的亲水性，在亲水性区域以9个氨基酸为肽链单位的固相重叠钛链库（每相邻两个肽链之间仅有一个氨基酸不同）被Auto-spot Robot制备，用Dot-ELISA在合成的肽链库上筛选B细胞表位，含有B细胞表位的肽链免疫BALB／c小鼠，ELISA鉴别特异性IgG抗体亚类的产生。结果 由758个氨基酸组成的日本血吸虫calpain蛋白含有2个主要的亲水区，其存在区域分别在氨基酸229－375和555－613；当我们测定合成的肽链文库时，在亲水区内筛选出4个B细胞的表位，分别是氨基酸234－251（YAHLSGGT）；290－297（CLMGCSIH）；338－346（PWGDSHEW）；358－364（AWCDGAPQ）；与对照组鼠相比较免疫鼠血清中IgG1、IgG2a、IgG2b特异性抗体有显著性意义的上升。结论 日本血吸虫calpain是一个具有免疫原性的蛋白，能够激发宿主产生高水平的免疫球蛋白，提示calpain的B细胞表位可以成为日本血吸虫的诊断抗原和日本血吸虫疫苗候选分子。     

Study of antibody and T cell responses in rabbits immunized with synthetic human B cell epitope analogues of La (SSB) autoantigen

The aim of this study was to investigate the immunogenicity of four synthetic peptides, representing linear B cell epitopes of the human La/SSB autoantigen: 145-164 aa (p1), 289-308 aa (p2), 301-318 aa (p3) and 349-364 aa (p4), in rabbits. New Zealand White rabbits were immunized with each of the above peptides attached in four copies on tetrameric sequential oligopeptide carriers (SOC) in duplicate. Control immunizations were also performed (one rabbit each, immunized with Freud's complete adjuvant alone or with the SOC carrier alone). Animals were bled at regular intervals and sera were analysed for anti-La/SSB activity by ELISA assays using as antigen the various synthetic peptides, as well as the whole La/SSB protein. Four months after the last immunization, the animals were killed and peripheral blood mononuclear and spleen cells were co-cultured with either the peptides, the SOC carrier, or 27 peptides, covering the entire length of the human La/SSB molecule (23 amino acids long, overlapping by eight residues to each other). A specific, IgG, anti-peptide antibody response was detected, initially directed against the priming peptide, and subsequently expanded to the other La/SSB synthetic peptides. The antibody titres remained high, even 4 months after the last immunization. Sera from rabbits immunized with either p2 or p3 reacted also with the whole La/SSB protein, as was demonstrated by ELISA and immunoblot assays. No reactivities against either Ro60 or Ro52 autoantigen were found. Rabbit spleen cell reacted not only with the epitope used for the immunization but also with other La/SSB peptides. Immunization of rabbits with the major human La/SSB B cell antigenic determinants, linked to SOC carrier, induces strong and sustained antibody and T cell responses against multiple epitopes of the human La/SSB protein. Thus, La/SSB B cell linear epitopes are probably capable also of functioning as T cell epitopes, in this experimental animal.     

Immunogenicity of a recombinant fusion protein of tandem repeat epitopes of foot-and-mouth disease virus type Asia 1 for guinea pigs

In this study, the sequences of capsid protein VPI regions of YNAs1.1 and YNAs1.2 isolates of foot-and-mouth disease virus (FMDV) were analyzed and a peptide containing amino acids (aa) 133-158 of VP1 and aa 20-34 of VP4 of FMDV type Asia I was assumed to contain B and T cell epitopes, because it is hypervariable and includes a cell attachment site RGD located in the G-H loop. The DNA fragments encoding aa 133-158 of VP1 and aa 20-34 of VP4 of FMDV type Asia 1 were chemically synthesized and ligated into a tandem repeat of aa 133-158-20 approximately 34-133-158. In order to enhance its immunogenicity, the tandem repeat was inserted downstream of the beta-galactosidase gene in the expression vector pWR590. This insertion yielded a recombinant expression vector pAS1 encoding the fusion protein. The latter reacted with sera from FMDV type Asia 1-infected animals in vitro and elicited high levels of neutralizing antibodies in guinea pigs. The T cell proliferation in immunized animals increased following stimulation with the fusion protein. It is reported for the first time that a recombinant fusion protein vaccine was produced using B and T cell epitopes of FMDV type Asia 1 and that this fusion protein was immunogenic. The fusion protein reported here can serve as a candidate of fusion epitopes for design of a vaccine against FMDV type Asia 1.     

肿瘤抗原MAGE-A亚家族共同B细胞表位预测及分析

目的预测肿瘤抗原MAGE-A亚家族的B细胞表位,为基于多靶点的肿瘤疫苗设计提供依据。方法基于MAGE亚家族各成员蛋白质序列,采用Kyte-Doolittle的亲水性方案,Emini方案,Karplus方案和Jameson-wolf抗原指数方案,并辅以MAGE蛋白的二级结构柔性区域分析,预测MAGE基因家族的B细胞共同表位。结果共预测出了5条共同表位,且部分B细胞表位高度相似或一致。结论二级结构与B细胞表位相结合的预测方法为一种高效、准确的表位预测方法,可为肿瘤治疗性疫苗的设计提供实验依据。     

Identification of human T cell epitopes in the Mycobacterium leprae heat shock protein 70-kD antigen.

In a number of pathogens, heat shock proteins (hsp) stimulate humoral and cellular immune responses despite significant sequence identity with host hsp. The 70-kD hsp of Mycobacterium leprae, which shares 47% identity with human hsp70 at the protein level, elicited a T cell response in most Myco. bovis (bacille Calmette-Guérin (BCG)) vaccinees as well as leprosy and tuberculosis patients and their contacts. In order to locate T cell epitopes, DNA fragments encoding portions of the 70-kD hsp were expressed in the vector pGEX-2T and tested for T cell reactivity in an in vitro proliferative assay. Cultures of peripheral blood mononuclear cells (PBMC) from BCG vaccinees indicated that the C-terminal half of the molecule contained multiple T cell epitopes, as the T cells from a majority of Myco. leprae hsp70-reactive individuals responded to C-344. Lower proportions of patients with paucibacillary leprosy (36%) and tuberculosis patients (16%) responded to C-344. The smaller C-142 fragment which includes the terminal 70 residues unique to Myco. leprae and is the target for the human antibody response elicited a cellular response in few patients and no vaccinees. In order to map T cell epitopes, two series of synthetic peptides encompassing the region 278-502 were prepared. Using overlapping 12mer and 20mer peptides, this region of the molecule was found to contain several potential T cell epitopes. The longer peptides gave a clearer indication of reactive sequences including regions of the molecule which were not identified with the 12mer peptides. Fine mapping of reactive peptide pools using the 12mer peptides identified two T cell epitopes. Although both were located in regions of the molecule shared with Myco. tuberculosis, one appeared to be cross-reactive with the equivalent human sequence, and thus has the potential to initiate autoimmune responses.     

嗜肺军团菌MompS抗原二级结构分析及表位预测

目的分析嗜肺军团菌MompS抗原的二级结构并预测其B细胞表位,初步判断其活性多肽所在区域。方法联合运用多种方法对MompS的二级结构和表面特性,如亲水性、理化性质、可及性、免疫原性和可塑性等方面进行分析,预测其抗原表位。结果 MompS存在多个潜在抗原表位位点,可能的蛋白质抗原表位分布于三个区域：M1（353-546）、M2（1-215）、M3（216-399）。体外实验证明,所预测抗原表位区域基本能与免疫血清发生抗原特异性反应。结论应用DNA Star和胞外区在线分析软件能够成功预测MompS抗原的B细胞表位,M3区域可用于后续的活性肽表位筛选区域。     

Analysis of antibody response to the measles virus using synthetic peptides of the fusion protein Evidence of non-random pairing of T and B cell epitopes

The measles virus induces a life-long immune response associated with antibodies specific for the fusion protein. To map the linear immunodominant recognition sites of the fusion (F) protein of the measles virus, we have reacted a complete set of 108 overlapping pentadecapeptides with purified IgG obtained from donor sera with elevated anti-measles titers. The antibodies recognized about 20% of the peptides and generated a characteristic binding pattern, defining about 6 or 7 distinctive regions (31–75; 111–145; 151–165; 191–215; 271–320; 421–440; 481–530) which include the major hydrophobic segment (111–145) of the intersubunit region and the C-terminal Cys-cluster region. The binding sites were located in close proximity of the few experimentally defined T cell epitopes. This pairing of T and B cell epitopes was corroborated by computer-assisted T cell prediction. The significance of a non-random association of T and B cell epitopes for processing and presentation is discussed. It is speculated that in long-term immunity against measles (F protein), B cells of the same sIg specificity play an important role both as antigen presenting cells and as antibody producing cells. In contrast to human sera from late convalescent donors, mouse and rabbit MV antisera with high neutralizing titers as well as neutralizing MV-F specific monoclonal antibodies did not react with the peptides.