超抗原TSST－1的T细胞表位预测

本文采用可及性和可塑性方案对超抗原ＴＳＳＴ－１的Ｔ细胞表位进行预测，结果显示：Ｔ细胞表位可能位于残基６５～７８、９０～９５、１０８～１１２、１４４～１５２和１５８～１８０或它们附近。它们的二级结构均含无规则卷曲。在这些预测的Ｔ细胞表位中，有一个与文献报道的ＴＳＳＴ－１之Ｔ细胞表位基本相符，还有一个含有数个已确定的ＴＳＳＴ－１超抗原之必需氨基酸残基。本研究为用合成肽对ＴＳＳＴ－１Ｔ细胞表位的研究提供了线索。     

人DAO氨基酸序列片段B-细胞表位的多参数预测

目的 预测人二氨氧化酶（ＢＡＯ）氨基酸序列片段（ａａＮｏ．５２４－６１８）的Ｂ－细胞表位。方法 应用６６中参数和方法进行综合分析。包括Ｈｏｐｐ ＆ Ｗｏｏｄｓ亲水性参数、抗原性参数、可及性参数、β－转角、万氏及吴氏综合预测方法。结果 显示Ｂ－细胞识别的表位可能在５４３－５３和５５９－５９５残基或其附近,５６９－５９５残基４种参数和方法的预测值均高于５４３－５５３残基,这两个被预测的表位均含有γ－志     

肿瘤抗原MAGE—12的表位及二级结构预测

目的 预测肿瘤抗原MAGE－12的α－螺旋二级结构、B细胞表位和MAGE－12的HLA－A2限制性CTL表位。方法 用Garnier-Robson和Chou-Fasman方案预测肿瘤抗原MAGE－12的α－螺旋二级结构;用Kyte-Doolittle亲水方案预测肿瘤抗原MAGE－12的B细胞表位;用简单基序（simple motifs)和延展基序（extended motifs）对肿瘤抗原MAGE－12的HLA－A2限制性CTL表位进行预测。结果 MAGE－12可以含有较多的α－螺旋;B细胞识别的表位可能在82－93残基（QSDEGSSNEE－QE）或附近和3－14残基（LEQRSQHCKPEE）或附近;发现1个HLA－A2限制性CTL表位为FLWGPRALV（271－279）。结论 用亲水性方案和基序法预测肿瘤抗原MAGE－12的B细胞表位和MAGE－12的HLA－A2限制性CTL表位,为实验方法探索MAGE－12的表位提供有用线索。     

IFN-γ和TNF-α诱导Fas表达在β胰岛细胞杀伤中的作用

目的：研究人β胰岛细胞Ｆａｓ的表达及细胞因子诱导Ｆａｓ表达量的增加在β胰岛细胞杀伤中的作用。方法：用ＦＡＣＳ检测ＩＦＮ－γ和ＴＮＦ－α作用于人β胰岛细胞株（ＮＩＴ）前后Ｆａｓ表达水平及ｓＦａｓＬ和抗Ｆａｓ介导细胞凋亡的变化。结果：ＮＩＴ表达无Ｆａｓ表达,ＩＦＮ－γ和ＴＮＦ－α可促进其Ｆａｓ表达增加,以及对ｓＦａｓＬ和ａｎｔｉ－Ｆａｓ介导细胞毒敏感性增加。结论：细胞因子诱导β胰岛细胞表面Ｆａｓ的表达可能在Ⅰ型糖尿病（ＩＤＤＭ）的病理损伤中起重要作用。     

合成多肽体外诱导乙肝病毒抗原特异性CTL杀伤机制研究

为探讨合成多肽体外诱导乙肝病毒抗原特异性Ｔ细胞杀伤机制，应用免疫组化检测ＨＧＶ－ＣＴＬｓＦａｓ配体表达情况，燕分析培养上清一氧化氮含量与细胞毒活性的关系。结果显示，ＨＢＶ－ＣＴＬｓ对转染ＨＢＶ ＤＮＡ的肝癌细胞存在明显的特异性细胞毒活性，其Ｆａｓ配体表达阳性率分别为５８％，５６％，明显高于ＣＤ３－ＡＫ细胞组，细胞培养上清ＮＯ含量动态分析显示，ＨＢＶ－ＣＴＬｓ细胞培养上清ＮＯ含量与细胞毒活性存在正相     

蛋白顺序性抗原决定簇的多参数综合预测

通过分析氨基酸序列的某些参数，可达到预测抗原决定簇。但没有一种单参数预测获得较满意结果。故有必要进行多参数联立综合预测，选用６个参数加权叠加，首先假设形成表位的残基上的原子数正比于Ｎ＾２／３（Ｎ为整蛋白中残基蛋白数），再对３４个共１６９个已知抗原位点的蛋白进行性综合预测，选出最佳权重。结果表明，Ｈｏｐｐ＆Ｗｏｄｄｓ亲水性参数和Ｊａｎｉｎ可及性参数在综合中很重要。对ＣＲＧＰ，ＳＣＸ２－ＡＮＤＡＮ，Ｔ     

慢性肝炎组织中CD95（Fas／APO—1）抗原的分布及其意义

ＣＤ９５（Ｆａｓ／ＡＰＯ－１）是存在于细胞表面介导细胞凋亡的膜受体分子，属于ＴＮＦＲ／ＮＧＦＲ超家族的成员。本文用免疫组织化学法研究Ｆａｓ抗原在乙型和丙型肝炎病毒引起的慢性肝炎肝组织中的分布，探讨细胞凋亡启动因子Ｆａｓ在病毒性肝炎发病机制中的作用。结果显示，Ｆａｓ抗原表达阳性细胞在肝小叶中多呈散在或灶状分布于肝小叶周边靠近汇管区的碎屑样坏死区内，周围有淋巴细胞浸润，但也有少数病例Ｆａｓ抗原表达在肝     

Apo－1／Fas抗原与细胞程序化死亡

Ａｐｏ－ｌ／Ｆａｓ抗原是一种跨膜糖蛋白，属于肿瘤坏死因子（ＴＮＦ）受体超家族的一个成员，Ａｐｏ－ｌ／Ｆａｓ是细胞程序化死亡信号传导系统的重要组成部份。Ａｐｏ－ｌ／Ｆａｓ系统介导的细胞程序化死亡，与粘附分子ＣＤ５４、原癌基因Ｂｃｌ－２的表达，以及二磷酸腺苷多聚化过程有关。Ａｐｏ－ｌ／Ｆａｓ系统的研究，有助于自身免疫疾病的发病机制，以及抗肿瘤基因治疗方案的设计和研究。     

IFNαA－HBVPre－S融合基因的克隆及序列测定

乙型肝炎病毒（ＨＢＶ）Ｐｒｅ－Ｓ蛋白是ＨＢＶ与靶细胞结合的重要蛋白。ＩＦＮ是生物体内具有多种生物功能的细胞因子，ＩＦＮ在乙型肝炎的防治中具有重要意义。通过ＰＣＲ技术，我们在体外扩增了ＩＦＮαＡ基因的全序列和ＨＢＶＰｒｅ－Ｓ基因的全序列。为了便于融合基因的克隆和表达，我们在引物的５’端设计了相应的酶切位点，保护位点，起始密码和终止密码。通过基因克隆技术，我们构建了ＩＦＮαＡ－ＨＢＶＰｒｅ－Ｓ融合基因的克隆并进行了序列测定。大量研究表明，ＨＢＶ和靶细胞的结合可能是由ＨＢＶ包膜上的Ｐｒｅ－Ｓ蛋白表位介导的，因此带有附着位点的Ｐｒｅ－Ｓ蛋白，可能比ＨＢｓＡｇ疫苗保护效果好。另一方面，α－干扰素作为治疗乙型肝炎的重要生物制剂，也是乙肝免疫接种过程中良好的免疫性剂。ＩＦＮαＡ－ＨＢＶＰｒｅ－Ｓ融合基因克隆的成功，为表达同时具有ＩＦＮαＡ生物学活性以及ＨＢＶＰｒｅ－Ｓ蛋白免疫原性的双特性蛋白奠定了基础。     

干扰素对人胃癌细胞IAP－2表达的调节

应用基因重组干扰素－ａ和－γ（ＩＦＮ－ａ和－γ）体外诱导三株人胃癌细胞系ＳＧＣ＿（７９０１）、ＭＧＣ＿（８０３）和ＭＫＮ＿（４５），ＡＢＣ－ＣＥＬＩＳＡ法测定诱导组和对照组细胞表面免疫抑制酸性蛋白Ⅱ型（ＩＡＰ－２）的表达量。在基础培养条件下，三株细胞表达ＩＡＰ－２均呈低水平。低浓度（＜１０００ｕ／ｍｌ）ＩＦＮ－ａ或－γ能增加这三株细胞ＩＡＰ－２表达量；而高浓度（＞１０００ｕ／ｍｌ）ＩＦＮ－ａ或－γ反使其ＩＡＰ－２表达量显著减少。这些结果提示：（１）ＩＦＮ－ａ和－γ可能对胃癌细胞ＩＡＰ－２表达呈双向调节作用；（２）癌细胞ＩＭＰ－２表达水平检测作为临床应用ＩＦＮｓ治疗癌症患者的疗效判别指标可能具有一定价值。     

旋毛虫抗原分子克隆及其T细胞和B细胞表位预测

目的 克隆旋毛虫肌幼虫Mr21 000抗原蛋白基因(Ts21),预测其T细胞和B细胞表位.方法 旋毛虫(河南地理株)感染小鼠后收集肌幼虫,提取肌幼虫总RNA,应用RT-PCR技术获取目的基因Ts21,构建重组质粒pUC18-Ts21并测序,应用生物信息分析软件预测其T细胞和B细胞表位.结果 成功构建克隆载体pUC18-Ts21.旋毛虫Mr21 000抗原的T细胞表位位于第9～23、135～150位氨基酸位点;B细胞表位位于第31～35、53～56、98～104、124～130、133～157、160～172位氨基酸位点.结论 成功克隆了旋毛虫河南地理株肌幼虫Mr21 000抗原的编码基因,T细胞和B细胞表位预测结果表明该抗原蛋白具有较好的抗原性,可作为旋毛虫病免疫诊断和预防的候选抗原.     

H1N1亚型流感病毒血凝素Th和B细胞表位预测及抗原性分析

目的:应用生物信息学方法预测H1N1亚型流感病毒血凝素Th和B细胞相关抗原表位,并初步分析其抗原性,为研制H1N1亚型流感病毒的表位疫苗奠定基础.方法:依据近年流感病毒流行趋势,从GenBank下载具有代表性的H1N1亚型流感病毒HA蛋白氨基酸序列.进行生物信息学综合分析预测,获得Th和B细胞相关抗原表位,并比较其保守性和特异性.通过Balb/c小鼠H1N1亚型流感病毒阳性血清与表位肽的结合试验,初步鉴定候选表位抗原性.结果:综合多项预测及空间构像模拟结果,我们获得了三条候选Th和B细胞表位,分别为HA_(73～87)、HA_(125～139)、HA_(188～205).候选表位处于H1N1亚型流感HAI蛋白序列上相对保守的区域内,且与目前流行的H1N1亚型流感病毒HA相应区域具有较好的一致性.而不同候选表位在BMB/e小鼠H1N1亚型流感病毒阳性血清反应中显示了不同抗体结合能力,预示了其成为功能表位的可能.结论:所筛选的表位具有成为H1N1亚型流感病毒HA Th和B细胞相关抗原表位的可能.此研究为深入揭示流感病毒感染与免疫机制,H1N1亚型流感功能表位认知及表位疫苗研究奠定了基础.     

Synthetic peptides approach to identification of epitopes on bovine leukemia virus envelope glycoprotein gp51

Peptides corresponding to residues 21-28, 39-48, 57-67, 59-69, 78-92, 144-155, 144-157, 195-205, 255-268, and 260-268 of envelope glycoprotein gp51 of bovine leukemia virus (BLV) were chemically synthesized and coupled to keyhole limpet hemocyanin or tetanus toxoid. All peptides were immunogenic in rabbits and induced production of antipeptide antibodies. Enzyme-linked immunosorbent assays using Tween 80-purified gp51 or BLV particles showed that antibodies against peptides 78-92, 255-268, and to a lesser extent 39-48 and 144-157 were able to react with the parent glycoprotein, purified or as an integer part of BLV particles. Antisera against peptides 39-48, 78-92, and 144-157 neutralized VSV (BLV) pseudotypes in vitro, the highest neutralization titer being obtained with the 78-92 cyclized peptide. These observations confirm that the NH2 moiety of gp51 carries epitopes involved in virus infectivity.     

The binding sites of monoclonal antibodies to the non‐reducing end of Francisella tularensis O‐antigen accommodate mainly the terminal saccharide

We have previously described two types of protective B‐cell epitopes in the O‐antigen (OAg) of the Gram‐negative bacterium Francisella tularensis: repeating internal epitopes targeted by the vast majority of anti‐OAg monoclonal antibodies (mAbs), and a non‐overlapping epitope at the non‐reducing end targeted by the previously unique IgG2a mAb FB11. We have now generated and characterized three mAbs specific for the non‐reducing end of F. tularensis OAg, partially encoded by the same variable region germline genes, indicating that they target the same epitope. Like FB11, the new mAbs, Ab63 (IgG3), N213 (IgG3) and N62 (IgG2b), had higher antigen‐binding bivalent avidity than internally binding anti‐OAg mAbs, and an oligosaccharide containing a single OAg repeat was sufficient for optimal inhibition of their antigen‐binding. The X‐ray crystal structure of N62 Fab showed that the antigen‐binding site is lined mainly by aromatic amino acids that form a small cavity, which can accommodate no more than one and a third sugar residues, indicating that N62 binds mainly to the terminal Qui4NFm residue at the nonreducing end of OAg. In efficacy studies with mice infected intranasally with the highly virulent F. tularensis strain SchuS4, N62, N213 and Ab63 prolonged survival and reduced blood bacterial burden. These results yield insights into how antibodies to non‐reducing ends of microbial polysaccharides can contribute to immune protection despite the smaller size of their target epitopes compared with antibodies to internal polysaccharide regions.     

Responses of cattle to gastrointestinal colonization by Escherichia coli O157:H7

Recent research has established that the terminal rectum is the predominant colonization site of enterohemorrhagic Escherichia coli O157:H7 in cattle. The main aim of the present work was to investigate pathological changes and associated immune responses at this site in animals colonized with E. coli O157:H7. Tissue and gastrointestinal samples from a total of 22 weaned Holstein-cross calves challenged with E. coli O157:H7 were analyzed for bacterial colonization and pathology. Five unexposed age-matched calves were used as comparative negative controls. E. coli O157:H7 bacteria induced histopathological alterations of the rectal mucosa with enterocyte remodeling. This was often associated with removal of the colonized epithelial layer. Immunogold labeling and transmission electron microscopy (TEM) showed E. coli O157 bacteria on pedestals, as part of attaching and effacing lesions. These pathological changes induced a local infiltration of neutrophils that was quantified as larger in infected animals. Rectal mucosal immunoglobulin A responses were detected against the E. coli O157:H7 antigen. This work presents evidence that E. coli O157:H7 is not a commensal bacteria in the bovine host and that the mucosal damage produced by E. coli O157:H7 colonization of the terminal rectum induces a quantifiable innate immune response and production of specific mucosal antibodies.     

Characterization of cross-reactive and serotype-specific epitopes on the nucleocapsid proteins of hantaviruses

The hantavirus nucleocapsid (N) protein fulfills several key roles in virus replication and assembly and is the major antigen in humoral immune responses in humans and mice. Here we report on epitopes involved in serotype-specific and cross-reactive recognition of the N proteins of hantaviruses using monoclonal antibodies (mAbs) against the N proteins of Andes virus (ANDV) and Sin Nombre virus (SNV). The mAbs define at least twelve different epitopic patterns which span eight sequences, including amino acids 17-59, 66-78, 79-91, 157-169, 222-234, 244-263, 274-286 and 326-338 on the SNV and ANDV N proteins. Studies on the cross-reactivity of these mAbs with different hantavirus N proteins indicated that epitopes located within amino acids 244-286 are related to serotype specificity. We analyzed further the location of epitopes with available three-dimensional structure information including the N-terminal coiled-coil and derived exposed and hidden residues of these epitopes. The generated recombinant N proteins and the characterized mAbs are functional tools being now available for hantavirus diagnostics and replication studies.     

Heterogeneity of monoclonal antibody-reactive epitopes on mycobacterial 30-kilodalton-region proteins and the secreted antigen 85 complex and demonstration of antigen 85B on the Mycobacterium leprae cell wall surface.

Proteins of the antigen 85 complex in the 30-kDa region secreted by live mycobacteria are important in the immune response against mycobacterial infections and may play an important biological role in the host-parasite interaction. In the present study, we have characterized epitopes of the 30-kDa-region proteins and the antigen 85 complex by using a panel of 13 monoclonal antibodies (MAbs) reacting with these antigens, 6 of which have not been described before. By using five previously characterized related secreted proteins of Mycobacterium tuberculosis, MPT44 (85A), MPT59 (85B), MPT45 (85C), MPT51 (27 kDa), and MPT64 (26 kDa), we have identified at least 10 different MAb-reactive epitopes on the proteins of the antigen 85 complex. A heterogeneous distribution of epitopes was observed within the components of the antigen 85 complex. Two distinct epitopes specific for antigen 85B and two other epitopes restricted to the 85A and 85B components were recognized. Two of them were shared with a previously unidentified 27-kDa protein present in M. tuberculosis culture fluid from which all MPT proteins were derived. The rest of the MAb-reactive epitopes were found to be present mostly in antigens 85A and 85B and to a lesser extent in antigen 85C. None of these MAbs recognized component 85C alone nor did they bind to the related MPT51 and MPT64 proteins. Interestingly, most of the MAbs reacted with purified native proteins of the antigen 85 complex but not to them in their denatured forms. In contrast, reactivity of the MAbs with the cytosol fraction of M. tuberculosis in immunoblotting revealed that they bound to a closely related cytosolic 30-kDa protein(s) even when they were denatured. Heterogeneity of these MAb-reactive epitopes of the antigen 85 complex was further evident as they were found to be distributed in various patterns among 19 different mycobacterial species. By using fusion proteins of the Mycobacterium leprae 30/31-kDa antigen 85 complex, we have localized at least six different epitopes within amino acid residues 55 to 266 of the M. leprae antigen 85 complex. Finally, by immunohistochemical analysis, we have demonstrated the in situ expression of one of the novel MAb-reactive epitopes specific for antigen 85B on the cell wall surface of M. leprae within macrophages in lepromatous leprosy lesions and thus provide direct evidence for the presence of the B component of the antigen 85 complex on the surface of intact M. leprae.     

Epitope evolution in poliovirus maturation

Eight monoclonal antibodies specific for native (N) poliovirus antigen all recognized empty capsids extracted from infected HeLa cells; only three of them recognized 14S particles. The facts point to the existence of two different epitopes N1 and N2, only one of which (N1) is present on 14S particles (these observations confirm and extend findings by EMINI et al). Another epitope of 14S particles is recognized by antibodies to heated (H) poliovirus antigen. Infected cell extract-catalyzed polymerization of 14S particles yielded mainly empty capsids carrying the N1 and N2, but no H epitopes.     

Inhibition of Fas-mediated apoptosis by the B cell antigen receptor through c-FLIP

Cross-linking of the B cell antigen receptor (BCR) induces resistance to Fas (APO-1 / CD95)-dependent apoptosis and thereby regulates one mechanism of B cell selection during antigen stimulation. To investigate the molecular mechanism by which BCR signaling regulates the Fas pathway, we examined the expression of constituents of the death-inducing signaling complex (DISC), including Fas, FADD, caspase-8 and cellular FLICE-inhibitory protein (c-FLIP). No significant changes in the cellular levels of Fas, FADD or caspase-8 were observed after BCR cross-linking. By contrast, the long isoform of c-FLIP (c-FLIP(L)) was significantly up-regulated by BCR cross-linking in primary B cells and in two B cell lines, A20 and WEHI-279. Moreover, transfection of c-FLIP(L) into A20 cells inhibited Fas-dependent apoptosis and suppressed recruitment of caspase-8 to the DISC. BCR cross-linking or FLIP overexpression also protects B cells from TRAIL-induced apoptosis. Thus, BCR signaling up-regulates c-FLIP(L) and suppresses the Fas- and TRAIL-receptor apoptosis pathways which could be important for tolerance and selection of antigen-specific B cells.     

H5N1型高致病性禽流感病毒血凝素蛋白及神经氨酸酶的B细胞抗原表位预测

目的预测H5N1亚型高致病性禽流感病毒HA蛋白和NA蛋白的B细胞表位,为基于B细胞表位的预防性疫苗设计提供依据。方法基于HA蛋白和NA蛋白的蛋白质序列,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HA蛋白和NA蛋白的B细胞表位。结果分别预测出了6条血凝素蛋白(Hemagglutinin,HA)以及6条神经氨酸酶(Neuraminidase,NA)B细胞优势表位。结论这些B细胞表位可为禽流感疫苗的研制提供实验依据。