捕捉法ELISA检测脊髓灰质炎IgA抗体方法的建立与应用

建立了一种检测脊髓灰质炎(简称脊灰)IgA抗体的捕捉法ELISA(Aac-ELISA)。方法敏感,快速,特异,用于检测144份脊灰可疑病人的血清,IgA抗体检出率为77.8％(112/144).而这些血清的IgM抗体检出率为65.2％(94/144)。如同时检测IgM和IgA抗体,则阳性率可达91.7％(132/144)。麻痹后1～3天内IgA的检出率为76.5％(13/17),4～7天内为95％(19/20)。最长检出IgA的一例可疑病人,其血清收集于病后第59天。本方法在一部分16天后可疑病人IgM阴性血清中查出IgA阳性,故可以作为查IgM抗体诊断方法的补充,尤其适用于诊断感染后未能及时收到血清标本,IgM已经转阴而IgA抗体仍为阳性的病人。     

MacELISA、RPHI和IFAT用于流行性出血热早期诊断的比较

比较了IgM捕获ELISA(MacELISA)、反向间接血凝抑制试验(RPHI)和间接免疫荧光抗体试验(IFAT)检测流行性出血热(EHF)病人血清特异性抗体的结果。MacELISA对急性期血清IgM抗体的阳性检出率与RPHI对总抗体的阳性检出率相近,两法都具有较高的敏感性。而IFAT检测IgG抗体的阳性率则较低。总抗体滴度(RPHI)与IgG抗体滴度(IFAT)相关(r=0.542,P<0.01),而与IgM抗体滴度(MacELISA)无明显相关(r<0.1)。但进一步研究发现,3日内血清IgM抗体滴度与总抗体滴度(RPHI)存在相关关系(r=0.701,P<0.01),表明IgM抗体可能也与发病初期RPHI的较高的阳性检出率有关。本工作表明,MacELISA作为一种早期诊断方法具有高度的特异性和敏感性,而RPHI操作简便、快速、敏感性高,但存在一定的非特异性。研究还发现,流行区临床诊断为EHF的病人,IFAT(IgG)和RPHI检测均阳性,而MacELISA(IgM)阴性,提示用RPHI进行血清学诊断时,检查双份血清是必要的。     

ELISA间接法检测呼吸道合胞病毒和副流感病毒血清IgM和IgA抗体

建立了检测呼吸道合胞病毒(RSV)和副流感病毒(PFV)血清特异性IgM和IgA抗体的间接ELISA方法。在方法统一的基础上比较了检测IgG、IgM和IgA抗体的结果,证明检测血清IgM和IgA可以作为RSV和PFV感染的早期诊断指标。检测了120份临床急性下呼吸道感染患儿的血清,RSV-IgM检出率为33.3％,RSV-IgA为36.7％;PFV-IgM为27.5％,PFV-IgA为31.6％。提出了对RSV和PFV感染以检测特异性IgA替代IgM或两者互补的设想。     

血清中Epstein-Barr病毒膜抗原IgA抗体检测法的改进及应用

用萄葡球菌菌体A蛋白(SPA)预先处理被检血清,以去除抗体IgG部份的竞争性结合,提高了间接免疫荧光法检查鼻咽癌病人血清中EB病毒膜抗原IgA(IgA/MA)抗体的敏感性及特异性,检查48例鼻咽癌病人血清IgA/MA抗体,阳性率为100％,血清几何平均滴度为141;40例其它恶性肿瘤病人和46例正常人都检不出IgA/MA抗体,免疫荧光法测得IgA/MA抗体阴性的6例鼻咽癌病人血清,SPA吸收后呈阳性反应,此改进方法可用以追踪观察鼻咽癌病的病程及预后。     

嗜肺军团菌和弯曲杆菌在间接荧光抗体试验中的血清学交叉反应

50名培养证实弯曲杆菌胃肠炎的患者血清中作了嗜肺军团菌抗体检查。间接免疫荧光试验检测有10名患者(20％)出现阳性滴度(≥16)。36份急性期患者血清只有1份检测到抗体,而14份在症状出现10天以上获得的血清中却有10份(71％)有抗体。所有阳性血清均含有特异性IgM抗体而特异性IgG或IgA未能在任何标本中检测到。从42例类似沙门氏菌胃肠炎病人血清中未能检测到军团菌抗体。这些结果显示在嗜肺军团菌和弯曲杆菌之间有血清学交叉反应。     

鼻咽癌患者血清中Epstein-Barr病毒早期抗原特异性抗体的IgA类抗独特型抗体的检测

用3.5％PEG(MW6000)预先处理被检血清以除掉免疫复合物及干扰抗原之后,用新建立的ELISA方法测定血清中Epstein-Barr病毒早期抗原特异性抗体的抗独特型(Anti-Id)抗体。67例鼻咽癌患者中,80％IgA类的Anti-Id抗体阳性(P/N值≥2.1),而56例正常人群除1例阳性外,其余均阴性。测定46例鼻咽癌患者血清EA/IgA滴度与Anti-Id的关系表明,Anti-Id抗体P/N值与IgA/EA滴度呈负相关(r=-0.6,P<0.001)。12例鼻咽癌病人血清中EA抗体的IgG类Anti-Id抗体则与正常人无显著差别。     

测定Epstein-Barr病毒IgA/EA抗体的改进方法

用免疫酶法(IE)检查鼻咽癌(NPC)病人血清中IgA/EA抗体,阳性率为73％,几何平均滴度为25,将血清用马抗人IgG血清或葡萄球菌菌体A蛋白(SPA)处理后,以除去竞争性IgG类抗体后,阳性率可增高至92％,几何平均滴度提高到89,有15例NPC病人血清,经马抗人IgG血清处理前IgA/EA抗体为阴性,处理后均呈阳性反应。     

用转染EB病毒基因片段的真核细胞检测鼻咽癌病人的抗EB病毒核抗原-1(EBNA-1)抗体

用转染EBV DNA Bam HI K片段后稳定表达EBNA-1的K_4细胞作为靶细胞,检测50份鼻咽癌病人和38份健康对照者血清中的IgG/EBNA-1抗体;阳性率分别为100％和92％。前者的平均几何滴度为89.4,后者为18.3,前者约为后者的5倍。同一批被检血清经SPA吸收去除IgG竞争性抑制后,鼻咽癌病人的IgA/EBNA-1抗体阳性率达78％(GMT 20.9),健康人的IgA/EBNA-1抗体阳性率仅5.3％,效价亦很低(GMT 5.2)。表明IgA/EBNA-1抗体对鼻咽癌是比较特异的,可考虑作为鼻咽癌血清学诊断的指标之一。     

HFRS患者特异性IgA、IgE抗体及其免疫复合物测定

为进一步研究HFRS免疫损伤机制,用ELISA法同步测定了108例不同临床型、不同病日、病期HFRS患者血清中特异性IgA、IgE抗体以及HFRS病毒特异性IgA、IgE型CIC的水平及检出率.发现HFRS-IgA型抗体在轻型病例高于中、重型病例;HFRS-IgE型抗体及IgE型CIC在重型病例高于中、轻型病例.上述差异在病程早期(发热、休克少尿期,或是3～8病日)尤为突出.IgA型CIC则未见到上述差异.     

基因工程抗体的获得

一、抗体结构和抗体基因 1.抗体结构 抗体分为五类,即IgG、IgM、IgA、IgD和IgE,其理化性质各不相同,在体内的比例、分布及代谢速率也很不一样。IgG是最重要的血清免疫球蛋白,分为四种亚型:IgG1是主要的亚型(占IgG总量的67％),其次是IgG2、IgG3、IgG4。IgA是主要的分泌型Ig,分为IgA1,IgA2两个亚型。IgM是一五聚体分子,由10条H链、10条L链和一条J链通过二硫键连接而成。它是一个多价体。在B细胞膜上的IgM作为抗原受体与B细胞成熟、分化有关。     

治疗性单克隆抗体研究进展

杂交瘤技术使鼠源单克隆抗体（鼠单抗）被广泛用于人类疾病的诊断和研究,建立了治疗性抗体的第一个里程碑。但随后出现的人抗鼠抗体等副作用极大地限制了鼠单抗的临床应用。随着生物学技术的发展和抗体基因结构的阐明,应用DNA重组技术和抗体库技术对鼠单抗进行人源化改造,先后出现了嵌合抗体、改型抗体和全人抗体,同时也涌现了各种单抗衍生物,它们从不同角度克服了鼠单抗临床应用的不足,未人类疾病治疗带来新的曙光。我们就上述治疗性抗体人源化的研究进展做简要综述。     

基因工程抗体研究进展

临床治疗中人抗鼠抗体反应的出现使鼠源性单克隆抗体的应用受到了极大的限制。为降低其免疫原性,人们利用基因工程技术对鼠源抗体进行改造,以减少其鼠源成分。简要概述了目前研究比较多的几种基因工程抗体及其临床应用。     

Monoclonal antibody therapeutics with up to five specificities: Functional enhancement through fusion of target-specific peptides

The recognition that few human diseases are thoroughly addressed by mono-specific, monoclonal antibodies (mAbs) continues to drive the development of antibody therapeutics with additional specificities and enhanced activity. Historically, efforts to engineer additional antigen recognition into molecules have relied predominantly on the reformatting of immunoglobulin domains. In this report we describe a series of fully functional mAbs to which additional specificities have been imparted through the recombinant fusion of relatively short polypeptides sequences. The sequences are selected for binding to a particular target from combinatorial libraries that express linear, disulfide-constrained, or domain-based structures. The potential for fusion of peptides to the N- and C- termini of both the heavy and light chains affords the bivalent expression of up to four different peptides. The resulting molecules, called zybodies, can gain up to four additional specificities, while retaining the original functionality and specificity of the scaffold antibody. We explore the use of two clinically significant oncology antibodies, trastuzumab and cetuximab, as zybody scaffolds and demonstrate functional enhancements in each case. The affect of fusion position on both peptide and scaffold function is explored, and penta-specific zybodies are demonstrated to simultaneously engage five targets (ErbB2, EGFR, IGF-1R, Ang2 and integrin αvβ3). Bispecific, trastuzumab-based zybodies targeting ErbB2 and Ang2 are shown to exhibit superior efficacy to trastuzumab in an angiogenesis-dependent xenograft tumor model. A cetuximab-based bispecific zybody that targeting EGFR and ErbB3 simultaneously disrupted multiple intracellular signaling pathways; inhibited tumor cell proliferation; and showed efficacy superior to that of cetuximab in a xenograft tumor model.     

嵌合抗体研究进展

抗体在疾病诊断,治疗和预防中发挥着重要作用,近几年来将基因工程应用到抗体生产的基因工程抗体技术发展迅速,本就基因工程抗体中的重要组成部分－嵌合抗体的研究进展加以综述。     

Isolation and optimization of camelid single-domain antibodies: Dirk Saerens' work on nanobodies

It is well established that all camelids have unique antibodies circulating in their blood. Unlike antibodies from all other species, these special antibodies are devoid of light chains, and are composed of a heavy chain homodimer. These so-called heavy-chain antibodies (HCAbs) are expressed after a V-D-J rearrangement and require dedicated constant gamma genes. An immune response is raised in these HCAbs following a classical immunization protocol. These HCAbs are easily purified from serum, and their antigen-binding fragment interacts with parts of the target that are less antigenic to conventional antibodies. The antigen binding site of the dromedary HCAb comprises one single domain, referred to as VHH or nanobody (Nb), therefore, a strategy was designed to clone the Nb repertoire of an immunized dromedary and to select the Nb with specificity for our target antigens. The monoclonal Nb is produced well in bacteria, is very stable and highly soluble, and it binds the antigen with high affinity and specificity. Currently, the recombinant Nb has been developed successfully for research purposes, as a probe in biosensors, to diagnose infections, or to treat diseases such as cancer or trypanosomiasis.     

Monoclonal antibodies: technologies for early discovery and engineering

Antibodies are essential in modern life sciences biotechnology. Their architecture and diversity allow for high specificity and affinity to a wide array of biochemicals. Combining monoclonal antibody (mAb) technology with recombinant DNA and protein expression links antibody genotype with phenotype. Yet, the ability to select and screen for high affinity binders from recombinantly-displayed, combinatorial libraries unleashes the true power of mAbs and a flood of clinical applications. The identification of novel antibodies can be accomplished by a myriad of in vitro display technologies from the proven (e.g. phage) to the emerging (e.g. mammalian cell and cell-free) based on affinity binding as well as function. Lead candidates can be further engineered for increased affinity and half-life, reduced immunogenicity and/or enhanced manufacturing, and storage capabilities. This review begins with antibody biology and how the structure and genetic machinery relate to function, diversity, and in vivo affinity maturation and follows with the general requirements of (therapeutic) antibody discovery and engineering with an emphasis on in vitro display technologies. Throughout, we highlight where antibody biology inspires technology development and where high-throughput, “big data” and in silico strategies are playing an increasing role. Antibodies dominate the growing class of targeted therapeutics, alone or as bioconjugates. However, their versatility extends to research, diagnostics, and beyond.     

噬菌体抗体库技术及其应用研究进展

噬菌体呈现抗体库是近年发展的一项分子生物学新技术,它的建立是抗体技术领域中的一次革命性进展。它以其独特的构建和筛选系统,彻底改变了抗体制备的传统途径,使抗体工程技术进入了一个新的发展阶段,并对生物学领域中许多技术的发展起到了巨大的推动作用。该技术是迄今发展最成熟、应用最广泛的制备抗体技术。我们简要综述此项技术的研究应用进展。     

Structural understanding of stabilization patterns in engineered bispecific Ig‐like antibody molecules

Bispecific immunoglobulin‐like antibodies capable of engaging multiple antigens represent a promising new class of therapeutic agents. Engineering of these molecules requires optimization of the molecular properties of one of the domain components. Here, we present a detailed crystallographic and computational characterization of the stabilization patterns in the lymphotoxin‐beta receptor (LTβR) binding Fv domain of an anti‐LTβR/anti‐TNF‐related apoptosis inducing ligand receptor‐2 (TRAIL‐R2) bispecific immunoglobulin‐like antibody. We further describe a new hierarchical structure‐guided approach toward engineering of antibody‐like molecules to enhance their thermal and chemical stability. Proteins 2009. © 2009 Wiley‐Liss, Inc.     

治疗性抗体的研究进展

作为一种具有靶向性的生物大分子,单克隆抗体始终是人们关注的热点之一,被广泛用于治疗肿瘤、病毒感染和抗移植排斥等。但鼠源单克隆抗体的临床应用受限于诱导产生人抗鼠抗体、肿瘤渗入量低、亲和力低和半衰期短等。随着分子生物学技术的发展及其向各学科的渗透,通过基因操作技术对抗体进行改造,可使其适用于多种疾病的治疗。抗体人源化已经成为治疗性抗体的发展趋势,同时各种抗体衍生物也不断涌现,它们从不同角度克服了抗体本身的应用局限,也为治疗人类疾病提供了利器。本文简要介绍上述技术的基本原理、特点和治疗性抗体的研究进展。