从1名健康疫苗接种者分离到的重组3型/2型脊髓灰质炎病毒及其包含的嵌合核壳VP1的鉴定

从接种口服脊髓灰质炎疫苗后约 1 2周的 1名 2岁男孩的粪便标本中分离到Sabin3/Sabin2 /Sabin3( S3/2 /3)型间重组脊髓灰质炎病毒。　　由于该分离株的初步鉴定为嵌合 Sabin3/Sabin2核壳结构 ;从而使作者进一步研究了这个病毒的整个基因组序列、抗原特性和温度敏感性。　　研究表明 ,第 1个重组连接位于编码VP1核壳蛋白的基因区 ,在 32 74和 32 85位核苷酸之间 ;第 2个连接则位于 RNA聚合酶区域 ( 6 82 4和 6 82 5位核苷酸 )。重组把 6个 Sabin2衍生氨基酸引入 Sabin3核壳中的VP1羧基末端。重组病毒的全基因组与其亲代 Sabin株在 33…     

我国肠道病毒71型（EV71）疫苗株生物信息学分析

目的 比较3个EV71疫苗株病毒的生物信息学特点,为疫苗的质控和探讨该病毒疫苗的免疫机制提供参考.方法 本研究利用DNAstar MegAlign、DNAMAN Alignment、ANtheProt等生物学软件,比较了我国已进入临床试验的3家EV71全病毒灭活疫苗毒株的基因组及氨基酸序列,并对英衣壳蛋白二级结构及可能存在的抗原表位进行了预测分析.结果 3个疫苗株病毒基因同源性为97％～99％;氨基酸同源性为98％～99％;二级结构一致率在95％以上;均存在35个潜在抗原表位区域.结论 3个疫苗株生物信息学分析结果存在高度的一致性,提示疫苗具有相似的抗原性和免疫原性.     

戊型肝炎病毒及其病毒样颗粒疫苗的研究进展

戊型肝炎(hepatitis E,HE)是全球最主要的病毒性肝炎之一,由戊型肝炎病毒(hepatitis E virus,HEV)感染导致.因为HEV不能在体外细胞培养体系中有效生长,因此HE灭活或减毒活疫苗的研制不可行.目前HE疫苗研究主要集中在有免疫原性的重组病毒衣壳蛋白上.HEV的开放读码框架2编码的蛋白为病毒衣壳蛋白,可在体外自行组装成病毒样颗粒(virus-like particle,VLP).形成的VLP在动物和人体中均可诱导产生高滴度的保护性抗体,是理想的预防性疫苗组分.此文就HEV的流行病学、HEV VLP的形成机制和结构特征以及VLP疫苗的研究现状作一综述.     

序贯接种由重组痘苗病毒和杆状病毒产生的SLE病毒PrM/E蛋白的效果

圣路易脑炎(SLE)是见于美国、南美及加拿大部分地区的蚊传疾病。第二次世界大战以来,一直以SLE病毒Webster株制备的灭活鼠脑疫苗预防此病,效果很好。缺点是该疫苗中含有脑组织。近年来的研究表明,由不同表达系统制备的重组黄病毒疫苗都具有良好的免疫原性。为综合利用不同表达系统的优点,作者研究了由痘苗病毒和杆状病毒表达的SLE病毒前膜和包膜(PrM/E)蛋白的保护效果。 首先以痘苗病毒(pSC11)和杆状病毒(pAcYM1)为载体,表达SLE病毒MSI-7株的PrM/E蛋白,通过免疫印迹、等电聚焦及放射免疫法分析确证,重组E蛋白的特性与SLE病毒的E蛋白相似,两种表达系统的表     

染性法氏囊病病毒分离株变异的研究

为了了解我国传染性法氏囊病病毒(IBDV)的变异现状,并为研究高效疫苗打下基础,用琼脂糖凝胶电泳,SDS-PAGE和序列分析等分子生物学方法,分析IBDV病毒RNA,结构蛋白的变异情况。结果表明⑴3种不同源IBDV均由双节段RNA组成,大小基因片段的电泳迁移率各病毒间无差异;⑵不同源IBDV的结构蛋白带谱相同,但各蛋白带的百分含量有差异;⑶IBDV血清Ⅰ型不同亚型的JS3和JS4毒株主要保护性抗原VP2高变区核酸序列的同源性最高达98%,与已发表的vvIBDV,IBDV变异株,IBDV经典株及IBDV弱毒株核苷酸序列同源性在92%～98%之间。根据IBDV的大开放读框推导出该片段编码蛋白的氨基酸序列,JS3和JS4的同源性最高达97%,与上述其它毒株的同源性在91%～97%之间;七肽区的氨基酸序列,在强毒株完全相同,而在弱毒株有一个丝氨酸突变成其它氨基酸。     

噬菌体展示耐药突变HIV-1蛋白酶敏感切割位点六肽随机文库的构建

目的构建耐药性突变HIV-1蛋白酶(protease PR)敏感切割位点序列体外噬菌体筛选模型,研究HIV-1蛋白酶耐药性突变与敏感切割序列的关系。方法用含随机核苷酸序列的引物PCR方法对HIV-1gag基因上的CAP2片段的PR切割位点处的氨基酸序列进行随机化,再将重组CAP2片段和NC片段拼接克隆于噬菌体展示载体LD3-pCANT-AB5S上,建立HIV-1蛋白酶靶蛋白切割位点随机化的噬菌体展示文库。结果该噬菌体展示文库库容量为2.6×106,滴度为4.1×1015TU·L-1,CAP2片段插入率为47.8%;序列分析显示切割位点中随机化的核苷酸与氨基酸均呈随机性分布。结论成功地构建HIV-1蛋白酶的敏感切割序列噬菌体筛选文库,为筛选到突变PR敏感切割序列噬菌体及研究耐药HIV-1蛋白酶抑制剂与突变PR的关系打下基础。     

脊髓灰质炎病毒嵌合体诱生广泛反应性HIV-1中和抗体

1型人类免疫缺陷症病毒(HIV-1)包膜蛋白(env)具有广泛的序列异质性和抗原变异性,也存在着抗原性保守位点.理想的疫苗应含有此保守位点,以便诱生能与许多病毒分离株起反应的抗体.作者选用HIV-1跨膜糖蛋白gp41(组特异性抗原决定簇),以Ⅰ型脊髓灰质炎病毒Sabin疫苗株为表达载体(pCASl),用DNA重组技术构建成脊髓灰质炎病毒/HIV-1抗原嵌合体Sl/env/3.     

传染性法氏囊病病毒分离株变 异的研究

为了了解我国传染性法氏囊病病毒（IBDV）的变异现状,并为研究高效疫苗打下基础,用琼脂糖凝胶电泳,SD－PAGE和序列分析等分子生物学方法,分析IBDV病毒RNA,结构蛋白的变异情况,结果表明：（1）3种不同源IBDV均由双节段RNA组成,大小基因片段的电泳迁移率各商毒间无差异;（2）不同源IBDV的结构蛋白带谱相同,但各蛋白带的百分含量有差异;（3）IBDV血清I型不同亚型的JS3和JS4毒株主要保护性抗原VP2高变区核酸序列的同源性最高达98％,与已发表的vvIBDV,IBDV变异株,IBDV经典株及IBDV弱毒株核苷酸序列同源性在92－98％之间,根据IBDV的大开放读框推导出该片段编码蛋白的氨基酸序列,JS3和JS4的同源性最高达97％,与上述其它毒株的同源性在91－97％之间,七肽区的氨基酸序列,在强毒株完全相同,而在弱毒株有一个丝忱酸突变成其它氨基酸。     

噬菌体展示技术生物淘选CTGF表位的研究

噬菌体展示技术筛选缔组织生长因子（CTGF，connective tissue growth factors）蛋白表位。用含有30mmol／L葡萄糖的DMEM培养液干预人肾小球系膜细胞2d后，提取CTGF天然蛋白，应用Western blot—ting方法鉴定CTGF单克隆抗体的特异性；以CTGF单克隆抗体为筛选工具，对噬菌体随机12肽库进行筛选，逐步增加选择压力，经过3轮筛选后随机挑取4个克隆测序，用竞争抑制和间接ELISA方法检测噬菌体阳性克隆的特异性。Westernblotting分析显示，CTGF单克隆抗体能与CTGF天然蛋白及重组蛋白特异性结合。噬菌体文库经过3轮筛选后得到的阳性克隆，测序结果表明4个克隆的序列高度一致，推导获得小肽序列，命名为ZD521；竞争抑制和间接ELISA分析与预期结果一致。本研究用噬菌体展示技术成功获得与CTGF单抗高度结合的小肽，为CTGF功能研究以及进一步以该肽为疫苗预防和治疗纤维化疾病打下基础。     

克隆的口蹄疫病毒蛋白疫苗:牛和猪的应答

本疫苗是用口蹄疫病毒A12株免疫原性衣壳蛋白VP3连接到大肠杆菌色氨酸△LE-1413蛋白,合成的一种重组疫苗。作者制成含有亚基因组的互补DNA(c-DNA)插入物的一系列质体。通过对这些插入物的核苷酸顺序的分析,确定了VP3基因的位置,位于口蹄疫病毒基因组中心附近。几乎所有VP3蛋白的密码顺序都是从质体pT465用限制性核酸内切酶Pst Ⅰ和Pvu Ⅱ     

Characterization, primary structure and molecular evolution of anticoagulant protein from Agkistrodon actus venom.

An anticoagulant protein named AaACP was isolated from Agkistrodon actus (hundred-pace snake of Taiwan, Viperidae) venom. AaACP inhibited the factor Xa-induced plasma coagulation in a concentration-dependent manner. Thus, AaACP seems to bind to factor Xa in prothrombinase complex. AaACP was composed of A and B chains linked by disulphide bond(s). The amino acid sequences of A and B chains of AaACP were analysed with a few residues unidentified which were complemented from the nucleotide sequences of their cDNAs. The A chain consisted of 129 amino acid residues and the B chain 123 amino acid residues. Their amino acid sequences were highly similar to those of A and B chains of a series of anticoagulant proteins which had been purified from the venoms of some Viperidae snakes. The A and B chains structurally belong to C-type lectin-like protein family of snake venom origin. Construction of phylogenetic tree of C-type lectins and C-type lectin-like proteins based on their amino acid sequences indicated that their A and B chains diverged before speciation of snake species. The comparison of the nucleotide sequences of the cDNAs encoding A and B chains of AaACP and of Trimeresurus flavoviridis (Viperidae) venom-gland factors IX/X-binding protein and factor IX-binding protein showed that the mature protein-coding region is much more variable than the signal peptide-coding domain and the 5'- and 3'-untranslated regions, being in contrast to the case of the ordinary isoprotein genes. The ratios of the numbers of nucleotide substitutions per nonsynonymous site (K(A)) and per synonymous site (K(S)) in the mature protein-coding region in the cDNA pairs were about three times greater than those for the ordinary isoprotein genes, suggesting that these genes have been evolving in an accelerated manner. Taking account of the functional diversities of venom-gland C-type lectins and C-type lectin-like proteins including factors IX and/or X-binding proteins, it can be said that their functional diversities have been acquired by accelerated evolution.     

亲水突变法提高抗VEGFR2单链抗体的体外亲和力

为了提高抗VEGFR2单链抗体AK404R的亲和力,本研究采用亲水突变法将AK404R的重链CDR3区进行突变,建立次级突变单链抗体库。利用噬菌体展示技术从次级突变库中筛选具有抗VEGFR2特异性、高亲和力抗体,获得的抗体突变株经大肠杆菌HB2151分泌表达,镍亲和色谱柱纯化,并采用竞争性ELISA法、生物信息学方法分别对其亲和力和结构进行了分析。本研究最终建立了6.4×105的次级突变单链抗体库,其中两株突变株的亲和力有明显提高,两株突变株经分离纯化得到电泳纯的蛋白,竞争性ELISA结果显示突变体WZ01和WZ02的亲和力比亲本提高了3倍;生物信息学方法分析突变体与抗原的作用面增大、契合紧密,这可能是亲和力提高的原因之一。研究结果表明,在重链CDR3区引入亲水性氨基酸构建抗体突变库,可有效提高scFv的亲和力。     

Screening of phage displayed human liver cDNA library against dexamethasone

This paper described an attempt to establish a new method to screen the target biomolecule from phage displayed cDNA library against small molecule drug insoluble in water. Dexamethasone was selected as the model drug, and the screening was carried out in an Eppendorf tube packed with the drug. The whole procedure was monitored by PCR with the enriched specific phage clone as the template. After four rounds screening, the PCR products of selected phages with the lengths of 400 and 600 bp were sequenced, and revealed identical sequences with cytochrome c oxidase subunit III and albumin respectively by GenBank searching. Furthermore, frontal analysis-capillary electrophoresis (FA-CE) was performed to study the interaction between dexamethasone and albumin, and the binding constant was calculated to be 1.153 x 10(3), validating the weak specific interaction between the drug and the target protein. All these results demonstrated that with insoluble drug as the solid phase directly, the screening of target large molecule expressed in phage display cDNA library was feasible, which might pave an easy way to screen the candidate drug targets.     

A quantitative PCR screening method for adeno-associated viral vector 2-mediated gene doping

Gene therapy is currently prohibited in human and equine athletes and novel analytical methods are needed for its detection. Most in vivo products use non-integrating, recombinant viral vectors derived from adeno-associated virus (AAV) to deliver transgenes into cells, where they are transcribed and translated into functional proteins. Although the majority of wild-type AAV (WTAAV) DNA is removed from recombinant AAV (rAAV) vectors, some sequences are conserved. The goal of this study was to develop a quantitative polymerase chain reaction (QPCR) screening test targeting conserved AAV sequences to enable theoretical detection of all rAAV gene therapy products, regardless of encoded transgenes while excluding the presence of WTAAV DNA in horses. Primer sets were developed and validated to target an AAV2 sequence highly conserved across rAAV viral vectors and a sequence only found in wild type AAV2 (WTAAV2). Six horses were administered an intra-articular injection of rAAV. Plasma and synovial fluid were collected on days 0, 1, 2, 4, 7, 14, 28, 56, and 84. Using QPCR, rAAV was detected in plasma for up to 2–4 days in all horses. rAAV DNA was detected for 28 days in synovial fluid from two horses for which synovial fluid samples were available. No WTAAV2 DNA was detected in any sample. This is the first study to develop a QPCR test capable of screening for rAAV vectors that may be used for gene doping in horses.     

Structural conservation in globular proteins

Some well sequenced classes of homologous proteins have been analysed in the light of their representative tertiary structures to reveal the nature of structural conservation during protein evolution. Within ‘the sphere of influence’ around conserved residue sites preferential association of other conservative sites has been observed to be a feature of natural selection valid for all residue types. An information theory approach evolved to examine residue variability reveals that even some non-conservative sites scaffold clusters of high biochemical specificity and intermediate folding units.     

Peptide G protein agonists from a phage display library

G proteins may serve as targets for pharmacological activation of signaling pathways bypassing the regulatory events that may counteract the effect of the external stimulus on the level of receptors. We sought to identify peptides as lead structures interacting with G proteins utilizing a commercially available phage-display library. The heptapeptide library was screened for binding to human G alpha(i1) which was modified with a hexahistidine tag and immobilized on a Ni(2+)-coated surface. After several rounds of phage selection a number of phage clones with consensus sequences were found. Peptides with such sequences were chemically synthesized and their effect on [35S]GTP gamma S binding to G alpha(i1) and other G protein alpha subunits was determined. Through this process two peptide 'families' with the capability to activate G proteins were identified. The peptides showed no structural similarity to known peptide or nonpeptide G protein activators with a cationic amphiphilic structure like mastoparan or alkylamines. The functional relevance of the peptide-G protein interaction was shown by an increased sensitivity for guanine nucleotides of high-affinity agonist binding to A(1) adenosine receptors. The peptide G protein activators may, therefore, serve as novel tools for further investigation of receptor-independent activation of G proteins.     

晚期糖基化终产物受体胞外段的原核表达及其相互作用蛋白的筛选

目的构建晚期糖基化终产物受体(receptor for ad-vanced glycation end-product,RAGE)胞外段基因的原核表达载体并诱导表达,应用噬菌体展示技术筛选其相互作用蛋白。方法用RT-PCR方法扩增人RAGE胞外段cDNA,构建于原核表达载体pET14b,转化大肠杆菌BL21,IPTG诱导RAGE胞外段融合蛋白表达,用Ni2+-NTA亲和层析柱进行纯化并行Western blot鉴定。以重组RAGE胞外段蛋白为靶分子,进行3轮噬菌体展示环七肽库的筛选,从第3轮洗脱物中随机挑选分隔良好的噬菌体克隆扩增后进行ELISA鉴定。对获得的阳性噬菌体克隆分别进行扩增、纯化,提取DNA测序后翻译为氨基酸序列,用BLAST软件搜索Gen-Bank中的同源序列。结果成功构建并表达、纯化了RAGE胞外段融合蛋白。经过3轮筛选后,随机挑取的24个噬菌体克隆中11个可与RAGE胞外段结合。对11个噬菌体测序后用BLAST软件搜索同源序列,得到14个编码蛋白。结论应用噬菌体展示技术筛选到与RAGE胞外段相互作用的蛋白,为进一步研究其功能和作用机制提供新线索。     

Identification and characterization of surrogate peptide ligand for orphan G protein-coupled receptor mas using phage-displayed peptide library

In the present study, a phage-displayed random peptide library was used to identify surrogate peptide ligands for orphan GPCR mas. Sequence analysis of the isolated phage clones indicated a selective enrichment of some peptide sequences. Moreover, multiple alignments of the isolated phage clones gave two conserved peptide motifs from which we synthesized peptide MBP7 for further evaluation. Characterization of the representative phage clones and the synthetic peptide MBP7 by immunocytochemistry revealed a strong punctate cell surface staining in CHO cells expressing mas-GFP fusion protein. The isolated phage clones and synthetic peptide MBP7 induced mas internalization in a stable CHO cell clone (MC0M80) over-expressing mas. In addition, MBP7-stimulated phospholipase C activity and intracellular calcium mobilization in these same cells. In summary, we have demonstrated a systematic approach to derive surrogate peptide ligands for orphan GPCRs. With this technique, we have identified two conserved peptide motifs which allow us to identify potential protein partners for mas, and have generated a peptide agonist MBP7 which will be invaluable for functional characterization of the mas oncogene.