建立一种用重组蛋白检测抗口蹄疫病毒抗体的间接ELISA方法

目的研究以重组蛋白作为包被抗原检测口蹄疫病毒（FMDV）感染后的动物血清中特异性抗体的可能性,为建立一种非病毒颗粒的ELISA检测试剂盒提供实验依据。方法利用自行构建表达的O型口蹄疫病毒VP1表位肽重组蛋白（VP1epi）作为包被抗原,采用间接ELISA方法确定抗原的最佳工作浓度和包被方法,优化各项实验条件,并以FMDV感染后的豚鼠血清作为标准阳性血清确定ELISA方法的特异性和灵敏度。结果FMDV感染后的阳性豚鼠血清可以很好地识别VP1epi重组蛋白,用此蛋白包被检测抗FMDV抗体的灵敏度可达1∶3200,并证明所检测的抗体是FMDV特异性的。结论VP1epi重组蛋白可以替代FMDV颗粒用于建立检测抗FMDV抗体的ELISA试剂盒。     

牛AsiaⅠ型口蹄疫病毒重组蛋白疫苗的构建及功能研究

目的为了取代有安全隐患的牛AsiaⅠ型口蹄疫病毒灭活疫苗,我们构建了基因工程重组蛋白疫苗。方法应用PCR方法合成含有表位的基因片段,经过克隆连接获得重组基因,在大肠杆菌中表达后经镍亲和层析纯化重组蛋白。重组蛋白免疫豚鼠后,分别经ELISA和乳鼠中和实验检测血清中抗FMDV抗体水平。结果构建了牛AsiaⅠ型口蹄疫病毒重组蛋白疫苗的结构基因,并成功表达和纯化了该重组蛋白。功能实验表明,该蛋白在豚鼠体内诱生了高水平的抗牛AsiaⅠ型口蹄疫病毒的中和性抗体。结论该重组蛋白为制备牛AsiaⅠ型口蹄疫病毒新型疫苗提供了有价值的线索。     

抗O型口蹄疫病毒VP1单克隆抗体的制备与鉴定

目的：制备抗O型口蹄疫病毒（FMDV）衣壳蛋白VP1的单克隆抗体（mAb）并进行特性鉴定。方法：以自行构建表达的O型FMDV—VP1表位重组蛋白（VP1epi）为抗原免疫BALB／c小鼠，按常规方法进行细胞融合。采用有限稀释法和间接ELISA法克隆和筛选阳性杂交瘤细胞株，用Western blot、间接ELISA和斑点免疫测定法对mAb的特异性进行鉴定。结果：成功地获得1株分泌抗VPlepi重组蛋白mAb的杂交瘤细胞株“C7”，其分泌的mAb为IgG1亚类，能特异性地识别VP1epi重组蛋白，其腹水效价可达1：12800。斑点免疫测定法显示，该mAb能很好地识别灭活的FMDV。结论：VP1epi重组蛋白可代替FMDV制备抗天然FMDV—VP1的mAb。抗O型FMDV—VP1 mAb的成功制备，为进一步研究开发新型FMDV的检测方法奠定了基础。     

预测的SARS冠状病毒刺突蛋白S2亚基B细胞表位肽在大肠杆菌中的表达及其抗原性的鉴定

目的研究预测的SARS冠状病毒刺突蛋白S2亚基B细胞表位肽在大肠杆菌中的表达及其模拟S2蛋白的抗原性。方法用DNAStar软件对S2亚基序列进行分析,预测B细胞表位所在肽段。通过4轮PCR反应人工搭建预测表位cDNA序列并克隆到含有伴侣10基因的pET28a( )载体中,构成重组载体pET28-chap10-S2epi。重组蛋白Chap10-S2epi在E.coliBL21(DE3)中表达并以SDS-PAGE和Westernblot进行鉴定。用纯化的chap10-S2epi免疫家兔制备抗血清,并通过ELISA判断Chap10-S2epi的抗原性。结果成功构建并在大肠杆菌中表达了Chap10-S2pei融合蛋白。Chap10-S2epi免疫的抗血清能识别真核细胞表达的SARS冠状病毒全长S2刺突蛋白。结论预测的SARS冠状病毒S2刺突蛋白B细胞表位肽能够诱导家兔产生针对S2蛋白的抗体,为研制抗SARS病毒基因工程疫苗奠定了基础。     

抗O型口蹄疫病毒DNA疫苗的建立

目的 :研制抗“O”型FMDV的DNA疫苗。方法 :以“O”型口蹄疫病毒 (FMDV)Vp1免疫活性肽基因串联片段取代猪IgGH链可变区的CDR3区 ,并与真核表达载体pCDM8相连构建表达载体pCDM FH。用表达载体pCDM FHDNA对豚鼠及猪进行肌肉注射 ,检测该疫苗的免疫效果。结果 :该DNA疫苗可诱导出抗FMDV专一性的中和抗体及效应性T细胞。攻毒试验表明 ,DNA疫苗pCDM FH可使被免疫豚鼠及猪发病推迟 ,症状减轻。结论 :该DNA疫苗可激发明显的免疫应答及保护效果。为进一步改进或探索同类DNA疫苗提供有益启示     

人肠道病毒71型VP0蛋白的原核表达及多克隆抗体制备

目的:原核表达并纯化人肠道病毒71型(EV71)VP0蛋白,免疫豚鼠制备多克隆抗体,并鉴定其用于EV71检测的反应性和特异性。方法:PCR方法扩增VP0基因,构建原核表达质粒pET-VP0并转化大肠杆菌,诱导表达并纯化VP0重组蛋白,免疫豚鼠制备抗VP0多克隆抗体,ELISA方法检测抗VP0抗体效价,细胞免疫荧光和Western blot方法鉴定抗体特异性。结果:VP0重组蛋白在大肠杆菌BL21中高效表达,制备的抗VP0抗体效价为1∶106。细胞免疫荧光及Western blot检测结果显示,抗VP0多克隆抗体可以识别原核表达及EV71感染细胞中的VP0蛋白。结论:原核表达了EV71的VP0蛋白并制备出抗VP0多克隆抗体,为EV71的临床诊断、疫苗开发和分子病毒学研究提供了新的研究工具和手段。     

柯萨奇病毒B 组5 型VP1 蛋白的外源表达及多克隆抗体的制备

目的:原核表达柯萨奇病毒B组5型的VP1蛋白,并制备其多克隆抗体及检测。方法:提取在Vero细胞中柯萨奇病毒B组5型的RNA,通过逆转录PCR(RT-PCR)扩增获取VP1基因序列,构建原核表达载体,大量诱导表达重组VP1蛋白。用His Trap HP亲和层析柱纯化重组蛋白,以纯化的目的蛋白为抗原,免疫雄性SD大鼠获得VP1蛋白多克隆抗体血清,ELISA测定该抗体的效价,微量中和实验测定抗体的中和活性,Western blot检测抗体的特异性,免疫组化检测抗体对组织中抗原的识别。结果:成功构建了VP1-pET-28a重组载体,并且在BL21细胞中成功诱导表达,亲和层析柱纯化后蛋白纯度大于90%。ELISA测得抗体的效价为1∶128 000,微量中和实验显示抗体没有中和活性,Western blot分析显示抗体能与CVA16和EV71交叉反应,免疫组化实验表明抗体能够识别组织中的CVB5抗原。结论:本研究成功制备了CVB5 VP1蛋白的高效价的多克隆抗体,为CVB5病毒疫苗和病毒诊断的研发提供了有效的工具。     

AsiaⅠ口蹄疫病毒VP1蛋白单克隆抗体的制备与鉴定

目的:制备AsiaI口蹄疫病毒VP1蛋白单克隆抗体(mAb)并进行鉴定。方法:用纯化的AsiaI型口蹄疫病毒VP1表位重组蛋白为抗原免疫6～8周龄的雌性BALB/c小鼠,经过3次免疫后,取其脾细胞与Sp2/0骨髓瘤细胞融合。采用有限稀释法和间接ELISA克隆和筛选阳性杂交瘤细胞株,用SDS-PAGE电泳、间接ELISA以及微量细胞中和试验对所获得的mAb的特异性进行鉴定。结果:成功获得3株能稳定传代并分泌抗AsiaImAb的杂交瘤细胞株,分别命名为:1B8、5E1、5E2,其分泌的mAb为IgG1(1B8)和IgG2a(5E1、5E2)亚类,他们均能特异性的识别VP1重组蛋白和AsiaI型全病毒,其腹水效价在1:105～1:106。微量细胞中和试验表明该mAb能很好地识别灭活的FMDV,中和效价达1:1024以上。交叉试验表明该mAb具有高度特异性,型间无交叉反应,证明所获得的mAb均完全针对AsiaI FMDV抗原决定簇。结论:在口蹄疫病毒mAb的研究中,VP1重组蛋白有望代替活病毒来制备mAb。AsiaI口蹄疫病毒VP1mAb的成功制备,为进一步研究和开发新型口蹄疫的检测方法和抗原表位奠定了基础。     

AsiaI口蹄疫病毒VP1蛋白单克隆抗体的制备与鉴定

目的：制备AsiaI口蹄疫病毒VP1蛋白单克隆抗体（mAb）并进行鉴定。方法：用纯化的AsiaI型口蹄疫病毒VP1表位重组蛋白为抗原免疫6～8周龄的雌性BALB／c小鼠，经过3次免疫后，取其脾细胞与sp2／0骨髓瘤细胞融合。采用有限稀释法和间接ELISA克隆和筛选阳性杂交瘤细胞株，用SDS-PAGE电泳、间接ELISA以及微量细胞中和试验对所获得的mAb的特异性进行鉴定。结果：成功获得3株能稳定传代并分泌抗AsiaImAb的杂交瘤细胞株，分别命名为：188、5E1、5E2，其分泌的mAb为IgG1（188）和IgG2a（5E1、5E2）亚类，他们均能特异性的识别VP1重组蛋白和AsiaI型全病毒，其腹水效价在1：10^5～1：10^6。微量细胞中和试验表明该mAb能很好地识别灭活的FMDV，中和效价达1：1024以上。交叉试验表明该mAb具有高度特异性，型间无交叉反应，证明所获得的mAb均完全针对AsiaI FMDV抗原决定簇。结论：在口蹄疫病毒mAb的研究中，VP1重组蛋白有望代替活病毒来制备mAb。AsiaI口蹄疫病毒VP1 mAb的成功制备，为进一步研究和开发新型口蹄疫的检测方法和抗原表位奠定了基础。     

口蹄疫病毒多抗原表位基因融合表达产物的抗原性分析

目的:筛选出高抗原性的口蹄疫病毒(FMDV)抗原表位组合体, 为能有效启动细胞免疫、高广谱性的口蹄疫植物疫苗的研究提供研究基础.方法:通过化学方法合成O、 A型口蹄疫病毒的5个T细胞表位基因和2个B细胞表位基因单链, 采用套叠PCR的方法将T或是B细胞表位基因分别融合成融合体T或B, 利用同尾酶的性质将融合体T和B连接成3种不同融合方式的串连体, 即5′-T-B-T-3′、 5′-T-T-B-3′和5′-B-T-T-3′; 利用马铃薯X病毒(potato virus X, PVX)载体在烟草叶片中表达各串连体基因、融合体T基因、融合体B基因和O型口蹄疫病毒的VP1基因; RT-PCR检测各基因在烟草(N.benthamiana)叶片中的转录水平; 间接ELISA及Western Dotblot 检测表达产物的抗原性.结果:各抗原基因在烟草叶片中成功获得了表达, 表达产物的抗原性因不同的融合方式而呈现差异, 其中以5′-T-B-T-3′的融合方式为最高, 5′-B-T-T-3′次之, 再是5′-T-T-B-3′, 但都高于VP1基因的表达产物, 更高于融合体T或B基因的表达产物.结论:通过融合口蹄疫病毒的多个表位基因有可能找到一种研制有效启动细胞免疫反应广谱抗口蹄疫病毒的基因工程疫苗的方法, 且T、 B细胞表位的不同组合方式对免疫活性很可能存在一定的影响.     

Promising multiple-epitope recombinant vaccine against foot-and-mouth disease virus type O in swine

In order to develop a completely safe immunogen to replace the traditional inactivated vaccine, a tandem-repeat multiple-epitope recombinant vaccine against foot-and-mouth disease (FMD) virus (FMDV) type O was developed. It contained three copies each of residues 141 to 160 and 200 to 213 of VP1 of the O/China/99 strain of FMDV coupled with a swine immunoglobulin G heavy-chain constant region (scIgG). The data showed that the multiple-epitope recombinant vaccine elicited high titers of anti-FMDV specific antibodies in swine at 30 days postvaccination (dpv) and conferred complete protection against a challenge with 103 50% swine infective doses of the O/China/99 strain. The anti-FMDV specific antibody titers were not significantly different between the multiple-epitope recombinant vaccine and the traditional vaccine (t test, P > 0.05). The number of 50% pig protective doses was 6.47, which is higher than the number recommended by the World Organization for Animal Health. The multiple-epitope recombinant vaccine resulted in a duration of immunity of at least 6 months. We speculate that the multiple-epitope recombinant vaccine is a promising vaccine that may replace the traditional inactivated vaccine for the prevention and control of FMD in swine in the future.     

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.     

Comparison of immune responses against foot-and-mouth disease virus induced by fusion proteins using the swine IgG heavy chain constant region or beta-galactosidase as a carrier of immunogenic epitopes

Previously, we demonstrated that a fusion protein (Gal-FMDV) consisting of beta-galactosidase and an immunogenic peptide, amino acids (141-160)-(21-40)-(141-160), of foot-and-mouth disease virus (FMDV) VP1 protein induced protective immune responses in guinea pigs and swine. We now designed a new potential recombinant protein vaccine against FMDV in swine. The immunogenic peptide, amino acids (141-160)-(21-40)-(141-160) from the VP1 protein of serotype O FMDV, was fused to the carboxy terminus of a swine immunoglobulin G single heavy chain constant region and expressed in Escherichia coli. The expressed fusion protein (IgG-FMDV) was purified and emulsified with oil adjuvant. Vaccination twice at an interval of 3 weeks with the emulsified IgG-FMDV fusion protein induced an FMDV-specific spleen proliferative T-cell response in guinea pigs and elicited high levels of neutralizing antibody in guinea pigs and swine. All of the immunized animals were efficiently protected against FMDV challenge. There was no significant difference between IgG-FMDV and Gal-FMDV in eliciting immunity after vaccination twice in swine. However, when evaluating the efficacy of a single inoculation of the fusion proteins, we found that IgG-FMDV could elicit a protective immune response in swine, while Gal-FMDV only elicited a weak neutralizing activity and could not protect the swine against FMDV challenge. Our results suggest that the IgG-FMDV fusion protein is a promising vaccine candidate for FMD in swine.     

Modified-live infectious bovine rhinotracheitis virus vaccine expressing monomer and dimer forms of foot-and-mouth disease capsid protein epitopes on surface of hybrid virus particles

Summary Modified-live, attenuated infectious bovine rhinotracheitis (IBR) hybrid virus vaccines have been constructed by inserting in the major IBRV glycoprotein g III gene chemically synthesized deoxyribonucleotide sequences encoding the bovine growth hormone signal sequence and monomeric or dimeric forms of the foot and mouth disease virus (FMDV) VP 1 epitope sequences. The foreign DNA sequences were inserted at the N-terminal end of the IBRV g III coding sequence and were driven by the IBRV g III promoter. The sequences encoding the first 38 and the first 21 amino acids of the IBRV g III were deleted from the hybrid viruses containing inserts of the monomeric and dimeric FMDV epitope sequences, respectively, to avoid redundant signal sequences. Plaque immunoassay experiments with guinea pig and bovine anti-FMDV peptide antisera, and with anti-IBRV g III monoclonal antibodies demonstrated that IBRV-FMDV fusion proteins were expressed in virus-infected MDBK cells. Immunoelectron microscopy analyses demonstrated that the IBRV-FMDV fusion proteins were expressed as repeated structures on the surface of virus particles. Experiments showed that the recombinant IBRV-FMDV viruses protected cattle from IBRV (Cooper) challenge and induced anti-FMDV peptide antibodies, thereby demonstrating that the FMDV epitopes were expressed in vivo.     

Construction and immunogenicity of a recombinant fowlpox virus containing the capsid and 3C protease coding regions of foot-and-mouth disease virus

Foot-and-mouth disease virus (FMDV) is an important pathogen with worldwide economic consequences. Consequently, an important goal is the development of a vaccine that can provide rapid protection while overcoming the potential risk associated with the production of conventional inactivated vaccines. An important secondary feature of the vaccine would be the ability to distinguish vaccinated from infected animals. A recombinant fowlpox virus (vUTAL3CP1) containing FMDV capsid polypeptide and 3C coding regions of O/NY00 was constructed and evaluated for its ability to induce humoral and cellular responses in mice and guinea pigs. In addition, the ability to protect guinea pigs against homologous virus challenge was examined. Mice and guinea pigs were given booster vaccinations twice and once, respectively, and guinea pigs were challenged 20 days after the booster vaccination. Control groups included animals inoculated with commercial vaccine, fowlpox virus or phosphate-buffered saline (PBS). All animals vaccinated with vUTAL3CP1 developed specific anti-FMDV antibody and neutralizing antibody, as well as T lymphocyte proliferation response and CTL cytotoxic activity. Three of four guinea pigs vaccinated with vUTAL3CP1 were completely protected from viral challenge. The results demonstrated the potential of a fowlpox virus-based recombinant FMD vaccine.     

Recombinant adenovirus co-expressing capsid proteins of two serotypes of foot-and-mouth disease virus (FMDV): in vitro characterization and induction of neutralizing antibodies against FMDV in swine

Human adenovirus type 5 (Ad5) has been evaluated as a novel gene delivery vector for the development of live-viral vaccines for foot-and-mouth disease (FMD). In this study, we constructed an Ad5 vector co-expressing the capsid precursor proteins, P1, of FMD virus (FMDV) field strains A24 Cruzeiro and O1 Campos and examined the neutralizing antibody responses in swine after inoculation with the vector. To construct the Ad5 vector, a bicistronic expression cassette containing a cytomegalovirus promoter, the P1 coding sequence of FMDV A24, the internal ribosomal entry site (IRES) of FMDV A12, the P1 coding sequence of FMDV O1 Campos and the coding region of A12 3C protease was inserted into the E1 region of an E1/E3-deleted Ad5. The recombinant adenovirus, Ad5A24+O1, was generated by transfection of 293 cells with full-length pAd5A24+O1 recombinant plasmid DNA. The recombinant Ad5 co-expressed P1 of both A24 and O1 in infected 293 cells and P1 of both serotypes was processed to produce VP0, VP3, and VP1. We further demonstrated the formation of capsid protein complexes by co-precipitation of VP0, VP3, and VP1 with monoclonal antibodies against viral capsid proteins. Swine inoculated with Ad5A24+O1 generated neutralizing antibodies against both A24 and O1. However, the overall neutralizing antibody response was considerably lower than that induced by a commercial FMD vaccine or a monovalent Ad5-A24 vaccine.     

C-terminal region of VP1 of selected foot-and-mouth disease virus serotypes: expression in E. coli and affinity purification

Foot-and-mouth disease (FMD), one of the most contagious and economically important diseases of farm animals, is caused by a FMD virus (FMDV) which belongs to the family of Picornaviridae. The virus occurs as seven serotypes of which four (A, O, C and Asia 1) are prevalent in India. Immunoprophylaxis supported by precise diagnosis is the prime requirement for achieving the success in controlling the disease. Recently, recombinant DNA technology is gaining importance for the production of cost-effective and safer diagnostics and immunogens. Based on this approach, cDNA of a part of gene for major variable immunogenic region, VP1, of FMDV of four serotypes (A22, O, C and Asia 1) was amplified by PCR and cloned into expression vector. The expression of the 16 K protein gene from the clones was induced with IPTG and analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) and [35S]-methionine labeling. The immunoreactivity of the labeled proteins was assayed by immunoprecipitation with anti-FMDV type-specific sera. Since the proteins contain 6 His residues at the N-terminal end, their affinity purification was carried out using nickel nitrilo-tri-acetic acid (Ni-NTA) agarose matrix. The proteins were found to be immunoreactive and the useful in the FMD diagnosis.     

Protective immune response of the capsid precursor polypeptide (P1) of foot and mouth disease virus type 'O' produced in Pichia pastoris

Foot and mouth disease virus (FMDV) is the aetiological agent of a highly contagious vesicular disease of cloven-hooved animals. The gene coding for the capsid polyprotein (P1) of FMDV from serotype 'O' vaccine strain (O75Madras) was cloned and expressed in yeast Pichia pastoris. The expressed P1 protein was characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western Blot analysis. Immunisation of Guinea pigs with recombinant P1 induced FMDV type O specific immune response. The humoral response to vaccine was measured by indirect ELISA and a serum neutralisation test (SNT). The Guinea pig sera showed high titres both in ELISA and SNT. Upon challenge with virulent Guinea pig adapted homologous type 'O' virus, the animals showed a protective index of 2.52. This study shows that the yeast expressed FMDV P1 could be a safe vaccine in non-endemic countries and a cost-effective vaccine in endemic countries. This is the first report on the production of FMDV structural proteins in yeast and their application as a vaccine.     

Immune responses to the oral administration of recombinant Bacillus subtilis expressing multi-epitopes of foot-and-mouth disease virus and a cholera toxin B subunit

Bacillus subtilis has been engineered successfully to express heterologous antigens for use as a vaccine vehicle that can elicit mucosal and systemic immunity response. In this study, a recombinant B. subtilis expressing the B subunit of cholera toxin (CT-B) and an epitope box constituted with antigen sites from foot-and-mouth disease virus (FMDV) type Asia 1 was constructed and named 1A751/CTB-TEpiAs. Its capability to induce mucosal, humoral, and cellular responses in mice and guinea pigs was evaluated after oral administration with vegetative cells of 1A751/CTB-TEpiAs. In addition, its capability to protect guinea pigs against homologous virus challenge was examined. All animals were given booster vaccination at day 21 after initial inoculation and guinea pigs were challenged 3 weeks after booster vaccination. The control groups were inoculated with a commercial vaccine or administered orally with 1A751/pBC38C or an oral buffer. All animals vaccinated with 1A751/CTB-TEpiAs developed specific anti-FMDV IgA in lung and gut lavage fluid, serum ELISA antibody, neutralizing antibody as well as T lymphocyte proliferation, and IFN-γ secretory responses. Three of the five guinea pigs vaccinated with 1A751/CTB-TEpiAs were protected completely from the viral challenge. The results demonstrate the potential viability of a B. subtilis-based recombinant vaccine for the control and prevention of FMDV infections.