SARS冠状病毒核衣壳蛋白的重组表达及其单克隆抗体的制备

目的: 表达SARS冠状病毒核衣壳蛋白(N蛋白),并以表达产物为免疫原制备特异性单克隆抗体 (mAb)。方法: 采用RT- PCR方法, 从灭活的病毒抗原标本中扩增编码N蛋白的基因。测序确认后, 再亚克隆至原核表达载体中。从SDS -PAGE凝胶中回收原核表达产物后免疫BALB/c小鼠, 经融合、筛选制备特异性mAb。结果: 从标本中扩增出 1 269bp的DNA, 测序结果证实为N蛋白基因。将该基因克隆至原核表达载体中后, 在大肠杆菌中获得了较好的表达。表达产物经SDS- PAGE后, 在Mr约为 43 000处可见 1条明显的诱导表达带。Westernblot的结果表明, 该电泳带与SARS患者的恢复期血清呈特异的免疫反应。从SDS- PAGE凝胶中回收表达产物并免疫BALB/c小鼠, 制备出 3株抗N蛋白的mAb。这些mAb与SDS- PAGE凝胶上Mr约为 43 000的蛋白带也呈现很强的免疫反应。结论: 所获的重组N蛋白及特异性mAb, 将为进一步建立SARS病毒感染早期诊断的方法奠定了基础。     

重组冠状病毒核衣壳蛋白血清抗体检测

目的 SARS冠状病毒的核衣壳(Nucleocapsid)蛋白(N蛋白)是病毒的主要结构抗原，重组N蛋白可用作抗原检测患者血清中相应抗体。方法 以纯化的目的蛋白N-1，N-2分别包被96孔板，检测正常人群及患者血清中抗SAKS病毒抗体。结果 检测SAKS感染患者血清，N-1阳性检出率为55．68％，N-2阳性检出率为56．82％，与华大基因试剂盒相比符合率分别为90．12％和87．65％。结论 重组核衣壳蛋白可做为检测SARS抗体的抗原蛋白。     

SARS-CoV核衣壳蛋白重组表达及单克隆抗体特性鉴定

SARS-CoV具有与其他冠状病毒相类似的结构。在有关动物冠状病毒的研究中发现,N蛋白是病毒主要的免疫原蛋白和良好病毒抗体检测抗原。在所有冠状病毒的结构蛋白中,无论从mRNA水平还是蛋白表达水平,N蛋白是病毒在整个感染过程中含量最丰富的蛋白。同时N蛋白含有大量的极性氨基酸残基且不含糖基化位点,因此即使在原核体系中表达,也不会改变其免疫特性。基于SARSCoVN蛋白以上这些特性,决定了可以利用纯化的N蛋白及制备的单克隆抗体研制诊断检测试剂,建立特异的血清学诊断方法,以利于快速、高效检测血清中的病毒抗体。为寻找针对SARS的…     

SARS-CoV核衣壳蛋白抗原性鉴定和基因免疫研究

目的　了解SARS冠状病毒 (SARS CoV)核衣壳蛋白 (N蛋白 )的抗原性及其基因疫苗的免疫原性。方法　用大肠杆菌表达SARS CoV的N蛋白 ,用SARS患者恢复期血清对其进行抗原性鉴定。再构建N蛋白基因疫苗 ,肌肉注射接种小鼠 ,检测小鼠血清中的抗N蛋白IgG抗体、脾细胞增殖和迟发型超敏反应。结果　大肠杆菌重组表达的SARS CoVN蛋白具有强抗原性 ,其基因疫苗能在小鼠有效诱导N蛋白特异性抗体和CD4 、CD8 T淋巴细胞免疫应答。结论　SARS CoV的N蛋白可作为重要的SARS血清学诊断抗原 ,并对于SARS的特异性预防和治疗有潜在的应用价值。     

SARS-CoV、HCoV-229E和OC43核衣壳蛋白的克隆表达及抗原相关性分析

目的克隆表达SARS冠状病毒(SARS-CoV)和人冠状病毒(HCoV-229E、HCoV-OC43)核衣壳(N)蛋白,并对其重组蛋白的抗原相关性进行探讨。方法RT-PCR扩增SARS-CoV、HCoV-229E和HCoV-OC43的N基因全长序列,克隆到原核表达载体pQE30,IPTG诱导表达重组蛋白,用Westernblot和免疫荧光鉴定。结果获得SARS-CoV、HCoV-229E和HCoV-OC43His-N融合蛋白的相对分子质量(Mr)分别约为47×103、44×103、50×103,与相应预测值相符,Westernblot和免疫荧光证实,3种融合蛋白仅与相应的免疫血清特异性结合,3种蛋白的抗原性相互间无交叉反应。结论获得具有免疫原性的SARS-CoV、HCoV-229E和HCoV-OC43的核衣壳融合蛋白,其3种N蛋白抗原性在免疫动物血清中不存在交叉反应。     

基于荧光纳米粒子的新型冠状病毒核衣壳蛋白免疫层析快速检测试剂的 研制

目的：建立新型冠状病毒(SARS-CoV-2)抗原快速检测试剂的制备方法，并对检测试剂的性能指标进行评价。方法：以羧基荧光纳米粒子标记的羊抗SARS-CoV-2核衣壳蛋白(NP)多克隆抗体及鸡IgY为标记抗体，硝酸纤维素膜上分别包被鼠抗N蛋白单克隆抗体和羊抗鸡IgY抗体作为检测线和质控线制备免疫荧光试纸条，对试剂最低检出限、交叉反应性、重复性、临床诊断灵敏度和特异性进行性能评价。结果：检测N全长重组蛋白及热灭活培养物的最低检出限分别为13.8pg/ml和1.6×10~2TCID₅₀/ml；测试16种常见呼吸道病原体高浓度样本均无交叉反应；高、低两个浓度参考品变异系数(CV)分别为7.68%和4.98%。临床鼻咽拭子样本及健康人群鼻拭子样本测试，诊断灵敏度为86.36%(19/22)，特异度为99.16%(355/358)，总符合率为98.42%(374/380)；一致性检验Kappa值为0.8553(P<0.05)。结论：SARS-CoV-2荧光抗原检测试剂检测灵敏度和特异性高，检测速度快，操作便携，可作为现有核酸检测法的补充手段，用于新型冠状病毒的早期筛查...     

SARS-CoV核衣壳蛋白单克隆抗体识别抗原位点的分析

SARS CoV主要的结构蛋白包括刺突糖蛋白(spikeglycoprotein ,S)、包膜小蛋白 (smallenvelope ,E)、膜蛋白 (membrane ,M)和核衣壳蛋白 (nucleocap sidprotein ,N)。研究发现 ,N蛋白诱导机体产生很强的免疫应答〔1〕,我们用SARS CoV全病毒免疫小鼠制备的单克隆抗体 ,发现有 80 %是针对N蛋白的抗体 ,证明N蛋白具有很强的免疫原性 ,这与以往对动物冠状病毒N蛋白研究结果是一致的〔2〕。本研究通过对SARS CoVN蛋白单克隆抗体结合抗原位点分析 ,以及用SARS CoV抗体阳性血清与单抗对N蛋白进行竞争抑制试验 ,分析自然状态下机体对N蛋…     

SARS病毒核衣壳蛋白抗体消长规律

研究SARS病毒抗体的消长规律对于评价患者的愈后及SARS疫苗的使用效果具有重要意义。本项目选用了军事医学科学院生物工程研究所研制的双抗原夹心SARSN蛋白抗体ELISA诊断试剂。对2 79例临床确诊的、发病不同时间SARS患者的血清进行检测,并同时跟踪检测了4 1例SARS患者在不同发病时间(发病3d至16 0d)的血清标本,对抗体产生的时间规律进行了研究。材料和方法标本来源:所用的SARS病例标本为本院检验科从2 0 0 3年2月7日开始,从本院收治病人及广州市中山二院、177医院、广州市第八人民医院、北京小汤山医院收集的SARS病人血清标本…     

重组SARS-CoV核衣壳蛋白的表达及免疫原性研究

我们利用全基因合成方式及原核表达系统获得大量纯化的N蛋白，为SARS-CoV的早期诊断及进一步研究提供新的思路。由于长片段目的基因在原核系统中不易表达，根据抗原性预测分析将N蛋白分成两部分表达，第一部分为N-4蛋白1-549bp，第二部分为N-2蛋白496-1269bp，上下游分别设计BamH Ⅰ、     

汉滩病毒核衣壳蛋白C-端T细胞表位鉴定

目的　鉴定汉滩病毒核衣壳蛋白 (HTNVNP)C 端T细胞表位 ,为肾综合征出血热(HFRS)发病机理、疫苗研制及抗病毒免疫反应研究奠定基础。方法　采用Ficoll密度梯度离心法分离HFRS恢复期患者外周血单个核细胞 (PBMC)。用IFN γELISPOT实验和T细胞增殖实验 ,测试 7名患者PBMC对 2 3条NPC 端合成多肽的T细胞应答。结果　IFN γELISPOT实验结果表明 ,2名供体(3、4 )可分别检测到对 5 1、70号 2条多肽特异性T细胞应答。在供体 3,70号肽特异性T细胞频率为4 5SFC 10 6 PBMC ;在供体 4 ,5 1号肽特异性T细胞频率为 82SFC 10 6 PBMC。T细胞增殖实验与ELISPOT结果基本一致 ,但 5 3号肽和 6 4号肽还可分别刺激供体 1和供体 4的T细胞增殖 ,而未能诱导IFN γ分泌。结论　 5 1号和 70号多肽可能是NPC 端较强的T细胞表位。     

Expression and one-step purification of Plasmodium proteins in dictyostelium

Nearly full-length Circumsporozoite protein (CSP) from Plasmodium falciparum, the C-terminal fragments from both P. falciparm and P. yoelii CSP and a fragment comprising 351 amino acids of P.vivax MSPI were expressed in the slime mold Dictyostelium discoideum. Discoidin-tag expression vectors allowed both high yields of these proteins and their purification by a nearly single-step procedure. We exploited the galactose binding activity of Discoidin Ia to separate the fusion proteins by affinity chromatography on Sepharose-4B columns. Inclusion of a thrombin recognition site allowed cleavage of the Discoidin-tag from the fusion protein. Partial secretion of the protein was obtained via an ER independent pathway, whereas routing the recombinant proteins to the ER resulted in glycosylation and retention. Yields of proteins ranged from 0.08 to 3 mg l(-1) depending on the protein sequence and the purification conditions. The recognition of purified MSPI by sera from P. vivax malaria patients was used to confirm the native conformation of the protein expressed in Dictyostelium. The simple purification procedure described here, based on Sepharose-4B, should facilitate the expression and the large-scale purification of various Plasmodium polypeptides.     

SARS-CoV N蛋白的原核表达及其免疫原性研究

为了研究SARS-CoV病毒N蛋白基因的原核表达及其免疫原性,为进一步的研究奠定基础,我们以PCR方法在全病毒基因组文库中获得全长N基因,分别克隆到pcDNA3和pET32a载体中获得重组质粒pcDNA3-N和pET32a-N。以亲和层析方法分离纯化pET32a-N转化的BL21细菌裂解液中的重组N融合蛋白,并以ELISA方法检测pcDNA3-N质粒基因免疫小鼠诱导后血清中的特异性抗体。结果pET32a-N转化BL21细菌后可检测到重组SARS-CoVN融合蛋白表达并分离纯化,pcDNA3-N基因免疫能够诱导产生N特异的体液免疫应答。研究的结果表明,SARS-CoVN蛋白可以在原核细胞中有效表达并有良好免疫原性,可以为进一步的功能研究和血清学诊断提供条件。     

Comparative analyses of the nucleocapsid genes of several strains of infectious bronchitis virus and other coronaviruses.

The natural sequence variations of the nucleocapsid genes of the Gray, Arkansas99 (Ark99), and Holland52 (Holl52) strains of infectious bronchitis virus (IBV) were determined. These were compared with previously published sequencing data of other IBV strains, as well as other coronaviruses, in order to correlate the serological and evolutionary relationship of coronaviruses. IBV nucleotide sequence alignment shows that overall the sequences are highly conserved, with homologies from 91.1 to 96.5%. However, there are also two regions (730 to 800 and 1138 to 1166) that appear to be even more highly conserved. Overall, the nucleocapsid protein is highly variable both in size and composition between coronavirus major antigenic groups but is conserved within these groups. A phylogenetic tree of the nucleocapsid protein of various coronaviruses indicates that the coronaviruses fall into distinct groups that correspond to the three major antigenic groups; however, a phylogenetic tree of the IBV nucleocapsid shows that this does not hold true for the type specific antigenic groups of IBV.     

Pathogenic murine coronaviruses. II. Characterization of virus-specific proteins of murine coronaviruses JHMV and A59V

We have identified nine intracellular virus-specific proteins in cells infected with JHMV or A59V. Seven virus-specific proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two additional virus-specific proteins were detected by two-dimensional gel electrophoresis. The A59V- and JHMV-specific proteins differ slightly in molecular weight. Four of the nine proteins are structural proteins. The synthesis of the nine virus-specific proteins is noncoordinate with respect to time.     

Expression cloning and humoral immune response to the nucleocapsid and membrane proteins of equine arteritis virus.

To provide a convenient and sensitive method for the detection of equine arteritis virus (EAV)-specific serum antibodies, we developed an immunoblot assay employing the EAV nucleocapsid (N) and membrane (M) proteins expressed in a procaryotic expression vector (pMAL-c2) for the production of recombinant maltose-binding (MBP) fusion proteins (MBP-N and MBP-M). The antigenic reactivity of the recombinant fusion proteins and their Xa factor cleavage EAV products was confirmed by immunoblot using horse antisera to EAV. Some horse sera, however, showed immune reactivity to the MBP fusion partner protein. Based on a total of 32 horse sera analyzed for the presence of EAV antibodies by immunoblot, using the MBP-N or -M fusion proteins and the Xa factor cleavage EAV products, and in the serum neutralization test, there was 100% concordance between the assays. Sera from horses experimentally infected with EAV were reactive in the immunoblot test with both the MBP-N and the MBP-M fusion proteins by day 14 after EAV exposure. The reactivity continued to the end of the experiment at day 145 after infection. This immune reactivity correlated with the detection of neutralizing antibodies in the serum samples. Based on these findings, the recombinant N and M proteins might be useful for serodetection of EAV-infected animals.     

Chemical crosslinking of bacteriophage phi 6 nucleocapsid proteins

phi 6 is a lipid-containing dsRNA bacteriophage of Pseudomonas syringae. Its nucleocapsid (NC) has common features with Reoviridae core particles. We report here the crosslinking of phi 6 NC proteins with cleavable 12-A span chemical crosslinker, dithiobis(succinimidyl propionate). The crosslinked complexes were analyzed in two-dimensional polyacrylamide gels or by using monoclonal antibodies to uncleaved protein complexes in one-dimensional protein gels. The NC surface protein (P8) forms a series of multimeric homopolymers. The phi 6 lytic enzyme, protein P5, is associated with P8 on the NC surface. The interior NC proteins P1 and P4, associated with the virus polymerase activity, are also in contact with the P8 shell. A P1 + P4 complex is also formed. Only one of the NC proteins (P7) did not easily form complexes with the other NC proteins. These results indicate a very closely packed P8 surface lattice with specific contacts to the internal NC proteins.     

Generation of henipavirus nucleocapsid proteins in yeast Saccharomyces cerevisiae

Hendra and Nipah viruses are newly emerged, zoonotic viruses and their genomes have nucleotide and predicted amino acid homologies placing them in the family Paramyxoviridae. Currently these viruses are classified in the new genus Henipavirus, within the subfamily Paramyxovirinae, family Paramyxoviridae. The genes encoding HeV and NiV nucleocapsid proteins were cloned into the yeast Saccharomyces cerevisiae expression vector pFGG3 under control of GAL7 promoter. A high level of expression of these proteins (18-20 mg l(-1) of yeast culture) was obtained. Mass spectrometric analysis confirmed the primary structure of both proteins with 92% sequence coverage obtained using MS/MS analysis. Electron microscopy demonstrated the assembly of typical herring-bone structures of purified recombinant nucleocapsid proteins, characteristic for other paramyxoviruses. The nucleocapsid proteins revealed stability in yeast and can be easily purified by cesium chloride gradient ultracentrifugation. HeV nucleocapsid protein was detected by sera derived from fruit bats, humans, horses infected with HeV, and NiV nucleocapsid protein was immunodetected with sera from, fruit bats, humans and pigs. The development of an efficient and cost-effective system for generation of henipavirus nucleocapsid proteins might help to improve reagents for diagnosis of viruses.     

Characterization of truncated hantavirus nucleocapsid proteins and their application for serotyping

Hemorrhagic fever with renal syndrome (HFRS) is a fulminant infectious disease characterized by fever, hemorrhage, renal impairment, and thrombocytopenia. Hantaviruses associated with this belong to different serotypes: Hantaan (HTN), Seoul (SEO), Dobrava/Belgrade (DOB), and Puumala (PUU). The first two, HTN and SEO, are endemic in China. To investigate the epidemiology of HFRS and virus transmission in China, we constructed prokaryotic plasmids encoding truncated recombinant HTN and SEO nucleocapsid proteins (NPs), which lacked 154 amino acid (aa), 99 aa, or 49 aa in the N-terminal region, respectively. After expression, the truncated rNPs were tested as serotyping antigens, particularly for use in the enzyme-linked immunosorbent assay (ELISA). In addition, 68 acute and 52 convalescent sera were collected from HFRS patients from Harbin, Lantian, and Kaifeng regions in China in 2004, which had hantavirus specific antibodies by IFA. A neutralization test was used to differentiate these, which showed that 73 were due to HTN infection, 33 to SEO infection, and 14 undetermined. By ELISA, the truncated rNPs, that lacked 99 (rNP100) or 49 (rNP50) N-terminal amino acids of the NPs of HTN and SEO, were able to differentiate HTNV and SEOV-specific immune sera, but the rNP155 could not. Particularly, the ELISAs based on the rNP50s had a result comparable to PRNT. Thus, the rNP50 is recommended as efficient serotyping antigen for hantavirus infection diagnosis by ELISA.