Construction and Identification of siRNA Expression Vector Targeting Nucleocapsid Protein N gene of PRRSV

[ Objective] The aim of this study was to investigate the construction and identification of siRNA expression vector targeting nucleocapsid protein N gone of PRRSV. [Method] Three siRNA oligonucleotides targeting nucleocapsid protein N gone sequence of PRRSV were designed or synthesized, and then inserted into CMV promoter downstream to clone into pSilencer 4,1 -CMV eukaryotic expression vector. The recombinant expression vector was identified by enzyme digestion and DNA sequencing. [ Result] The results showed that the siRNA interference recombinant plasmid vector pSilencer-N targeting nucleocapsid protein gone expression had been successfully constructed. [ Conclusion] This study lays a foundation for studies on the controlling PRRSV by RNA interference technique .

禽流感病毒NP蛋白单克隆抗体的制备与鉴定

为获得禽流感病毒(Avian influenza virus,AIV)NP蛋白的单克隆抗体,将构建的重组表达质粒pET-30a-NP转化BL21细胞,经IPTG诱导表达、纯化后作为免疫原,免疫8周龄Balb/c雌性小鼠,并按常规方法制备杂交瘤细胞。通过ELISA方法、Western-blot方法进行筛选,获得3株杂交瘤细胞株,命名为3A6、2H12、5F7,并进行了培养特性、分泌抗体活性、分泌抗体亚类的鉴定。结果显示:3株细胞株连续传10代均稳定分泌单克隆抗体,分泌的单克隆抗体亚型均为IgG2b,轻链类型均为Kappa。制备并纯化了以上3株单克隆抗体,浓度分别为2.9、2.5、2.8 mg/mL,纯度不低于90%。West-blot检测,单抗与H7血凝抑制试验抗原、H5血凝抑制试验抗原、H9N2病毒能发生特异性反应,说明单抗具有广谱性,且与IBDV、REV、IBV、MDV、ALV、AE、ILT、NDV、EDSV等均无特异性条带出现,说明特异性良好。本研究制备的3株针对禽流感NP蛋白的单抗,具有较好的特异性、保守性和广谱性,为下一步开展AIV诊断试剂如IFA检测试剂盒、ELISA检测试剂盒等的研制奠定了物质基础。

Serial Expression of the Truncated Fragments of the Nucleocapsid Protein of CCHFV and Identification of the Epitope Region

The Crimean-congo hemorrhagic fever virus(CCHFV)is a geographically widespread fatal pathogen. Identification of the epitope regions of the virus is important for the diagnosis and epidemiological studies of CCHFV infections.In this study,expression vectors carrying series truncated fragments of the NP(nucleocapsid protein)gene from the S fragment of CCHFV strain YL04057 were constructed.The recombinant proteins were expressed in E.coli and purified for detection.The antigenic of the truncated fragments of NP was detected with a polyclonal serum(rabbit)and 2 monoclonal(mAbs)(14B7 and 43E5)against CCHFV by Western-blot analyses. The results showed that the three expressed constructs,which all contained the region 235AA to 305AA could be detected by mAbs polyclonal serum.The results suggest that region 235-305 aa of NP is a highly antigenic region and is highly conserved in the NP protein.

Production of spike and nucleocapsid recombinant proteins of porcine epidemic diarrhea virus for antibody detection by ELISA

Porcine epidemic diarrhea (PED), a devastating enteric disease in pigs, is caused by PEDvirus (PEDV)(1)Reduced severity of clinical diseases was reported to associate with neutralizing antibody titers in colostrum. However, viral neutralization assay(VN) is laborious and not suitable for routine diagnosis. Spike protein plays an important role in stimulating neutralizing antibody that might be suitable for PEDV diagnosis.

Indirect Enzyme-Linked Immunosorbent Assay Based on the Nucleocapsid Protein of SARS-like Coronaviruses

The nucleocapsid protein(N) is a major structural protein of coronaviruses. The N protein of bat SARS-like coronavirus(SL-CoV) has a high similarity with that of SARS-CoV. In this study,the SL-CoV N protein was expressed in Escherichia coli,purified and used as antigen. An Indirect Enzyme-Linked Immunosorbent Assay(indirect ELISA) was developed for detection of SARS-or SL-CoV infections in bat populations. The detection of 573 bat sera with this indirect ELISA demonstrated that SL-CoVs consistently circulate in Rhinilophus species,further supporting the proposal that bats are natural reservoirs of SL-CoVs. This method uses 1-2 μl of serum sample and can be used for preliminary screening of infections by SARS-or SL-CoV with a small amount of serum sample.

Characterization of Influenza H5N1 Nucleocapsid Protein for Potential Vaccine Design

Avian influenza, subtype H5N1, causes occasional but serious infections in humans and efforts to produce vaccines against this strain continue. Current influenza vaccines are prophylactic and utilize the two major antigens, hemagglutinin and neuraminidase. Nucleocapsid protein (NP) is an attractive alternative antigen because it is highly conserved across all influenza strains, has been shown to increase the rate of viral clearance, and potential therapeutic vaccines would elicit cytotoxic T lymphocyte responses in an infected person. The NP antigen from H5N1 was characterized using a variety of physico-chemical methods to gain insights into both the biological and physical properties of the antigen which are important from a regulatory viewpoint when considering therapeutic vaccines. Results obtained to date show that NP is relatively unstable and indicate that the conformation of the H5N1 NP antigen is highly dependent upon purification procedure, buffer conditions, pH and the presence or absence of RNA. These factors will need to be clearly defined and taken into consideration when manufacturing and regulating NP vaccine preparations.

Expression of Hantaan virus 26 kD fragment of nucleocapsid protein in insect cells and prelimimary study on its immunogenicity

Objective: To express the 26 kD fragment of Hantaan virus nucleocapsid protein that contains the major antigenic epitopes in insect cells, and make a preliminary analysis of its immunological characteristics. Methods: The recombinant baculovirus bac-S0.7 with the 700 bp fragment of S gene 5' terminal of Hantaan virus was constructed, and the antigenicity of the expression product was tested. Mice were injected with Sf9 cells infected by the recombinant baculovirus. The humoral and cellular immunological effects were identified by indirect immunofluorescence assay, micro-cell culture neutralization test and T lymphocytes stimulation test. Results: Immunized by bac-S0.7 infecting insect cells, specific antibody with the highest titer of 1∶1 600 was observed. The stimulation indexes of splenocytes of immunized mice to nucleocapsid protein of Hantaan virus was higher than the negative control. Conclusion: The expression product of S0.7 gene fragment in insect cells is immunogenic.

Identification and Characterization of Nuclear Localization Signals within the Nucleocapsid Protein VP15 of White Spot Syndrome Virus

The nucleocapsid protein VP15 of white spot syndrome virus (WSSV) is a basic DNA-binding protein. Three canonical bipartite nuclear localization signals (NLSs), called NLS1 (aa 11-27), NLS2 (aa 33-49) and NLS3 (44-60), have been detected in this protein, using the ScanProsite computer program. To determine the nuclear localization sequence of VP15, the full-length open reading frame, or the sequence of one of the three NLSs, was fused to the green fluorescent protein (GFP) gene, and transiently expressed in insect Sf9 cells. Transfection with full-length VP15 resulted in GFP fluorescence being distributed exclusively in the nucleus. NLS1 alone could also direct GFP to the nucleus, but less efficiently. Neither of the other two NLSs (NLS2 and 3) was functional when expressed alone, but exhibited similar activity to NLS1 when they were expressed as a fusion peptide. Furthermore, a mutated VP15, in which the two basic amino acids (11RR12) of NLS1 were changed to two alanines (11AA12), caused GFP to be localized only in the cytoplasm of Sf9 cells. These results demonstrated that VP15, as a nuclear localization protein, needs cooperation between its three NLSs, and that the two residues (11RR12) of NLS1 play a key role in transporting the protein to the nucleus.

Study on the Cytotoxic T Lymphocytes Clone Specific for the Nucleocapsid Protein of Hantaan Virus from Peripheral Blood in Patients with Hemorrhagic Fever with Renal Syndrome

In order to elucidate the molecular and immunological mechanisms as well as the pathogenesis of hemorrhagic fever with renal syndrome (HFRS), the CD8 + cytotoxic T lymphocytes (CTL) clone was established directly from peripheral blood mononuclear cells (PBMC) of patients with HFRS. The activities of CTL were detected as usual with EBV-transformed lymphoblastoid cell line (BLCL) as target cells. The results showed that the CTL clone could recognized and killed the target cells with specificity of nucleocapsid protein of Hantaan virus (HTNVNP) with the cytotoxicity percentages of 50.2%, 25.4% and 39.0% respectively. These results demonstrated that the antigenic epitopes of HTNVNP mainly located on the C-terminal of the viral nucleocapsid protein.

稳定表达猪德尔塔冠状病毒N蛋白的Vero细胞系的建立及鉴定

为获得稳定表达猪德尔塔冠状病毒(PDCoV)核衣壳(N)蛋白的非洲绿猴肾(Vero)细胞系,本研究将PDCoV-N基因克隆入慢病毒载体中,获得重组质粒pLVX-PDCoV-N,利用慢病毒包装系统转染293T细胞,包装成表达N蛋白的慢病毒颗粒,慢病毒感染Vero细胞,嘌呤霉素加压筛选目的细胞。RT-PCR扩增N基因和测序表明细胞系基因组中存在N蛋白编码序列,Western blot和IFA试验表明N蛋白可在细胞系中稳定表达。应用制备的细胞系对临床PDCoV阳性血清样品进行检测,与ELISA检测结果符合率达到100%。本研究成功建立了稳定表达PDCoV N蛋白的Vero细胞系,为PDCoV N蛋白生物学特性研究和PDCoV的临床检测、流行病学调查奠定了基础。

汉坦病毒疫苗株Z10与Z37重组核蛋白NP的表达纯化及其特异结合基因组末端反向重复序列的功能研究

汉坦病毒是引起肾综合征出血热(HFRS)和汉坦病毒型肺炎综合征(HPS)的主要病原体。其基因组由三节段的单股负链RNA组成,即S、M与L基因片段。汉坦病毒基因组的一个重要特点是每个基因片段的两个末端都有一段长18个核苷酸的高度保守的反向重复序列,互补可形成双链发夹结构,并且这一特点为不同型病毒所共有。为了研究该基因组末端保守的反向重复序列的功能,首先构建了汉坦病毒中国疫苗株Z10(汉滩型)及Z37(汉城型)的核蛋白原核表达载体,并在大肠杆菌中高效表达。经NI NAT亲和柱和HiPrep16/10DEAE离子交换柱液相色谱(FPLC)二步提纯,获得高纯度的重组核蛋白,并分别以胰蛋白酶消化后,用Westernblotting进行区分和鉴定。以T4DNA激酶同位素标记一对人工合成互补的18个核苷酸反向重复序列,制备双链探针。然后将该探针与纯化的Z10、Z37株的核蛋白NP进行非变性凝胶电泳迁移改变实验(EMSA)后发现,重组的Z10、Z37株的核蛋白NP,在体外均可特异地结合其基因组末端反向重复序列形成的双链探针。该结果表明,汉坦病毒基因组末端的反向重复序列是核蛋白重要结合位点,这对理解汉坦病毒核蛋白功能以及病毒复制过程中病毒粒子的包装机制有重要的意义。

新城疫病毒V4株NP和P基因及其间隔区序列的克隆与分析

采用RT-PCR技术克隆了新城疫病毒(NDV)V4株长约4 200 bp的核苷酸序列,并进行了序列测定与分析。结果表明,该序列中包含有NDV V4株NP基因编码区、NP和P基因间隔区以及P基因的全部核苷酸序列。NDV V4株NP和P基因与其他8个NDV毒株相应部分进行同源性比较,与Quuesland V4株的同源性最高。NDV V4株NP和P基因间隔区序列与其他13株NDV毒株相应部分的比较结果表明,F48E9等强毒株较La sota等弱毒、无毒毒株和试验用V4株在这个区域多了6个碱基,这6个碱基插入的位置在La sota等弱毒、无毒毒株全基因组序列的1647-1648 nt处;参比的14株NDV在这个区域的同源性为63．9％-100％,弱毒株之间的同源性较高,弱毒株与强毒株之间及强毒株之间的同源性差异较大。

汉滩病毒核壳蛋白（NP）在杆状病毒系统的表达及其免疫原性研究

应用杆状病毒表达载体成功地表达了汉滩病毒７６－１１８株（ＨＴＮＶ）核壳蛋白。将ＨＴＮＶＳ基因插入杆状病毒转染质粒ｐＡｃＹＭＩＢ的多角体基因启动子下游附近，与经Ｂｓｕ３６Ｉ酶切线性化的杆状病毒（ＡｃｖＥＰＡ）ＤＮＡ共同转染Ｓｆ９细胞，经空斑筛选获得了高效表达ＮＰ的重组杆状病毒（ＡｃＶＨａｎＳ）。经ＳＤＳ－ＰＡＧＥ和Ｗｅｓｔｅｒｎｂｌｏｔ证实，表达产物与ＨＴＮＶ毒粒ＮＰ分子量均为５０ｋＤ左右，紫外扫描显示表达量约占细胞总蛋白量的１２．１％，ＥＬＩＳＡ滴度达１：３２００～１：６４００。用一批抗ＮＰ单克隆抗体和病人血清证实，重组ＮＰ与毒粒ＮＰ的免疫反应性完全一致。

牡蛎疱疹病毒结构蛋白真核表达系统构建及多聚化特性

牡蛎疱疹病毒(OsHV-1)在全球范围内导致牡蛎、扇贝与蚶类的大规模死亡,成为双壳贝类养殖产业的重要威胁。为了解OsHV-1的结构与致病机制。本研究利用人胚胎肾细胞(HEK293t),构建OsHV-1主要核衣壳蛋白(ORF104和ORF33)的真核表达系统,并对ORF104和ORF33潜在相互作用进行分析。实验首先通过特异性PCR扩增技术得到orf 104和orf 33的基因序列,根据其编码蛋白的理化性质、跨膜区与三维结构等生物信息学分析结果,选择pCDNA3.1(+)构建两种基因的重组表达质粒。重组质粒经大肠杆菌扩增、提取后,利用转染试剂Lipo8000™将pCDNA3.1(+)-orf 104与pCDNA3.1(+)-orf 33分别单独或共转染至HEK293t。然后,将转染后的细胞培养18 h后裂解收集蛋白。最后利用蛋白免疫印迹(Western blot,WB)与负染电镜检测两种目的蛋白的表达情况。结果显示,实验成功构建了OsHV-1衣壳蛋白ORF104和ORF33的重组表达质粒载体,通过真核细胞表达得到大小约为135与35 ku的目的蛋白。研究表明,表达质粒可在真核表达系统中实现蛋白单独转染与共转染,共转染蛋白间可能存在相互作用的趋势并形成多聚体,其中,ORF33自身即可形成分子质量不同的多聚体。本研究首次利用真核表达系统开展OsHV-1关键结构蛋白的表达,为进一步开展该病毒结构蛋白功能与互作,以及病毒入侵机制研究奠定基础。

牛副流感病毒3型NP单抗的制备及初步应用

为制备牛副流感病毒3型(BPIV3)核衣壳蛋白(NP)单克隆抗体(MAb),本研究利用原核表达并纯化的重组NP(rNP)免疫BALB/c小鼠,取免疫后小鼠脾细胞与骨髓瘤细胞SP2/0融合。采用以BPIV3为检测抗原的间接ELISA方法筛选阳性细胞克隆,经3次克隆纯化后获得1株稳定分泌抗NP特异性MAb的杂交瘤细胞株(5E5)并制备腹水,采用rNP及BPIV3包被的ELISA效价分别是2×106和1.28×105。间接ELISA、western blot、IFA试验表明该MAb具有良好的反应性和特异性。经抗体亚类鉴定该MAb亚类为IgG1/κ。特异性试验表明该MAb不与牛传染性鼻气管炎病毒、牛病毒性腹泻病毒反应。免疫组化试验表明该MAb可以检测BPIV3感染动物体内的病原。该MAb还可用于建立检测BPIV3病原及抗体的诊断方法,同时为研究NP的结构和功能提供了条件。

禽流感病毒NP基因的真核表达及抗体检测芯片的建立

为建立一种检测A型禽流感病毒(AIV)抗体的蛋白芯片,本研究以AIV总RNA为模板,RT-PCR方法扩增NP基因,与真核表达载体pFastBacHTa连接,并在昆虫细胞中表达。重组蛋白经纯化及westernblot鉴定,点样于醛基包被的载玻片上,制备检测AIV抗体的蛋白芯片。确定芯片反应最佳条件为:点样浓度2mg/mL,固定24h,1%BSA进行封闭,一抗稀释度1∶100,二抗稀释度1∶2000。利用蛋白芯片分别对15个亚型流感病毒免疫血清、SPF鸡血清、抗新城疫病毒血清、抗法氏囊病毒血清和现地血清样品进行检测,通过与血凝抑制试验比较,表明建立的蛋白芯片方法具有良好的灵敏性和特异性,为AIV抗体检测及制备检测AIV不同亚型或多种病原抗体的蛋白芯片提供方法。

靶向鸭肠炎病毒NP基因RNAi对DEV增殖的影响

为探究核衣壳蛋白(NP)对鸭肠炎病毒(DEV)增殖的影响,笔者根据GenBank上DEV-NP基因序列,设计并构建pSilencer-DEV-NP,采用三种不同方式处理转染鸭胚成纤维(DEF)细胞后,应用荧光显微镜法和FQ-PCR法分析pSilencer-DEV-NP对DEV增殖的影响,结果显示:经荧光显微镜法观察,pSilencer-DEV-NP-l^4在DEF细胞中均呈现绿色荧光;FQ-PCR法扩增并计算,pSilencer-DEV-NP-l^4对DEV增殖的沉默效率分别为81.10%、72.69%、77.35%和67.69%;采用三种方法处理,pSilencer-DEV-NP-1对DEF细胞中DEV的增殖均有沉默作用,但沉默效率不尽一致,其中先后转染后感染时pSilencer-DEV-NP-1的沉默效果最好,在处理60h时沉默效率高达69.20%;同时转染和感染时pSilencer-DEV-NP-1的沉默效果次之,在处理48h时沉默效率最好仅达63.79%;先感染后转染时pSilencer-DEV-NP-1的沉默效果较差,在处理60h时沉默效率最高仅为52.58%。上述研究结果提示,核衣壳蛋白对鸭肠炎病毒增殖具有一定的影响,为阐明核衣壳蛋白在鸭肠炎病毒复制与增殖的作用机制奠定了理论基础。

鹅源新城疫病毒NP、P和L基因的克隆与P基因的表达鉴定

将鹅源新城疫病毒的NP、P和L基因通过RT PCR方法从尿囊液中扩增后分别克隆进pGEM Teasy载体 ,再分别亚克隆到真核表达载体pCI neo上 ,通过酶切、PCR和测序验证克隆正确。利用P基因开放性阅读框 (ORF)上靠近终止密码上游的AgeI位点 ,将报告基因绿色荧光蛋白 (GFP)基因克隆进P基因真核表达重组质粒 ,分别转染COS 1细胞和CEF细胞 ,在倒置荧光显微镜下可见到绿色荧光 ,表明GFP基因已得到表达 ,由此证明P基因也已得到表达。鹅源新城疫病毒NP、P和L基因的克隆成功 。

H5N1亚型禽流感病毒核衣壳蛋白(NP)基因的进化及原核表达

参考GenBank上H5N1亚型禽流感病毒(AIV)的核衣壳蛋白(NP)基因序列设计引物,PCR扩增NP基因,对其进行序列分析并构建分子进化树。将克隆的NP基因插入原核表达载体pET32a,在大肠杆菌中进行诱导表达,对诱导表达的NP重组蛋白进行纯化、Western-Blot鉴定及免疫原性分析。结果表明,克隆的NP基因与GenBank上发表的另外2个河南AIV毒株亲缘关系较近,诱导表达的NP重组蛋白主要以可溶性形式存在,分子量约为70 kDa,并且能够与H5亚型AIV阳性血清发生特异性反应,具有良好的抗原性。

禽流感病毒同义NP蛋白的原核表达及其间接ELISA检测方法的建立

为建立通用型禽流感病毒(AIV)快速检测方法,本研究将合成的同义NP(ConsNP)基因克隆于pET30a中,利用大肠杆菌系统进行原核表达,以纯化重组ConsN P蛋白作为包被抗原,建立了检测AIVNP抗体的间接ConsNP-ELISA方法,并优化了反应条件。结果表明:抗原包被量为1μg/孔;封闭剂为5%脱脂乳;一抗血清稀释度为1∶200;H RP标记的兔抗鸡IgG(酶标二抗)稀释度为1∶20 000;阴阳性临界值为:O D490nm值>0.239。该间接ELISA方法与其他亚型A IV阳性血清均呈阳性反应,与新城疫病毒,马力克病病毒,禽传染性囊病病毒阳性血清无交叉反应,具有良好的特异性和敏感性。本研究为进一步研制通用型的禽流感ConsN P-ELISA检测试剂盒奠定了基础。