鸭肠炎病毒gD蛋白亚细胞定位及其对病毒感染相关作用分析

本试验旨在研究鸭肠炎病毒(DEV)gD蛋白亚细胞定位及其对病毒感染的相关作用.本研究经过对DEV病毒扩增处理,利用原核表达系统获得重组gD基因胞外区蛋白(gDw),以兔抗gDw IgG为抗体,进行免疫荧光反应,对比病毒对照组,检查gD蛋白在吸附、侵入以及传播之间起到的作用.结果表明,经过荧光显微镜观察,接种DEV后4h...     

鸭肠炎病毒UL18基因的转录、表达特征及原核表达蛋白的初步应用

为了探讨鸭肠炎病毒(duck enteritis virus,DEV)UL18基因的特性和功能,本研究运用生物信息学软件对DEV UL18基因及其编码蛋白进行了分析。构建原核表达质粒pET32a-UL18,并将其转化大肠杆菌BL21(DE3),经IPTG诱导后获得了大小约为55 000的pET32a/DEV-UL18重组蛋白。将该重组蛋白纯化后免疫家兔,获得了兔抗pET32a/DEV-UL18重组蛋白高免血清。采用荧光定量RT-PCR和Western blot对DEV感染鸭胚成纤维细胞(DEF)后UL18基因的转录和表达情况进行检测,采用间接免疫荧光对DEV感染鸭的肠道和食道进行检测。生物信息学分析结果表明,DEV UL18基因大小969bp,编码1条由322个氨基酸残基组成的多肽,含15个潜在的磷酸化位点和2个N-糖基化位点,含15个潜在的B细胞表位;系统进化树分析表明,DEV UL18属于ɑ-疱疹病毒的1个成员,与MeHV-1亲缘关系最近;密码子偏爱性分析结果表明,若对DEV UL18基因进行外源表达,真核表达系统可能更容易,若选择原核表达系统,则需对宿主表达菌进行选择和条件优化。荧光定量RT-PCR和Western blot结果表明,DEV感染DEF后2h,UL18基因开始转录,感染后12h开始表达,感染24h后转录和表达产物急剧上升,到36和48h后转录和表达产物分别达最大值,之后逐渐下降。间接免疫荧光结果表明,被DEV感染鸭肠道、食道等组织能检测到明显的阳性信号,表明制备的DEV UL18原核表达蛋白及其兔抗多克隆抗体可用于DEV的诊断试剂材料。     

鸭TLR3基因胞外区的原核表达及抗体制备

采用PCR方法扩增鸭TLR3基因胞外区,将其克隆至原核表达载体p ET-32a(+)中,转化大肠杆菌BL21(DE3)菌株,经IPTG诱导后,表达重组TLR3蛋白,并从包涵体中纯化重组蛋白。结果显示,PCR扩增得到972 bp的TLR3基因胞外区,用纯化的重组TLR3蛋白免疫实验兔,制备TLR3的多克隆抗体,用Western blot和ELISA检测其特异性及效价。本研究成功表达了TLR3基因胞外区,用该蛋白免疫实验兔后,制备的多抗能与TLR3特异性反应。     

鸭肠炎病毒C-KCE株TK基因的原核表达及其多克隆抗体的制备

为了探究鸭肠炎病毒(DEV)TK基因编码蛋白在相关细胞上作用与功能及其在病毒感染周期、机体免疫应答中的作用,试验以DEV C-KCE株基因组DNA为模板扩增获得TK基因,在p ET-32a(+)/Rosetta(DE3)p Lys系统中原核表达,并用IPTG诱导DEV TK重组蛋白。结果表明:经SDS-PAGE分析,外源基因主要以包涵体形式表达,分子质量约为59 ku;经Ni-NTA纯化后免疫新西兰白兔制备多克隆抗体,抗体效价可达到1∶4;经Western-blot分析,制备的多克隆抗体可特异性识别重组蛋白;间接免疫荧光试验证实,制备的多克隆抗体与DEV的TK基因编码产物反应性良好。说明TK基因表达蛋白在鸭肠炎感染周期及机体的免疫应答中发挥着至关重要的作用。     

鸭肠炎病毒gB抗原优势区的表达及其多克隆抗体的反应特性

拟制备鸭肠炎病毒(DEV)gB抗原优势区的多克隆抗体,初步应用于该病毒的检测。以本实验室克隆的DEVC-KCE株ul27基因序列为参考序列设计特异性引物,通过PCR获得DEV gB优势表位区域基因片段gB-AD(331—570bp),并在pET-32a(+)/Rosetta(DE3)pLysS系统中进行原核表达。经IPTG诱导获得与预期大小相符的重组蛋白质,以Ni-NTA柱亲和层析法纯化重组蛋白质,利用DEV阳性血清检测重组蛋白质的抗原性,并用切胶纯化的重组蛋白质免疫家兔,制备兔抗DEV gB-AD血清。结果显示,重组蛋白质可被DEV阳性血清特异性识别,制备的兔源多克隆抗体I-ELISA效价为1∶10 240,且其具有中和活性;兔源多克隆抗体在还原电泳条件下显示DEV gB的相对分子质量约为66ku,而在非还原电泳条件下DEV gB显示为相对分子质量约120和66ku的两条目的带,通过间接免疫荧光试验和中和试验进一步证实制备的兔源多克隆抗体可特异性识别鸭肠炎病毒感染细胞所合成的gB蛋白。结果表明,所制备的兔抗DEV gB-AD多克隆抗体可作为检测DEV的试剂,为DEV检测及gB的功能研究提供必要的基础数据和材料。     

鸭瘟病毒疫苗株基因组复制非必需区的筛选

为探寻鸭瘟病毒(DEV)基因组中的复制非必需区,本研究在已建立的DEV疫苗株5粘粒拯救系统的基础上,利用转座子随机插入技术,将含eGFP表达框架的基因片段随机插入DEV US区,救获两株表达绿色荧光蛋白的重组DEV(rDEV-us7eGFP、rDEV-us8us1eGFP)。将两株重组病毒在鸡胚成纤维细胞中连续传至20代后,通过PCR、荧光表达鉴定分析,结果显示gfp基因能够在重组病毒中稳定存在并正确表达;生长动力学结果表明,重组病毒在CEF中的增殖效率与DEV疫苗株无显著差异。攻毒保护实验结果表明,将rDEV-us7eGFP和rDEV-us8us1eGFP以10~5TCID_(50)的剂量免疫SPF鸭后,其对鸭瘟强毒攻击的保护效率与DEV疫苗株一致,均为100%。本研究成功筛选到DEV基因组中的两个可供外源基因插入的复制非必需区,分别位于us7基因内部及us8与us1基因之间,为以DEV为载体构建相关重组疫苗奠定了重要基础。     

TK基因缺失对鸭肠炎病毒在鸡胚成纤维细胞中复制影响的评价

为鉴定鸭肠炎病毒(DEV)的非必需基因,本研究利用增强型绿色蛋白(EGFP)基因为报告基因,通过在转染的鸡胚成纤维细胞(CEF)中同源重组,将其插入DEV基因组的TK基因中,经筛选和纯化绿色荧光病毒蚀斑,获得表达EGFP的重组DEV,命名为r DEVTK-EGFP。对重组病毒与亲本病毒DEV Clone-03复制动力学比较结果显示,重组病毒滴度显著低于亲本病毒(p0.01)。对重组病毒在复制过程中感染细胞能力和荧光表达时相检测结果表明,在感染后48 h~72 h表达荧光信号细胞明显增多,该结果与重组病毒复制动力学一致。将重组病毒在CEF中连续传代至20代,仍具有遗传稳定性。该研究结果表明,TK基因为DEV复制非必需基因,可以作为外源基因插入位点,用于禽用新型基因工程疫苗的研制。     

鸭甲肝病毒鸡胚化弱毒MY株Vp1重组蛋白的免疫保护效果试验

将鸭甲肝病毒鸡胚化弱毒MY株Vp1基因原核表达工程菌(pET32a+Vp1,BL21(DE3)PlysS)对基因Yp1进行大量表达和纯化,得到鸭甲肝弱毒MY株Vp1重组蛋白作为抗原制备亚单位疫苗,免疫雏鸭,用间接ELISA检测方法对免疫后抗体生成水平进行监测,并通过动物攻毒试验评价免疫保护效果.结果显示:Vp1重组蛋白免疫家兔后血清检测琼扩效价≥1∶64,细胞中和试验效价为1/45;雏鸭免疫后抗体生成水平呈明显上升趋势,对攻毒起到了保护作用.首次揭示了DHAV-1结构蛋白Vp1刺激机体产生抗体使雏鸭获得保护的能力.     

猪流行性腹泻病毒荧光抗体的制备及应用

本研究旨在建立一种可辅助猪流行性腹泻病毒(PEDV)分离鉴定的直接荧光抗体检测方法。借助基因工程技术融合表达PEDVS1基因中和抗原表位区域(COE),层析柱法纯化兔源免疫球蛋白IgG,搅拌法标记荧光素。通过Western blotting和动物免疫试验测定表达融合蛋白的抗原性,间接ELISA方法测定免疫后的抗体效价,直接免疫荧光法测定标记荧光抗体的特异性,梯度稀释方法测定标记抗体的最佳工作浓度。结果显示,本研究成功将423bp的S1基因中和抗原表位COE进行融合表达,表达蛋白大小约40ku,蛋白命名为pGEX-6P/COE;Western blotting检测结果表明,融合蛋白具有良好的反应原性;ELISA检测结果显示,免疫后35d的血清抗体效价达1∶25 600;与猪传染性胃肠炎病毒(TGEV)、猪轮状病毒(PoRV)、猪瘟病毒(CSFV)及猪细小病毒(PPV)等均无非特异性反应,标记的荧光抗体具有良好的特异性,最佳工作稀释度为1∶32~1∶64。综上所述,本试验制备的直接免疫荧光抗体可用于细胞平台上的PEDV快速检测,能直观地提供相关检测数据,对于病毒分离过程的取舍具有重要指导意义。     

鸭肠炎病毒SORF3基因的原核表达及其多克隆抗体的制备

以鸭肠炎病毒(DEV)C-KCE株基因组DNA为模板,PCR扩增获得SORF3(S3)基因,在pET-32a(+)/Rosetta(DE3)pLys系统中原核表达。S3重组蛋白经IPTG诱导,SDS-PAGE分析显示外源基因以包涵体形式表达为主,分子质量约为52ku。重组蛋白经Ni-NTA纯化后免疫新西兰白兔制备多克隆抗体,琼脂扩散法测得抗体效价为1:4。经Western blotting分析制备的多克隆抗体具有较高的特异性,间接免疫荧光试验证实制备的多克隆抗体与DEV的SORF3编码产物反应性良好,为进一步研究DEVSORF3结构与功能特性奠定了基础。     

鸭肠炎病毒gL蛋白在鸡胚成纤维细胞中动态表达的检测

为研究鸭肠炎病毒(DEV)gL蛋白在感染鸡胚成纤维细胞(CEF)过程中的表达情况,本研究以DEVClone-03基因组为模板,应用PCR方法分别扩增得到截短的(gLt,181 bp～711 bp)和全长的gL(1 bp～711 bp)两个基因片段。将gLt基因片段克隆至pET-30a原核表达载体,转化E.coli BL21(DE3),经IPTG诱导表达并对表达产物进行纯化复性,免疫BALB/c小鼠,制备鼠抗gL蛋白多克隆抗体。同时将全长gL基因克隆至真核表达载体pcDNA3.1(+),构建真核表达重组质粒pcDNA-gL,转染293T细胞。采用获得的抗gL蛋白抗体检测DEV感染CEF后及真核表达质粒pcDNA-gL转染293T细胞后gL蛋白在不同时间点的表达情况。结果表明,在pcDNA-gL转染293T细胞后12 h应用western blot方法能够检测到gL蛋白的表达,其表达量随着转染时间增加而增加;在病毒感染CEF后24 h应用间接免疫荧光方法能够检测到gL蛋白少量的表达,western blot方法在病毒感染CEF48 h后检测到gL蛋白的表达,其表达量随着病毒感染时间增加而增加。上述结果提示,编码gL蛋白基因可能是病毒复制的晚期表达基因。     

Identification and characterization of duck enteritis virus dUTPase gene

Deoxyuridine triphosphatase (dUTPase) is a ubiquitous and important enzyme that hydrolyzes dUTP to dUMP. Many viruses encode virus-specific dUTPase, which plays an essential role in maintaining the integrity of the viral DNA both by reducing the dUTP levels and by providing the substrate for the thymidylate synthase. A 1344-bp gene of duck enteritis virus (DEV) homologous to herpesviral dUTPase was first reported in this paper. The gene encodes a protein of 477 amino acids, with a predicted molecular mass of 49.7 kDa. Multiple sequence alignment suggested that DEV dUTPase was quite similar to other identified herpesviral dUTPase and functioned as a homotrimer. The five conserved motifs of DEV dUTPase with 3-1-2-4-5 arrangement have been recognized, and the phylogenetic analysis showed that DEV dUTPase was genetically close to the avian herpesvirus. Furthermore, RNA dot blot, western blot, and immunofluorescence analysis indicated that the enzyme was expressed at early and late stages after infection. Immunofluorescence also confirmed that DEV dUTPase localized in the cytoplasm of DEV-infected duck embryo fibroblasts as early as 4 hr postinfection (hpi). Later, the enzyme transferred from cytoplasm to nucleus at 8 hpi, and then reached its expression peak at 12 hpi, both in the cytoplasm and nucleus. The results suggested that the DEV dUTPase gene might be an early viral gene in DEV vitro infection and contribute to ensuring the fidelity of genome replication.     

Serologic detection of duck enteritis virus using an indirect ELISA based on recombinant UL55 protein

A recombinant UL55 protein (pUL55) of duck enteritis virus (DEV), produced in Escherichia coli, was tested for diagnostic applicability in an indirect enzyme-linked immunosorbent assay (1-ELISA) as a coating antigen. Serum dilutions of 1:6400 (0.025microg) are the maximum detection limits of the pUL55-ELISA, according to the determined cut-off value of 0.330. Antigenic cross-reactivity investigation in heterologous sera of ducks failed to provide evidence that other viruses of ducks could hamper the serodiagnosis of DEV, and the inhibition assay revealed that the specific binding of antigen and antibody can be inhibited by pUL55, both of which demonstrated a good specificity of the established pUL55-ELISA. This assay was further validated by comparison with a commercial 1-ELISA based on DEV (DEV-ELISA) and a neutralization test (NT). The results suggested that the sensitivity of pUL55-ELISA was almost as good as DEV-ELISA but was much higher than NT. The established pUL55-ELISA is a rapid, simple, sensitive, specific, and inexpensive serodiagnosis for detecting antibodies against DEV and has a potential to complement the traditional assays for serodiagnosis of DEV; it can be used as a diagnosis alternative candidate for serologic surveillance of DEV infection.     

鸡抗鸭病毒性肝炎高免卵黄抗体的研制及应用

应用雏鸭病毒性肝炎病毒（DHV）弱毒疫苗和DHV油乳剂灭活苗多次免疫产蛋鸡，制备鸡抗鸭病毒性肝炎高免卵黄抗体，自制鸭病毒性肝炎病毒高免卵黄抗体的疗效取决于卵黄抗体的中和效价及治疗的时间。实验室试验及临床应用结果表明，卵黄抗体的中和效价应达2^8以上，并且在感染DHV 24h以内对雏鸭进行肌肉注射，治疗效果最为理想。     

伪狂犬病病毒弱毒株LY株的分离鉴定

从辽阳某猪场的10日龄仔猪中分离到1株病毒,经纯化后测得其毒价为107.29TCID50/mL.细胞中和试验表明,该病毒能被猪伪狂犬病病毒标准阳性血清所中和.电镜下可见到典型的疱疹病毒粒子,具有囊膜及外周纤突.所分离的病毒对氯仿、胰蛋白酶、乙醚敏感,在pH5.0～9.0下稳定,56℃ 30 min可以灭活.应用特异性引物,通过PCR能扩增出伪狂犬病病毒1 240 bp的gD基因.分离病毒对3日龄乳鼠有一定的致病力,但对家兔、3～5日龄仔猪及妊娠母猪都有很高的安全性.用不同剂量的病毒培养液肌肉注射于3～5日龄仔猪,14 d后用105.7TCID50伪狂犬病病毒强毒攻击,所有试验仔猪均可得到有效保护.用分离毒免疫母猪,其后代可获高滴度的母源抗体,15日龄的仔猪能抵抗105.7TCID50强毒的攻击.试验的结果初步说明,所分离的病毒为伪狂犬病病毒(命名为PRV LY株),并可能是一株弱毒株,而且具有很好的免疫保护作用.     

鸭病毒性肠炎病毒强毒在人工感染鸭体内形态结构和发生学的电镜观察

为研究鸭病毒性肠炎病毒(DEV)CH强毒株在感染鸭体内的分布和形态学发生规律，应用透射电镜和超薄切片技术对人工感染DEV的成年鸭各组织器官进行观察。结果表明：感染后12h在脾脏和法氏囊首先观察到少量的DEV出现，24h后在脾、胸腺和法氏囊以及死亡鸭的肝、肠和胰中均观察到具有典型的疱疹病毒粒子及其核衣壳形态的DEV。DEV病毒核衣壳有空心型、致密核心型、双环型和内壁附有颗粒型4种形态，存在胞核和胞浆两种装配方式。病毒成熟有两种方式：一为细胞核内核衣壳在核内获得皮层，通过核内膜获得囊膜成为成熟病毒；二为核内核衣壳通过内外核膜进入胞浆，核内和胞浆内的核衣壳在细胞浆中获得皮层，然后在各种质膜上获得囊膜，最后成熟病毒通过细胞破裂或其他方式释放到细胞外。伴随着病毒的复制、装配和成熟，细胞中出现多种核内和胞浆包涵体、核内致密颗粒、核内微管和中空短管、胞浆电子致密小体等结构。     

口蹄疫A型油佐剂和leo佐剂弱毒灭活疫苗免疫持续期的研究

用实验室配制的口蹄疫油佐剂和leo佐剂A型弱毒灭活疫苗各免疫6月龄健康敏感牛（乳鼠中和抗体滴度小于1：4）5头，免疫后每月采血一次，分离血清；采用固定病毒稀释血清的方法，通过乳鼠中和试验检测免疫牛血清中的口蹄疫A型中和抗体的产生与消长情况，用karber法计算中和效价，绘制动态曲线图。结果显示，口蹄疫弱毒灭活疫苗免疫牛，可以产生高滴度的血清中和抗体，免疫牛血清中和抗体效价均在免疫后1个月左右达到高峰。油佐剂疫苗免疫的牛，血清中和抗体效价比较高，但下降比较迅速；leo佐剂疫苗免疫的牛，血清中和抗体效价比较低，但下降比较平缓。     

猪伪狂犬病不同佐剂灭活疫苗对兔免疫原性初探

采用分离鉴定的猪伪狂犬病毒（HB—J株）以4种佐剂研制成4批灭活疫苗,以研究其对兔的免疫原性。疫苗分别免疫PRV抗体阴性兔后,用乳胶凝集试验法（LAT）和中和试验法（SNT）对试验兔进行血清抗体检测;于免疫后21、28d对试验兔分别进行攻毒,观察兔保护情况。试验结果表明,兔对不同佐剂的猪伪狂犬病疫苗均产生良好的免疫应答反应,且当兔免疫后血清凝集价≥1：32或血清抗体中和指数≥1479或中和价≥1：16时,可以抵抗10LD50剂量强毒的攻击;当兔免疫后血清凝集价≥1：64或血清抗体中和指数≥2187或中和价≥1：32时,可以抵抗100LD50剂量强毒的攻击;4种佐剂灭活疫苗均具有良好的免疫效果。     

Intestinal mucosal immune response against virulent duck enteritis virus infection in ducklings

Duck virus enteritis (DVE) is an acute and contagious herpes virus infection of duck, geese and swans with high morbidity and mortality. The development of specific mucosal immune system against duck enteritis virus (DEV) infection for ducks has been hindered by a lack of knowledge concerning the purification of immunoglobulin A (IgA) of duck. In the present work, the method for purification of duck immunoglobulin A was developed, and the induction of intestinal mucosal immune responses against DEV was studied by orally infected ducklings with virulent DEV. The results showed that a continuous increased DEV DNA levels were observed in blood and various organs examined of orally infected ducklings throughout the infection, which was accompanied by the development of infection in ducklings from mild progressed to severe pathological lesions. Furthermore, a marked increased level of DEV-specific IgA and IgG antibodies in bile, serum and the intestinal tract, as well as the density of IgA⁺ cells in intestine were detected between 1 and 12 days p.i., followed by a drastic reduction of the antibody levels and the density of IgA⁺ cells at 15 days p.i. The results indicate that the DVE infection can stimulate both IgA-dominated antibody immune responses in the intestinal tract, and IgG-dominated antibody systemic immunity in the serum of ducklings orally inoculated with virulent DEV. The severe lesions of the villus epithelial cells and the lymphoid organs can suppress the intestinal mucosal immune responses.     

Potential of DNA-mediated vaccination for equine herpesvirus 1.

The potential of DNA-mediated immunisation to protect against equine herpesvirus 1 (EHV-1) disease was assessed in a murine model of EHV-1 respiratory infection. Intramuscular injection with DNA encoding the EHV-1 envelope glycoprotein D (gD) in a mammalian expression vector induced a specific antibody response detectable by two weeks and maintained through 23 weeks post injection. Immune responses were proportional to the dose of DNA and a second injection markedly enhanced the antibody response. EHV-1 gD DNA-injected mice developed neutralising antibodies, and a predominance of IgG2a antibodies after the DNA injection was consistent with the generation of a type 1 helper T-cell (Th1) response. Following intranasal challenge with EHV-1, mice immunised with 50 microg of EHV-1 gD DNA were able to clear virus more rapidly from lung tissue and showed reduced lung pathology in comparison with control mice. The data indicate that DNA-mediated immunisation may be a useful strategy for vaccination against EHV-1.