分子克隆化禽网状内皮组织增生症病毒传染性及其前病毒全基因组序列研究

利用脂质体转染技术,将含有SNV株禽网状内皮组织增生症病毒 （REV）前病毒全基因组cDNA克隆质粒转染鸡胚成纤维细胞（CEF）.用对REV的单克隆抗体和抗REV env-gp90的鼠血清作间接免疫荧光反应,在原始的转染细胞及随后传代的细胞中均显示病毒特异性抗原.而且,在连续传代细胞中的阳性率明显升高.用REV特异性引物对进一步传代后的细胞基因组作PCR,也检测出REV基因组.这些结果均表明所得到的分子克隆化病毒具有传染性,因而也进一步证明所用的质粒克隆包含有具感染性的全病毒基因组.对该全基因组cDNA克隆进行酶切所获得的数个亚克隆进行测序,并将序列进行拼接,完成了REV全基因组序列.REV的这个传染性克隆将有助于进一步研究REV的分子生物学特性.     

表达猪瘟病毒石门株E0基因重组鸡痘病毒的构建及动物免疫试验

应用PCR从质粒pMD18-T-E0中扩增编码CSFV E0蛋白的基因片段,定向克隆到重组鸡痘病毒表达载体FPV-P11上,进一步构建出重组鸡痘病毒转移载体FPV-pSY-E0.用脂质体将该质粒转染至鸡痘病毒感染的鸡胚成纤维细胞(CEF)后,通过蓝斑纯化实验筛选出重组鸡痘病毒FV282-CSFV-E0.PCR证实E0基因已整合至鸡痘病毒基因组中,Western blot检测到重组病毒感染CEF细胞中E0蛋白的表达.重组病毒3次腹腔接种小鼠,ELISA检测血清抗体滴度高达1∶4 096.重组病毒免疫猪3次之后,接种猪瘟病毒强毒进行攻毒试验,结果对免疫组产生75%的保护率,为研制猪瘟活载体疫苗奠定了基础.     

流行性乙型脑炎病毒(JEV)全长感染性克隆的制备及恢复病毒的获得

根据JEV病毒减毒株SA14—14—2基因组序列,设计覆盖全长的4对重叠引物,以提取的活疫苗病毒RNA为模板,RT—PCR扩增出4个片段,并克隆到质粒载体中,进一步构建两个半端分子克隆,然后将全长cDNA序列克隆到一个新改造的低拷贝质粒载体pBR—kpn中,构建我国流行性乙型脑炎病毒(JEV)基因组全长cDNA克隆。经过体外转录后得到的转录子转染BHK-21细胞,重新获得JEV的恢复病毒,通过生物学特性、分子生物学水平、蛋白水平等几个方面对恢复病毒进行鉴定。结果获得了稳定的全长cDNA克隆,转录子转染BHK-21细胞后,第4天开始出现细胞病变(CPE),第6～7天时CPE为 ,经过Vero细胞进一步放大培养后,间接免疫荧光实验和RT—PCR实验均为阳性。证实了构建的JEV的全长cDNA克隆有感染性,为进一步的研究奠定了基础。     

表达禽流感病毒M2基因的重组马立克氏病病毒的构建

将禽流感病毒M2基因克隆于真核表达质粒pIRES-EGFP中,使其位于pCMV启动子的调控下,并与绿色荧光蛋白基因（EGFP）串联后,将上述串联基因插入到含MDV CVI988的非必需区US基因的重组质粒pUS2中,构建带标记的重组质粒,然后将此重组质粒转染感染了MDV CVI988的鸡胚成纤维细胞,利用同源重组的方法,筛选了表达禽流感病毒M2基因的重组病毒MDV1。经PCR、Dot-blotting,Western-blotting等实验的结果表明,禽流感病毒M2基因的确插入到MDV1（CVI988）基因组中并获得表达。重组MDV1免疫1日龄SPF鸡21天后,用ELISA可检测到M2蛋白的特异性抗体。接种了重组病毒rMDV的鸡体内针对H9N2疫苗血凝素的抗体滴度(p<0.05)明显提高,以禽流感病毒AIV A/Chicken/Guangdong/00（H9N2）攻毒后进行病毒重分离试验的结果发现,重组病毒能有效地降低病毒的排出量(p<0.01),说明该重组病毒可以用于防制禽流感的免疫。     

超强毒IBDV细胞克隆化毒回归鸡后的致病性与VP2基因高变区的分子变化

为了研究超强毒鸡传染性法氏囊病病毒(vvIBDV)的致病性及其VP2基因高变区的分子变化,以vvIBDV GX8/99株囊毒为研究对象,将该毒在SPF鸡胚连传10代后,再在鸡胚成纤维细胞(CEF)上连续盲传.该病毒在CEF上传至22代时开始引发CEF细胞病变,随之在96孔细胞培养板上用无限稀释法连续克隆2次后获得了4个病毒克隆,再将该4个病毒克隆分别连续回传3～5周龄SPF鸡10代.分别比较4个克隆毒及其回传SPF鸡后不同传代毒,对4～6周龄SPF鸡的致病性及VP2高变区氨基酸分子的变化,结果表明,4个克隆化毒的细胞培养毒对SPF鸡只有0～6.7%的致死率,不同克隆毒的SPF鸡传代毒对SPF鸡的致病性却都逐渐增强,但程度差异很大,其中克隆#5在回鸡1、5和10代后的致死率从0分别增加到10%、20%和27%;克隆#4从6.7%增加至13%、17%和23%;但克隆#1和#3的致病性变化相对较小.相对于原始囊毒及鸡胚毒,4个克隆化毒在测序的VP2高变区的约145个氨基酸中,有10个位点发生了相同的变异,变得与适应细胞的疫苗毒D78株基本一致,在回鸡传代导致对鸡毒力增强的过程中,这10个位点中大多数氨基酸不再变化,只有第253位和256位氨基酸从囊毒的Q和I变为细胞适应毒的H和V后,有些病毒克隆回鸡至第10代时又变为原囊毒的Q和I,这表明VP2高变区大多数氨基酸的变异可能与病毒的致病性关系不密切,而与对细胞培养或组织的亲和性的关系更为密切.本研究最重要的意义在于建立的超强毒GX8/99株细胞克隆化毒及其相应的回鸡传代毒系列,为研究vvIBDV其它基因变异与致病性及其它生物学特性的关系,提供了一个新的思路和必要的研究材料.     

禽白血病病毒J亚群囊膜蛋白env基因的克隆和表达

禽白血病病毒J亚群（ALV－J）是90年代鉴定出的ALV的新亚群,其囊膜蛋白env基因序列别与ALV A－E亚群的有相当大的差别。为ALV－J env基因及春表达产物的特点,用PCR方法扩增出ADOL－4817毒株的env基因,并克隆进TA载体,经电泳鉴定大小为1.7kb。将克隆出的env基因与杆状病毒pBlue-Bac4表达质粒DNA连接,构建成转移性载体pBac4817env,通过与Bac-N-Blue杆状病毒DNA共转染,区得了重组病毒rBac4817env-2。该重组杆状病毒感染Sf9细胞,能高效表达env基因产物,免疫荧光分析结果证明,单克隆抗体G2或多价兔抗env gp37血清能识别Sf9细胞,能高效表达env基因表达的特异性抗原;Western blotting分析结果表明,表达的重组基因产物的分子量大小约为90kD-94kD。用这些重组基因产物免疫鸡可以诱导鸡导鸡产生出高滴度的抗ALV－J特异性抗体。这一结果提示,这种杆状病毒表达的重组基因产物有助于ALV－J env基因生物学特性的深入研究。     

携带人二氢叶酸还原酶基因慢病毒表达载体构建及鉴定

目的:构建携带人二氢叶酸还原酶(DHFR)基因的慢病毒表达载体pWPI。方法:采用PCR方法扩增二氢叶酸还原酶cDNA全长,与EZ-T克隆载体连接,HindIII及BamHI-HF限制性内切酶双酶切回收的PCR片段并补平其缺口。慢病毒系统载体使用pWPI系统,采用PmeI酶切载体后回收片段,将其磷酸化,T4酶连接载体与目的基因。表达载体鉴定均采用核苷酸序列测定,重组质粒采用脂质体转染293T包装细胞后获得包装的病毒颗粒。结果:成功扩增二氢叶酸还原酶全长并连接入pWPI载体构建成重组表达载体DHFR-pWPI,重组质粒测序结果显与DHFR基因的同源性达100%,按标准生产程序转染293T后有DHFR基因的表达。结论:成功采用慢病毒载体系统构建了二氢叶酸还原酶重组慢病毒转基因,为探讨DHFR在肿瘤多药耐药过程中的分子机理奠定基础。     

稳定表达貉犬瘟热病毒细胞受体SLAM的Vero细胞系的建立及应用

[目的]信号淋巴激活分子(SLAM又称CD150)为犬瘟热病毒(Canine distemper virus,CDV)的细胞受体.本研究目的在于建立稳定表达犬瘟热易感动物貉SLAM基因的Vero细胞系,用于犬瘟热诊断及CDV强毒株的快速分离.[方法]从重组质粒pMD-18-T-rSLAM扩增rSLAM基因编码区,通过分子克隆技术构建真核表达质粒pIRES2-EGFP-rSLAMhis.将该质粒转染Vero细胞后,经EGFP荧光观察、G418抗性压力和单细胞克隆化及RT-PCR筛选表达rSLAM阳性细胞系.应用获得细胞系对临床犬瘟热病例进行病毒分离,对分离得到CDV进行RT-PCR鉴定及动物回归试验.[结果]经过RT-PCR和免疫组化试验证实,本实验筛选获得一株能稳定表达rSLAM的Vero细胞系——Vero-rSLAM.该细胞系接种CDV阳性样品36-48h即可产生典型CDV致细胞融合病变,而其亲本Vero细胞接种至6d均无可见细胞病变出现.应用Vero-rSLAM细胞系从狐狸、貉犬瘟热阳性病料中分离获得了3株犬瘟热病毒.其中犬瘟热病毒LN(10) f1株对易感狐狸、貉均可产生致死性感染.[结论]成功建立了稳定表达rSLAM的Vero细胞系,用它分离的CDV对本动物保持较强的毒力.     

我国地方品种鸡分离到的一个禽白血病病毒新亚群的鉴定

为探明我国地方品种鸡群禽白血病病毒(Avian leukosis virus,ALV)的特点,通过接种DF-1细胞及细胞培养上清液p27抗原的检测,从芦花鸡中分离得到三株外源性ALV禽白血病病毒,分别是JS11C1、JS11C2和JS11C3,并对其进行亚群鉴定分析。用PCR方法扩增env基因测序,并与已知鸡源各亚群ALV的囊膜蛋白(gp85)作氨基酸同源性比较。这三株ALV的env基因的gp85大小为1 005bp,编码335个氨基酸;env基因的gp37大小为609bp,编码203个氨基酸。三个毒株之间gp85的同源性为91.9%～97.0%。与A、B、C、D和E五个经典亚群在GenBank中已发表的18个毒株的gp85的同源性仅在77.7%～84.6%间,显著低于鸡群中常见的A、B、E各亚群内的同源性范围(分别为88.2%～98.5%,91.6%～98.8%和97.9%～99.4%),而与J亚群参考株的同源性更是只有34.2%～36.5%。上述结果表明,芦花鸡分离到的三株病毒可能是不同于鸡源ALV已知6个亚群的一个新亚群,按国际上对ALV亚群分类的习惯,初步将其定名为K亚群。     

YXXM 基序对J 亚群禽白血病病毒复制的影响

[目的]毒株NX0101是骨髓瘤病变型J亚群禽白血病病毒,其早期感染细胞能诱导PI3 K/Akt信号转导通路的激活,本文针对NX0101毒株是否存在YXXM基序及其作用进行了探讨.[方法]利用TMpred软件对NX0101毒株囊膜蛋白(Env)的氨基酸序列进行生物信息学分析,通过搭桥PCR方法将YXXM基序相应的核苷酸序列突变后,构建突变质粒并转染DF-1细胞,拯救出YXXM突变体毒株NX0101 mt( Y/F,M/A),利用real-time PCR和ELISA方法检测并比较YXXM突变前后毒株在RNA水平和蛋白水平的复制情况.[结果]NX0101毒株Env胞浆区554 -557位氨基酸存在典型的PI3K结合基序YXXM.YXXM基序突变后,病毒RNA转录水平和病毒蛋白合成水平都显著下降.[结论]YXXM基序对NX0101毒株在体外宿主细胞中复制发挥重要的作用.     

Evolution of gp85 gene of subgroup J avian leukosis virus under the selective pressure of antibodies

Subgroup J Avian leucosis virus (ALV-J) strain NX0101 was inoculated into chicken embryo fibroblasts (CEF) monolayers in 6-well plates. The six wells of CEF inoculated with NX0101 were divided into groups A (without anti-ALV-J serum in the medium) and B (with anti-ALV-J serum in the medium), then viruses from each well of both groups were separately passed in CEF every 6 d and formed their independent passage lineages. For each lineage of both groups, gp85 genes of the viruses in the 10th, 20th and 30th passages were amplified, cloned and sequenced. The sequence data indicated that the homologies of gp85 at aa level between the primary virus and the passed viruses of different passages of 3 lineages in group A were 97.7%-99.7%; and the homologies of gp85 between the primary virus and the passed viruses of different passages of 3 lineages in group B were 93.8%-96.1%. Analysis of the ratios of nonsynonium (NS) vs synonium (S) mutations of nucleic acids demonstrated that NS/S in 3 highly variable (hr-) regions at aa#110-120, aa#141-151 and aa#189-194 of gp85 in 3 lineages of group A were 2 (8/4), 1(3/3) and 1.3 (4/3), however, NS/S in the same 3 hr-regions of group B were 4.1 (13/3), 4.7 (14/3) and 3.3 (11/3). This study is the first demonstration of influence of immune selective pressure on evolution of ALV-J gp85 by specific antibodies under the controlled in vitro experiments.     

Evolution of gp85 gene of subgroup J avian leukosis virus under the selective pressure of antibodies

Subgroup J Avian leucosis virus (ALV-J) strain NX0101 was inoculated into chicken embryo fibroblasts (CEF) monolayers in 6-well plates. The six wells of CEF inoculated with NX0101 were divided into groups A (without anti-ALV-J serum in the medium) and B (with anti-ALV-J serum in the medium), then viruses from each well of both groups were separately passed in CEF every 6 d and formed their independent passage lineages. For each lineage of both groups, gp85 genes of the viruses in the 10th, 20th and 30th passages were amplified, cloned and sequenced. The sequence data indicated that the homologies of gp85 at aa level between the primary virus and the passed viruses of different passages of 3 lineages in group A were 97.7%–99.7%; and the homologies of gp85 between the primary virus and the passed viruses of different passages of 3 lineages in group B were 93.8%–96.1%. Analysis of the ratios of nonsynonium (NS) vs synonium (S) mutations of nucleic acids demonstrated that NS/S in 3 highly variable (hr-) regions at aa#110–120, aa#141–151 and aa#189–194 of gp85 in 3 lineages of group A were 2 (8/4), 1(3/3) and 1.3 (4/3), however, NS/S in the same 3 hr-regions of group B were 4.1 (13/3), 4.7 (14/3) and 3.3 (11/3). This study is the first demonstration of influence of immune selective pressure on evolution of ALV-J gp85 by specific antibodies under the controlled in vitro experiments.     

J亚群禽白血病病毒NX0101株的TCID50与p27抗原之间的相关性研究

为了研究J亚群禽白血病病毒在细胞上接种后的半数细胞培养物感染量(TCID₅₀)与p27抗原的酶联免疫吸附试验（ELISA）的S/P值之间的相关性,并探讨其意义。本试验将J亚群禽白血病病毒NX0101株接种鸡胚成纤维细胞（CEF细胞）,换维持液后连续10d取样,检测10d的TCID₅₀值与p27抗原的S/P值之间的相关性。同时,将该毒株在DF-1细胞系上传代至20代,取其中的第1代、第5代、第10代、第15代和第20代分别进行TCID₅₀滴度的测定和p27抗原检测。结果表明:在CEF细胞上接种的NX0101株J亚群禽白血病病毒连续10d的TCID₅₀值与p27抗原之间存在显著的相关性（r=0.85277;P<0.0001）呈正相关;在DF-1细胞系上传的不同代数之间也呈显著正相关（r=0.93000;P=0.0220）。由此可以推测J亚群禽白血病病毒的TCID₅₀与p27抗原呈显著正相关,因而可以用ELISA法测得的p27抗原的S/P值对病毒的TCID₅₀值进行估测。     

Persistence of genomes of both herpesvirus of turkeys and Marek's disease virus in a chicken T-lymphoblastoid cell line

A cell line tentatively designated as MDCC-BO1(T), was established from spleen cells of an apparently healthy chicken inoculated with herpesvirus of turkey (HVT). BO1(T) cells were T lymphoblastoid cells and the more than 95% of them had Marek's disease (MD) tumor-associated surface antigen (MATSA). However, no viral internal antigens or membrane antigens could be demonstrated in them by immunofluorescence tests using chicken anti-HVT and -MD virus (MDV) sera. The virus could be rescued from BO1(T) cells by co-cultivation with chick embryo fibroblasts (CEF). The DNA of the rescued virus was characterized as HVT DNA by its sedimentation profile in a neutral glycerol gradient and its endonuclease Hind III cleavage-pattern. Ultrastructural studies on CEF infected with the rescued virus revealed the presence of HVT-like virions. However, DNA-DNA reassociation kinetics showed that the BO1(T) cells contained a few copies of NVT and also MDV genomes.     

不同病变型J亚群禽白血病病毒LTR启动子序列分析及活性比较

从ALV-J中国地方分离株SCAU-HN06株(血管瘤病变型)、NX0101株和JS-nt株(骨髓瘤病变型)病毒的细胞培养物提取前病毒DNA,通过PCR扩增各毒株的LTR并克隆,随后进行测序分析。与国内外ALV-J参考毒株LTR序列比较发现:国内地方分离株与英国ALV-J原型株HPRS-103和美国ALV-J原型株ADOL-7501的LTR核苷酸序列相似性为88.0%~97.2%;LTR中的U5区及R区具有较高的保守性,而U3区内存在较大差异。将不同病变型ALV-J的LTR片段分别插入pCAT-basic载体CAT报告基因5'端。用所得的重组报告基因表达质粒转染DF-1细胞,48h后通过测定转染细胞中的CAT表达量来评价LTR启动子的活性。结果表明,SCAU-HN06株与骨髓瘤病变型ALV-J(JS-nt株,NX0101株)LTR启动子活性差异不显著。     

表达H5亚型禽流感病毒HA基因和鸡IL-18基因重组禽痘病毒的构建

[目的]获得共表达H5亚型AIV HA基因和鸡IL-18基因的重组禽痘病毒.[方法]将含痘病毒启动子LP2EP2的HA基因和鸡IL-18基因插入到禽痘病毒转移载体pSY681中,获得重组转移载体pSYHA/IL-18.用脂质体将其转染已感染亲本禽痘病毒S-FPV-017株的鸡胚成纤维细胞,使其在鸡胚成纤维细胞内与禽痘病毒基因组发生同源重组,产生表达HA和IL-18的重组禽痘病毒(rFPV-HA-IL-18).在含有X-gal的营养琼脂培养基上进行蓝斑筛选后,对重组禽痘病毒又进行了多次蚀斑克隆.[结果]以重组禽痘病毒DNA为模板,利用HA基因和鸡IL-18基因引物进行PCR,分别扩增出1条约1.7 kb带和1条0.6 kb左右的带.以间接免疫荧光试验、T细胞转化试验和SPF雏鸡免疫接种证实重组禽痘病毒能表达HA和鸡IL-18,并初步证明鸡IL-18增强HA免疫作用.[结论]重组禽痘病毒能表达具有生物学活性的HA和鸡IL-18.     

Replacement of primary chicken embryonic fibroblasts (CEF) by the DF-1 cell line for detection of avian leucosis viruses.

International regulations prescribe that the absence of avian leucosis viruses (ALV) in avian live virus vaccines has to be demonstrated. Primary chicken embryo fibroblasts (CEF) from special SPF chicken lines are normally used for detection of ALV. The suitability of the DF-1 cell line for ALV-detection, as alternative for primary CEF, was studied in three types of experiments: (1) in titration experiments without cell passage, (2) in experiments with passages in cell cultures according to European Pharmacopoeia requirements, and (3) in experiments with commercial live avian vaccines that had been spiked with known amounts of ALV. In all tests the sensitivity of ALV-A and ALV-J detections on DF-1 cells was at least as high as on primary CEF. The sensitivity of ALV-B detection was always superior when DF-1 cells were used. ALV were detected earlier in all comparative tests when DF-1 cells were used. ALV-A, ALV-B and ALV-J all induced CPE on DF-1 cells, whereas no clear CPE was seen on CEF-cells. For reasons of sensitivity, standardisation as well as reduction of animal use, the data support the use of DF-1 cells to monitor absence of ALV in vaccine virus seed lots or finished products.     

由反转录病毒载体转移的马立克病毒糖蛋白D基因在感染细胞中的表达

用ＥｃｏＲＩ、ＰｓｔＩ将已分离和克隆的马立克氏病病毒糖蛋白Ｄ基因从重组ｐＭｇＤ１８质粒中切出,克隆进反转录病毒质粒载体（ＲＣＡＳ）的连接质粒载全ＰＵＣＣｌａ１１２Ｎ的相同位点。用ＣｌａＩ再次ｇＤ基因切出,构建于ＲＣＡＳ的ＣｌａＩ位点。通过原位杂交筛选重组ＲＣＡＳ,并结合酶切分析鉴定出ｇＤ插入方向正确的重组ＲＣＡＳ。用磷酸钙沉淀法将ｇＤ重组ＲＣＡＳ转染鸡胚成纤维细胞（ＣＥＦ）,转染后第９天收集细胞上