突变型猪表皮生长因子在毕赤酵母中的表达

使用α因子做为信号肽的酵母系统分泌表达猪表皮生长因子(pEGF)时,由于对信号肽末端Glu-Ala氨基酸残基切除不完全,表达产物是Glu-Ala-pEGF和pEGF的混合物.本研究为了获得单一表达的pEGF产物,对pEGF基因进行适当的突变修改,构建缺失Glu-Ala重复基因序列的重组载体.把重组载体pPIC9-pEGF1-48电转化毕赤酵母,用同位素标记随机引物斑点杂交法筛选多拷贝整合转化子,并诱导大量表达.用硫酸铵沉淀及超滤的方法浓缩和纯化蛋白,并用Bradford检测方法对蛋白浓度进行了初步测定.结果表明,构建的重组载体经过BglⅡ线性化后稳定转入毕赤酵母中,转化子表型主要为MutS型;选的多拷贝MutS型转化子经诱导后成功表达约6 000的pEGF1-48蛋白,经检测蛋白表达水平约为34 mg/L.     

Effect of plasmid DNA encoding the porcine granulocyte-macrophage colony-stimulating factor on antigen-presenting cells in pigs

We previously demonstrated that intradermal (ID) delivery of plasmid DNA encoding the porcine granulocyte-macrophage colony-stimulating factor (GM-CSF) 7 days before DNA vaccination enhances both cellular and humoral responses in pigs. In the present work, we studied the effect of the GM-CSF gene on antigen-presenting cells (APC) in pigs. We demonstrated that ID delivery of this gene significantly increased the number of epidermal CD1(+) cells (Langerhans' cells, skin dendritic cells) at the injection site at day 7. This was accompanied by an enhanced percentage of APC at the immune induction site following DNA vaccination, whereas a positive effect on APC maturation could not be demonstrated. Taken together, our data suggest that both DC recruitment to the immunization site and expansion of APC in the draining LN following DNA vaccination might contribute to the immune enhancing effect of plasmid encoded GM-CSF in pigs.     

PGM-CSF对手工克隆猪生产效率的影响

为了优化猪的手工克隆技术方案,从而提高猪手工克隆效率,通过比较不同浓度(2和10 ng/m L)的猪粒细胞-巨噬细胞集落刺激因子(PGM-CSF)对孤雌胚胎和克隆胚胎的囊胚发育率及囊胚细胞数的影响,并将PGM-CSF处理过的手工克隆囊胚进行移植,比较对照组和试验组的妊娠率、产仔率及克隆整体效率。结果显示:用10 ng/m L PGM-CSF处理重构胚后,试验组胚胎细胞数统计略高于对照组((47.74±3.88)vs(43.69±3.72)),囊胚率高于对照组((39.10±0.01)%vs(36.27±0.02)%),但差异均不显著(P0.05);试验组10只受体中有5只怀孕且分娩,而对照组10只受体只有1只怀孕且分娩;试验组出生仔猪存活率略高于对照组(36.36%vs 30.00%),克隆总效率略高于对照组(0.37%vs 0.30%),但没有显著差异(P0.05)。综上所述,PGM-CSF有利于提高猪手工克隆胚胎整体发育能力,有提高猪手工克隆对受体的利用率的潜在可能性。     

猪γ-干扰素在毕赤酵母中的分泌表达及其抗病毒作用

为了获得高效分泌表达重组猪γ-干扰素(rPoIFNγ),将去除信号肽的编码梅山猪γ-干扰素成熟蛋白基因(mPoIFNγ)插入酵母-大肠杆菌穿梭载体pPIC 9K中,构建成分泌型重组表达载体pPIC 9K-mPoIFNγ.将线性化的pPIC 9K-mPoIFNγ以化学方法(LiCl)转化入毕赤酵母菌株GS115(组氨酸缺陷型),转化子经MD平板筛选和PCR分析鉴定后,以G418(4 g/L)筛选到多拷贝菌株.SDS-PAGE和Western-blot检测结果表明,所获得的重组子能够分泌表达出17 000和23 000左右的mPoIFNγ特异蛋白,其表达量约为120 mg/L,占分泌型总蛋白的65%;细胞病变抑制法(CPE50)测定干扰素生物活性,结果表明rPolIFNγ具有较高的抗病毒生物活性,在MDBK中的抗VSV比活性为1.67×106 U/mg.     

猪α-干扰素在毕赤酵母中的分泌表达及其生物活性测定

利用基因工程技术,将编码梅山猪α-干扰素成熟蛋白基因(mPoIFNα,501 bp)亚克隆到含分泌信号肽序列的毕赤酵母表达载体pPIC9K中,构建成分泌型重组表达载体pPIC9K-mPoIFNα。用化学方法(LiCl)将线性化的mPoIFNα与ssDNA共转化入毕赤酵母菌株GS115,转化子经MD平板筛选和PCR鉴定后,得到的阳性菌株再以高浓度的G418筛选多拷贝重组子。该高拷贝菌株经1%甲醇连续诱导4 d,表达产物经SDS-PAGE和Western-blot检测,结果表明在毕赤酵母中猪α-干扰素获得分泌型表达,表达产物约为20 000,在GS115中的表达量约为40mg/L,占GS115表达的可分泌型总蛋白的40.1%。对表达产物进行理化分析发现,重组酵母菌表达的蛋白耐酸(pH2),对热(56℃)部分敏感,并能被特异性抗猪α-干扰素抗体中和而不与抗猪γ-干扰素抗体反应。细胞病变抑制法(CPE50)测定干扰素生物活性,试验结果表明rPolIFNα具有较高的抗病毒生物活性,在MDBK中的抗VSV比活性为8.0×106U/mg。     

粒细胞-巨噬细胞集落刺激因子基因佐剂对DNA疫苗的免疫调节作用

DNA疫苗具有制备简单,不需要蛋白质的合成、提取与纯化,免疫效果维持时间长,稳定性好,易保存等特点。但由于种与种之间免疫遗传差异,DNA疫苗往往对大动物特别是对哺乳动物的免疫效果不理想。细胞因子常作为基因佐剂用以增强DNA疫苗的免疫原性。粒细胞-巨噬细胞集落刺激因子(GM-CSF)是一个具有多项潜能的造血生长因子,在免疫反应中具有重要作用,编码GM-CSF的质粒能增强DNA疫苗的免疫效果。本文就GM-CSF的分子结构、对增强疫苗免疫原性、协同其他因子作用等方面作一综述。同时介绍了基因佐剂与目的基因表达质粒的构建方案。     

Bovine recombinant granulocyte-macrophage colony-stimulating factor enhancement of bovine neutrophil functions in vitro

Neutrophils were purified from blood of dexamethasone-treated (0.04 mg/kg of body weight) and untreated calves. Cells were untreated (controls) or cultured in media containing 5 or 10 ng of bovine recombinant granulocyte-macrophage colony-stimulating factor (rbGM-CSF)/ml for 10 to 12 hours before being tested for various functions. Dexamethasone treatment of calves decreased luminol-dependent chemiluminescence, decreased phagocytosis of Pasteurella multocida and several Staphylococcus spp by various degrees, and decreased antibody-dependent cell-mediated cytotoxicity against bovine herpesvirus-infected cells by 26 to 32%. The percentage phagocytosis of coagulase-positive S aureus and S intermedius was higher than that of coagulase-negative S epidermidis for neutrophils from all calves. Culture of neutrophils with rbGM-CSF significantly increased (P less than 0.05) all of the aforementioned functions, compared with control neutrophils; however, rbGM-CSF-induced increases in function tended to be higher in neutrophils from dexamethasone-treated calves than in neutrophils from untreated calves.     

Cloning and expression of the cDNA for bovine granulocyte-macrophage colony-stimulating factor

A sequence encoding bovine granulocyte-macrophage colony-stimulating factor (GM-CSF) has been identified from a concanavalin A-stimulated bovine lymphocyte cDNA library. This sequence was isolated by hybridization with synthetic oligonucleotide probes based upon the human GM-CSF sequence. This bovine cDNA was engineered for expression and secretion of activity into the periplasmic space of E. coli. Periplasmic extracts contain a 14,500-dalton protein and stimulate colony formation of bovine bone marrow progenitor cells. The predicted protein is 70% homologous with human GM-CSF and 55% homologous with murine GM-CSF. Numerous structural features are conserved among these three proteins, such as location of cysteine residues, glycosylation sites, and overall change. The biological activity of bovine GM-CSF is species specific, since recombinant preparations do not cause proliferation of human or murine bone marrow cells. Similarly, murine GM-CSF does not exhibit activity on cells of bovine or human origin. However, human GM-CSF does stimulate colony formation of bovine bone marrow cells, although the specific activity appears reduced when compared to assays on human cells.     

猪α-干扰素在毕赤酵母中的分泌表达和下游工艺的研究

通过小量发酵、摇瓶发酵、大量发酵,研究猪α-IFN在毕赤酵母中表达的下游工艺,微量细胞板法测猪α-IFN体外抗VSV、PRRSV、TGEV的活性.猪α-IFN抗VSV的活性达到4.04×10~6IU/L,在PK15上抗TGEV的活性为10~7～10~8IU/L,在Mare 145上抗PRRSV的活性为10~6～10~7lU/L.30℃诱导培养96 h、甲醇添加1%、pH值6.0、DO 20%、0.25%～0.4%甲醛灭活,获得高活性的、安全的IFN.仔猪免疫后临床症状正常,未出现病理学变化.猪α-IFN体外抗病毒活性高,发酵后的抗病毒活性未下降,免疫动物未产生临床症状和病理变化,可用于临床治疗病毒性疾病.     

猪IL-2基因真核表达载体的构建及在酵母中的表达

用真核表达引物从pGEM-IL-2重组质粒中扩增出猪IL-2基因，将目的基因和真核表达载体pPIC9K连接转入E．coli的JM109中，得到了猪pPIC9K-IL-2重组表达质粒。通过电激法将经SalⅠ酶切线性化的pPIC9K-IL-2质粒转化到巴斯德毕赤酵母GS115感受态细胞中，利用甲醇诱导表达，经SDS-PAGE电泳分析，表明在摇床水平及发酵罐中均表达出约17ku大小的分泌性目的蛋白，采用Sephadex G-100分子筛层析对其表达产物进行纯化，纯化结果理想。     

猪繁殖与呼吸综合征病毒ORF7基因的克隆及其在毕赤酵母中表达

用RT-PCR扩增猪繁殖与呼吸综合征病毒(PRRSV)重庆分离株C14-2的ORF7基因(384 bp),构建克隆质粒pMD19-T-ORF7,经EcoR Ⅰ /Not Ⅰ双酶切回收ORF7基因插入酵母表达载体pPIC9K,构建了重组表达质粒pPIC9K-ORF7,进行PCR鉴定和双酶切鉴定.鉴定的pPIC9K-ORF7经Sac Ⅰ线性化后电转化毕赤酵母宿主菌GS115,筛选获得阳性重组菌GS115(pPIC9K-ORF7),再经G-418/YPD筛选获得高拷贝重组菌,重组子经表型鉴定为Mut.重组菌GS115(pPIC9K-ORF7)经甲醇诱导表达,在96 h表达的N蛋白量最大,N蛋白经SDS-PAGE鉴定大小约为15 000;Western blot表明N蛋白能与美洲型PRRSV阳性血清发生特异性反应,具有良好的反应活性.本研究为开展PRRSV ORF7基因在毕赤酵母中表达及应用奠定基础.     

牛白细胞介素-2在毕赤酵母中的表达

将编码牛白细胞介素-2(BoIL2)成熟肽的cDNA克隆到巴斯德毕赤酵母(Pichia pastoris)表达载体pPICZB中，构建出含BoIL2基因的重组质粒BoIL2-pPICZB。将经Sac Ⅰ酶切后线性化的BoIL2-pPICZB电转化到巴斯德毕赤酵母X-33中，转化子经高浓度Zeoein抗性筛选鉴定后，用1％甲醇诱导目的蛋白表达。经SDS-PAGE及Western blotting检测，表明BoIL2在酵母中获得了胞内表达；通过金属螯合亲和层析(MCAC)获得纯化的重组蛋白；培养小鼠CTLL2细胞进行活性检测，证实所表达的重组BoIL2具有生物活性。     

牛乳溶菌酶在毕赤酵母中的分泌表达及活性分析

为真核表达牛乳溶菌酶,本研究在通过酵母偏爱密码子改造并人工合成LYZ1基因的基础上,将LYZ1基因经克隆构建了高效表达具有生物活性牛乳溶菌酶的分泌型表达载体pPICZα-A-LYZ1,将其经SacⅠ酶切线性化后电转化毕赤酵母菌株GS115中,通过Zeocin筛选和PCR鉴定后的阳性重组菌用甲醇诱导60h后,进行SDS-PAGE和western blot鉴定,用溶壁微球菌对其进行活性检测,并对其进行体外抑菌效果检测分析。结果表明:分泌表达的重组目的蛋白约16ku,而且抗血清具有良好的反应原性。活性检测表明,培养液中重组溶菌酶活性达到2842u/mL。体外抑菌试验结果表明,重组牛乳溶菌酶对标准葡萄球菌及大肠杆菌菌株具有较好的抗菌作用,而对无乳链球菌、停乳链球菌、乳房链球菌作用较弱。     

Effects of recombinant bovine granulocyte-macrophage colony-stimulating factor on bovine peripheral blood neutrophil functions in vitro and in vivo

Effects of recombinant bovine granulocyte-macrophage colony-stimulating factor (rboGM-CSF) on bactericidal activity of bovine peripheral blood neutrophils in vitro and in vivo were studied. In in vitro experiment, bovine blood neutrophils were cultured for 9 hr in media containing 0.005, 0.05 or 0.5 microg/ml of rboGM-CSF. Neutrophils treated with rboGM-CSF showed significantly higher luminol-dependent chemiluminescence (LDCL) than control cells. In in vivo experiment, neutrophils isolated from cows injected 5.0 microg/kg of rboGM-CSF showed significantly higher Nitrobluetetrazolium (NBT) reduction value than that from control cows 24 hr post injection. Total leukocyte counts of cows injected rboGM-CSF sharply decreased 6 hr post injection and recovered to normal level 2 days post injection. Body temperature of these cows rose 6 hr post injection and back to normal level at 24 hr post injection. It was suggested that rboGM-CSF enhanced bactericidal activity of bovine neutrophils both in vitro and in vivo.     

鸭白细胞介素-2基因在毕赤酵母中的表达

根据GenBank中登录的鸭IL-2基因序列设计并合成了1对特异性引物,以经ConA诱导的广州鸭外周血淋巴细胞提取的总RNA为模板,用RT—PCR方法扩增出长度为360bp的目的基因片段,并将该基因克隆到pMD18-T载体上。酶切鉴定、PCR鉴定及序列测定结果表明,获得了鸭IL-2成熟蛋白基因的完整克隆。测序结果表明,该成熟蛋白基因由360个核苷酸组成,共编码119个氨基酸。克隆的鸭IL-2基因与GenBank上序列号为AY173028及AF294322的鸭IL-2基因的同源性高达99．4％。将目的基因克隆至真核表达载体pPICZαC上,构建了重组质粒pPICZαC—DuIL-2。酵母转化子经甲醇诱导发酵分泌表达了鸭IL-2基因。SDS-PAGE分析证实,鸭IL-2基因在毕市酵母（Pichiapastoris）中表达成功,表达的重组蛋白的分子质量约为14．3ku。     

猫血清白蛋白在毕赤酵母中的分泌表达

【目的】在毕赤酵母中构建猫血清白蛋白(feline serum albumin, FSA)表达系统,并探索其最适的基本表达条件,为FSA的生产提供一种新方法。【方法】在GenBank上获取FSA碱基序列,进行密码子优化并合成,将优化的密码子构建到载体pPIC9K上,经PCR和双酶切验证后通过电击转化将重组质粒FSA-pPIC9K转化毕赤酵母GS115,依次经MD平板和G418筛选后进行菌落PCR获得阳性菌株,随机选取阳性菌株经甲醇诱导表达96 h后,取表达上清液进行Western blotting验证。选取表达量较高的菌株分别在不同温度(24、26、28和30℃)、pH(4.0、5.0、6.0、7.0和8.0)和甲醇诱导量(其中1组为每24 h添加0.5%,其余4组为每12 h分别添加0.5%、1.0%、1.5%和2.0%)的条件下诱导表达96 h,取表达上清液进行Western blotting验证。【结果】菌落PCR结果显示,获得2条大小分别约为2.3和2.2 kb的目的基因条带和毕赤酵母AOX1基因扩增条带,诱导表达96 h后取表达上清液进行Western blotting验证,...     

猪瘟病毒E2基因在毕赤酵母中的表达

猪瘟是严重危害养猪业的一种烈性传染病,病死率高,被世界动物卫生组织(OIE)列为必须报告的动物疫病。E2蛋白是猪瘟病毒中最主要的保护性抗原,因此,围绕E2的基因工程疫苗研究已成为热点。本研究以含有猪瘟E2基因的重组质粒pMD18-T-E2为模板,设计一对特异性引物扩增去除跨膜区的E2基因,将PCR产物插入巴斯德毕赤酵母表达载体pPICZαA中,构建重组质粒pPICZαA-E2,将该质粒用SacⅠ酶切线性化后,电穿孔导入巴斯德毕赤酵母X-33中,经Zeocin筛选得到高拷贝转化子,通过甲醇诱导表达、SDS-PAGE和Western bolt试验验证,结果表明E2蛋白在酵母中获得成功表达。     

Effects of recombinant granulocyte-macrophage colony-stimulating factor on bovine peripheral blood and mammary gland neutrophil function in vitro.

Modulation of peripheral blood and mammary gland neutrophil function following in vitro exposure to recombinant bovine granulocyte-macrophage colony-stimulating factor (rBoGM-CSF) was studied. Bovine blood and mammary gland neutrophils were cultured for 9 h in media containing 0.005, 0.05 or 0.5 microgram/mL rBoGM-CSF. Neutrophils treated with rBoGM-CSF exhibited significantly more chemotactic and bactericidal activities and tended to produce more superoxide anion than control cells. The effects of rBoGM-CSF on bovine neutrophil populations appeared to be dose-dependent. The production of superoxide anion and the bactericidal activity of mammary gland neutrophils were consistently higher than blood neutrophils. Only moderate increases in lipopolysaccharide-induced mammary gland neutrophil functions were observed following incubation with rBoGM-CSF which suggests that there may be a threshold of immunomodulation for these prestimulated cells. It may be possible to augment the functional capacity of bovine neutrophil populations in vivo through the therapeutic application of rBoGM-CSF and consequently enhance resistance of dairy cattle to bacterial infections.