表达VP3重组减毒沙门氏菌的构建和融合蛋白纯化

寻求有效的肿瘤基因疗法,构建鸡贫血病毒VP3的减毒鼠伤寒沙门氏菌疫苗,并获得较纯的表达VP3基因的融合蛋白,初步研究其免疫原性.采用PCR技术扩增VP3基因,并将其与原核载体pET32α( )重组.将重组后质粒转染E.coli BL21,得到表达VP3的融合蛋白,并将此蛋白通过50%的Ni -NTA亲和树脂纯化.同时将重组质粒转染减毒沙门氏菌SL7207.经双酶切和PCR鉴定,成功构建了表达VP3的减毒沙门氏菌苗.融合蛋白通过50%的Ni -NTA亲和树脂纯化,得到纯度在90%以上的纯化蛋白.成功构建了表达VP3的减毒沙门氏菌苗,并且获得纯化的表达VP3的融合蛋白,为进一步研究VP3的免疫保护作用及对抗肿瘤疫苗的研制打下基础.     

抗菌肽Cec4a的重组表达和抗菌活性研究*

目的:构建Cec4a的原核重组表达体系,通过诱导表达、酶切纯化获得重组蛋白,并检测产物的抗菌活性。方法:基于Cec4a的序列设计引物,克隆Cec4a基因的DNA片段。利用原核表达载体(pCold-SUMO)构建重组原核表达质粒,并将其转化到大肠杆菌C41(DE3)等感受态细胞,使用IPTG进行诱导表达。通过Ni-NTA亲和层析柱纯化,获得含有His-SUMO标签的重组Cec4a融合蛋白。在SUMO蛋白酶酶切后,再次使用Ni-NTA亲和层析纯化,得到目的蛋白,最后用鲍曼不动杆菌(ATCC19606)作为指示菌检测表达产物的抗菌活性。结果:成功构建pCold-SUMO-Cec4a原核表达质粒,测序分析其序列与预期结果一致。Cec4a融合蛋白表达量为42.8mg/L,纯化后的Cec4a重组蛋白对鲍曼不动杆菌的MIC为4 μg/mL。结论:通过原核表达,并经Ni-NTA亲和层析纯化,获得了具有抗菌活性的重组蛋白Cec4a,为研究Cec4a的生物活性、抗菌机制及应用奠定了基础。     

白念珠菌天冬氨酸蛋白酶基因SAP2在大肠杆菌中的表达及产物纯化

目的构建SAP 2重组原核表达载体并表达、纯化出可溶性的蛋白,为抗体制备及Sap2抗原检测奠定基础。方法提取白念珠菌基因组DNA为模板,经PCR方法获取SAP 2目的基因。双酶切SAP 2基因与原核表达载体pMAL-c2x(+),连接酶切产物,转化大肠杆菌TOP10感受态细菌,筛选菌落和测序鉴定。将pMAL-c2x/SAP2重组质粒转化大肠杆菌BL21(DE3)感受态细胞,经异丙基硫代-β-D-半乳糖苷(IPTG)诱导表达出可溶性的融合蛋白,经直链淀粉树脂亲和层析、蛋白酶Factor Xa切割标签获得纯化的Sap2蛋白。结果经PCR扩增获得正确的SAP 2序列并定向插入原核表达载体pMAL-c2x(+)中。重组原核表达载体pMAL-c2x/SAP2经IPTG诱导14 h后表达出可溶性的融合蛋白,并经纯化、切除标签后得到目的蛋白。结论成功构建了白念珠菌天冬氨酸蛋白酶原核表达质粒pMAL-c2x/SAP2,该质粒在BL21(DE3)中可获得高效融合表达,通过亲和层析纯化及标签切割得到了氨基酸序列同天然蛋白一致的目的蛋白。     

大鼠D-双功能蛋白基因原核表达载体的构建及表达

利用原核表达系统构建大鼠D-双功能蛋白表达载体。设计基因拼接引物,通过RT-PCR合成DBP基因cDNA序列,将酶切、纯化的DBP基因与经相同处理的表达载体pET-28 a相连接,转化感受态大肠杆菌DH5α,筛选阳性重组子。将通过酶切及序列分析鉴定阳性的重组子质粒转入感受态大肠杆菌BL21-gold表达菌中,经IPTG诱导表达,通过SDS-PAGE分析目的蛋白表达情况。结果显示,成功获得了包含DBP基因的双链cDNA序列,酶切、序列分析及Western blotting证实成功构建了DBP基因的原核表达载体。通过原核表达系统,DBP蛋白以包涵体形式产生,复性后可获得高表达的目的蛋白。     

人纤溶酶原饼环区5(hPK5)基因的分泌型表达

构建人纤溶酶原饼环区5(hPK5)基因的原核可溶性表达载体并进行表达和纯化,获取大量高纯度、具有生物活性的hPK5蛋白。以纤溶酶原cDNA为模板,PCR扩增了hPK5基因,经过适当酶切后构建表达载体pET22b(+)hPK5,转入大肠杆菌BL21(DE3)进行表达并经组氨酸亲和层析获得纯化。带有重组质粒pET22b(+)hPK5的大肠杆菌经IPTG诱导后以可溶性形式表达16kDa的蛋白,其表达量占菌体总蛋白的30%以上,纯化后目的蛋白纯度达95%以上,Western印迹表明重组蛋白具有Histag抗原活性。构建了pET22b(+)hPK5重组质粒并成功地在大肠杆菌中获得可溶性表达,为获得大量hPK5基因工程产品奠定了实验基础。     

宫颈癌相关BLCAP基因的原核表达及条件优化

目的利用大肠埃希菌表达系统表达宫颈癌相关BLCAP基因,并优化表达条件。方法利用PCR技术从逆转录病毒重组载体pL（BLCAP）SN中扩增宫颈癌相关BLCAP基因,将其插入到原核表达载体pET-32（a）中,从而构建原核表达重组质粒pET-32（a）-BLCAP,随后将阳性重组质粒转化到表达宿主菌中,通过IPTG诱导表达并优化表达条件,所表达的带有His标签目的融合蛋白经Ni^2＋亲和层析纯化回收,并采用SDS—PAGE和Western印迹对目的蛋白进行分析和鉴定。结果构建的重组表达质粒经PCR、酶切和DNA测序鉴定与预期的结果一致,含有重组质粒的表达宿主菌经过IPTG诱导表达了分子量约为28ku的融合蛋白,并经优化确定了最佳的诱导表达条件。结论成功构建了pET-32（a）-BLCAP原核表达质粒,表达并经纯化得到了BLCAP目的蛋白,为研究该蛋白的性质及其制备针对该蛋白的抗体奠定了基础。     

家蝇幼虫抗菌肽Attacin基因的克隆表达及抑菌生物学活性

目的克隆家蝇幼虫Attacin抗菌肽基因．构建原核融合表达载体,建立Attacin体内抗菌活性检测系统,优化表达和纯化Attacin目的蛋白,并初步研究其抗菌生物学功能。方法以pUC m-T／Attacin重组质粒为模板,设计特异性引物,PCR扩增Attacin编码区序列,分别克隆至原核表达载体pET30a（＋）和pGEX-4T-1。构建原核重组质粒,转化大肠埃希菌,表达重组Attacin蛋白,并在大肠埃希菌中体内检测Attacin的抗菌活性。利用亲和层析柱纯化重组融合蛋白Attacin,SDS-PAGE进行纯度分析,琼脂糖平板抑菌试验鉴定其生物活性。结果pET30a（a＋）／Attacin和pGEX-4T—1／Attacin重组质粒分别转化大肠埃希菌后,以IPTG诱导表达,与未诱导对照相比,含有重组质粒的宿主菌生长受到抑制。从pET30a（＋）／Attacin重组质粒的表达宿主菌中未能获得His-Attacin融合蛋白,而从pGEX-4T—1／Attacin重组质粒转化菌种获得GST-Attacin融合蛋白。SDS-PAGE分析表明Attacin重组蛋白分子量与预期结果一致,琼脂糖平板抑菌试验显示重组Attacin具有抗菌活性。结论Attacin基因在原核系统中成功表达,并且纯化后具有抑菌活性,为下一步研究Attacin的生物学功能及其应用开发奠定了基础。     

人vasorin蛋白的基因克隆、表达及纯化简

目的：克隆、表达人vasorin（VASN）蛋白。方法：利用PCR方法从HepG2细胞的cDNA中扩增获得目的基因,并插入带有6xHis标签的原核高效可溶性表达载体pET28a中,构建重组表达质粒pET28a-VASN,将重组表达质粒转化大肠杆菌BL21（DE3）,经IPTG诱导后目的基因获得表达,对融合目的蛋白进行Ni^2＋金属螯合柱纯化。结果：内切酶鉴定及基因序列测定证实重组表达质粒构建成功;对目的蛋白进行了原核表达,SDS-PAGE显示相对分子质量为61x10^3的特异表达条带;Western印迹证实目的蛋白为VASN,且主要以包涵体形式存在;对经尿素变性的表达产物进行了亲和层析纯化,有利于以后的变性、复性过程。结论：获得了人VASN融合蛋白,为其进一步的生物学功能研究奠定了基础。     

耐甲氧西林葡萄球菌PBP2a的质粒克隆与构建

目的克隆并构建耐甲氧西林金黄色葡萄球菌（MRSA）青霉素结合蛋白2a（PBP2a）全长及转肽酶区的原核表达质粒。方法登录基因文库查找获得mecA基因的编码序列,应用PCR技术扩增获得DNA片段,将此基因片段插入PET-32a载体,同时酶切鉴定阳性克隆,DNA序列测定验证序列正确性。结果 PCR扩增获得了mecA基因全长及转肽酶区DNA片段,成功插入到原核表达载体PET32a,双酶切鉴定及DNA序列测定证实插入片段正确。结论成功构建了PBP2a全长及转肽酶区片段表达质粒,为该蛋白的纯化表达和疫苗研究奠定了基础。     

人vasorin蛋白的基因克隆、表达及纯化

目的:克隆、表达人vasorin(VASN)蛋白。方法:利用PCR方法从HepG2细胞的cDNA中扩增获得目的基因,并插入带有6×His标签的原核高效可溶性表达载体pET28a中,构建重组表达质粒pET28a-VASN,将重组表达质粒转化大肠杆菌BL21(DE3),经IPTG诱导后目的基因获得表达,对融合目的蛋白进行Ni2+金属螯合柱纯化。结果:内切酶鉴定及基因序列测定证实重组表达质粒构建成功;对目的蛋白进行了原核表达,SDS-PAGE显示相对分子质量为61×103的特异表达条带;Western印迹证实目的蛋白为VASN,且主要以包涵体形式存在;对经尿素变性的表达产物进行了亲和层析纯化,有利于以后的变性、复性过程。结论:获得了人VASN融合蛋白,为其进一步的生物学功能研究奠定了基础。     

鸡贫血病毒VP1和VP1蛋白在家蚕中的联合表达

将鸡贫血病毒vp1和vp2基因分别克隆入转移载体pBacPAK8中,获得重组转移质粒pBac-vp1和pBac-vp2。以上两质粒分别与CunI酶切线性化的亲本病毒Bm-Bacpak6DNA共转染家蚕细胞,通过蓝白斑筛选,纯化得到重组病毒Bm-vp1和Bm-vp2。PCR分析表明vp1和vp2基因已整合进杆状病毒基因组中。将Bm-vp1和Bm-vp2共感染5龄家蚕,通过表达产物免疫SPF鸡产生的抗血清与CAV感染的MDCC－MSB1细胞的间接荧光抗体分析,证明表达产物能诱导鸡产生的抗体,而且能够保护子代鸡免受CAV的攻击。该研究表明,表达VP1和VP2蛋白的重组家蚕杆状病毒（Recombinant BmNP)是很有前途的CAV亚单位疫苗的生产系统。     

猪水泡病病毒VPl基因抗原区的原核表达

利用RT-PCR和nested PCR(nPCR)技术扩增出猪水泡病病毒VPl基因的抗原区,将其克隆到表达载体pProEX-HTb中,获得重组质粒,经PCR、酶切和序列分析鉴定表明,目的基因插入的位置、大小和读码框均正确。将重组质粒导入BL21(DE3),经IPTG诱导表达后SDS-PAGE检测表明,重组菌能表达猪水泡病病毒VPl抗原区蛋白;Western blot检测表明,诱导表达的抗原区蛋白能与猪水泡病阳性血清发生特异性反应。     

埃博拉病毒GP和VP40蛋白在哺乳动物细胞中的共表达及病毒样颗粒装配

目的：制备基因重组埃博拉病毒样颗粒,为疫苗研究及埃博拉病毒特异抗原、抗体检测提供基础。方法：根据埃博拉病毒扎伊尔株的GP和VP40蛋白氨基酸序列,以哺乳动物细胞基因表达密码子偏好性进行基因优化设计;化学合成GP和VP40基因片段并分别构建于表达质粒pcDNA3.1或同时构建到具有双表达单元的质粒pBudCE4.1;重组质粒经lipofectamine2000转染293FT细胞;以Western blot检测重组蛋白GP和VP40的表达;通过电镜观察病毒样颗粒。结果：构建的重组质粒经酶切鉴定及测序分析证实构建成功;Western blot结果显示,共转染分别表达GP和VP40的两个质粒或转染共表达两个蛋白的质粒都发现GP特异反应条带产生,且大小与预期相符,此外,转染共表达质粒产生的GP蛋白表达明显强于两个质粒共转染,并同时可检测到VP40的表达;电镜观察到典型的丝状的埃博拉病毒样颗粒。结论：在293FT细胞中基因优化的埃博拉病毒GP和VP40可有效表达并装配为病毒样颗粒,为进一步研究奠定了基础。     

Synthesis, cloning, and expression of artificial genes, coding antigenic determinants of the foot-and-mouth virus substrain A22]

Chemical-enzymatic synthesis and cloning in Escherichia coli of double-stranded DNAs, coding for simple and complex antigenic determinants of foot-and-mouth disease virus (FMDV) strain A22, have been carried out. The simple antigenic determinants are a part of the viral coat protein VP1 (amino acid sequence 131-152 or 131-160) whereas the complex antigenic determinants comprise additionally the amino acid sequence 200-213 of VP1 linked to N-terminus of simple antigenic determinants through a tetrapeptide spacer Pro-Pro-Ser-Pro. Recombinant DNAs containing genes for antigenic determinants of FMDV fused with C-terminus of gene for human tumor necrosis factor (hrTNF) have been constructed. Expression of the hybrid genes and properties of the proteins coded were studied. All recombinant proteins were shown to interact specifically with polyclonal antibodies both against hrTNF and FMDV strain A22. The recombinant proteins produced by bacteria are perspective for study as a vaccine against FMDV.     

犬细小病毒VP2亲水性编码区的表达与免疫原性分析

目的：探讨犬细小病毒VP2亲水性编码区的免疫原性,为进一步研究基因工程亚单位疫苗奠定基础。方法：利用蛋白质分析软件Protean对已克隆的犬细小病毒VP2基因序列进行分析,选择亲水性好、抗原性强的293-520位氨基酸区域（命名为VP2S）作为靶序列,然后以已有VP2序列作为模版通过PCR扩增的方法获得VP2S,将VP2S克隆入pQE-31载体获得pQE-31-VP2S;将pQE-31-VP2S的原核表达产物经Western-blotting确认后免疫小鼠,用血凝抑制试验测定抗体水平。结果：293～520位氨基酸区域的亲水性好、抗原性强;重组质粒pQE-31-VP2S可成功表达大约29KDa的能被CPV抗血清识别的VP2S;VP2S能诱导小鼠产生高滴度的血凝抑制（HI）抗体（25）。结论：VP2S具有较强的免疫原性,能作为基因工程亚单位疫苗进行开发研究。     

The relationship between capsid protein (VP2) sequence and pathogenicity of Aleutian mink disease parvovirus (ADV): a possible role for raccoons in the transmission of ADV infections.

Aleutian mink disease parvovirus (ADV) DNA was identified by PCR in samples from mink and raccoons on commercial ranches during an outbreak of Aleutian disease (AD). Comparison of DNA sequences of the hypervariable portion of VP2, the major capsid protein of ADV, indicated that both mink and raccoons were infected by a new isolate of ADV, designated ADV-TR. Because the capsid proteins of other parvoviruses play a prominent role in the determination of viral pathogenicity and host range, we decided to examine the relationship between the capsid protein sequences and pathogenicity of ADV. Comparison of the ADV-TR hypervariable region sequence with sequences of other isolates of ADV revealed that ADV-TR was 94 to 100% related to the nonpathogenic type 1 ADV-G at both the DNA and amino acid levels but less than 90% related to other pathogenic ADVs like the type 2 ADV-Utah, the type 3 ADV-ZK8, or ADV-Pullman. This finding indicated that a virus with a type 1 hypervariable region could be pathogenic. To perform a more comprehensive analysis, the complete VP2 sequence of ADV-TR was obtained and compared with that of the 647-amino-acid VP2 of ADV-G and the corresponding VP2 sequences of the pathogenic ADV-Utah, ADV-Pullman, and ADV-ZK8. Although the hypervariable region amino acid sequence of ADV-TR was identical to that of ADV-G, there were 12 amino acid differences between ADV-G and ADV-TR. Each of these differences was at a position where other pathogenic isolates also differed from ADV-G. Thus, although ADV-TR had the hypervariable sequence of the nonpathogenic type 1 ADV-G, the remainder of the VP2 sequence resembled sequences of other pathogenic ADVs. Under experimental conditions, ADV-TR and ADV-Utah were highly pathogenic and induced typical AD in trios of both Aleutian and non-Aleutian mink, whereas ADV-Pullman was pathogenic only for Aleutian mink and ADV-G was noninfectious. Trios of raccoons experimentally inoculated with ADV-TR and ADV-Utah all became infected with ADV, but only a single ADV-Pullman-inoculated raccoon showed evidence of infection. Furthermore, none of the ADV isolates induced pathological findings of AD in raccoons. Finally, when a preparation of ADV-TR prepared from infected raccoon lymph nodes was inoculated into mink and raccoons, typical AD was induced in Aleutian and non-Aleutian mink, but raccoons failed to show serological or pathological evidence of infection. These results indicated that raccoons can become infected with ADV and may have a role in the transmission of virus to mink but that raccoon-to-raccoon transmission of ADV is unlikely.     

Identification of a cell surface protein from Crandell feline kidney cells that specifically binds Aleutian mink disease parvovirus

Aleutian mink disease parvovirus (ADV) is the etiological agent of Aleutian disease of mink. The acute disease caused by ADV consists of permissive infection of alveolar type II cells that results in interstitial pneumonitis. The permissive infection is experimentally modeled in vitro by infecting Crandell feline kidney (CrFK) cells with a tissue culture-adapted isolate of ADV, ADV-G. ADV-G VP2 empty virions expressed in a recombinant baculovirus system were analyzed for the ability to bind to the surface of CrFK cells. Radiolabeled VP2 virions bound CrFK cells specifically, while they did not bind either Mus dunni or Spodoptera frugiperda cells, cells which are resistant to ADV infection. The binding to CrFK cells was competitively inhibited by VP2 virions but not by virions of cowpea chlorotic mottle virus (CCMV), another unenveloped virus similar in size to ADV. Furthermore, preincubation of CrFK cells with the VP2 virions blocked infection by ADV-G. The VP2 virions were used in a virus overlay protein binding assay to identify a single protein of approximately 67 kDa, named ABP (for ADV binding protein), that demonstrates specific binding of VP2 virions. Exogenously added VP2 virions were able to competitively inhibit the binding of labeled VP2 virions to ABP, while CCMV virions had no effect. Polyclonal antibodies raised against ABP reacted with ABP on the outer surface of CrFK cells and blocked infection of CrFK cells by ADV-G. In addition, VP2 virion attachment to CrFK cells was blocked when the VP2 virions were preincubated with partially purified ABP. Taken together, these results indicate that ABP is a cellular receptor for ADV.     

猪水泡病病毒VP2基因抗原区在大肠杆菌中的表达

利用RT_PCR技术 ,以SVDVHK’70为材料 ,扩增出VP2基因抗原区。将目的基因的PCR扩增产物直接进行双酶切 ,然后将酶切产物与酶切后的表达载体pGEX 4T_1进行连接 ,转化BL2 1菌体并提质粒 ,经酶切、PCR鉴定为阳性的重组质粒命名为pGEX_VP2 ,并测序。测序结果表明 ,目的基因插入的位置、大小和读码框均正确 ,表达载体构建成功。将含有阳性质粒的BL2 1菌液经IPTG诱导后进行SDS_PAGE分析 ,出现预期的目的蛋白条带 ,此目的蛋白经Westernblot检测确定其有免疫活性。     

Expression of poliovirus complementary DNA coding for viral antigenic determinants in Escherichia coli

DNA sequences coding for the immunogenic capsid protein VP1 and/or VP3 of poliovirus strain LSc-2ab (Sabin 1) were prepared by digesting the cloned complementary DNA with restriction endonuclease PstI. The DNA fragments were inserted into the unique PstI site of Escherichia coli plasmid vectors pBR322, pKT 280 and/or pKT 287 that lay in the region expressed under control of the penicillinase promoter system. In the expression vectors, poliovirus sequences were designed to be read in phase and therefore to be expressed as fusion proteins with the bacterial peptides. In addition, the Escherichia coli tryptophan operon promoter-operator system was inserted upstream of the penicillinase system to obtain stronger expression of the poliovirus sequences. Escherichia coli transformed with these plasmids appeared to produce the antigenic polypeptides, which were detected by immunoprecipitation with antibodies to capsid proteins VP1 and/or VP3 followed by SDS-polyacrylamide gel electrophoresis.