鼠约氏疟原虫yoelii株Pydyn基因的内含子序列分析

本研究测定并分析鼠约氏疟原虫 (Plasmodiumyoeliiyoelii)动力素蛋白基因 (Pydyn) 3′端内含子序列 ,比较约氏疟原虫yoelii虫株的Pydyn基因与约氏疟原虫 17XNL虫株基因组序列内含子间序列的多态性。方法 :应用PCR技术扩增约氏疟原虫动力素蛋白基因 (Pydyn)基因组 3′端序列 ,将其克隆入pGEM TEasy载体。阳性克隆经酶切和PCR鉴定正确后测序 ,并用分子生物学WINSTAR软件进行基因结构和同源性分析。结果 :用PCR方法成功扩增出约 80 0bp的Pydyn基因特定片段 ,阳性克隆经酶切及PCR扩增确定。基因序列分析表明 ,约氏疟原虫yoelii虫株的Pydyn基因含有 3个内含子 ,并且与约氏疟原虫 17XNL虫株基因组序列在内含子间存在着几个变异。结论 :确定了鼠约氏疟原虫动力素蛋白基因 (Pydyn) 3′端内含子序列 ,其内含子具有序列短且AT含量较高的特点 ,两末端的碱基具有一般真核基因内含子共有的剪接位点。多态性分析表明 ,将约氏疟原虫yoelii虫株的Pydyn基因的 3个内含子与人恶性疟原虫动力素基因Pfdyn内含子保守序列相比 ,Pydyn基因内含子上游下游序列具有一定的同源性。另外 ,约氏疟原虫yoelii虫株与约氏疟原虫 17XNL虫株的内含子间存在着多态性 ,存在着几个变异 ,这些变异属于点突变     

蛔虫过敏原ABA-1融合基因在大肠杆菌中的表达及鉴定

背景：利用蛔虫基因融合技术,可将过敏原ABA-1的主要基因进行融合。 目的：利用大肠杆菌表达系统重组表达蛔虫主要过敏原ABA-1融合蛋白。 方法：从Gene Bank和Protein Database中获取蛔虫主要过敏原ABA-1基因和蛋白序列,选定其中的ABA-1B1,ABA-1A2与ABA-1A1基因重组为融合基因BAA,经密码子优化后,全基因合成目的基因BAA并构建于表达载体PET-44a上,经KCM法转化入大肠杆菌JM109中进行克隆,PET-44a/BAA经NdeⅠ和PstⅠ双酶切及DNA测序正确后,转化入大肠杆菌RosettaBlueTM中,经IPTG诱导表达。表达蛋白经Ni柱亲和层析纯化后,通过Western blot和氨基酸测序鉴定目的蛋白。 结果与结论：大肠杆菌的融合蛋白BAA表达量约占总蛋白的40%,纯化后蛋其白纯度可达90%左右。Western Blot结果显示在相对分子质量45 000处可见一特异目的条带,氨基酸测序显示N端15个氨基酸与目的蛋白完全相同。结果证实,融合蛋白BAA在大肠杆菌中得到高效的表达。     

恶性疟原虫杂合抗原基因的表达及其产物免疫功能的研究

化学合成的人恶性疟原虫杂合多肽抗原 AB 基因,编码子孢子 CSP重复序列 NANP、CSPTh2R和红内期spf35.1、spf83.1、spf55.1、spf83.18、pf155/RESA-5’端重复区共7个不同免疫功能表位,与大肠杆菌质粒pWR450-1重组,构建成pWR450-1/AB表达载体。在乳糖操纵子调控下以β-半乳糖苷酶-恶性疟原虫杂合多肽抗原融合蛋白形式,在大肠杆菌中高效表达。表达产物经SDS-PAGE电泳分离纯化后,加福氏佐剂免疫家兔,诱导产生较高滴度的抗血清。抗血清对人恶性疟原虫体外生长有明显的抑制作用,24h抑制率为65.92％;72h的抑制率为72.63％。对照血清无抑制作用。分离纯化的表达产物能与鼠抗恶性疟原虫和疟疾患者抗血清起免疫反应。这些结果表明合成基因的表达产物具有较好的免疫原性。     

广东省SARS流行株M基因序列分析

目的：测定广东省不同流行时期13份SARS病毒(SARS CoV)标本的M基因序列，通过分析该基因序列的变异情况，初步了解广东省SARS病毒在流行过程中是否发生了变异。方法：提取病毒RNA，用M基因特异引物进行RT-PCR，将产物纯化后直接测定核苷酸序列。结果：13份标本M基因核苷酸序列同源性很高，为99．7％～100％，M基因核苷酸序列只在2个位点(80和203位)发生变异，1株80位点的变化引起编码的氨基酸从苯丙氨酸(F)变为半胱氨酸(C)，3株203位变化为无义突变。结论：M基因核苷酸序列变异不大，初期和后期M基因核苷酸序列与流行高峰期的毒株相差1个碱基，但氨基酸序列相同；从香港感染病人分离的1株病毒M基因与广东本地感染分离株存在1个氨基酸的差异。     

抗淋巴样增强因子-1羧基端单克隆抗体的制备及其表位的初步鉴定

目的 制备抗淋巴样增强因子-1(LEV-1)羧基端86个氨基酸(Lct86)特异性单克隆抗体,并初步明确其表位,为进一步研究LEF-1 C端特异序列的功能奠定基础.方法 从Jurkat细胞株中扩增LEF-1 C端特异序列eDNA,并克隆入PQE40、pET32a原核表达载体;分别转化入M15、BL21(DE3)感受态菌,IPIG诱导表达;纯化PQFAO-Lct86融合蛋白作为免疫原免疫Balb/c小鼠制备单克隆抗体,以pET32a-Lct86融合蛋白鉴定单克隆抗体特异性.LEF-1 C端特异序列不同长度的基因片段定向克隆人PQE40,鉴定各片段的表达,利用Western blotting初步鉴定单克隆抗体的表位.结果 成功构建了PQE40-Lct86、pET32a-Lct86重组原核表达载体;纯化获得PQE40-Lct86融合蛋白;得到一株特异性的抗LEF-1 C端单克隆抗体TMAb1,证实其表位位于437aa～454aa.结论 成功制备了一株特异性的抗LEF-1 C端单克隆抗体TMAb1,并鉴定其抗原识别表位位于437aa～454aa,为进一步研究LEF-1 C端的功能奠定基础.     

弓形虫HT分离株ROP5蛋白基因的克隆、序列分析及其表达研究

目的克隆和表达弓形虫虎源分离株（HT株）ROP5蛋白基因。方法运用RT—PCR技术从弓形虫HT株中扩增出ROP5基因，将其克隆人T载体中进行测序和分析．并将目的基因亚克隆到大肠杆菌表达载体pET28a中进行诱导表达。结果该基因全长1650bp，编码549个氨基酸。其中前24个氨基酸构成信号肽序列。与GenBank中报道的RH株相比，有12个核苷酸有差异，导致7个氨基酸发生改变，两者核苷酸和推导氨基酸序列的同源性分别为99．2％和98．9％。转化重组质粒pETROP5的大肠杆菌BL21（DE3）在IPTG的诱导下，可表达出相对分子质量为64800的重组蛋白，并且能与弓形虫抗体发生血清学反应，表达量占菌体蛋白的15．6％。结论成功克隆和表达了弓形虫HT株ROP5蛋白基因，表达的重组蛋白具有良好的反应原性。     

恶性疟原虫FCC—1／HN株环子孢子蛋白基因分枝杆菌——大肠杆穿梭表达重组质粒的构建及序列测定

本文对恶性疟原虫环子孢子蛋白(circumsporozoiteprotein,CSP)基因片段进行克隆和序列测定。根据恶性疟原虫837株基因编码序列设计合成一对引物,采用PCR技术从恶性疟原虫FCC-1/HN株基因组DNA中特异扩增CSP基因片段的Ⅰ区、中央重复区、重复区后可变区和Ⅱ区;经纯化的扩增产物用BamHⅠ和KpnⅠ双酶切后,定向克隆入大肠杆菌——分枝杆菌穿梭表达质粒,转化感受态大肠杆菌DH5α,重组克隆经抗性筛选和快速凝胶电泳鉴定,再经PCR和酶切鉴定,并对重组子进行序列测定。结果表明从恶性疟原虫FCC-1／HN株基因组DNA中可特异扩增出约1171bp的基因片段,阳性重组质粒经双酶切和PCR鉴定与预期的结果一致,序列测定表明所克隆的基因和编码环子孢子抗原的基因片段相符。     

弓形虫缓殖子期特异抗原SAG2C基因的克隆、鉴定与生物信息学分析

目的克隆并鉴定弓形虫PRU株表面抗原SAG2C基因序列和cDNA序列，对比不同毒力弓形虫株（PRU、RH、ME49）中SAG2C基因序列。进行生物信息学分析。方法根据SAG2C基因已知序列设计合成一对引物，应用PCR技术从Prugniaud（PRU）株弓形虫基因组DNA和总RNA中扩增SAG2C基因，克隆入pMD19-T载体并进行序列测定。应用DNAMAN软件、NCBI网站（http：／／www。ncbi．nlm．nih.gov／）分析3种虫株之间SAG2C基因的同源性；利用生物信息学网站ExPASy（http：／／us.expasy．org／）对获得的基因及推导出的氨基酸序列进行生物信息学分析。结果PCR扩增得到弓形虫PRU株SAG2C基因及其全长cDNA序列．酶切及PCR鉴定获得了正确的重组质粒。测序结果表明，获得SAG2C基因序列1225bp，全长cDNA序列1095bp，编码364个氨基酸。同源性分析显示。弓形虫Prugniaud株和RH株SAG2C基因同源性为97．14％；Prugniaud株与ME49株cDNA序列同源性为96．89％；编码氨基酸序列同源性为92％。N端为信号肽，C端疏水序列预测它为糖基磷脂酰肌醇固着蛋白．存在13个潜在抗原表位及多个保守功能区域。结论成功克隆了弓形虫缓殖子期特异抗原SAG2C基因序列及其全长cDNA序列。序列分析显示其为糖基磷脂酰肌醇固着蛋白。     

恶性疟原虫海南株裂殖子表面蛋白1基因第1至第4区的多态性分析

本对5株恶性疟原虫海南株MSP1基因5'端（第1～第4区）进行体外扩增，其中2株的目的基因扩增产物直接用末端标记循环测序法测定其DNA序列，另3株虫株的目的基因片段用pGEM-T载体克隆化后再测序，结果获得了6个MSP1分子第1～第4区的序列片段，与已报告的MSP1分子比较，证明属MAD20等位基因型。同时发现，6个序列片段中，除了HN3和HN5株的序列彼此完全一致，其余株序列的保守区（第1和第3区）也一致外，可变区的第2区和第4区的氨基酸序列存在一定的差异，与MAD20的序列也略有不同，序列分析也证明海南株的MSP1也存在基因内重组现象，此外，3株经克隆化处理的虫株中，发现1株含2种不同的MSP1等位基因，本研究初步提供了我国恶性疟原虫海南株MSP1存在多态性的依据。     

应用基因工程方法制备新型重组人肿瘤坏死因子-α

目的　应用基因工程技术 ,制备一种新型的重组人肿瘤坏死因子 α (novelrecombinanthumantumornecrosisfactor α ,nrhTNF α) ,并对其生物学活性、理化性质进行鉴定 ,为进入临床前研究提供基础。方法　应用PCR技术 ,将hTNF α基因的 5′端 17个氨基酸的编码序列删除 ,基因中Pro8Ser9Asp10 的编码序列用Arg Lys Arg的编码序列取代 ,同时Leu157的密码子被Phe的密码子所取代。将hTNF α突变基因 ,插入原核高效表达载体pBV2 2 0中 ,构建高表达工程菌株。纯化表达产物 ,对连续 3批制备的新型rhTNF α,按人用《重组DNA制品质量控制要点》检定要求进行鉴定。结果DNA序列分析和蛋白质N末端、C末端部分氨基酸序列分析表明 ,nrhTNF α与天然的hTNF α相比较 ,N末端缺失了 7个氨基酸 ,13位氨基酸为Arg Lys Arg ,其后为天然hTNF α 11位以后的氨基酸。 15 7位Leu的密码子被Phe的密码子所取代。产物表达量占菌体蛋白的 6 7.4 %。经 (NH4) 2 SO4沉淀、Q SepharoseF .F .及S SepharoseF .F .柱层析分离纯化后 ,产品的纯度达 99% ,比活性达 1× 10 9IU/mg蛋白。结论成功地制备了nrhTNF ,对连续 3批制备的nrhTNF α按人用《重组DNA制品质量控制要点》检定要求进行鉴定 ,所有项目均合格     

恶性疟原虫信号肽肽酶原核表达载体的构建及融合表达蛋白的鉴定

目的构建恶性疟原虫PfSPP基因pMAL-p2x的原核表达载体,并鉴定表达,为其功能研究奠定基础。方法体外培养恶性疟原虫（3D7株和FCR3株）,提取虫体总RNA,进行反转录后,采用RT-PCR扩增PfSPP的全编码区基因,将其克隆入原核表达载体pMAL-p2x,PCR、双酶切鉴定重组质粒,并进行序列测定,将测序正确的重组质粒转化入大肠杆菌进行表达获得MBP-PfSPP融合蛋白,采用Western blotting对表达产物进行鉴定。结果成功构建pMAL-PfSPP,转化菌经诱导表达出分子量约为77 000Mr的MBP-PfSPP融合蛋白,抗MBP多克隆抗体可特异性地识别表达的融合蛋白。结论成功表达具有多个跨膜结构的膜蛋白PfSPP,从而为深入研究PfSPP的酶活性及生物学功能奠定基础。     

The clinical-grade 42-kilodalton fragment of merozoite surface protein 1 of Plasmodium falciparum strain FVO expressed in Escherichia coli protects Aotus nancymai against challenge with homologous erythrocytic-stage parasites

A 42-kDa fragment from the C terminus of major merozoite surface protein 1 (MSP1) is among the leading malaria vaccine candidates that target infection by asexual erythrocytic-stage malaria parasites. The MSP1(42) gene fragment from the Vietnam-Oak Knoll (FVO) strain of Plasmodium falciparum was expressed as a soluble protein in Escherichia coli and purified according to good manufacturing practices. This clinical-grade recombinant protein retained some important elements of correct structure, as it was reactive with several functional, conformation-dependent monoclonal antibodies raised against P. falciparum malaria parasites, it induced antibodies (Abs) that were reactive to parasites in immunofluorescent Ab tests, and it induced strong growth and invasion inhibitory antisera in New Zealand White rabbits. The antigen quality was further evaluated by vaccinating Aotus nancymai monkeys and challenging them with homologous P. falciparum FVO erythrocytic-stage malaria parasites. The trial included two control groups, one vaccinated with the sexual-stage-specific antigen of Plasmodium vivax, Pvs25, as a negative control, and the other vaccinated with baculovirus-expressed MSP1(42) (FVO) as a positive control. Enzyme-linked immunosorbent assay (ELISA) Ab titers induced by E. coli MSP1(42) were significantly higher than those induced by the baculovirus-expressed antigen. None of the six monkeys that were vaccinated with the E. coli MSP1(42) antigen required treatment for uncontrolled parasitemia, but two required treatment for anemia. Protective immunity in these monkeys correlated with the ELISA Ab titer against the p19 fragment and the epidermal growth factor (EGF)-like domain 2 fragment of MSP1(42), but not the MSP1(42) protein itself or the EGF-like domain 1 fragment. Soluble MSP1(42) (FVO) expressed in E. coli offers excellent promise as a component of a vaccine against erythrocytic-stage falciparum malaria.     

鼠疟模型作为恶性疟原虫多表位疫苗保护性的探索试验

目的为寻找恶性疟原虫基因工程多表位疫苗保护性评价的模型动物，利用小鼠约氏疟原虫(Plasmodiumyoelii)及小鼠伯氏疟原虫(Plasmodiumberghei)模型对本实验室构建的恶性疟原虫(Plasmodiumfalciparum)多阶段、多表位基因工程候选疫苗进行了体内保护性及免疫模式探索试验。结果在约氏疟原虫模型，先用该疫苗基因的大肠杆菌表达蛋白免疫，后用含同一基因的重组痘苗病毒加强免疫组，与野生型痘苗病毒免疫组及空白对照组相比，小鼠的死亡时间延长(P<0.01)。结果初步显示，约氏疟原虫鼠疟模型可用作该基因工程多表位恶性疟原虫候选疫苗的保护性评价。     

恶性疟原虫环子孢子蛋白单链抗体与按蚊cecropin A融合基因的构建、原核表达及生物学活性的初步分析

根据按蚊偏嗜性密码子对鼠源性恶性疟原虫环子孢子蛋白单链抗体2a10基因进行改造,并融合按蚊抗菌肽cecropin A编码基因。将获得的cecrop-m2a10融合基因克隆入原核表达载体pET32a（＋）中,对表达产物进行SDS-PAGE、Western-blot分析并利用琼脂糖扩散法检测其抗菌活性。结果对鼠源性环子孢子蛋白单链抗体2a10中6种氨基酸的170个核苷酸进行了改造,融合cecropinA编码基因,成功构建了cecrop-m2a10融合基因。靶基因在大肠杆菌中以融合蛋白和包涵体的形式高效表达,包涵体经尿素溶解变性及透析复性后表达蛋白的纯度达75%并具备抗大肠杆菌DH5α的活性。本实验为进一步研究cecrop-m2a10在转基因蚊中的多重抗病原效应提供了基础。     

恶性疟原虫裂殖子表面主要蛋白对裂殖子入侵人红细胞的抑制作用

恶性疟原虫裂殖子表面主要蛋白－１（ＭＳＡ１），又称Ｐ１９５，与人红细胞具有结合作用，这种结合是裂殖子识别红细胞的基础。为了确定Ｐ１９５蛋白与识别有关的位点，本研究在大肠杆菌中分８段表达了ＭＡＤ２０株恶性疟原虫的Ｐ１９５蛋白。各段蛋白用镍亲和层析柱分离，然后复性。在体外培养疟原虫至成熟裂殖体期，将各段蛋白分别加入到培养基上清中，继续培养２４小时，检查红细胞感染率，通过感染率了解各段蛋白对裂殖子入侵红细胞的影响。结果发现Ｐ１９５蛋白中氨基酸序列为３８４－５９５的一段蛋白（Ｍ６），呈剂量依赖性抑制恶性疟原虫裂殖子入侵人红细胞，且Ｍ６对疟原虫生长无细胞毒性作用。这表明Ｍ６可能含红细胞结合位点，该位点与裂殖子竞争性结合红细胞，而使感染率下降     

Effect of codon optimization on expression levels of a functionally folded malaria vaccine candidate in prokaryotic and eukaryotic expression systems

We have produced two synthetic genes that code for the F2 domain located within region II of the 175-kDa Plasmodium falciparum erythrocyte binding antigen (EBA-175) to determine the effects of codon alteration on protein expression in homologous and heterologous host systems. EBA-175 plays a key role in the process of merozoite invasion into erythrocytes through a specific receptor-ligand interaction. The F2 domain of EBA-175 is the ligand that binds to the glycophorin A receptor on human erythrocytes and is therefore a target of vaccine development efforts. We designed synthetic genes based on P. falciparum, Escherichia coli, and Pichia codon usage and expressed recombinant F2 in E. coli and Pichia pastoris. Compared to the expression of the native F2 sequence, conversion to prokaryote (E. coli)- or eukaryote (Pichia)-based codon usage dramatically improved the levels of recombinant protein expression in both E. coli and P. pastoris. The majority of the protein expressed in E. coli, however, was produced as inclusion bodies. The protein expressed in P. pastoris, on the other hand, was expressed as a secreted, soluble protein. The P. pastoris-produced protein was superior to that produced in E. coli based on its ability to bind to red blood cells. Consistent with these observations, the antibodies generated against the Pichia-produced protein prevented the binding of recombinant EBA to red blood cells. These antibodies recognize EBA-175 present on merozoites as well as in sporozoites by immunofluorescence. Our results suggest that the Pichia-based EBA-F2 vaccine construct has further potential to be developed for clinical use.     

恶性疟原虫多表位疫苗M.RCAg-1在大肠杆菌中的表达和纯化

在大肠杆菌中表达和纯化恶性疟原虫随机重组多表位蛋白疫苗M.RCAg-1,将目的蛋白纯度最高化,回收率最大化。从工程菌BL21(DE3)-M.RCAg-1/pDS-eX提取重组质粒进行测序验证,用IPTG诱导表达,分别采用Ni亲和纯化,阴离子交换层析和凝胶过滤层析等不同组合方式的5种纯化方案进行纯化,根据最终纯度和回收率选择最佳纯化方案。Ni-NTA Agarose特异性好,一步纯化后M.RCAg-1纯度可达79.98%,后续的两步阴离子交换和分子筛纯化能显著提高M.RCAg-1的纯度,最终纯度可超过99%,回收率大于15%。试验确立了恶性疟原虫多表位蛋白疫苗M.RCAg-1在大肠杆菌中的表达和纯化方案,为下游放大生产和进一步研究M.RCAg-1的效果奠定了基础。     

Heterologous expression of proteins from Plasmodium falciparum: results from 1000 genes

As part of a structural genomics initiative, 1000 open reading frames from Plasmodium falciparum, the causative agent of the most deadly form of malaria, were tested in an E. coli protein expression system. Three hundred and thirty-seven of these targets were observed to express, although typically the protein was insoluble. Sixty-three of the targets provided soluble protein in yields ranging from 0.9 to 406.6 mg from one liter of rich media. Higher molecular weight, greater protein disorder (segmental analysis, SEG), more basic isoelectric point (pI), and a lack of homology to E. coli proteins were all highly and independently correlated with difficulties in expression. Surprisingly, codon usage and the percentage of adenosines and thymidines (%AT) did not appear to play a significant role. Of those proteins which expressed, high pI and a hypothetical annotation were both strongly and independently correlated with insolubility. The overwhelmingly important role of pI in both expression and solubility appears to be a surprising and fundamental issue in the heterologous expression of P. falciparum proteins in E. coli. Twelve targets which did not express in E. coli from the native gene sequence were codon-optimized through whole gene synthesis, resulting in the (insoluble) expression of three of these proteins. Seventeen targets which were expressed insolubly in E. coli were moved into a baculovirus/Sf-21 system, resulting in the soluble expression of one protein at a high level and six others at a low level. A variety of factors conspire to make the heterologous expression of P. falciparum proteins challenging, and these observations lay the groundwork for a rational approach to prioritizing and, ultimately, eliminating these impediments.     

恶性疟原虫复制蛋白PfRPA2的原核表达及多抗制备

目的克隆表达恶性疟原虫复制蛋白PfRPA2亚基,制备多抗,为该蛋白的功能研究奠定基础。方法PCR扩增目的基因片段,克隆到表达载体pGEX．KG中,构建PjRPA2／pGEX-KG原核表达载体,IPTG诱导表达,SDS—PAGE电泳分析表达产物．谷胱甘肽柱纯化蛋白,Western blot检测其抗原性,以纯化的GST-PfRPA2免疫小鼠,制备抗tyRPA2的多抗．间接ELISA法检测鼠血清效价,Western blot鉴定多抗特异性。结果成功构建了重组踯PA2／pGEX．KG原核表达质粒,并在大肠杆菌中以可济眭形式高效表达,纯化表达产物,制备抗邸PA2的鼠多抗,效价为10-7,Western blot证实此抗体可识别恶性疟原虫内与PJRPA2蛋白位置对应的特异性条带。结论恶性疟原虫复制蛋白PfRPA2亚基在大肠杆菌中获得可溶性高效表达,纯化表达产物能诱导小鼠生产能识别天然蛋白的特异性抗体。     

Two-step chromatographic purification of recombinant Plasmodium falciparum circumsporozoite protein from Escherichia coli

The Plasmodium falciparum circumsporozoite (PfCS) protein (aa 19-405) has been cloned and expressed in E. coli. The protein was purified in a two-step process that was rapid and reproducible. E. coli cells were grown to a high density before induction for 1 h. Cells were disrupted by high pressure microfluidization and the total bacterial protein solubilized in 6 M Gu-HCl. The protein was refolded while bound to Ni-NTA agarose by exchange of 6 M Gu-HCl for 8 M urea and then slow removal of the urea. The eluted protein was further purified on Q Sepharose Fast Flow using conditions developed to remove E. coli proteins and reduce endotoxin (to 10 EU/50 microg). Yield was 20 mg of PfCS protein from 10 g of wet cell paste. The final protein product bound to HepG2 liver cells in culture and inhibited the invasion of those cells by sporozoites in an ISI assay greater than 80% over control cultures when used at 10 microg/ml.