Rabies virus glycoprotein expression in Drosophila S2 cells. I. Functional recombinant protein in stable co-transfected cell line

Recombinant rabies virus glycoprotein (rRVGP) was expressed in Drosophila melanogaster Schneider 2 (S2) cells. The cDNA encoding the entire RVGP gene was cloned in an expression plasmid under the control of the constitutive actin promoter (Ac), which was co-transfected into S2 cells together with a hygromycin selection plasmid. Selected S2 cell populations (S2AcRVGP) had a decreased ability to grow and consume substrates, when compared to the non-transfected cells (S2). They were shown, by PCR, to express the RVGP gene and mRNA and, by immunoblotting, to synthesize the rRVGP in its expected molecular mass of 65 kDa. ELISA kinetic studies showed the rRVGP expression in cell lysates and supernatants attaining concentrations of 300 microg/L. By flow cytometry analysis, about 30% of the cells in the co-transfected populations were shown to express the rRVGP. Cell populations selected by limiting dilution expressed higher rRVGP yields. Mice immunized with rRVGP were shown to synthesize antibodies against rabies virus and be protected against experimental infection with rabies virus. The data presented here show that S2 cells can be suitable hosts for the rRVGP expression, allowing its synthesis in a high degree of physical and biological integrity.     

人呼吸道合胞病毒融合蛋白(F)片段原核表达、纯化和鉴定

目的克隆并表达人呼吸道合胞病毒(Human respiratory syncytial virus,HRSV)兰州株的融合蛋白(F)基因片段。方法利用PCR技术扩增HRSV兰州株的融合蛋白基因片段,克隆于原核表达载体pET-42b(+),转化大肠杆菌(Rosetta),经IPTG诱导表达,镍离子亲和层析柱纯化,SDS-PAGE和Western-blot分析重组蛋白的表达及其反应原性。结果 PCR扩增得到951 bp的DNA片段,重组质粒pET42b-F经酶切鉴定和测序分析,表明质粒构建正确。表达的重组蛋白的相对分子质量为68 710,表达的重组蛋白占总菌体蛋白的7%,纯化后蛋白纯度达80%。经Western-blot分析,重组蛋白与抗RSV的单抗呈专一性强阳性反应。结论成功构建了HRSV兰州株F基因片段原核表达载体,并在大肠杆菌Rosetta中获得了表达,表达的重组蛋白具有反应原性和特异性,为HRSV感染引起的疾病血清学诊断以及试剂盒的研发提供了材料。     

禽网状内皮组织增生病病毒gp90全长蛋白的原核表达、纯化及其免疫原性分析

摘要：【目的】原核表达免疫原性良好的禽网状内皮组织增生病病毒（( Reticuloendotheliosis virus, REV )gp90蛋白,并制备抗gp90蛋白高效价多克隆血清。【方法】利用PCR技术,以pMD18T-env为模板,扩增得到REV的gp90蛋白编码基因,将其克隆入表达载体pET-28a(+)中,将构建的原核表达质粒pET28-gp90,转化大肠杆菌（Escherichia coli ) BL21 (DE3) 感受态细胞,经异丙基硫代-β-D-半乳糖苷(IPTG)诱导后进行gp90蛋     

HBx-EGFP-TLM融合蛋白表达载体的构建、蛋白表达纯化及活性检测

乙型肝炎病毒X蛋白 (HBx) 具有广泛的转录激活作用,但是由于细胞类型和实验条件的差异,外源启动子介导的HBx瞬时表达水平常表现出不均一性,为其功能的研究带来困难。为了解决HBx研究过程中遇到的这些难题,利用PCR扩增获得HBx及含转导肽TLM的EGFP编码序列,经酶切后插入pGEX-4T-1原核表达载体,成功构建重组质粒pGEX-HBx-EGFP-TLM和pGEX-EGFP-TLM。重组质粒转化大肠杆菌BL21(DE3) 感受态细胞,融合蛋白经IPTG诱导表达,采用?KTATM Purifier 蛋白纯化系统纯化并进行SDS-PAGE和Western blotting分析,确定为目的蛋白。将纯化后的融合蛋白分别与AML12和SMMC-7721细胞共孵育,Western blotting和激光共聚焦显微镜检测证实TLM转导肽能够介导HBx-EGFP和EGFP进入细胞,同时进入细胞的HBx-EGFP-TLM能够发挥转录激活活性,为HBx功能的深入研究奠定了基础。     

Expression and purification of the matrix protein of Nipah virus in baculovirus insect cell system

Nipah virus (NiV) causes fatal respiratory illness and encephalitis in humans and animals. The matrix (M) protein of NiV plays an important role in the viral assembly and budding process. Thus, an access to the NiV M protein is vital to the design of viral antigens as diagnostic reagents. In this study, recombinant DNA technology was successfully adopted in the cloning and expression of NiV M protein. A recombinant expression cassette (baculovirus expression vector) was used to encode an N‐terminally His‐tagged NiV M protein in insect cells. A time‐course study demonstrated that the highest yield of recombinant M protein (400–500 μg) was expressed from infected cells 3 days after infection. A single‐step purification method based on metal ion affinity chromatography was established to purify the NiV M protein, which successfully yielded a purity level of 95.67% and a purification factor of 3.39. The Western blotting and enzyme‐linked immunosorbent assay (ELISA) showed that the purified recombinant M protein (48 kDa) was antigenic and reacted strongly with the serum of a NiV infected pig. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:171–177, 2016     

Construction and identification of the helper plasmids for reverse genetic system of rabies virus street strain

To obtain the helper plasmids for a reverse genetics system of rabies virus, the cDNAs of the complete open reading frames of the N, P, G, and L genes of rabies street virus stain HN10 were each cloned into expression vector pVAX1, These four plasmids were identified by restriction enzyme digestion and gene sequencing. The plasmid encoding the N protein was selected to determine the expression effect of these plasmids in NA cells. The results showed that the helper plasmids for a reverse genetics system of rabies street virus strain HN10 had been successfully constructed.     

Molecular characterization of viral G gene in emerging and Re-emerging areas of rabies in China, 2007 to 2011

In recent years (2007 to 2011),although the overall number of rabies cases in China has decreased,there is evidence of emerging or re-emerging cases in regions without previous rabies cases or with low...     

Intracellular behavior of rabies virus matrix protein (M) is determined by the viral glycoprotein (G).

To investigate the nature and intracellular behavior of the matrix (M) protein of an avirulent strain (HEP-Flury) of rabies virus, we cloned and sequenced the cDNA of the protein. Using expression vectors pZIP-NeoSV(X)1 and pCDM8, the cDNA was transfected to animal cells (BHK-21 and COS-7) with or without coexpression of viral glycoprotein (G). When M protein alone was expressed in the cells, it displayed homogeneous distribution in the whole cell including the nucleus. In contrast, coexpression with G protein resulted in the abolishment of nuclear distribution of M antigen, and both of the antigens displayed a colocalized distribution in the cell, especially at the cellular membrane as seen in the virus-infected cells, while the distribution of G antigen was not affected by coexpressed M antigen. Immunoprecipitation studies revealed that M protein was coprecipitated with G protein by anti-G antibody, and vice versa, although cross-linking with dithiobis(succinimidyl propionate) was necessary for coprecipitation because of their easier dissociation in the presence of sodium deoxycholate. These results suggest that M protein intimately associates with G protein, which may affect or regulate the behavior (e.g., intracellular localization) of M protein. Studies with deletion mutants of M protein indicate that an internal region around the amino acids from 115 to 151 is essential for the M protein to preserve its binding ability to G protein.     

链球菌蛋白G的构建、重组表达及鉴定

化学合成链球茵蛋白G的C3D基因片段,通过分子生物学的方法对蛋白G（proteinG）的C3片段进行PCR扩增,拼接形成含有两个和三个重复C3片段的重组链球茵蛋白G,C3片段间以链接区D连接,即形成C3DC3和C3DC3DC3的形式,进而克隆到质粒pET21中,在大肠杆菌BL21（DE3）中表达。重组表达的蛋白经过DEAE—Sepharose和IgG—Sepharose纯化,得到纯化的重组蛋白。采用非竞争性酶免疫法对重组蛋白与不同来源IgG的结合常数进行测定,实验结果显示两种重组链球茵蛋白G均可有效地与小鼠、兔及山羊等多种不同来源抗体特异性结合。这些实验结果为下一步研究奠定了基础。     

登革病毒衣壳蛋白在大肠杆菌中的表达及其自组装活性的研究

采用高保真RT-PCR自登革2型病毒43株基因组RNA中扩增全长C基因及缺失羧基端Cv片段,分别构建可表达C及Cv的重组质粒pLEX—C和pLEX—Cv,转化E．coliGI724后用色氨酸诱导表达。经SDS—PAGE分析,表达的C及Cv蛋白相对分子质量分别约为12000和10000,分别约占菌体蛋白总量的19％和13％。Western印迹检测表明重组表达的C蛋白均可被特异识别登革病毒衣壳蛋白的单克隆抗体特异识别。表达的蛋白经过硫酸铵沉淀和蔗糖密度梯度离心后,通过琼脂糖凝胶电泳和负染电镜均未能检测到衣壳样颗粒的存在,说明登革病毒衣壳蛋白可能不具体外自组装活性。     

Expression and purification of human respiratory syncytial virus recombinant fusion protein

The Human Respiratory Syncytial Virus (HRSV) fusion protein (F) was expressed in Escherichia coli BL21A using the pET28a vector at 37 °C. The protein was purified from the soluble fraction using affinity resin. The structural quality of the recombinant fusion protein and the estimation of its secondary structure were obtained by circular dichroism. Structural models of the fusion protein presented 46% of the helices in agreement with the spectra by circular dichroism analysis. There are only few studies that succeeded in expressing the HRSV fusion protein in bacteria. This is a report on human fusion protein expression in E. coli and structure analysis, representing a step forward in the development of fusion protein F inhibitors and the production of antibodies.     

庚型肝炎病毒全长基因在体外的表达

利用第二军医大学微生物学教研室克隆的庚型肝炎病毒 (HGV)全长基因组 (HGVqz) ,构建由不同启动子调控的HGV表达载体 ,将 2种表达载体及HGV全长基因片段进行体外表达 ,探讨此HGV全长基因克隆的功能。利用脂质体将HGV全长基因cDNA以及表达载体转入Changliver或NIH 3T3细胞进行瞬时表达 ,分别提取转染72h后转染细胞的RNA及蛋白质进行RT PCR及Westernblotting ,以检测HGV基因的表达。RT PCR及Westernblotting结果表明 ,HGV全长基因cDNA以及 2种表达载体均可以在体外培养的细胞内表达 ,其表达产物为HGV前体蛋白 ,分子量约为 310ku。第二军医大学微生物学教研室克隆的HGV全长基因具有正确的开读框架和可表达性 ,能表达HGV前体蛋白 ,但在体外培养细胞内不能完成前体蛋白的剪切     

Expression and purification of a recombinant Fip-fve protein from Flammulina velutipes in baculovirus-infected insect cells

Aims: To develop an efficient and facile expression system supply of high purity and stable activity of rFip-fve for oral administration, medicinal study and applications. Methods and Results: A recombinant virus that contained the chimera gene, encoding a bombyxin signal peptide sequence fused to a Fip-fve-6His sequence, was constructed. The rFip-fve was purified from the supernatant of the infected Sf21 cells using a nickel-chelated affinity column, and was verified by Western blot and MALDI-MS (matrix-assisted laser desorption ionization mass spectrometry) analyses. Results showed that a glycosylated mature rFip-fve was produced and secreted into the infected cell supernatant. The immunomodulatory activity of rFip-fve was evaluated by measuring the amount of interleukin-2 released from murine splenocytes. Conclusions: A reliable scheme to express and purify active rFip-fve in a baculovirus/insect cell system for medicinal applications and genetic study is a feasible means of solving potential problems related to the production and activity of rFip-fve protein. Significance and Impact of the Study: The rFip-fve expressed in insect cells was processed and modified in a manner more similar to that of its native counterpart than that in bacterial cells. Therefore, the potential applications of rFip-fve that is generated in Sf21 cells can be more effectively evaluated that produced in Escherichia coli.     

小量快速浓缩病毒蛋白的研究

采用甘油透析浓缩及ＰＥＧ－６０００沉淀相结合的方法,对细胞病毒培养液进行处理,获得了较为纯化的病毒蛋白。该方法适用于病毒蛋白小量快速分析。纯化的病毒蛋白回收率约为５３μｇ／ｍｌ。     

单纯疱疹病毒II型糖蛋白G主要抗原表位的表达和抗原性检测*

利用PCR拼接技术,合成含单纯疱疹病毒II型糖蛋白G(gG2)抗原表位（氨基酸序列第561～578位）的片段,并进一步利用基因工程技术获得该表位的双拷贝片段,克隆入pET-KDO表达载体进行原核表达。经IPTG诱导后,高效表达出分子量大小约为39,000D的融合蛋白,经Western-blot检测具有良好的抗原性。表达的融合蛋白经凝血酶切割和亲和层析纯化,得到双拷贝gG2（561～578aa）目的蛋白,经ELISA检测具有良好的灵敏度和特异性。该重组抗原的构建和表达可用于HSV-2特异性血清学诊断的研究。     

Production and purification of recombinant DP1B silk-like protein in plants

Spider dragline silk of Nephila clavipes consists of two highly repetitive proteins, spidroin 1 and spidroin 2. To develop a plant platform for production of recombinant silk-like protein, two plant-optimized DP1B genes were synthesized to mimic spidroin 1. DP1B-8P encodes for a 64 kD DP1B silk-like protein and DP1B-16P for a 127 kD DP1B silk-like protein. Both genes have been introduced into Arabidopsis for leaf-based production driven by the 35S promoter and for seed-specific production driven by the -conglycinin subunit promoter, respectively. They have also been expressed in somatic soybean embryos under the control of the -conglycinin subunit promoter. The results demonstrate the synthesis and accumulation of DP1B silk-like protein in leaves and seeds of Arabidopsis, as well as in somatic soybean embryos. They suggest that seeds are the more preferred tissue for DP1B production since they offer higher production yield and quality. In addition, a simplified protocol for purifying DP1B from plant tissue is discussed.     

Expression,purification, and characterization of recombinant human H-chain ferritin

Based on their nanocage architectures, ferritins show their potential applications in medical imaging and therapeutic delivery systems. However, the recombinant human H-chain ferritin (rHF) is prone to form inclusion bodies in Escherichia coli. In our study, the cDNA of rHF was cloned into plasmid pET28a under the control of a T7 promoter. Molecular chaperones, including GroES, GroEL, and trigger factor, were coexpressed with rHF to facilitate its correct folding. The results showed that the solubility of rHF was increased more than threefold with the help of molecular chaperones. Taking advantages of its N-terminal His-tag, rHF was then purified with Ni-affinity chromatography. With a yield of 15?mg/L from bacterial culture, the purified rHF was analyzed by circular dichroism spectrometry for its secondary structure. Moreover, the rHF nanocages were characterized by transmission electron microscopy and dynamic light scattering. Our results indicate that rHF is able to self-assemble into nanocages with a narrow size distribution.     

Novel and economical purification of recombinant proteins: intein-mediated protein purification using in vivo polyhydroxybutyrate (PHB) matrix association

This work combines two well-established technologies to generate a breakthrough in protein production and purification. The first is the production of polyhydroxybutyrate (PHB) granules in engineered strains of Escherichia coli. The second is a recently developed group of self-cleaving affinity tags based on protein splicing elements known as inteins. By combining these technologies with a PHB-specific binding protein, a self-contained protein expression and purification system has been developed. In this system, the PHB-binding protein effectively acts as an affinity tag for desired product proteins. The tagged product proteins are expressed in E. coli strains that also produce intracellular PHB granules, where they bind to the granules via the PHB-binding tag. The granules and attached proteins can then be easily recovered following cell lysis by simple mechanical means. Once purified, the product protein is self-cleaved from the granules and released into solution in a substantially purified form. This system has been successfully used at laboratory scale to purify several active test proteins at reasonable yield. By allowing the bacterial cells to effectively produce both the affinity resin and tagged target protein, the cost associated with the purification of recombinant proteins could be greatly reduced. It is expected that this combination of improved economics and simplicity will constitute a significant breakthrough in both large-scale production of purified proteins and enzymes and high-throughput proteomics studies of peptide libraries.