抗肉毒毒素A人源单链抗体在酵母细胞中的分泌表达*

将特异肉毒抗毒素基因克隆入载体pPIC9k,G418抗性加压筛选阳性整合克隆,在毕赤酵母细胞GS115中进行分泌表达。获得了稳定分泌表达ScFv的工程菌,SDS-PAGE分析可见,目的蛋白分子量约为26kD,通过放大体积来探索重组抗毒素的诱导表达条件及纯化工艺,结果发现,1%甲醇诱导后72～84h,目的蛋白的表达达到高峰,占酵母培养上清中总蛋白的15%以上,经两步层析纯化,目的蛋白纯度可达95%。竞争活性测定结果表明,重组抗毒素在体外具有良好的活性,可竞争肉毒抗毒素马血清与毒素的特异结合。     

破伤风毒素保护性抗原在毕氏酵母中的分泌表达

采用PCR方法．从C.Tetani 64008菌株中扩增大小为1353bp的破伤风毒素与靶细胞起结合作用的重链C端基因(Tetc),直接连接pGEM-T栽体进行测序,并以pPIC9K为表达栽体构建重组表达质粒,经线形化的重组质粒电转化毕氏酵母细胞GS1l5和KM71．甲醇诱导获得了分泌表达,表达产物存在于培养上清中,占分泌蛋白的10％,通过免疫印迹可以检测到重组表达产物,活性测定表明,重组蛋白具特异结合活性,本研究通过实现破伤风毒素保护性抗原在酵母系统中的分泌表达、研究其影响因素,为其它细菌毒素蛋白高效可溶性表达,及进一步抗原片段介导保护性免疫研究及抗毒素制备奠定了基础。     

钙网蛋白-N58在毕赤酵母中的表达及活性分析

目的：利用毕赤酵母表达系统表达Calreticulin-N58蛋白。方法：利用重叠延伸PCR方法合成Calreticulin-N58基因,构建成分泌型的重组表达载体pPIC9K-CRT-N58。该重组表达载体经SacI线性化后,电激转化入毕赤酵母GSll5,经MD板和不同浓度G418筛选得到多拷贝重组菌株。经甲醇诱导表达目的蛋白,SDS-PAGE分析重组蛋白的表达情况,在鸡胚中进行活性分析。结果：重组质粒pPIC9K-CRT-N58在毕赤酵母中经甲醇诱导能分泌表达CRT-N58蛋白,摇瓶表达量大约为60mg／L,纯化的目的蛋白有显著的血管生成抑制作用。结论：实验成功地在毕赤酵母表达系统中实现了Calreticulin-N58的分泌表达。为Calreticulin-N58蛋白的进一步药用研究奠定了基础。     

A型肉毒毒素轻链的原核表达、纯化及活性鉴定

目的:在大肠杆菌中表达、纯化A型肉毒毒素轻链(Bo NT/A LC),研究其生物学活性。方法:根据Gen Bank中报道的Bo NT/A LC基因序列设计特异引物,从肉毒梭菌中扩增Bo NT/A LC基因片段,构建重组大肠杆菌p ET-32a Bo NT/A LC/BL21(DE3)Rosetta,IPTG诱导目的蛋白高效表达,表达产物经Ni螯合亲和层析纯化,SDS-PAGE鉴定目的蛋白,并利用相应底物对纯化产物进行生物活性分析和酶活动力学测定。结果与结论:构建了重组大肠杆菌p ET-32a Bo NT/A LC/BL21(DE3)Rosetta,原核表达获得高水平可溶性重组Bo NT/A LC,纯化得到纯度较高的蛋白质,重组Bo NT/A LC的酶活略高于A型肉毒毒素全毒素,可作为试剂用于Bo NT/A LC抑制剂高通量体外检测方法研究。     

人精氨酸酶在毕赤酵母的高效表达、纯化和活性研究

目的：人精氨酸酶（Arginase, Arg）的基因arg在毕赤酵母高效分泌表达,建立相应纯化工艺路线,研究重组人精氨酸酶的活性。方法：将人精氨酸酶基因arg按正确的阅读框架插入到毕赤酵母表达载体pPIC9α信号肽基因后,构建得到重组毕赤酵母表达质粒。转化毕赤酵母GS115筛选高表达菌株。结果：成功构建了酵母表达载体pPIC-Arg,转化毕赤酵母GS115后筛选到分泌表达目的蛋白Arg的菌株,目标蛋白可以分泌到培养基中。经过膜过滤和凝胶过滤层析对培养基上清进行纯化,即可获得纯度达到95%的活性产物。活性测定表明,纯化的Arg比活性为310 IU/mg。结论：成功构建了Arg的毕赤酵母高效表达菌种,建立了目标物质的分离纯化工艺。     

A型肉毒毒素Hc结构域在大肠杆菌中的高水平表达及免疫原性

对A型肉毒毒素受体结合区Hc基因的全序列进行优化和人工合成,获得了全长1287bp,编码429aa的Hc基因。以pTIG-Trx为原核表达载体,实现了Hc在大肠杆菌中的高效可溶性表达及纯化,该表达水平可占可溶性全菌总蛋白的36%～53%,经一步亲和层析纯化可获得电泳级纯度的目的蛋白,在常规培养条件下,产量达到30mg/L以上。然后,纯化的重组蛋白Hc免疫小鼠后能够诱导产生高滴度特异性的抗体,也能诱导产生特异性的细胞免疫应答反应。小鼠体内A型肉毒毒素中和试验结果表明免疫组小鼠血清中含高滴度的体内中和抗体。结果表明,利用本实验的原核表达系统不仅能够高水平可溶性地表达A型肉毒毒素受体结合区Hc,而且重组Hc具有良好的免疫原性,可以用于制备治疗性抗毒素和作为亚单位候选疫苗用于预防A型肉毒毒素中毒。     

IEF纯化重组A型肉毒毒素保护性抗原

在大肠杆菌中高效表达的重组A型肉毒毒素保护性抗原（rBoNTaH468),是以包涵体形式存在,将表达菌株发酵后,裂解菌体,制备包涵体,溶解后的包涵体溶液经样品处理,通过等地电聚焦制备型电泳纯化,纯化的重组A型肉毒毒素保护性抗原（rBoNTaH468)纯度高于90%,产量及回收率高,纯化的重组表达产物酶联检测具有结合活性,这为下一步A型肉毒毒素抗毒素的研制打下基础。     

乙酰氨基半乳糖转移酶14(GALNT14)在毕赤酵母中的表达纯化及活性鉴定

将GALNT14全长编码区克隆到分泌型酵母表达载体pPIC9K中,构建重组载体pPIC9K-T14,经电转至毕赤酵母GS115中表达,使用G418筛选高表达重组菌,并对诱导条件进行优化,表达产物使用SDS-PAGE分析、Western blot鉴定、Sephadex G-100纯化、最后经HPLC检测活性。结果显示,在提供更好的供氧量条件下,用0.75％甲醇诱导可提高目的蛋白的表达量而降低杂蛋白的表达。培养上清液经SDS-PAGE检测显示目的蛋白分子量约64 kDa;Western blot结果显示在相应分子量处有一条特异性条带;利用Sephadex G-100成功分离纯化了目的蛋白;活性测定结果显示所获得的目的蛋白具有催化活性,为深入研究GALNT14的结构与功能奠定了基础。     

重组人GALNT3-sol蛋白在毕赤酵母中的高效表达和活性鉴定

目的:为了获得有催化活性的人乙酰半乳糖胺转移酶3(GALNT3),构建了GALNT3可溶性区域(GALNT3-sol)的真核分泌表达载体,在巴斯德毕赤酵母中表达并纯化GALNT3-sol蛋白,体外检测其转糖基活性。方法:以构建好的pET15b/GALNT3-sol为模板进行PCR,扩增编码人GALNT3-sol的cDNA片段(1 755 bp),将其克隆至真核表达载体pPIC9K,载体线性化后采用电击法转化毕赤酵母GS115。通过MD平板和G418平板筛选出阳性高拷贝重组菌株。阳性菌株经过甲醇诱导表达人GALNT3-sol重组蛋白,表达上清进行Ni-NAT分离纯化。分别采用SDS-PAGE和Western blot鉴定纯化的重组蛋白,并使用HPLC和MALDI-TOF/MS分析其转糖基化反应的活性。结果:成功构建了能够分泌表达GALNT3-sol的毕赤酵母菌株。阳性表达菌株在BMMY培养基(pH 6.0)中20℃培养,经0.5%甲醇诱导表达96 h,摇瓶表达量可达5mg/L。SDS-PAGE和Western blot结果显示表达重组蛋白为糖基化形式。活性检测显示表达的重组蛋白具有转糖基活性。结论:成功获得可以高效分泌表达具有活性的人GALNT3-sol蛋白的毕赤酵母菌株,为进一步研究人GALNT3的性质及其应用提供了基础。     

血小板衍生生长因子BB亚型在毕赤酵母中的表达及纯化

目的:用毕赤酵母表达系统表达重组人血小板衍生生长因子BB亚型(PDGF-BB)。方法:采用PT-PCR从人早幼粒白血病细胞系HL-60细胞中获得目的基因,克隆到表达载体p MEX9K中,质粒线性化后转化酵母表达菌株GS115,筛选后的酵母表达菌株经BMGY/BMMY培养基体系诱导表达后,通过疏水作用、离子交换、凝胶过滤纯化获得目的蛋白,采用SDS-PAGE、Western印迹、N端氨基酸序列和MTT增殖活性测定等方法检测目的蛋白性质及生物活性。结果:重组人PDGF-BB为分泌表达,表达量大于100 mg/L;经三步纯化,获得纯度高于95%且具有较高活性(5.0×105IU/mg)的目标蛋白。结论:利用毕赤酵母表达系统表达重组人PDGF-BB,表达产量高,成本低,工艺简单,易于工业化放大,有良好的市场前景。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.