定向进化人α型干扰素基因家族的研究

应用DNA改组(DNAshuffling)技术重组了12种人α型干扰素基因,并结合噬菌体表面呈现(phagedisplay)技术构建了噬菌体干扰素改组文库,采用简便的、功能性的定向竞争筛选方法,获得了比活达1 0×109IU/mg的新型α型基因工程复合干扰素,是目前国际上已投产的α2型干扰素的5倍,具有生产应用前景,上述策略也为其它细胞因子或酶的改造提供了借鉴方法。     

高效构建卵清白蛋白scFv噬菌体文库及其筛选

目的:建立一种高效噬菌体文库构建方法,获得抗鸡卵清蛋白(ovalbumin,OVA)的单链抗体(scFv)噬菌体展示文库,筛选鉴定获得OVA单链抗体。方法:用OVA蛋白免疫Balb/C小鼠,选取血清抗体效价高的小鼠提取脾脏RNA,利用RT-PCR方法扩增获得小鼠重链和小鼠轻链基因。通过无缝连接酶一步将小鼠重链基因、轻链基因和linker DNA连接起来,插入噬菌体表达载体中,构建OVA scFv噬菌体展示文库。测定文库容量,对文库进行富集筛选,ELISA鉴定阳性克隆,测序后构建真核表达载体,转入Expi-CHO悬浮细胞进行真核表达,利用Western blot进行鉴定。结果:成功获得库容量为1. 2×10~7cfu的OVA scFv噬菌体展示文库,并从中筛选出8个阳性克隆,选取效价最高的2号克隆,在Expi-CHO悬浮细胞中表达获得可溶性抗体。结论:建立了一种高效构建scFv噬菌体文库的方法,筛选获得高结合活性的OVA单链抗体,并成功进行了真核表达,为OVA ELISA检测试剂盒的研制奠定了基础。     

BLyS受体TACI、BCMA与人IgG1 Fc融合蛋白在哺乳动物细胞中的表达与鉴定

从人肝脏和肾脏cDNA文库中扩增了人IgG1Fc与B淋巴细胞刺激因子 (BLyS)的受体TACI及BCMA的胞外编码区 ,构建了TACI Fc及BCMA Fc融合表达质粒pSec1 Fc TACI与 pSec1 Fc BCMA ,并使用电穿孔法转染COS 7细胞 ,从 1L无血清培养上清中可纯化得到分泌表达的TACI Fc与BCMA Fc融合蛋白约 2mg。为获得TACI Fc与BCMA Fc的稳定来源 ,构建了TACI Fc与BCMA Fc的CHO稳定表达细胞株。免疫沉淀和ELISA结果显示 ,TACI Fc及BCMA Fc能特异性地结合其配体BLyS而不与BLyS同家族的TNF结合。TACI Fc及BCMA Fc可阻断BLyS对体外培养的小鼠B淋巴细胞的促增殖作用     

B3HM细胞免疫小鼠脾细胞scFv噬菌体展示文库的构建及表达

目的: 利用噬菌体展示技术构建B3HM细胞免疫小鼠的脾细胞表达scFv文库。方法: 用人骨髓细胞系B3HM细胞免疫小鼠,取其脾细胞采用RT-PCR方法扩增VH 和Vk基因并克隆入噬菌体展示表达载体,构建scFv文库,测定文库的库容量,BstNI酶切单克隆分析文库的多样性,对文库进行富集检测,鉴定单克隆噬菌体与B3HM细胞结合反应。结果:文库的库容为5×106cfu,单克隆的BstNI酶切图谱显示多样性,单克隆噬菌体抗体与B3HM细胞呈阳性反应。结论:噬菌体展示文库的成功构建为寻找新的致白血病相关基因,阐明白血病发病机理奠定了基础。     

BLyS对噬菌体随机12肽库的筛选

用B淋巴细胞刺激因子（BLyS）对噬菌体随机12肽库进行亲和淘洗,3轮筛选后阳性噬菌体得到富集。用ELISA鉴定噬菌体克隆,多个阳性克隆测序后得到了同一个小肽序列(RHKIQLRQNIIT)。将该小肽与GST融合,在大肠杆菌中进行表达及纯化,ELISA实验进一步验证了其具有与BLyS特异结合的活性。该小肽有可能成为其天然受体的拮抗剂。      

噬菌体展示HIV-1 Tat38-61碱性区51和55位随机突变体文库的构建

为了构建噬菌体展示Tat38-61(51N/55N) 碱性区突变体文库,进一步研究HIV-1 Tat38-61表位的分子进化筛选,采用含随机核苷酸序列的引物,通过Overlap PCR的方法获得51和55位氨基酸随机突变的全长Tat编码序列,再以此为模板PCR扩增出两端含有Xba I识别序列的Tat38-61突变体片段HIV-1 Tat38-61(51N/55N),克隆至噬菌体展示载体pCANTAB5S上,转化大肠杆菌TG1,经M13K07辅助噬菌体拯救,构建噬菌体展示Tat38-61(51N/55N) 碱性区突变体文库。结果显示文库的库容量为5.0×106,滴度为2.65×1012 TU/mL,阳性克隆率为56.50％;序列分析显示文库中51、55位核苷酸与氨基酸均呈随机性分布,达到了对文库进行分子进化筛选的要求,为获得可用作疫苗候选物的新型Tat突变体奠定基础。     

噬菌体cDNA文库筛选方法的改良

cDNA文库的构建和简便、快速的筛选是获得全长基因的重要途径,基于PCR的筛库方法具有快捷、灵敏的特点。研究改进了基于PCR的噬菌体cDNA文库筛选方法,用液体分装的方法,替代了文库筛选的关键步骤——涂板分区,省去了噬菌体文库铺平板、浸染、培养、划块洗脱的操作过程,使筛库的工作量减少,进一步提高了筛选速度和获得阳性克隆的效率。     

双峰驼源天然噬菌体纳米抗体展示库的构建及抗GDH纳米抗体筛选

目的:构建噬菌体天然纳米抗体展示库,以期用于筛选不同抗原分子的纳米抗体筛选平台,并用艰难梭菌谷氨酸脱氢酶(GDH)抗原筛选靶向GDH的纳米抗体,对所构建的噬菌体天然纳米抗体展示库进行验证。方法:采用Oligo DT提取双峰骆驼脾脏总RNA进行反转录,通过巢氏PCR获取全套重链可变区基因,将其构建到噬菌粒pCANTAB5E载体,经多次电转化至E. coil TG1构建初级噬菌体抗体库,经辅助噬菌体拯救后构成噬菌体展示库,并对噬菌体展示库的库容及多样性进行分析和鉴定。同时以GDH为靶向抗原对文库进行淘筛,计算淘筛回收率,并对第三轮淘筛后平板的单克隆进行ELISA鉴定。结果:构建的天然噬菌体纳米抗体库的插入率为95%左右,随机挑取的9个克隆氨基酸同源性为66. 17%,经MEGA分析后具有较好的多样性,同时经辅助噬菌体拯救后,得到的噬菌体展示库滴度为4×10~(12)CFU/ml。在三轮淘筛过程中,回收率逐步升高,噬菌体得到了有效的富集,同时对阳性克隆进行测序及分析,最终得到2条抗GDH纳米抗体序列。结论:成功构建了双峰驼源天然噬菌体纳米抗体展示文库且多样性良好,为后续筛选其他的靶向抗原奠定了基础,同时筛选获得两条抗GDH纳米抗体序列,为制备艰难梭菌谷氨酸脱氢酶诊断抗体提供技术支撑。     

莱茵衣藻基因组文库的构建

以莱菌衣藻CC-849为材料,提取基因组DNA,利用BamHⅠ和BglⅡ对基因组DNA进行酶解,获得了可用于构建基因组文库的6-12 kb的基因组片段,并浓缩至200 ng/μL。该片段与λDNA载体连接,经噬菌体蛋白包装、侵染大肠杆菌XL1-blue后,获得了莱菌衣藻基因组文库。该文库的滴度为2.12×10~5 pfu/mL,共有转化子4.26×10~4个,插入片段的平均长度约为9kb,扩增后基因组文库滴度为9.5×10~6 pfu/mL。     

人尿道上皮细胞T7噬菌体展示cDNA文库的构建与鉴定

[目的]构建人尿道上皮细胞(SV-HUC-1)T7噬菌体展示c DNA文库,为研究人尿道上皮细胞与生殖道感染病原体的相互作用奠定基础。[方法]用Trizol试剂提取SV-HUC-1细胞总RNA,分离纯化出mRNA,经反转录合成得到其双链c DNA,在双链c DNA末端加上定向的EcoRⅠ/HindⅢ黏性末端,然后收集并纯化200bp以上的双链c DNA片段,连接于T7噬菌体载体,经体外包装后转入BLT5403宿主菌,T7噬菌体展示c DNA文库构建成功。[结果]将文库扩增后,用噬斑试验检测其库容,结果为1.2×106pfu/cm3。用PCR鉴定随机挑取的噬菌斑,计算其重组率达93.75%,且插入片段都大于200bp。[结论]成功构建了SV-HUC-1细胞T7噬菌体展示c DNA文库,为下一步研究泌尿生殖道感染病原体与人尿道上皮细胞的相互作用奠定了前期实验基础。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.