从噬菌体抗体库中淘选血纤维蛋白特异的单链抗体

为构建小鼠噬菌体抗体库 ,以获得对人血纤维蛋白特异的抗体 ,由小鼠脾脏提取 m RNA,经反转录 PCR扩增出抗体重链、轻链可变区基因片段 ,将二者和一段编码十五肽 (Gly4 Ser) 3的 DNA接头借助重组 PCR组装成为单链抗体 (single- chain antibody,Sc Ab)基因 .将单链抗体基因插入噬菌体展示载体 p CANTAB- 5E,通过电击法转化大肠杆菌 TG1细胞 ,用辅助噬菌体 M1 3K0 7超感染 ,构建了库容量在 1 0 8以上的噬菌体单链抗体库 .利用亲和选择方法 (淘选 ) ,从噬菌体抗体库中选得血纤维蛋白特异的单链抗体 .模拟抗体成熟过程 ,用 DNA改组 (DNA shuffling)技术使抗体基因重新组合 ,构建新的改组抗体库 ,并从中选择到提高了亲和力的噬菌体单链抗体 .抗体基因在大肠杆菌中表达 ,表达蛋白经 Sephadex G- 75柱层析分离 ,得到初步纯化的单链抗体蛋白 .     

噬菌体抗体库的构建及抗乳腺癌细胞单链抗体的筛选

构建抗人乳腺癌细胞MCF 7的噬菌体单链抗体库 ,从中筛选MCF 7细胞特异性单链抗体。用MCF-7细胞免疫BALB C小鼠 ,取脾脏 ,提取总RNA ,用RT-PCR技术扩增小鼠抗体重链 (V_H)和轻链 (V_L)可变区基因 ,经重叠PCR(SOE-PCR) ,在体外将V_H和V_{L连接成单链抗体 (scFv)基因 ,并克隆到噬菌粒载体pCANTAB5E中 ,电转化至大肠杆菌TG1,经辅助噬菌体超感染 ,构建噬菌体单链抗体库。从该抗体库中筛选特异性识别MCF-7细胞的噬菌体单链抗体 ,将表面展示单链抗体的单克隆噬菌体转化大肠杆菌TOP10进行可溶性表达。成功地构建了库容为12×10⁶ 的抗MCF-7乳腺癌细胞的单链抗体库 ,初步筛选到了与MCF 7细胞特异性结合的scFv,Westernblot检测表明 ,在大肠杆菌TOP10中实现了单链抗体可溶性表达}     

鼠源E型肉毒毒素免疫噬菌体单链抗体库的构建及筛选

目的:构建鼠源E型肉毒毒素(BoNT/E)免疫噬菌体单链抗体库,筛选BoNT/E特异性抗体。方法:从E型肉毒类毒素免疫小鼠的脾细胞中提取总RNA,反转录成cDNA,分别扩增出小鼠重链可变区基因和轻链可变区基因;通过重叠延伸PCR将重链可变区基因和轻链可变区基因组装成scFv基因,重组于噬粒pS100中,电转化大肠杆菌TG_1,合并所有克隆成初级库;随机挑取克隆进行核苷酸序列测定,对初级库序列多样性进行分析;在辅助噬菌体M_(13)K_(07)的拯救下,构建成scFv噬菌体抗体库;用纯化的BoNT/E对鼠源BoNT/E免疫噬菌体单链抗体库进行3轮富集筛选,制备单克隆的噬菌体抗体颗粒进行酶联免疫吸附试验,阳性克隆进行核苷酸序列测定。结果:鼠源BoNT/E免疫噬菌体单链抗体库的库容为7.09×10~7,随机挑取的20个克隆序列各不相同,序列正确率为85%,基本覆盖了IgHV、IgKV、IgLV的优势家族;纯化的BoNT/E作为抗原通过3轮筛选,噬菌体抗体富集了66倍,第3轮筛选后随机挑取90个克隆制备噬菌体抗体颗粒,酶联免疫吸附试验分析有88个呈现阳性反应,序列比对得到了24个不同序列的BoNT/E特异性抗体。结论:构建了库容量达7.09×10~7的鼠源BoNT/E免疫噬菌体单链抗体库,筛选得到了24个不同序列的BoNT/E特异性抗体。     

抗整合素β3胞外区噬菌体抗体库的构建及筛选

用RT-PCR的方法从人胶质瘤BT-325细胞中扩增人整合素β3胞外区,并克隆到载体pET-24a中构建表达载体.表达的人整合素β3胞外区经变性、复性和纯化后免疫BALB/c小鼠,提取脾脏总RNA,用RT-PCR技术扩增小鼠抗体重链(VH)和轻链(VL)可变区基因,经重叠PCR(SOE-PCR)将VH和VL连接成单链抗体(scFv)基因,并克隆到噬菌粒载体pCANTAB5E中,电转化至大肠杆菌TGl,经辅助噬菌体M13KO7超感染,构建噬菌体单链抗体库.通过淘选从该抗体库中筛选特异性识别人整合素β3胞外区的噬菌体单链抗体.结果表明,成功构建了库容为2.6×106的抗人整合素β3胞外区的单链抗体库,初步筛选到了与人整合素β3胞外区特异性结合的单链抗体.     

噬菌体抗体库技术

噬菌体抗体库技术用ＰＣＲ扩增出抗体的全套可变区基因,通过噬菌体表面表达技术,把Ｆａｂ段或单链抗体表达在噬菌体表面,经过“吸附－洗脱－扩增”过程筛选并富集特异性抗体。     

鼠源抗B型肉毒毒素单链抗体噬菌体文库的构建筛选及抗体免疫学活性的初步研究

B型肉毒毒素重链C-端片段(BoNTB/Hc)经金属螯和层析法纯化后免疫Balb/c小鼠,从其脾淋巴细胞中提取总RNA,反转录成cDNA,用抗体可变区混合引物进行全套抗体重、轻链可变区基因的扩增,体外随机装配成单链抗体(scFv)。将其克隆至pCANTAB5E中,构建单链抗体噬菌体抗体库。结果表明经过4轮"吸附-洗脱-扩增"的富集过程,筛选获得高亲和力的克隆。序列测定符合抗体可变区结构特点。     

人源抗汉坦病毒核衣壳蛋白T7噬菌体抗体库的构建

构建人源T7噬菌体单链抗体(scFv)库筛选抗汉坦病毒核衣壳蛋白(NP)抗体。从肾综合征出血热恢复期患者外周血淋巴细胞中提取总RNA,反转录合成cDNA第一条链,PCR分别扩增抗体重链可变区基因(VH)和轻链可变区基因(VL),经重叠延伸拼接(SOE)PCR组成scFv基因,并将其与T7噬菌体载体的2个臂相连接。体外包装后,在宿主菌BLT5403中,扩增重组噬菌体抗体库。以基因工程表达NP进行4轮“吸附-洗脱-扩增”的筛选,酶免疫实验检测抗体活性。所建抗体库库容为1.35×107,扩增后初级库滴度为2.12×1010pfu/mL。以NP抗原筛选后抗体出现特异性富集,经酶免疫实验鉴定,得到2株与NP抗原特异结合的噬菌体抗体。结果表明,研究成功构建了人源抗NP蛋白T7噬菌体抗体库。     

抗人大肠癌重组单链抗体的研制

应用重组噬菌体抗体系统制备了重组单链抗体。首先从抗人结肠癌ND-1单抗杂交瘤细胞中提取mRNA,利用反转录多聚酶链反应(RT-PCR)扩增出单抗重链可变区(V_H)及轻链可变区(V_L)片段,再通过连接DNA合成单链抗体可变区片段(ScFv),然后经双酶切后克隆到pCANTAB5E载体中,在E.coliTGI细胞中表达出噬菌体融合蛋白,用抗原阳性噬菌体感染E.coliHB2151细胞,产生单链抗体,该单链抗体既保持了原单抗的特异性,应用上又优于原单抗。     

大容量人天然抗体库的构建、鉴定及初步应用

从未经主动免疫的健康志愿者的外周血淋巴细胞中提取总RNA,用RT-PCR扩增人抗体重链(VH)和轻链(VL)可变区基因,得到了6种VH家族基因,11种VL家族基因,这些抗体基因家族覆盖了人抗体基因多样性的95%以上。采用改进的SOEPCR法将VH基因和VL基因连接成人单链抗体(scFv)基因,并克隆到噬菌粒载体pCANTAB5E中,将连接产物电转化大肠杆菌TG1,经辅助噬菌体M13KO7超感染,构建了库容为5.58×109的噬菌体单链抗体库。采用BstNI酶切法证明,构建的噬菌体单链抗体库具有良好的多样性。以TNF-α为靶,从该抗体库中筛选到了抗TNF-α抗体,这说明该抗体库可用于人源抗体的筛选。     

抗松材线虫纤维素酶单链抗体库的构建及筛选

构建鼠源性松材线虫纤维素酶（Bursaphelenchus xylophilus cellulase, BXC）的噬菌体单链抗体库,从中筛选特异性BXC的单链抗体。以BXC为抗原免疫BALB/C小鼠,从脾脏提取总RNA,用RT-PCR技术扩增小鼠抗体重链（V_H）和轻链(V_L)可变区基因。经重叠PCR(SOE-PCR)在体外将V_H和V_L连接成单链抗体(scFv)基因,并克隆到噬菌粒载体pCANTAB5E中,电转化至大肠杆菌TG1,经辅助噬菌体超感染,成功构建了库容为5×10⁴的Anti-BXC单链抗体库,并从该抗体库中初步筛选到了特异性识别BXC的噬菌体单链抗体scFv。将表面展示单链抗体的单克隆噬菌体转化大肠杆菌HB2151进行可溶性表达,SDS-PAGE及Western blot分析结果显示,可溶性scFv获得表达,且与BXC具有结合活性,为松材线虫的检验检疫以及病理学研究奠定了基础。     

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.     

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.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.