应用HTS-ELISA筛选方法制备抗黄曲霉毒素M1单抗

摘要：【目的】 确立基于高通量酶联免疫（HTS-ELISA）筛选方法制备高亲和力抗黄曲霉毒素M1单克隆抗体的方法体系。【方法】 采用AFM1-BSA （Aflatoxin M1-bovine serum albumin）免疫Balb/C小鼠,利用HTS-ELISA方法筛选分泌抗黄曲霉毒素 M1单抗的杂交瘤细胞株,并分析抗体的特性。【结果】筛选到14株具有分泌高活性抗黄曲霉毒素M1单克隆抗体的杂交瘤细胞株,纯化的最佳抗体的亲和力为5.5×10-10 mol/L。与黄曲霉毒素M1及其结构类似物黄曲霉毒素M2、B1、B2、G1、G2以及其他物质脱氧雪腐镰刀菌烯醇和BSA的交叉反应率分别为100%、4.5%、21.5%、1.0%、16.6%、1.0%、0%、0%。间接竞争ELISA检测最低检测限可达0.01 μg/L,线性范围为0.1-10 μg/L,竞争性抑制抗体反应50%的抑制浓度IC50为0.82 μg/L,添加0.25-5 μg/L黄曲霉毒素的牛奶间接竞争ELISA检测回收率在60.3%-152.8之间。【结论】HTS-ELISA方法可以制备具有高亲和力的抗黄曲霉毒素M1单克隆抗体,可为黄曲霉毒素M1免疫检测体系的建立提供优质抗体材料。     

抗黄曲霉毒素B1单链抗体的筛选和鉴定

目的】从Tomlinson（I）噬菌体抗体库中筛选人源化抗黄曲霉毒素B1单链抗体蛋白（scFv）并进行鉴定。【方法】分别采用甘氨酸洗脱、胰蛋白酶洗脱、游离AFB1竞争洗脱和AFB1竞争洗脱加胰蛋白酶处理4种方法对噬菌体抗体进行特异性洗脱。将筛选到的噬菌体阳性克隆转化到大肠杆菌 (Escherichia.coli ) HB2151,IPTG诱导表达scFv。ELISA检测和基因序列测定。【结果】比较四种洗脱方法,发现用AFB1竞争加胰蛋白酶洗脱筛选到阳性克隆的的概率最高,把此方法得到的阳性噬菌体克隆转化大肠杆菌HB2151表达,竞争性ELISA检测得到2个能特异性结合游离的AFB1阳性克隆。间接性ELISA测定相对亲和力分别为0.4 μg/mL和0.7 μg/mL 。测序证实scFv属于人类免疫球蛋白可变区。【结论】利用噬菌体展示技术获得高特异性抗黄曲霉毒素B1的人源化单链抗体,本实验方法可以为其它抗半抗原重组抗体的筛选提供一定的借鉴意义。     

抗人B7-H1单克隆抗体的制备和鉴定

目的:采用杂交瘤技术制备抗人B7-H1单克隆抗体,并对其进行鉴定。方法:经抗原免疫的小鼠脾细胞与小鼠骨髓瘤细胞以常规方法融合;用间接ELISA法筛选分泌抗体的杂交瘤细胞株;阳性克隆用有限稀释法获得稳定分泌抗人B7-H1单克隆抗体的杂交瘤细胞株;扩增杂交瘤细胞注射进小鼠腹腔后制备腹水;纯化腹水中的单克隆抗体并对其亚型进行鉴定;用间接ELISA法测抗体效价;将肺癌组织制成石蜡切片,用抗人B7-H1抗体进行免疫组化染色。结果:获得1株稳定分泌抗人B7-H1单克隆抗体的杂交瘤细胞株,所分泌的单抗类型为IgG1;抗体效价为1×108,纯化后的抗体含量为6.76g/L;免疫组化实验中,单抗可与肺癌组织表面的B7-H1蛋白特异地结合。结论:制备了人B7-H1单克隆抗体,为B7-H1检测试剂盒的研制奠定了基础。     

抗黄曲霉毒素B1单克隆抗体的制备及特性

用杂交瘤技术制备了5株产生抗黄曲霉毒紊B₁单克隆抗体的杂交瘤细胞株。对其中之一AFB1－2H8进行了较系统的研究。AFB1一2H8属IgC3。纯化腹水抗体效价约5×10⁶。ELISA检测标准毒素的线性范围为0．5～50ng／ml。最低检出量为0．01ng／ml。该单抗与参试的其它黄曲霉代谢物的交叉反应系数为0～0．21,该抗体有较大的应用价值。     

赭曲霉毒素 A 的高灵敏时间分辨荧光免疫分析

采用时间分辨荧光免疫分析 (TRFIA) 技术建立快速的高灵敏度的赭曲霉毒素 A (OTA) 全自动检测方法 . 将 OTA-BSA 作为免疫分子免疫 Balb/c 小鼠, OTA-KLH 为筛选用抗原包被板,用间接酶联免疫分析 (ELISA) 法筛选出专一针对 OTA 的高效价的阳性克隆 3G9 ,用杂交瘤细胞制备抗 OTA 单克隆抗体 . 用 OTA-BSA 包被 96 孔板为固相抗原,与游离 OTA 共同竞争有限的抗 OTA 单克隆抗体,以稀土离子 Eu3+ 标记的羊抗鼠抗体进行示踪,采用间接竞争免疫分析方法在解离增强荧光免疫分析体系中建立 OTA-TRFIA. 该方法的灵敏度为 0.03 μg /L ,测量范围为 0.03 ~1 000 μg /L ,批内和批间变异分别为 3.7% 和 5.3% ,平均回收率为 94.2% ,与赭曲霉毒素 B 的平均交叉反应为 3.7% ,与黄曲霉毒素 B1 、 牛血清白蛋白和苯基丙氨酸无交叉反应,说明抗体的特异性很好 . 8 条不同时间进行的间接竞争 OTA-TRFIA 的效应点均值 ED80 、 ED50 、 ED20 分别为 (0.33±0.02) μg /L、 (1.44 ±0.08) μg /L 和 (5.22 ± 0.12) μg /L ,说明方法的稳定性好,样品经 TRFIA 和 ELISA 试剂盒同时检测 OTA ,两者的相关系数为 0.925 ,结果相符 . 研究表明, OTA-TRFIA 是目前报道的 OTA 检测中最灵敏的方法,该分析方法稳定性好,可测范围宽,具有很好的应用前景 .     

高特异性抗桔霉素单克隆抗体的制备及鉴定

以1, 4-丁二醇二缩水甘油醚(双环氧试剂)为偶联剂,合成桔霉素-蛋白偶联抗原CIT-BSA,将偶联抗原免疫BALB/C小鼠,取脾细胞与小鼠骨髓瘤细胞SP2/0进行融合,应用有限稀释法进行筛选,经过克隆化后筛选到一株稳定分泌抗桔霉素抗体的杂交瘤细胞株H2-F8．该单克隆抗体经过初步鉴定,抗体类型为IgM类,抗体的相对亲和力为4.17×10⁸ L/mol,单抗与黄曲霉毒素B1、赭曲霉毒素A、脱氧雪腐镰刀菌烯醇和玉米赤霉烯酮等毒素的交叉反应率均低于0.1%,与红曲色素中的橙色素和红色素的交叉反应率均低于0.01%．在此基础上建立了间接竞争ELISA检测方法,线性范围为0.05～1.0 μg/L,IC₅₀值为0.3 μg/L．结果为快速检测桔霉素的酶联免疫检测方法的建立和检测试剂盒的研制提供技术依据．     

抗微囊藻毒素单克隆抗体的制备与鉴定

构建了微囊藻毒素(Microcystin-LR , MC-LR)完全免疫原 MCLR-KLH, 免疫 BALB／ c 小鼠 , 采用杂交瘤技术制备抗 MCLR 单克隆抗体, 用间接竞争 ELISA 方法筛选抗体。经过 3 次克隆, 获得 2 株可稳定分泌抗 MCLR 单克隆抗体的杂交瘤细胞株, 腹水效价达 1:8×104; IC50 为 0.81 ng⋅mL−1, 最低检测限 0.10 ng⋅mL−1, 亲和常数 3.8×108 L⋅mol−1,电泳结果显示抗体由 1 条重链和 1 条轻链组成, 与 MC-LR 同系物 MC-RR、 MC-YR 有较强的交叉反应, 与 MC-LW 有弱交叉性反应, 与河豚毒素无交叉反应。实验结果表明该抗体质量较好, 将在微囊藻毒素的快速检测、产生机理等方面具有较大的科研和应用价值。     

群特异性蓝舌病病毒单克隆抗体的制备和鉴定

目的：制备群特异性抗蓝舌病病毒（BTV）单克隆抗体,并对其特性进行鉴定,为建立检测BTV抗原及抗体的ELISA方法奠定基础。方法：用纯化的BTV颗粒为免疫抗原免疫BALB/c鼠,以大肠杆菌表达的VP7蛋白作为筛选抗原,用间接ELISA法筛选杂交瘤细胞株;选取抗体效价最高的一株制备BTV单克隆抗体,以该抗体为捕获抗体与8种不同血清型BTV进行ELISA反应,结果与细胞病变反应进行比对;以该抗体为竞争抗体,与12种不同血清型绵羊BTV抗血清进行竞争ELISA反应,并将结果与参比c-ELISA试剂盒结果进行比对。结果：筛选出5株稳定分泌BTV单克隆抗体的杂交瘤细胞株,并选其中一株（3E2）制备了高纯度的单克隆抗体;该单抗用于检测不同血清型BTV,与细胞病变反应结果完全相符;用于检测不同血清型绵羊BTV抗血清,其结果与参比c-ELISA试剂盒符合率为100%,与鹿流行性出血热病毒抗原和抗体均无交叉反应。结论：制备的BTV单克隆抗体具有良好的群特异性,可用于检测不同血清型BTV抗原及BTV抗体。     

活化相关分泌蛋白1单克隆抗体的制备及其在保守结构域鉴定中的应用

目的:制备重组活化相关分泌蛋白1(ASP-1)的单克隆抗体,并用其鉴定保守结构域。方法:用原核表达并纯化的重组ASP-1不加佐剂免疫BALB/c小鼠,采用杂交瘤技术及有限稀释传代法筛选稳定分泌特异性抗体的杂交瘤细胞株,制备单抗腹水后用间接ELISA进行抗体特异性鉴定和效价检测,利用肽结合ELISA和Western印迹鉴定单抗识别的保守结构域。结果:获得5株能稳定分泌抗ASP-1单克隆抗体的杂交瘤细胞株,且5株单抗的识别区域均为21~28氨基酸残基的保守性结构域。结论:制备了抗ASP-1的单克隆抗体,为深入研究ASP-1佐剂的活性功能区及作用机制提供了有效工具。     

抗麻痹性贝毒素GTX2,3单克隆抗体的制备及特性分析

制备抗麻痹性贝毒GTX2,3单克隆抗体。利用醛化法将GTX2,3与载体牛血清白蛋白(BSA)偶联,制备完全抗原。免疫小鼠,取小鼠脾细胞与Sp2/0细胞融合。GTX2,3与钥孔血蓝蛋白(KLH)偶联作为检测抗原,用间接ELISA法筛选阳性克隆株。将筛选的阳性细胞株制备腹水。获得三株稳定分泌抗GTX2,3单克隆抗体的杂交瘤细胞株F4、F10、G9。间接ELISA法检测F10细胞株腹水抗体效价为1.4×10^-5。半抗原GTX2,3与载体蛋白偶联后,作为免疫原,可制备高滴度的抗GTX2,3抗血清和单克隆抗体。该抗体对于藻毒素具有高特异性和高亲和力,可用于污染海产品的麻痹性贝毒的检测。     

Amyloid-beta peptide binds to microtubule-associated protein 1B (MAP1B)

Extracellular and intraneuronal formation of amyloid-beta aggregates have been demonstrated to be involved in the pathogenesis of Alzheimer's disease. However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of targets have deleterious effects on cellular functions. In the present study we have shown for the first time that amyloid-beta 1-42 bound to a peptide comprising the microtubule binding domain of the heavy chain of microtubule-associated protein 1B by the screening of a human brain cDNA library expressed on M13 phage. This interaction may explain, in part, the loss of neuronal cytoskeletal integrity, impairment of microtubule-dependent transport and synaptic dysfunction observed previously in Alzheimer's disease.     

The human steroid hydroxylases CYP1B1 and CYP11B2

Major advances have been made during the last decade in our understanding of adrenal steroid hormone biosynthesis. Two key players in these pathways are the human mitochondrial cytochrome P450 enzymes CYP11B1 and CYP11B2, which catalyze the final steps in the biosynthesis of cortisol and aldosterone. Using data from mutations found in patients suffering from steroid hormone-related diseases, from mutagenesis studies and from the construction of three-dimensional models of these enzymes, structural information could be deduced that provide a clue to the stereo- and regiospecific steroid hydroxylation reactions carried out by these enzymes. In this review, we summarize the current knowledge on the physiological function and the biochemistry of these enzymes. Furthermore, the pharmacological and toxicological importance of these steroid hydroxylases, the means for the identification of their potential inhibitors and possible biotechnological applications are discussed.     

Aldehyde dehydrogenase 1B1 (ALDH1B1) is a potential biomarker for human colon cancer

Aldehyde dehydrogenases (ALDHs) belong to a superfamily of NAD(P)⁺-dependent enzymes, which catalyze the oxidation of endogenous and exogenous aldehydes to their corresponding acids. Increased expression and/or activity of ALDHs, particularly ALDH1A1, have been reported to occur in human cancers. It is proposed that the metabolic function of ALDH1A1 confers the “stemness” properties to normal and cancer stem cells. Nevertheless, the identity of ALDH isozymes that contribute to the enhanced ALDH activity in specific types of human cancers remains to be elucidated. ALDH1B1 is a mitochondrial ALDH that metabolizes a wide range of aldehyde substrates including acetaldehyde and products of lipid peroxidation (LPO). In this study, we immunohistochemically examined the expression profile of ALDH1A1 and ALDH1B1 in human adenocarcinomas of colon (N = 40), lung (N = 30), breast (N = 33) and ovary (N = 33) using an NIH tissue array. The immunohistochemical expression of ALDH1A1 or ALDH1B1 in tumor tissues was scored by their intensity (scale = 1–3) and extensiveness (% of total cancer cells). Herein we report a 5.6-fold higher expression score for ALDH1B1 in cancerous tissues than that for ALDH1A1. Remarkably, 39 out of 40 colonic cancer specimens were positive for ALDH1B1 with a staining intensity of 2.8 ± 0.5. Our study demonstrates that ALDH1B1 is more profoundly expressed in the adenocarcinomas examined in this study relative to ALDH1A1 and that ALDH1B1 is dramatically upregulated in human colonic adenocarcinoma, making it a potential biomarker for human colon cancer.     

Murine aldo-keto reductase family 1 subfamily B: identification of AKR1B8 as an ortholog of human AKR1B10

Aldo-keto reductase family 1 member B10 (AKR1B10), over-expressed in multiple human cancers, might be implicated in cancer development and progression via detoxifying cytotoxic carbonyls and regulating fatty acid synthesis. In the present study, we investigated the ortholog of AKR1B10 in mice, an ideal modeling organism greatly contributing to human disease investigations. In the mouse, there are three aldo-keto reductase family 1 subfamily B (AKR1B) members, i.e., AKR1B3, AKR1B7, and AKR1B8. Among them, AKR1B8 has the highest similarity to human AKR1B10 in terms of amino acid sequence, computer-modeled structures, substrate spectra and specificity, and tissue distribution. More importantly, similar to human AKR1B10, mouse AKR1B8 associates with murine acetyl-CoA carboxylase-α and mediates fatty acid synthesis in colon cancer cells. Taken together, our data suggest that murine AKR1B8 is the ortholog of human AKR1B10.     

Molecular modeling of protein tyrosine phosphatase 1B (PTP 1B) inhibitors

Binding modes of a series of aryloxymethylphosphonates and monoanionic biosteres of phosphate group from a series of benzylic alpha,alpha-diflluoro phosphate and its biosteres as protein tyrosine phosphatase 1B (PTP 1B) inhibitors have been identified by molecular modeling techniques. We have performed docking and molecular dynamics simulations of these inhibitors with PTP 1B enzyme. The initial conformation of the inhibitors for docking was obtained from simulated annealing technique. Solvent accessible surface area calculations suggested that active site of PTP 1B is highly hydrophobic. The results indicate that for aryloxymethylphosphonates, in addition to hydrogen bonding interactions, Tyr46, Arg47, Asp48, Val49, Glu115, Lys116, Lys120 amino acid residues of PTP 1B are responsible for governing inhibitor potency of the compounds. The sulfonate and tetrazole functional groups have been identified as effective monoanionic biosteres of phosphate group and biphenyl ring system due to its favorable interactions with Glu115, Lys116, Lys120 residues of PTP 1B found to be more suitable aromatic functionality than naphthalene ring system for benzylic alpha,alpha-diflluoro phosphate and its biosteres. The information generated from the present study should be useful in the design of more potent PTP 1B inhibitors as anti diabetic agents.     

B-1 B cell development

CD5+ B cells have attracted considerable interest because of their association with self-reactivity, autoimmunity, and leukemia. In mice, CD5+ B cells are readily generated from fetal/neonatal precursors, but inefficiently from precursors in adult. One model proposed to explain this difference is that their production occurs through a distinctive developmental process, termed B-1, that enriches pre-B cells with novel germline VDJs and that requires positive selection of newly formed B cells by self-Ag. In contrast, follicular B cells are generated throughout adult life in a developmental process termed B-2, selecting VDJs that pair well with surrogate L chain, and whose maturation appears relatively independent of antigenic selection. In the present study, I focus on processes that shape the repertoire of mouse CD5+ B cells, describing the differences between B-1 and B-2 development, and propose a model encompassing both in the generation of functional B cell subpopulations.