鼠源性抗雄性特异性抗原噬菌体Fab抗体库的构建

利用雄鼠脾细胞免疫6~7周龄C57BL/6雌鼠,加强免疫后取脾细胞,TRIZOL法提取细胞总RNA,并逆转录合成cDNA第一条链。以其为模板,利用特异性Ig基因的引物PCR扩增出重链Fd片段和κ链基因,并将扩增出基因重组到噬质粒载体pComb3中,重组噬质粒转化大肠杆菌XL1-Blue中,分别构建κ链基因库和抗体Fab段基因库。分别经蓝白斑筛选,计算转化效率,通过PCR反应和双酶切反应鉴定抗体库的重组率,轻链、重链Fd段基因的重组率均为80%。抗体Fab段基因库经过辅助噬菌体VCSM13超感染,成功构建了鼠源性噬菌体Fab抗体库,并测定噬菌体抗体库的库容和滴度,结果分别为1.5×107,3.2×1011pfu/mL。对噬菌体抗体库的18个克隆进行ELISA分析,结果显示以雄鼠脾细胞作为抗原时,有9个克隆含有雄性特异性的噬菌体抗体,而以雄鼠睾丸细胞作为抗原时,有8个克隆与睾丸细胞呈现结合活性。噬菌体抗体库的构建为雄性特异性抗原的鼠源性噬菌体抗体Fab片段的筛选及其应用、雄性特异性抗原和抗体功能性分子基础的研究奠定了坚实基础。     

禽流感免疫噬菌体抗体库构建及ELISA检测方法的建立

本研究应用噬菌体抗体库技术筛选禽流感亚型病毒Fab抗体,并建立相应ELISA检测方法。用禽流感亚型混合疫苗免疫小鼠,取其脾脏提取总RNA用于扩增免疫球蛋白轻链和重链基因,克隆至噬菌粒pComb3,然后转化入感受态细胞XL1-Blue中,以10¹² CFU辅助噬菌体VCSM13进行感染后,获得Fab抗体库容量为8×10⁷ CFU。以H5N1病毒为抗原进行4轮亲和筛选,获得特异性结合的克隆,利用获得的特异性克隆进行ELISA检测方法的建立。     

小鼠H-Y单克隆抗体ELISA检测方法的建立

以纯系 BAL B/ c雄性小鼠脾细胞腹腔注射免疫同系雌性小鼠 9次 ,获得的抗血清经雌、雄鼠脾细胞吸收后用于精子细胞毒性试验 ,测得 H- Y抗血清效价为 1/ 16 0。选取免疫应答最好的雌鼠脾细胞与 SP2 / 0骨髓瘤细胞融合 ,用精子细胞毒性方法筛选效价较高的细胞株制备腹水 ,建立优化的 EL ISA反应条件。优化后的 EL ISA反应条件为 :抗原4℃过夜 ,加 H- Y抗血清 37℃反应 12 0 m in,加 HRP- Ig G 37℃反应 30 min,加 TMB 2 5℃ 30 min。优化后的 EL ISA与常规 EL ISA比较 ,可以明显降低阴性吸光值 ,检测灵敏度从 1/ 32 0上升为 1/ 12 80     

IBRV特异性噬菌体单域抗体库的构建、筛选及鉴定

为了开发有效的用于治疗和诊断牛传染性鼻气管炎(infectious bovine rhinotracheitis,IBR)的抗体,试验用牛传染性鼻气管炎病毒(Infectious bovine rhinotracheitis virus,IBRV)免疫双峰驼,构建IBRV特异性噬菌体单域抗体库,并以IBRV gD蛋白为筛选抗原,对其进行筛选,对筛选得到的单域抗体进行诱导表达、纯化及鉴定。结果表明:构建得到的IBRV特异性噬菌体单域抗体库的库容为7×10~7;经3轮富集和筛选,phage-ELISA筛选出14个与gD蛋白结合的阳性克隆,并成功对阳性值较高的重组单域抗体IB68进行表达和纯化;经ELISA和Western-blot鉴定,重组单域抗体IB68可与gD蛋白产生抗原抗体结合反应,具有较高的亲和力。说明制备的IBRV特异性噬菌体单域抗体库具有较高的库容和多样性,且筛选得到的单域抗体具有较高的抗原抗体结合活性和免疫学反应性。     

雄性特异性抗原的研究进展

雄性特异性抗原为雄性动物特有,是引起同种雌性动物免疫排斥反应的物质的总称。这类物质广泛存在于哺乳动物及其他脊椎动物。依据其检测方式的不同,可分为细胞毒性T细胞相关性雄性特异性抗原和血清学相关性雄性特异性抗原。目前,已初步确定了几个细胞毒性T细胞相关性雄性特异性抗原的候选基因及抗原肽序列,它们都位于Y染色体上。对于血清学相关性雄性特异性抗原的研究则还处于初级阶段。近年发现了细胞毒性T细胞相关性雄性特异性抗原的抗体,揭示此两类物质具有内在的联系。     

H-Y抗原候选基因的研究进展

雄性特异性组织相容性抗原(male specific minor histompatibility antigens,H-Y抗原)是由Y染色体上的基因编码,在雄性动物细胞中普遍表达(包括胚胎和滋养层细胞)。H-Y抗原不仅能引起基因型相同的雌性动物排斥雄性组织,也能导致人白细胞抗原匹配干细胞移植术后出现移植抗宿主性疾病(GVH)。细胞毒性T淋巴细胞检测到几个不同的H-Y抗原表位,这些肽是从胞内蛋白分离出来,由主要组织相容性复合分子结合呈递在细胞表面。H-Y抗原肽与人白细胞抗原Ⅰ类和Ⅱ类分子特异结合参与免疫反应,从而影响移植结果。近年来越来越多的文献报道了H-Y抗原的相关研究,作者主要综述编码H-Y抗原的相关候选基因,并对它在疾病等方面的前景作出了一些展望。     

传染性法氏囊病毒VP2蛋白抗原表位多肽P22的免疫原性及生物学功能鉴定

为鉴定lBDV VP2蛋白线性B细胞抗原表位肽P22的免疫原性及生物学功能,作者采用固相多肽合成方法合成多肽P22,经纯化后用SMCC法分别与牛血清白蛋白(BSA)和细胞穿膜肽(PNT)进行偶联,得到免疫抗原P22-BSA和检测抗原P22-PNT;用P22-BSA免疫BALB/c小鼠3只,经3次免疫后得到多抗血清3份.应用ELISA检测了抗P22抗体的特异性,并通过抗P22多肽抗体作为特异性抗体检测了P22多肽结合CEF细胞的特性.结果经鉴定3份多抗血清均与P22多肽特异性反应,效价均达到1:105,且能特异性检测P22多肽与CEF细胞的特异性结合.本试验成功制备了P22免疫原,获得了效价高、特异性较好的鼠源抗P22多抗血清,并证明P22多肽与CEF细胞能够特异性结合,为进一步研究多肽疫苗的设计或试纸条的研制及表位单抗的制备提供了新的思路和基础.     

家畜胚胎的性别鉴定技术

1.H—Y抗原法krco及Goldberg在1976年首先用H-Y抗原鉴定胚胎的性别。他们从C57BL/6纯系雌鼠中收集各细胞期的胚胎,经链霉蛋白酶处理除去透明带,然后将这些无带的胚胎置于含有豚鼠补体的稀释H-Y抗血清中孵育,按溶解与否进行评定。结果发现,大约有一半的10到16细胞期的胚胎发     

天然鼠源噬菌体抗体库的构建及抗鸡堆型艾美耳球虫裂殖子单链抗体的筛选（英文）

从未经主动免疫的BALB/c小鼠脾脏淋巴细胞中提取总RNA,用RT-PCR扩增鼠抗体重链(VH)和轻链(VL)可变区基因,将轻链和重链可变区基因经重叠延伸拼接PCR反应,构建成单链抗体(ScFv)基因。将ScFv基因克隆到噬菌体载体PCANTAB-5E,转化入大肠杆菌TG1中,筛选出阳性克隆,接种于LB培养基,经辅助噬菌体M13KO7拯救,构建天然鼠源噬菌体抗体库,并进行抗体库滴度测定,通过DNA finger printing技术及单链抗体基因序列分析鉴定抗体库的多样性。以堆型艾美耳球虫裂殖子为靶抗原,对构建的噬菌体抗体库进行亲和筛选,将强阳性重组噬菌体克隆感染大肠杆菌HB2151,经IPTG诱导表达可溶性ScFv抗体,并对表达产物进行SDS-PAGE和Western blot鉴定,用ELISA法鉴定其对堆型艾美耳球虫裂殖子抗原的结合活性。结果表明,天然鼠源噬菌体抗体库成功构建,库容量约为2.50×10~(11) CFU/mol,单链抗体库具有一定的多样性。经过4轮亲和筛选,携带抗鸡堆型艾美耳球虫裂殖子表面抗原的特异性噬菌体抗体得到了富集。特异性ScFv抗体在E.coli中分泌表达,表达产物具有免疫活性。筛选出5个与鸡堆型艾美耳球虫裂殖子抗原结合活性较高的克隆,构建的单链噬菌体抗体库的有效表位具有多样性。本研究为进一步认识鸡球虫的各个发育阶段奠定理论基础,为鸡球虫病免疫控制研究提供参考。     

抗鼠棒状杆菌单克隆抗体制备及鉴定

以BALB/c小鼠为实验动物，将致敏的脾细胞与SP2/0瘤细胞进行融合，并采用间接ELISA进行克隆筛选，获得能分泌抗鼠棒状杆菌的特异性抗体且稳定生长的瘤细胞系。以此为基础，采用体内诱生腹水法制备单克隆抗体，测定其血清学效价、抗原反应灵敏度及亲和力。结果显示：制备的单抗血清学效价在1.6×10³～1.28×10⁴，抗体水平均值非常高，灵敏度高，与类似抗原交叉反应率极低，具备构建快速检测法的应用前景。     

禽网状内皮组织增生症病毒单抗制备及在外源病毒检测中的应用

为了建立外源病毒检验用间接免疫荧光染色方法,本研究将禽网状内皮组织增生症病毒囊膜蛋白gp90(SU)的基因合成后连接至原核表达载体中进行表达,获得REV-SU蛋白,通过Ni柱亲和层析获得纯化的重组蛋白,免疫BALB/C小鼠,应用杂交瘤技术获得1株分泌特异性抗REV SU蛋白的单克隆抗体杂交瘤细胞系(2A2株),该细胞株制备的腹水与不同REV毒株具有良好的反应性,荧光效价可达1：51200,与不同ALV毒株和其他常见禽的病原均没有交叉反应,特异性良好。采用该细胞株分泌的单克隆抗体建立的间接免疫荧光染色法能检出至少5个TCID50REV病毒感染量,与多克隆抗体作为检测一抗具有同等的效力,且检测背景更加纯净,适用于外源性REV病毒检验。     

Effect of papain digestion on the specificity of fluorescein-labeled immunoglobulins

During initial studies, we found that many fluorescein isothiocyanate-labeled anti-immunoglobulin conjugates were unstable and tended to aggregate and precipitate when used for indirect immunofluorescence microscopy. In some instances, the precipitate was extensive enough to interfere with interpretation of the test results. Attempts to resolve this problem resulted in a procedure by which such conjugates were digested with papain to Fab and Fc fragments before use. Aggregation and precipitation were prevented, while desired antibody activity was retained. Digestion with papain also reduced the diffuse background fluorescence (commonly referred to as nonspecific fluorescence or staining) that is often associated with conjugates before they are sorbed with tissue powders or chromatographed to remove highly labeled immunoglobulin molecules.     

Phage display selection and characterization of single-chain recombinant antibodies against Eimeria tenella sporozoites

A single-chain antibody library against Eimeria tenella sporozoites was constructed by phage display. Antibody-displaying phage was selected in five panning rounds against cryopreserved E. tenella sporozoites. A 1000-fold increase in phage output and a 3000-fold enrichment were obtained after three rounds of panning, as the binding clones became the dominant population in the library. Ten clones were randomly selected from the last selection round, and their nucleotide sequences were aligned and compared to chicken germ-line sequences. Analysis of the light chain variable regions revealed possible donor pseudogenes which act as donors in gene conversion events, and contribute to the diversification of the V(L) immune repertoire. Possible somatic hypermutation events, a consequence of affinity maturation, were also identified. Soluble antibody was produced in a non-suppressor E. coli strain, purified by nickel affinity chromatography, and characterized by immunoblotting. In an immunofluorescence assay, this recombinant antibody showed specific binding to E. tenella sporozoites.     

噬菌体展示系统的构建及其在疾病防控领域应用研究进展

噬菌体展示技术作为目前应用广泛的展示抗体技术,逐渐成为生产基因工程抗体的重要工具。噬菌体展示技术是以噬菌体或噬菌粒为载体,通过将外源多肽基因整合到噬菌体基因中,以融合表达的形式将外源蛋白展示在噬菌体表面的分子生物学技术。近年来,噬菌体展示技术在抗体筛选领域的应用越来越广泛,与传统制备抗体的方法相比,噬菌体展示技术具有通量高、成本低、操作简单等特点,且通过该技术筛选得到的抗体不仅可在标签蛋白的辅助下进行选择和纯化,还可通过基因测序的方法得到单链抗体的完整基因序列。笔者首先对噬菌体抗体库进行分类,根据抗体的来源将噬菌体抗体库分为天然抗体库和免疫抗体库,通过免疫动物制备的抗体文库的特异性、抗体阳性率明显高于天然抗体文库;其次简述了噬菌体抗体库的构建流程,其中噬菌体表达载体的选择是展示技术的关键,整合了噬菌粒基因的辅助噬菌体侵染其特异性菌株,从而通过抗生素平板对该系统进行选择性筛选;最后讨论了噬菌体展示技术在疾病防控领域应用的研究进展,抗体的首次人源化使同源性抗体在临床上应用成为可能,后续用于预防和治疗病毒性疾病的动物同源性抗体的研发进一步证明了噬菌体展示技术用于生产诊断或潜在治疗试剂的能力。该综述主要聚焦于噬菌体展示系统的构建及其在疾病防控领域的应用,以期对后续通过噬菌体展示技术筛选单链抗体的应用提供指导。     

Canine antinuclear antibodies: comparison of immunofluorescence staining patterns and precipitin reactivity

The occurrence of antinuclear antibodies (ANAs) against several specific nuclear antigens is clearly associated with certain systemic rheumatic disorders in human patients. Determination of ANAs on a routine basis, usually by indirect immunofluorescence (IIF) technique, has therefore become an important diagnostic tool. The subdividing of positive ANA-sera into different nuclear IIF staining patterns often gives clues to antibody specificity. The present investigation aimed at studying whether such subgroups of staining patterns in IIF ANA positive canine sera may represent certain specific ANAs that can be verified by standard methods used for specificity determination in humans. The presence of precipitating antibodies, determined by the Ouchterlony immunodiffusion (ID) technique, was found to be strictly associated with a positive IIF ANA, exhibiting a speckled staining pattern without any chromosomal reactivity. None of the sera with chromosomal reactivity contained precipitating antibodies. Among the ID positive serum samples, different antigenic reactivities were detected, represented by different ID subgroups. Only 1 of the 4 main subgroups obtained by ID showed identity with any of the common and disease-associated human ANA specificities, exhibiting anti-RNP reactivity. One of these serum samples concomitantly exhibited precipitating antibodies against the Sm antigen.     

A dominant antigenic epitope on SARS-CoV spike protein identified by an avian single-chain variable fragment (scFv)-expressing phage

Severe acute respiratory syndrome (SARS) is a newly emergent human disease, which requires rapid diagnosis and effective therapy. Among antibody sources, immunoglobulin Y (IgY) is the major antibody found in chicken eggs and can be used as an alternative to mammalian antibodies normally used in research and immunotherapy. In this study, phage-expressing chicken monoclonal scFv antibody was chosen and characterized with phage display antibody technology. Truncated fragments of SARS-CoV spike protein were cloned in pET-21 vector and expressed in BL-21 Escherichia coli (E. coli) cells. After purification, the purity of these recombinant spike proteins was examined on SDS-PAGE and their identity verified with Western blot analysis using anti-his antibodies and sera from convalescent stage SARS-CoV-infected patients. Using these bacteria-derived proteins to immunize chickens, it was found that polyclonal IgY antibodies in the egg yolk and sera were highly reactive to the immunogens, as shown by Western blot and immunocytochemical staining analysis. A phage displaying scFv library was also established from spleen B cells of immunized chicken with 5 x 10(7) clones. After four panning cycles, the eluted phage titer showed a 10-fold increase. In sequence analysis with chicken germline gene, five phage clones reacted, with large dissimilarities of between 31 and 62%, in the complementarity-determining regions, one dominant phage 4S1 had strong binding to fragment Se-e, located between amino acid residues 456-650 of the spike protein and this particular phage had significantly strong binding to SARS-CoV-infected Vero E6 cells. Based on the results, we conclude that generating specific scFv-expressing phage binders with the phage display system can be successfully achieved and that this knowledge can be applied in clinical or academic research.     

Immunofluorescence of bovine virus diarrhea viral antigen in white blood cells from experimentally infected immunocompetent calves.

A study to evaluate the detection of bovine virus diarrhea viral antigen using immunofluorescence testing of white blood cells was conducted. Five colostrum-deprived calves were inoculated intravenously with a cytopathic strain of the virus. Lymphocyte and buffy coat smears were prepared daily for direct immunofluorescent staining for detection of antigen. Lymphocytes were separated from heparinized blood using a Ficoll density procedure. Buffy coat smears were prepared from centrifuged blood samples collected using ethylenediaminetetraacetic acid as an anticoagulant. Bovine viral diarrhea virus antigen was detected by immunofluorescence between 3 and 11 days postinfection in lymphocyte smears and 3 to 12 days postinfection in buffy coat smears. Isolation of virus from both lymphocytes and buffy coat preparations correlated with detection of immunofluorescence. Serum neutralizing antibody to bovine virus diarrhea virus was detected on day 10 postinfection. Buffy coat smears were as sensitive as lymphocyte smears for the detection of antigen by immunofluorescence. It appeared that immunofluorescent staining of white blood cells was an effective method of detecting bovine virus diarrhea viral antigen.     

Serological detection of phage infection in Chlamydia psittaci recovered from ducks

Antiserum prepared against a phage which infects a Chlamydia psittaci isolate recovered from domestic ducks was used to screen other recent avian C psittaci isolates by indirect immunofluorescence. Two more phage infected strains from ducks were discovered. However, phage was not detected in every isolate examined from common source ducks, although such birds are likely to be infected with the same C psittaci strain. Moreover, phage could not always be demonstrated by indirect immunofluorescence in McCoy cell monolayers infected with the phage-containing strain. The results suggest that phage infection is probably an integral part of duck chlamydiosis in the United Kingdom at present, but that the infection is often cryptic.     

Freezing of Maiden Stallion Semen - Motility and Morphological Findings in Sperm Cells Assessed by Various Staining Methods Including a Monoclonal Antibody with Reactivity Against an Antigen in the Acrosomal Ground Substance

Contents: From a group of thirteen 3-year-old Hanoveranian maiden stallions ejaculates were collected on 5 consecutive days and frozen each in 3 different packaging forms. Fresh, resuspended and frozedthawed semen was tested for motility and morphology with special regard to acrosomal integrity. Concerning packaging form no differences were found between 4 ml maxi straw, flattened 1.7 ml straw and 0.5 ml straw. The comparison of 3 direrent conventional staining techniques with an immunofluorescence test, employing a monoclonal antibody against an antigen in the acrosomal ground substance, revealed that staining sperm cells with the antibody yielded far more reproducible and consistent results - especially in diluted semen - than staining with Karras, moded Karras or Spermac®.