抗STa多克隆抗体的制备、鉴定和纯化

产肠毒素大肠杆菌(ETEC)可引起人及动物急性腹泻,其关键毒力因子为耐热肠毒素(ST)。由于ST是一种具有强烈毒性但缺乏免疫原性的小分子肽,如何在保持其免疫原性的同时减弱其毒性已成为制备ST类毒素疫苗的研究热点。本试验以利凡诺法提纯兔血清白蛋白(RSA),经0.2%戊二醛活化,再与人工合成的甲醇可溶性STa偶联,十二烷基硫酸钠—聚丙烯酰胺凝胶电泳(SDS-PAGE)结果显示获得分子质量约108.5 ku的完全抗原。用该偶联物免疫新西兰白兔4次,采集抗血清并用Protein A/G 琼脂糖小珠进行纯化,斑点酶联免疫吸附试验(dot-ELISA)和免疫印迹(Western blotting)结果显示抗血清效价均为1:400。试验结果表明抗STa多克隆抗体成功制备,这为筛选ST结构类似物做有益的铺垫。     

CHO细胞表达牛病毒性腹泻病毒E2蛋白及免疫原性分析

旨在利用悬浮培养CHO细胞表达系统制备牛病毒性腹泻病毒(bovine viral diarrhea virus,BVDV) E2蛋白,并鉴定纯化E2蛋白的免疫原性。本研究以BVDV-1 NADL株基因序列为基础,构建BVDV E2蛋白的重组真核表达质粒pcDNA3.1-BVDV-E2,转染经悬浮培养的CHO细胞进行分泌表达,收集细胞培养上清,进行亲和层析法纯化,SDS-PAGE电泳鉴定蛋白表达和纯化,Western blot鉴定与His抗体和BVDV阳性血清反应性,利用纯化蛋白免疫新西兰大白兔,用细胞间接免疫荧光(IFA)和ELISA鉴定E2蛋白的反应活性。纯化E2蛋白经BCA蛋白定量试剂盒检测后表达量高达1.228 mg·mL^-1;Western blot结果显示,利用His抗体和BVDV阳性血清均可检测到目的蛋白的特异性条带;新西兰大白兔一免后第7天利用间接ELISA可检测到血清抗体阳性,并持续至免疫后第28天,血清抗体效价水平达到1∶1 024 000;IFA试验结果显示,该血清抗体可检测到BVDV感染MDBK细胞中E2蛋白的表达,进一步证实纯化的E2蛋白具有良好的免疫原性和特异性。本研究成功利用CHO悬浮培养真核表达系统制备了纯化的BVDV E2蛋白,该蛋白具有良好的免疫原性,为BVDV的诊断方法及其新型亚单位疫苗研制奠定了基础。     

牛病毒性腹泻病毒间接ELISA方法的建立

持续性感染和免疫耐受是牛病毒性腹泻病的重要特征,也是该病的防控难点.本试验将2种生物型的牛病毒性腹泻病毒(BVDV):致细胞病变(CP)型(BVDV OregonC24株)和非致细胞病变(NCP)型(BVDV Yak株),灭活、浓缩作为抗原,分别免疫家兔制备高免血清.同时,使用BVDV全病毒蛋白作为包被原,建立了检测BVDV的间接ELISA检测方法.本试验利用该方法对高免血清进行检测,探讨CP型BVDV与NCP型BVDV抗原免疫原性差异.结果显示,CP型BVDV的高免血清效价均比NCP型BVDV高免血清的效价高,平均高35%.结果表明,CP型BVDV的免疫原性优于NCP型BVDV,且CP型BVDV与NCP型BVDV的血清效价具有明显差异.这为在实践中疫苗毒株筛选及生产提供了理论指导.     

Expression and Immunogenicity Analysis of Porcine Pseudorabies Virus gB Protein

In order to study the expression and immunogenicity of porcine pseudorabies virus (PRV) gB protein,the specific primers were designed with the template of PRV preserved in the laboratory, and the 612 bp conserved gene fragments were amplified and sequenced, then it was cloned into the expression vector pET-28a and transformed into E.coli BL21 (DE3), the target protein was obtained after induced expression and purification.Western blotting was performed to analyse its immunogenicity. The results showed that gB protein was 30 ku, which mainly expressed in the form of inclusion body, and the concentration of the protein was 106 μg/mL, with well reactogenicity. 13 PRV positive serum and 16 negative serum in the samples were detected using ELISA Kit on sale, using positive serum, the PRV antibody detection method was initially established with the PRV gB protein as antigen package.     

重组蓖麻毒素A链表达及其与天然蓖麻毒素毒性比较研究

本试验旨在制备有高生物活性的重组蓖麻毒素A链(r-RTA)并与天然蓖麻毒素(n-RT)进行毒性比较.根据NCBI公布的RTA序列合成基因片段,并将其克隆于pET-28a载体后,利用大肠杆菌进行原核表达,镍柱亲和层析纯化上清,500 mmol/L咪唑溶液洗脱获得可溶性r-RTA蛋白,通过SDS-PAGE及Western blotting对其进行鉴定并用ELISA测定其免疫原性后,对r-RTA与n-RT进行动物和细胞试验毒性比较研究.结果显示,该r-RTA在上清中表达率为31.2%;每升细菌培养物纯化后可得20 mg目的蛋白,纯度≥90%,大小为32 ku.其免疫原性约为n-RT的1.27倍;通过获取的n-RT细胞半抑制浓度(IC₅₀为0.01 μg/mL)及动物半数致死量(LD₅₀为(3.27±0.44) μg/kg),以相同浓度进行细胞感染和动物攻毒试验,结果显示,同等剂量下,在细胞试验中,n-RT毒力是r-RTA的2 700倍;在动物试验中,n-RT组对动物致死率为40%,r-RTA组动物无死亡.结果表明,单独RTA,在没有RTB协助下,具有一定的毒性作用,但毒力将显著降低.该结果将为开发基于RTA的蓖麻毒素疫苗提供重要数据和理论支撑.     

猪伪狂犬病病毒gB蛋白表达及免疫原性分析

本试验旨在研究猪伪狂犬病病毒（pseudorabies virus,PRV） gB蛋白的表达并分析其免疫原性,以PRV病毒液为模板,设计特异性引物,扩增大小为612 bp的保守片段并测序,将其克隆到表达载体pET-28a中,转化表达菌BL21（DE3）,经诱导表达、纯化得到目的蛋白,进行Western blotting分析验证并分析免疫原性。结果表明,表达的gB蛋白大小为30 ku,主要以包涵体形式存在,复性后浓度为106 μg/mL,且具有良好的反应原性。应用市售试剂盒检测到样品中含13份PRV阳性血清和16份阴性血清,利用检出的阳性血清,初步可建立以PRV gB蛋白为包被抗原的PRV抗体ELISA检测方法。     

猪流行性腹泻病毒S基因与SEA基因融合表达及免疫原性评价

试验旨在构建pET-28a-S-SEA融合表达质粒,并评价S-SEA蛋白的免疫原性。根据大肠杆菌密码子偏嗜性,对我国猪流行性腹泻病毒(PEDV)流行毒株(GenBank:LT906620.1)的S基因与金黄色葡萄球菌肠毒素A(SEA)基因(GenBank:MH053151.1)进行优化,通过柔性连接肽(GGGGS)连接后,克隆至表达载体pET-28a,得到pET-28a-S-SEA重组质粒,转化至宿主菌BL21(DE3)中诱导表达,经SDS-PAGE和Western Blot检测后,对最佳表达条件进行摸索。在此基础上,将亲和层析后的重组蛋白,免疫6周龄的雌性BALB/c小鼠,对免疫小鼠的血清特异性抗体水平和淋巴细胞增殖指数进行检测。结果成功构建pET-28a-S-SEA质粒,且在大肠杆菌中获得高效表达;小鼠试验结果表明,纯化的S-SEA蛋白能够诱导小鼠产生特异性免疫反应,促进淋巴细胞增殖,具有良好的免疫原性,为进一步研究猪流行性腹泻亚单位疫苗提供帮助。     

P[1]型A群牛轮状病毒VP8重组蛋白的表达与免疫原性研究

【目的】 利用原核表达系统表达P[1]型A群牛轮状病毒(BRVA) VP8重组蛋白,并评价其反应原性与免疫原性。【方法】 根据国内流行毒株RVA/Cow-tc/CHN/SDA2/2018/G6P[1] VP8基因序列(GenBank登录号:MN937517)进行密码子偏好性优化,构建P[1]型BRVA VP8大肠杆菌原核表达系统,将重组质粒转化大肠杆菌BL21(DE3)感受态细胞,IPTG诱导表达,通过SDS-PAGE分析重组蛋白表达形式。镍琼脂糖亲和层析纯化重组蛋白,Western blotting鉴定重组蛋白与兔抗G6P[1]型BRVA血清特异性结合能力,并将P[1]型BRVA VP8重组蛋白免疫兔,首免后2周加强免疫1次,共免疫2次。分别用间接ELISA方法与中和试验评价其免疫原性。【结果】 本研究成功构建P[1]型BRVA VP8重组蛋白的原核表达系统;SDS-PAGE结果显示,高效表达大小为20 ku的P[1]型BRVA VP8重组蛋白,以可溶形式存在;Western blotting结果显示,P[1]型BRVA VP8重组蛋白能与兔抗G6P[1]型BRVA血清特异性结合;间接ELISA结果显示,P[1]型BRVA VP8重组蛋白亚单位疫苗能诱导兔产生抗体,兔首免1周后抗体开始出现并迅速上升,于第3周达到高峰,至第5周仍维持在较高水平;中和试验结果显示,第2次免疫后抗体最高的兔血清对G6P[1]型和G8P[1]型BRVA的中和效价分别为1∶17 783和1∶64。【结论】 本研究成功构建原核表达系统表达P[1]型BRVA VP8重组蛋白,并证实其具有良好的反应原性及免疫原性,为研制BRVA亚单位疫苗奠定基础。     

Comparative immunogenicity of M. hyopneumoniae NrdF encoded in different expression systems delivered orally via attenuated S. typhimurium aroA in mice

The Mycoplasma hyopneumoniae ribonucleotide reductase R2 subunit (NrdF) gene fragment was cloned into eukaryotic and prokaryotic expression vectors and its immunogenicity evaluated in mice immunized orally with attenuated Salmonella typhimurium aroA CS332 harboring either of the recombinant expression plasmids. We found that NrdF is highly conserved among M. hyopneumoniae strains. The immunogenicity of NrdF was examined by analyzing antibody responses in sera and lung washes, and the cell-mediated immune (CMI) response was assessed by determining the INF-gamma level produced by splenocytes upon in vitro stimulation with NrdF antigen. S. typhimurium expressing NrdF encoded by the prokaryotic expression plasmid (pTrcNrdF) failed to elicit an NrdF-specific serum or secretory antibody response, and IFN-gamma was not produced. Similarly, S. typhimurium carrying the eukaryotic recombinant plasmid encoding NrdF (pcNrdF) did not induce a serum or secretory antibody response, but did elicit significant NrdF-specific IFN-gamma production, indicating induction of a CMI response. However, analysis of immune responses against the live vector S. typhimurium aroA CS332 showed a serum IgG response but no mucosal IgA response in spite of its efficient invasiveness in vitro. In the present study we show that the DNA vaccine encoding the M. hyopneumoniae antigen delivered orally via a live attenuated S. typhimurium aroA can induce a cell-mediated immune response. We also indicate that different live bacterial vaccine carriers may have an influence on the type of the immune response induced.     

Prokaryotic Expression and Immunogenicity Analysis of Epitope Domain of NSP2 of Porcine Reproductive and Respiratory Syndrome Virus

This experiment was conduced to express and purify the recombinant NSP2 protein of PRRSV. The NSP2 gene was amplified using PCR method, and then it was subcloned into pET-28a(+) vector and expressed in E.coli. The molecular weight of the recombinant protein was 29 ku. The result of SDS-PAGE indicated that the expression efficiency of the recombinant protein was induced by 1 mmol/L IPTG for 8 h at 37 ℃.Western blotting result showed that the recombinant protein had high immunogenicity and could be recognized with positive serum of PRRSV. In this study, we expressed and purified the recombinant NSP2 protein of PRRSV, and the results laid the foundation for the further development of ELISA methods coated with NSP2 protein.     

猪繁殖与呼吸综合征病毒NSP2抗原表位区的原核表达及免疫原性分析

试验旨在表达纯化猪繁殖与呼吸综合征病毒NSP2重组蛋白。利用PCR技术扩增获得大小为750 bp的NSP2 226－475位氨基酸编码序列,然后将该序列亚克隆到pET-28a（+）表达载体上,通过pET-28a（+）表达载体在大肠杆菌Rosetta-gami 2（DE3）pLys中得以表达,获得大小为29 ku的重组蛋白,对重组蛋白诱导时间进行优化,SDS-PAGE显示重组蛋白在37 ℃经1 mmol/L IPTG诱导8 h时表达量最大,免疫印迹结果证实表达的蛋白能被PRRSV阳性血清识别,具有良好的免疫原性。本研究成功表达纯化了NSP2重组蛋白,为目标蛋白作为包被抗原建立检测PRRSV血清抗体的ELISA方法奠定了基础。     

应用单克隆抗体技术分析血清抗体成分的方法学研究——附56例鼻疽血清分析结果

本文建立了一种应用单克隆抗体(McAb)技术分析血清抗体成分的方法。经实验证明,本法特异性和重复性均较理想,并不受血清种属的限制。通过对56份鼻疽血清的检测,初步表明本法可用于血清抗体成分分析、血清学诊断以及观察单一抗原决定簇免疫原性等方面。     

猪瘟病毒E0蛋白的原核表达及多克隆抗体的制备

为表达猪瘟病毒E0蛋白并制备其多克隆抗体,本研究构建E0蛋白的原核表达载体,转化至BL21(DE3)菌株,IPTG诱导表达,亲和层析及切胶回收纯化重组蛋白。SDS-PAGE和Western blot分析显示E0重组蛋白主要以包涵体形式表达,亲和层析纯化获得了E0重组蛋白,用其免疫Balb/c小鼠4次制备E0重组蛋白的多克隆抗体。间接ELISA显示,免疫小鼠血清中E0蛋白抗体效价为1∶50 000。获得的E0蛋白多抗能与病毒感染细胞及E0-EGFP融合表达细胞中天然结构的E0蛋白发生特异性反应。本研究制备的E0重组蛋白及其多克隆抗体为进一步研究E0蛋白的功能和免疫原性奠定了基础。     

滑液支原体GDPD基因的原核表达、酶活性分析及亚细胞定位

为了解滑液支原体（Mycoplasma synoviae，MS）甘油磷酸二酯磷酸二酯酶（glycerophosphodoester phosphodiesterase，GDPD）的生物学功能，本试验参照GenBank中MS WVU1853株序列设计特异性引物，应用PCR技术扩增获得MS WVU1853株GDPD基因，在测序及序列分析的基础上将其克隆至pET-28a（+）质粒构建原核表达载体pET-GDPD，转化大肠杆菌BL21（DE3）感受态细胞后经IPTG诱导表达，纯化表达产物并分析其酶促活性，进而制备其多克隆抗体，应用间接ELISA和Western blotting检测其免疫原性并分析其在MS内的分布。结果表明，MS WVU1853株GDPD基因CDS全长726 bp，编码242个氨基酸，重组蛋白分子质量约为28 ku。酶促活性检测表明，重组蛋白可催化对硝基苯磷酸二钠（pNPP）转化为对硝基苯酚，且其作用的最适pH为9.0，最佳温度为37℃，Pb²⁺具有较强的抑制作用，而Ca²⁺对其具有较强的促进作用。间接ELISA及Western blotting检测结果表明，MS GDPD具有良好的免疫原性，可刺激新西兰兔产生高水平的抗体，血清效价高达1：160000；亚细胞定位结果表明，MS GDPD在细胞膜和细胞浆内均有分布，但在细胞膜的含量略高于细胞浆。本研究结果为探究MS GDPD生物学功能提供了一定的参考依据。     

Adjuvant anthracycline‐based vs metronomic chemotherapy vs no medical treatment for dogs with metastatic splenic hemangiosarcoma: A multi‐institutional retrospective study of the Italian Society of Veterinary Oncology

Treatment options for dogs with metastatic (stage III) splenic hemangiosarcoma are limited. A doxorubicin‐based chemotherapy regimen is commonly administered; however, there are no published data to support this practice. The aim of this study was to investigate the impact of maximum‐tolerated‐dose chemotherapy (MTD), metronomic chemotherapy (MC) and no adjuvant treatment on outcome in dogs with stage III splenic hemangiosarcoma undergoing splenectomy. Medical records of dogs with stage III splenic hemangiosarcoma that underwent splenectomy followed by MTD chemotherapy, MC or no adjuvant treatment were retrieved. Time to progression (TTP), survival time (ST) and toxicity were evaluated. One hundred three dogs were identified: 23 received adjuvant MTD, 38 MC and 42 were not medically treated. Overall median TTP and ST were 50 (95% confidence interval [CI], 39‐61) and 55 days (95% CI, 43‐66), respectively. Dogs treated with adjuvant MTD had a significantly longer TTP and ST compared with dogs receiving MC (median TTP, 134 vs 52 days, P = .025; median ST, 140 vs 58 days, P = .023, respectively). Dogs treated by splenectomy only had the shortest median TTP (28 days) and ST (40 days). However, treatment‐related adverse events (AEs) were significantly more frequent in the MTD group (P = .017). The outcome for dogs with metastatic splenic hemangiosarcoma is poor. While MTD showed greater efficacy compared to MC, toxicity was higher in this group. Treatment‐related AEs need to be carefully balanced against this modest survival prolongation when offering adjuvant MTD to dogs with advanced stage hemangiosarcoma.     

Prokaryotic Expression and Immunogenicity Analysis of N Protein from Vesicular Stomatitis Virus

This study was aimed to clone and express the specific antigen nucleoprotein (N) of vesicular stomatitis virus (VSV), and then purify and analyze its immunogenicity. Based on published VSV genome N gene sequence in GenBank, two kinds of N genes of VSV with different serotypes were synthesized, respectively. After sequence analysis, one pair of specific primers was designed and synthesized, N gene fragment with about 1 300 bp length was amplified by PCR, and subcloned into pCold Ⅰ expression vector. The recombinant N protein was induced with IPTG and purified by Ni-NTA. The results of SDS-PAGE showed that the N gene was successfully expressed in E. coli and the molecular weight of protein was 50 ku; The results of Western blotting showed that this recombined protein specifically reacted with polyclonal antibody serum of VSV. The recombinant vector with VSV-IND and VSV-NJ were successfully constructed, and the N protein was solubly expressed in E. coli, and the purified protein demonstrated promising immunogenicity.     

水泡性口炎病毒N蛋白原核表达及免疫原性分析

本研究旨在克隆和表达水泡性口炎病毒（vesicular stomatitis virus,VSV）特异性抗原N蛋白,进而纯化并分析其免疫原性。根据GenBank中已发表的VSV基因组N基因序列,分别合成VSV两种不同血清型的N基因,经序列对比分析后,设计合成1对特异性引物,PCR扩增获得约1 300 bp的N基因片段,将目的片段亚克隆至pCold Ⅰ原核表达载体中,经IPTG诱导表达后,采用Ni-NTA树脂亲和层析法纯化重组N蛋白。SDS-PAGE分析表明,N基因在大肠杆菌中得到表达,蛋白大小约为50 ku;Western blotting检测结果表明,该重组蛋白与VSV多克隆抗体发生特异性反应。本试验成功构建了VSV-IND和VSV-NJ的原核表达载体,实现了N蛋白在大肠杆菌中的可溶性表达,纯化后的重组蛋白具有良好的免疫原性。     

应用噬菌体展示技术筛选兔出血症病毒抗原模拟表位

以抗兔出血症病毒(RHDV)的单克隆抗体A3c作为靶物质,应用噬菌体展示技术筛选RHDV抗原表位。将纯化的单抗A3c包被固相载体,经3轮亲和筛选后,挑取25株噬菌体单克隆并扩增,用ELISA测定后,提取阳性克隆单链DNA并测序,用阳性噬菌体克隆免疫小鼠制备高免血清,检测筛选抗原表位的免疫原性。结果表明:3轮亲和筛选后,特异性噬菌体克隆得到了有效富集,25株噬菌体单克隆中有19株为阳性克隆;测序结果表明,获得了与抗原高度同源的序列GTDDMDPGTTAA,即抗原的模拟表位,其中,氨基酸基序DXXDP为表位中的核心氨基酸;制备的小鼠高免血清与抗原具有较好的反应性,阳性噬菌体克隆与兔RHDV高免血清也具有较好的反应性。因此,该表位具有良好的免疫原性和反应原性。该研究为RHDV抗原表位的研究和新型疫苗的探索积累了资料。     

动物组织中四环素类抗生素残留的ELISA检测研究——土霉素抗体的制备

四环素类抗生素属小分子半抗原物质 ,必须与大分子物质结合才能产生免疫原性。本试验采用重氮化法合成土霉素 牛血清白蛋白 (BSA OTC)及土霉素 鼠血清白蛋白 (RSA OTC)人工抗原 ,用紫外扫描对其进行鉴定。以BSA OTC免疫家兔制备抗血清 ,以RSA OTC为包被抗原 ,采用双向免疫扩散法和ELISA方法对抗血清进行鉴定。结果表明用重氮化法合成的人工抗原对四环素类药物有特异的抗原抗体反应 ,抗血清效价达 1 2 8× 1 0 5,完全能够满足四环素类药物残留的ELISA检测要求     

H9N2亚型猪流感病毒血凝素基因的表达及LAT诊断方法的研究

根据H9N2亚型猪流感病毒血凝素基因序列设计并合成引物,从本室分离保存的H9N2亚型猪流感病毒中扩增出血凝素基因,并将其克隆进pMD18-T载体,限制性酶切及序列测定后,进一步将其信号肽缺失并亚克隆到pGEX-KG中,使其在E.coli BL21（DE3）中与GST融合表达。SDS-PAGE显示表达的融合蛋白的相对分子质量约为90 000。Western印迹表明表达的蛋白质具有免疫学活性。表达产物位于包涵体中,包涵体经变性、复性处理,利用复性产物作为抗原,经碳二亚胺（EDAC）将表达产物和羧基化的乳胶共价偶联,建立了H9亚型猪流感病毒抗体的乳胶凝集试验的检测方法,结果表明,应用HA重组蛋白作为诊断抗原具有特异性强、敏感性高、重复性好的特点,可用于H9亚型猪流感抗体水平监测、流行病学调查和现地疫病普查。