猪流行性腹泻病毒流行株S蛋白高变区B细胞线性表位肽的鉴定

【背景】对猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV)经典毒株与流行毒株S蛋白氨基酸序列比对显示,变异位点主要集中在S蛋白的N端。【目的】鉴定PEDV流行毒株S蛋白高变区(S10A,1-496 aa)的B细胞线性表位肽,特别是流行毒株特异性B细胞表位肽。【方法】以SDS-PAGE割胶纯化大肠杆菌表达的PEDV流行株SD2014 S蛋白高变区片段(S10ASD2014),免疫新西兰大白兔制备多克隆抗体;在E. coli中谷胱甘肽巯基转移酶(Glutathione S-transferase,GST)融合表达覆盖S10ASD2014序列全长且彼此重叠8个氨基酸残基的系列16肽。以制备的抗S10ASD2014多抗为一抗,通过Western blot筛选系列16肽中的阳性反应性16肽,鉴定S10ASD2014上的B细胞线性表位肽;利用抗PEDV经典毒株(CV777)S蛋白高变区片段(S10ACV777)多抗血清鉴定S10ASD2014上的保守性B细胞线性表位肽。【结果】重组表达的S10ASD2014相对分子质量约为72 kD;纯化的S10ASD2014表位肽能被PEDV阳性血清识别。制备的抗S10ASD2014多抗可以识别PEDV DR13弱毒株。利用抗S10ASD2014血清和抗S10ACV777血清从61个GST融合表达的16肽中鉴定到28个阳性反应16肽,其中13个为2种血清共同识别16肽。对24株PEDV不同亚群代表毒株的对应区域进行同源性分析表明2个阳性16肽为保守性表位肽。【结论】确定了PEDV流行株SD2014 S蛋白高变区的B细胞线性表位肽,B细胞线性表位肽,特别是流行毒株特异性表位肽的确定有助于了解S蛋白的结构与功能,为建立以表位为基础的PEDV感染检测方法打下良好基础。     

猪流行性腹泻病毒S蛋白胞内区线性B细胞表位最小基序鉴定

[背景] S蛋白是猪流行性腹泻病毒（Porcine Epidemic Diarrhea Virus,PEDV）的主要结构蛋白和免疫原性蛋白,在前期的研究中,本课题组在S蛋白的胞内区鉴定到2个包含线性B细胞表位的短肽。[目的] 鉴定PEDV S蛋白胞内区线性B细胞表位的最小基序。[方法] 原核表达2个短肽的每次后移1个氨基酸的系列8肽,以兔抗S蛋白血清为一抗,通过Western Blot筛选阳性反应8肽,鉴定S蛋白胞内区线性B细胞表位的最小基序。[结果] S蛋白胞内区的2个包含线性B细胞表位的短肽共享一个表位,该表位的最小基序为¹³⁷¹QPYE¹³⁷⁴。同源性分析显示该B细胞表位基序为保守性表位。[结论] 确定了S蛋白胞内区线性B细胞表位的最小基序为¹³⁷¹QPYE¹³⁷⁴;S蛋白抗原表位的鉴定有助于提高对其结构和功能的理解。     

猪流行性腹泻病毒S蛋白主要抗原表位区的原核表达及间接ELISA检测方法的建立

【目的】建立一种快速、特异、敏感的检测血清中猪流行性腹泻病毒(PEDV)抗体的方法。【方法】利用生物学软件对PEDV S蛋白进行抗原位点分析,选择S蛋白的主要抗原表位区进行原核表达。采用SDS-PAGE和Western-blot对重组蛋白进行鉴定及抗原性分析。用纯化的重组蛋白作为包被抗原,经过条件优化、特异性和重复性试验,建立一种针对血清中PEDV抗体的间接ELISA检测方法。【结果】表达了重组S蛋白,重组的S蛋白能与PEDV阳性血清发生特异性反应,并建立一种基于重组S蛋白的间接ELISA检测方法。组内及组间变异系数均小于10%,重复性较好。建立的间接ELISA检测方法分别与商品化PEDV抗体检测试剂盒和Western-blot鉴定结果相比,两者符合率分别为86.67%和88.89%。【结论】建立的间接ELISA方法可以用于PEDV抗体的检测。     

PEDV S蛋白B细胞抗原表位的筛选和鉴定

以猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)S基因的免疫优势区S1(1～2367bp)为靶基因,利用基于gⅢ表达外源多肽的fd丝状噬菌体展示系统,构建S1基因噬菌体展示肽库,以纯化病毒制备的兔抗PEDV多克隆血清为靶蛋白,对S1基因噬菌体展示肽库进行3轮生物淘选,结果获得3个高亲和力的序列,分别命名为S1P1(248～280位氨基酸)、S1P2(442～499位氨基酸)和S1P3(697～742位氨基酸).ELISA和蛋白质印迹结果显示,S1P1、S1P2和S1P3短肽都能被兔抗PEDV多克隆血清识别,其中S1P3反应性最强.为了进一步揭示S1P1、S1P2和S1P3短肽的抗原性,制备了3个短肽GST融合蛋白和它们串连后GST融合蛋白的单因子血清,间接免疫荧光试验(IFA)结果证实,抗S1P2-GST、S1P3-GST和S1P123-GST融合蛋白的单因子血清能够识别Vero细胞培养物中天然的PEDV.     

猪δ冠状病毒(PDCoV)N蛋白的原核表达及多克隆抗体制备

旨在表达和纯化猪δ冠状病毒(PDCoV)N蛋白并制备该蛋白的多克隆抗体。以RT-PCR扩增PDCoV N基因并与表达载体pET-28a构建重组质粒,转化Transetta(DE3)菌株诱导表达,SDS-PAGE鉴定融合蛋白表达,以纯化的N蛋白免疫家兔制备多克隆抗体,Western blot验证兔抗血清特异性,间接ELISA测定抗血清效价。利用间接免疫荧光试验(IFA)、免疫荧光试验(IF)、流式细胞术(FCM)鉴定其诊断应用价值。重组N蛋白为可溶性表达,大小约为44 kD,制备的兔抗N蛋白抗体效价可达1∶204 800。IFA与FCM试验证实该抗体能与PDCoV特异性结合,与PEDV及TGEV无交叉反应,IF试验表明该抗体可用于检测小肠组织中的PDCoV。     

猪肺炎支原体Mhp366-N蛋白多克隆抗体的制备及应用

【背景】猪肺炎支原体是猪的一种重要的病原。该菌的研究工具较少,特别是缺少开展其致病机制研究需要的抗体。【目的】制备猪肺炎支原体Mhp366-N蛋白抗体并确定其应用范围和使用时的最佳稀释倍数。【方法】Escherichia coli BL21(DE3)-pET28a(+)-mhp366-N重组菌诱导表达Mhp366-N蛋白并纯化。纯化的蛋白免疫小鼠制备多克隆抗体。用免疫印迹和免疫荧光方法检测猪肺炎支原体AH株感染3D4/21细胞后的Mhp366蛋白,确定2种方法中Mhp366-N多克隆抗体的最佳稀释倍数;之后检测临床采集的猪肺泡巨噬细胞中的猪肺炎支原体;最后以免疫组化试验检测猪肺炎支原体感染的肺细胞。【结果】纯化的Mhp366-N蛋白纯度超过85%,免疫小鼠制备的抗血清效价在1:128 000-1:512 000之间。在免疫印迹试验中Mhp366-N多克隆抗体的最佳工作浓度为1:100 000稀释,免疫荧光试验中Mhp366-N多克隆抗体的工作浓度范围在1:1 000-1:10 000 000,其可用于临床采集的猪肺泡巨噬细胞和细胞系中猪肺炎支原体的检测。免疫组化试验结果显示猪肺炎支原体能够进入猪肺泡巨噬细胞、Ⅰ型和Ⅱ型肺泡上皮细胞。【结论】制备的Mhp366-N多克隆抗体为猪肺炎支原体致病机制研究提供了良好的研究工具。     

人细小病毒B19 VP1u多克隆抗体的制备及其保守区外N端氨基酸对sPLA2活性影响的初步研究

【目的】制备人细小病毒B19-VP1u的多克隆抗体,探究VP1u多克隆抗体及其保守区外N端氨基酸对病毒磷脂酶A2活性的影响。【方法】首先通过分子克隆方法构建相应原核表达载体;利用原核表达系统纯化含MBP标签的VP1u全长及N端系列截短突变融合蛋白;接着免疫新西兰大白兔制备全长VP1u蛋白的多克隆抗体;最后利用磷脂酶A2活性检测试剂盒检测了纯化蛋白的磷脂酶A2活性。【结果】Western blot及免疫荧光实验证实制备的多克隆抗体具有较高的特异性;磷脂酶A2活性检测发现全长VP1u-MBP融合蛋白具有一定的活性,该活性可以被VP1u的抗体抑制;N端保守区外截短系列蛋白的酶活检测发现,N端截掉12个氨基酸时酶活降低53%,截掉67个氨基酸时酶活性几乎完全丧失。【结论】首次发现VP1u保守区外N端氨基酸,尤其是第12个氨基酸前的区域以及第22-67个氨基酸之间的区域,对sPLA2活性的保持具有重要意义,推测该区域可能对维持正常的蛋白构象起重要的作用;而其特异性多克隆抗体的制备也为进一步研究B19病毒VP1u在病毒复制周期的作用奠定基础。     

西藏株小反刍兽疫病毒H蛋白的原核表达及其多克隆抗体的制备

【背景】小反刍兽疫是由小反刍兽疫病毒(Peste des petits ruminants virus,PPRV)引起的一种急性、烈性、接触性传染病,严重威胁我国养羊业的发展。【目的】原核表达PPRVH蛋白,并制备其多克隆抗体。【方法】根据GenBank中PPRV西藏株h基因序列,对其进行密码子大肠杆菌偏爱性优化,采用两步PCR法全化学合成全长h基因。将测序验证正确的h基因克隆至原核表达载体pET-28a、pET-30a、pET-32a,转化E. coli BL21(DE3)并利用IPTG诱导H蛋白表达。以经SDS-PAGE割胶纯化的重组H蛋白免疫新西兰大白兔制备抗PPRV H蛋白多克隆抗体。【结果】重组E. coli [pET-28a(-30a,-32a)-H]表达的重组H蛋白相对分子质量分别约为70、68和86 kD;诱导7 h时PRRV H蛋白表达量最高,而且主要以包涵体形式表达;重组E.coli(pET-30a-H)表达的H蛋白经SDS-PAGE割胶纯化后免疫新西兰大白兔制备的多抗血清能与表达的重组H蛋白发生特异性反应;ELISA法检测抗体效价在1:6400-1:25600之间。【结论】原核表达了PPRVH蛋白,并制备了高效价的抗H蛋白多克隆抗体,为进一步研究PPRV H蛋白的功能及H蛋白的线性B细胞表位作图奠定了基础。     

果蝇凋亡蛋白Strica的原核表达、多克隆抗体的制备及在放线菌酮诱导下的激活状态检测

【目的】细胞凋亡是真核生物中保守的细胞程序化死亡,由蛋白酶caspase介导。Strica是果蝇Drosophila中一个特殊的caspase,至今未有其商品化抗体且生化功能未知。本研究旨在通过克隆、原核表达纯化果蝇Strica蛋白并制备其多克隆抗体来初步研究其功能。【方法】根据果蝇Strica的基因序列构建原核表达载体并转化至大肠杆菌Escherichia coli BL21(DE3)感受态细胞,表达Strica蛋白;将表达纯化后的Strica蛋白免疫家兔制备多克隆抗体;通过间接ELISA和Western blot分别测定抗体效价和灵敏度;利用前期构建的过表达载体pAc5-V5-Strica进行转染果蝇S2细胞,设计合成siRNA进行RNAi验证该抗体的特异性;利用该抗体通过免疫荧光实验检测Strica在果蝇S2细胞中的亚细胞定位;利用该抗体通过Western blot实验探究放线菌酮(10 μg/mL)处理后果蝇S2细胞中Strica蛋白的激活状态。【结果】获得了果蝇Strica重组蛋白;ELISA检测Strica抗体的效价大于1∶25 600;Western blot鉴定该抗体在1∶10 000的稀释度下能与重组蛋白反应;该抗体可以检测到S2细胞中过表达以及内源性Strica蛋白;Strica蛋白在S2细胞质中呈现散点分布;放线菌酮介导Strica蛋白的切割激活。【结论】成功制备了兔抗果蝇Strica多克隆抗体。Strica响应凋亡刺激物放线菌酮激活,推测Strica参与果蝇的细胞凋亡过程。本研究为进一步深入研究Strica的功能奠定了实验基础。     

猪FcγRIII的原核表达及多克隆抗体的制备

目的：构建猪FcγRIII 基因的原核表达载体,诱导表达重组蛋白,制备鼠抗猪 FcγRIII 抗血清。方法：从质粒pTG19-T-FcγRIII中用PCR方法克隆到编码完整猪FcγRIII蛋白分子的基因片段,将其插入到原核表达载体pET-32a中,构建了猪FcγRIII 原核表达载体pET-FcγRIII ,转化大肠杆菌BL21 (DE3) ,IPTG诱导蛋白表达,经尿素洗涤纯化后,以纯化后的融合蛋白FcγRIII-His 为抗原免疫小鼠,获得抗血清。Western blotting、ELISA 法鉴定获得的抗血清,ELISA 结果显示抗体效价为1∶16000,具有高度特异性,免疫印迹结果显示制备的多抗可以与重组猪FcγRIII蛋白特异性结合。结果：成功构建猪FcγRIII原核表达载体,纯化到融合蛋白FcγRIII-His,用纯化的融合蛋白免疫小鼠制备了多克隆抗体,Western blotting、ELISA 法证实多克隆抗体制备成功。结论：成功获得了猪 FcγRIII 多克隆抗体,为进一步研究猪FcγRIII 蛋白的功能奠定了基础。     

Development and Application of an ELISA for the Detection of Porcine Deltacoronavirus IgG Antibodies

Porcine deltacoronavirus (PDCoV), also known as porcine coronavirus HKU15, was first detected in North America in early 2014 and associated with enteric disease in pigs, resulting in an urgent need to further investigate the ecology of this virus. While assays detecting nucleic acids were implemented quickly, assays to detect anti-PDCoV antibodies have not been available. In this study, an indirect anti-PDCoV IgG enzyme-linked immunosorbent assay (ELISA) based on the putative S1 portion of the spike protein was developed and utilized to determine the prevalence of anti-PDCoV IgG in U.S. pigs. The diagnostic sensitivity of the PDCoV ELISA was 91% with a diagnostic specificity of 95%. A total of 968 serum samples were tested including samples with confirmed infection with PDCoV, porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus or porcine respiratory coronavirus. There was no cross-reactivity with any of the other coronaviruses. Among 355 arbitrarily selected serum samples collected in 2014 and originating from 51 farms across 18 U.S. states, anti-PDCoV IgG antibodies were detected in 8.7% of the samples and in 25.5% of the farms whereas anti-PEDV IgG was detected in 22.8% of the samples and in 54.9% of the farms. In addition, anti-PDCoV IgG antibodies were detected in archived samples collected in 2010, perhaps indicating an earlier undetected introduction into the U.S. pig population. Overall, the obtained data suggest that PDCoV seroprevalence in U.S. pigs is lower compared to PEDV and PDCoV may have been introduced to the U.S. prior to PEDV.     

猪流行性腹泻病毒CH/JL毒株S基因的克隆、序列分析及线性抗原表位区的鉴定

以猪流行性腹泻病毒CH/JL毒株的RNA为模板,通过RT-PCR扩增获得的3个相互重叠的cDNA克隆覆盖了S基因,序列比对结果表明:PEDV CH/JL株S基因与CV777、Brl/87、JS、KPEDV和Chinju99毒株S基因核苷酸序列的同源性分别为96.97%、96.87%、96.41%、94.02%和93.93%,氨基酸序列的同源性分别为96.17%、95.88%、96.10%、92.36%和92.05%;分子进化树分析结果显示,PEDV CH/JL株S基因与JS毒株S基因亲缘关系最近,处于同一群。利用DNAstar Protean程序预测了PEDV CH/JL株S蛋白一个抗原表位区(83~276aa),将其克隆到原核表达载体pGEX-6p-1后转化E.coliBL21(DE3)感受态细胞,在终浓度1.0mmol/L的IPTG诱导下获得了表达,Western blot结果显示,预测的抗原表位区GST融合蛋白能与猪流行性腹泻病毒多克隆抗血清反应,提示该抗原表位区含有线性抗原表位。     

表达PEDV S和PoRV VP7蛋白的重组伪狂犬毒株构建

【背景】猪流行性腹泻、猪轮状病毒病与猪伪狂犬病是严重危害全球养猪业的3种重要传染病,混合感染往往导致猪场更严重的损失。【目的】利用同源重组技术构建共表达猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV) S蛋白和猪轮状病毒(Rotavirus,PoRV) VP7蛋白的猪伪狂犬三联基因工程疫苗株,并研究其部分生物学特性。【方法】通过序列比对、蛋白结构分析筛选s基因的475?804 aa和vp7基因的17?339 aa作为毒株构建的目的片段,依次构建了pMD-S、pMD-VP7、pMD-VP7.S克隆载体和pEGFP-VP7.S转移载体。将质粒pEGFP-VP7.S和PRV XJ亲本株同源重组,空斑纯化得到重组毒株PRV (CM),对其稳定性和增殖特性进行研究。【结果】构建了共表达S蛋白和VP7蛋白的伪狂犬基因工程病毒,连续传代20次,均能检测到vp7和s基因,而gE基因阴性;Western blotting证实2种外源基因在重组病毒中均能实现良好的表达;测定亲本毒株和重组毒株的TCID50分别是10?7.59/0.1 mL和10?7.25/0.1 mL。【结论】获得了伪狂犬基因工程重组弱毒株PRV (CM),外源基因稳定存在,毒力基因稳定缺失,增殖特性差异不大,为PRV、PEDV和PoRV基因工程三联苗研究奠定了基础。     

Porcine Epidemic Diarrhea Virus RNA Present in Commercial Spray-Dried Porcine Plasma Is Not Infectious to Na?ve Pigs

Porcine epidemic diarrhea virus emerged in North America in April 2013 and has since been identified in 30 U.S. States, Canada and Mexico. The rapid spread of PEDV has raised concerns about the role of feed and particularly pork-by-product components such as spray-dried porcine plasma (SDPP) in PEDV transmission. The aim of this study was to determine the infectivity of PEDV RNA present in commercial SDPP. Specifically, 40 3-week-old PEDV naïve pigs were randomly assigned to one of five treatment groups. At day post inoculation (dpi) 0, NEG-CONTROL pigs were sham-inoculated, PEDV-CONTROL pigs received cell culture propagated PEDV, and SDPP-CONTROL pigs were switched to a diet with 5% SDPP containing 5.1±0.1 log₁₀ PEDV RNA copies/g. To evaluate a potential positive effect of anti-PEDV antibodies in SDPP on PEDV challenge, four days prior to PEDV challenge the pigs in the SDPP-PEDV group were switched to and remained on a 5% SDPP diet through dpi 28. Another group, EGG-PEDV, was orally administered a commercial egg-derived liquid PEDV globulin product from dpi -4 through 6. All PEDV-CONTROL pigs began shedding PEDV in feces by dpi 3 and seroconverted between dpi 7 and 14, whereas pigs in NEG-CONTROL and SDPP-CONTROL groups remained PEDV RNA negative and did not seroconvert to PEDV for the study duration. This indicates no evidence of infectivity of the PEDV RNA in the SDPP lot utilized. Furthermore, under the study conditions SDPP or egg-derived liquid PEDV globulin addition did not significantly alter PEDV-shedding or overall disease course after experimental challenge.     

Production of antibodies to the alpha7-subunit of human acetylcholine nicotinic receptor with the use of immunoactive synthetic peptides

Potential B epitopes and T-helper epitopes in the N-terminal extracellular domain of the alpha7-subunit of human acetylcholine receptor (AChR) were theoretically calculated in order to reveal peptides that can induce the formation of specific antibodies to this domain. Four peptides structurally corresponding to four alpha7-subunit regions containing 16-23 aa and three of their truncated analogues were synthesized. Rabbits were immunized with both free peptides and protein conjugates of their truncated analogues, and a panel of antibodies to various exposed regions of the N-terminal extracellular domain of the AChR alpha7-subunit was obtained. All of the four predicted peptides were shown to induce the production of antipeptide antibodies in free form, without conjugation with any protein carrier. The free peptides and the protein conjugates of truncated analogues induced the formation of almost equal levels of antibodies. Most of the obtained antisera contained antibodies that bind to the recombinant extracellular N-terminal domain of the rat AChR alpha7-subunit and do not react with the analogous domain of the alpha1-subunit of the ray Torpedo californica AChR.