以重组mE2蛋白为抗原建立检测猪瘟病毒抗体间接ELISA方法 …

以在Ｅ．ｃｌｏｉ高效表达的猪瘟病毒Ｅ２基因主要抗原编码区为抗原，以辣根过氧化物酶标记的兔抗猪ＩｇＧ为二抗，建立了检测猪瘟病毒抗体的间接ＥＬＩＳＡ方法。经检测筛选出最佳反应条件为；１．２μｇ／孔纯化的Ｅ．ｃｏｌｉ表达的ｍＥ２重组蛋白包被酶标板，用１０％的兔血清或马血清进行封闭，以正常Ｅ．ｃｏｌｉ裂解上清液稀释待检血清。     

检测猪瘟抗体的PPA—ELISA诊断试剂盒的制备,标化和应用的研究

以猪瘟兔化毒接种猪肾细胞（ＰＫ－１５细胞系）,提取细胞培养物进行纯化,以纯化病毒抗原和酶标葡萄球菌Ａ蛋白探索建立了检测猪瘟病毒抗体的ＰＰＡ－ＥＬＩＳＡ方法,其最佳工作条件为：抗原包被浓度为２μｇ／ｍＬ,酶标Ａ蛋白浓度１：３０,底物作用时间３０ｍｉｎ。经对不同血清的检验,本法有较高的特异性和敏感性,同时本试验也证明ＥＬＩＳＡ与ＩＨＡ检测结果具较高相关性。     

非洲猪瘟间接ELISA诊断试剂盒的研究

用带有编码非洲猪瘟病毒衣壳蛋白Ｐ７２ 基因的重组杆状病毒（Ｂａｃｐ７２）作载体,在ｓｆ９细胞中表达并得到重组Ｐ７２蛋白,ＳＤＳ－ＰＡＧＥ可得到分子量在 ７２ｋＤａ左右的电泳带。用标准阳性非洲猪瘟血清对 Ｐ７２蛋白进行 ＥＬＩＳＡ检测,证明该蛋白具有生物学活性。用Ｐ７２作为间接法的包被抗原,对ＥＬＩＳＡ反应条件进行了优化。确定最佳包被液为ＰＢＳ（ｐＨ７．２）、最佳封闭液为１％ＰＣＴ、最佳血清稀释液为４％ＰＥＧ６０００／ＰＢＳ、最佳冲洗液为０．５Ｍ ＮａＣｌ／０．５％Ｔｗｅｅｎ－２０／ＰＢＳ（ｐＨ７．２）。本实验反应体系采用５０μｌ的微量法,可节约试剂及抗原。反应在２小时内即可完成,达到了快速诊断的目的。包被了抗原并用封闭液封闭后的酶标板密封后保存于－２０℃的冰箱中,至少可以保存５个月。阻断试验和交叉试验表明ＥＬＩＳＡ法有良好的特异性。间接ＥＬＩＳＡ比Ｄｏｔ－ＥＬＩＳＡ法具有更高的灵敏性。血清学调查没有得到阳性结果,与我国实际情况相符。用Ｂａｃｐ７２表达的非洲猪瘟病毒Ｐ７２蛋白抗原作为间接ＥＬＩＳＡ的检测抗原来检测非洲猪瘟血清具有快速、简单、无感染的特点。本实验为非洲猪瘟ＥＬＩＳＡ检测试剂盒的最终组装提供了实验依据。     

狂犬病病毒糖蛋白基因在原核细胞中的表达

将狂犬病病毒糖蛋白（ＲＶｇｐ）基因ＢｇｌⅡ片段（１６７５ｂｐ）分别正向插入到原核高效表达载体ｐＥＴ－１７ｂ和ｐＥＴ－１７ｂ２（用ＳａｃⅠ－ＮｄｅⅠ缺失掉ｐＥＴ－１７ｂ６０ｂｐ含起始密码子ＡＴＧ小片段）的ＢａｍＨⅠ切点，构建重组质粒ｐＥＴ－１７ｂＲＶｇｐ和ｐＥＴ－１７ｂ２ＲＶｇｐ。将其分别转化表达受体菌Ｅ．ｃｏｌｉＢＬ２１（ＤＥ３）和Ｅ，ｃｏｌｉＢＬ２１（ＤＥ３）ｐｌｙｓＳ．ＩＰＴＧ诱导表达，菌体经超声波裂解处理后ＳＤＳ－ｐＡＧＥ，染色，在分子量约６００００处可见重组质粒表达的较宽的蛋白带，以抗ＲＶｇｐＭｃＡｂ进行Ｗｅｓｔｅｒｎ－ｂｌｏｔ检测，表明该表达蛋白为ＲＶｇｐ。通过扫描显示，表达的ＲＶｇｐ占菌体总蛋白的１０％～１４％，其中ｐＥＴ－１７ｂ２ＲＶｇｐ在Ｅ。ｃｏｌｉＢＬ２１（ＤＥ３）中的表达量最高。     

鸡致病性埃希氏大肠杆菌不同菌株间同源性抗原的研究

通过兔制备了３株引起鸡败血症的埃希氏大肠杆菌（Ｅ．ｃｏｌｉ）高免血清，对分离自新疆不同地区的３０余株鸡致病性Ｅ．ｃｏｌｉ进行了玻板凝集试验和双向免疫扩散试验。结果证明，在琼扩试验中，不同的Ｅ．ｃｏｌｉ菌株间存在着同源性抗原成份，这种同源性抗原在绝大多数Ｅ．ｃｏｌｉ间都有数种之多。但是，这种相互间的同源抗原在玻板凝集试验中有时并不能表现，甚至有沉淀线出现的血清与抗原之间在玻板凝集试验中也不能检测出来。     

猪生殖与呼吸综合征病毒核衣壳蛋白在昆虫细胞中的表达及其用作诊断抗原的研究

对猪生殖与呼吸综合征病毒（ＰＲＲＳＶ）核衣壳蛋白（Ｎ）作为ＥＬＩＳＡ抗原进行了研究，将编码ＰＲＲＳＶＮ蛋白的基因０ＲＦ７ｃＤＮＡ插入杆状病毒表达载体ｐＢｌｕｅＢａｃＨｉｓ２Ａ，通过同源重组获得了重组杆状病毒ＯＲＦ７－ＡｃＭＮＰＶ，感染昆虫细胞ＳＦ９表达了Ｎ蛋白，占细胞总蛋白的７．０７％，纯化后作为抗原建立了间接ＥＬＩＳＡ，与ＩＤＥＸＸ公司的ＥＬＩＳＡ诊断试剂盒有９６％的符合率，与ＩＦＡ有１００％的符合率。试验证实：ＰＲＲＳＶＮ蛋白在昆虫细胞中得到高效表达且是检测ＰＲＲＳＶ抗体的良好抗原。     

猪瘟病毒表面抗原E2基因的克隆与原核表达

为获得可用于诊断的猪瘟病毒(Classical swine fever virus,CSFV)E2蛋白重组抗原,对CSFV-E2的多个B细胞抗原表位进行重构和表达。将人工合成的E2蛋白多抗原表位基因与p ET-28a(+)载体连接后,转化至宿主菌BL21(DE3),IPTG诱导表达,SDS-PAGE电泳分析蛋白可溶性,His亲和层析柱纯化蛋白并进行抗原性检测。重构后的猪瘟病毒E2基因多抗原表位基因大小约500 bp,PCR、双酶切鉴定结果显示与预期相符;重组蛋白为可溶性表达,大小约23 k Da;Western blot结果显示,重组蛋白可与猪瘟阳性血清发生特异性结合,具有良好的免疫反应性,可作为诊断抗原用于猪瘟病毒感染动物的血清抗体检测。     

非洲猪瘟病毒VP73蛋白主要抗原表位区的原核表达及多克隆抗体的制备

构建重组原核表达载体pET32a-VP73,将pET32a-VP73转化BL21感受态细胞,经IPTG诱导,VP73蛋白主要抗原表位区可稳定高效的表达,SDS-PAGE结果表明,IPTG终浓度为1.0 mmol/L,诱导5 h蛋白质表达量最高,表达蛋白为融合蛋白,分子质量约为42 ku。蛋白质纯化后,经SDS-PAGE及Western blotting鉴定,确定表达产物为非洲猪瘟病毒VP73主要抗原表位区融合蛋白。将纯化的蛋白质免疫新西兰大白兔,免疫前后收集血清。用间接ELISA方法测定血清抗体效价,并以非洲猪瘟阳性血清、兔免疫前后血清及猪瘟、猪繁殖与呼吸综合征、猪伪狂犬病阳性血清为一抗,确定该蛋白质的特异性。结果表明,制备的抗血清效价达到1∶1024000,能与纯化的VP73主要抗原表位区蛋白质发生反应。制备的多克隆抗体为VP73蛋白的免疫学研究和非洲猪瘟血清学诊断奠定了基础。     

检测微小隐孢子虫抗体的间接ELISA方法的建立

以在E．coli高效表达的微小隐孢子虫子孢子表面抗原CPl5／60为抗原，以辣根过氧化物酶(HRP)标记的山羊抗鼠IgG为二抗，建立了检测微小隐孢子虫抗体的间接ELISA方法。经检测筛选出最佳反应条件为1μg／孔纯化的E．coli表达的CPl5／60抗原包被酶标板，用10％的兔血清进行封闭，以正常E．coli裂解上清液稀释待检血清。结果表明应用CPl5／60重组蛋白作为诊断C．parvum抗原具有特异性高、抗原易纯化和成本低等特点。     

抗人红细胞/抗猪瘟病毒双功能单链抗体的制备及功能鉴定

旨在构建检测猪瘟病毒(CSFV)的双功能单链抗体。通过连接肽将抗人红细胞膜H抗原单链抗体基因2E8-ScFv和抗猪瘟病毒单链抗体基因CSFV-ScFv拼接成融合基因,大肠杆菌密码子优化及人工合成后,构建原核表达载体pCzn1-2E8-CSFV,转化BL21(Plyss)进行重组蛋白IPTG的诱导表达,利用SDS-PAGE对表达产物进行鉴定,通过间接免疫荧光(IFA)、ELISA和血凝试验,验证重组蛋白双功能活性。结果表明,重组蛋白主要以包涵体形式在大肠杆菌中表达,分子质量约为55 kDa。IFA和ELISA结果表明,纯化复性后的重组蛋白与猪瘟病毒具有良好的结合活性;红细胞凝集试验表明,重组蛋白能与人红细胞特异性结合,同时也能与猪瘟病毒发生特异性结合,具有双功能特性。本研究成功表达了抗人红细胞膜H抗原/抗猪瘟病毒双功能单链抗体,为进一步构建猪瘟病毒红细胞凝集试验快速检测方法奠定基础。     

重组M蛋白间接ELISA检测猪繁殖与呼吸综合征病毒抗体

用纯化的猪繁殖与呼吸综合征病毒重组M蛋白作包被抗原,建立了检测猪繁殖与呼吸综合征病毒抗体的间接ELISA方法,并确立了ELISA最佳工作条件:抗原包被浓度为3.5μg/mL,37℃1h加4℃过夜,血清(1:40)和酶标SPA(1:80)分别在37℃温育1h,加底物溶液常温显色5min。经重复性试验、交叉试验、阻断试验等试验结果表明该方法重复性好、特异性强、敏感度高;与美国IDEXX公司试剂盒相比较,特异性和敏感性分别为96.3%和93.5%,无显著性差异。用建立的方法检测临床血清样品168份,总阳性率为39.9%。     

基因重组抗原酶联免疫法检测兔出血症病毒抗体及其标准化

以重组兔出血症病毒(RHDV)VP60蛋白为抗原，建立了RHDV抗体间接ELISA检测方法。优化的试验反应务件为：重组VP60的包被质量浓度为1．0mg／L，用10％牛血清封闭，以大肠杆菌提取物稀释被检血清以消除非特异性反应。将所建立的ELISA与现行血凝抑制(HI)试验比较发现，不同免疫状态的兔血清的RHDV ELISA抗体与HI抗体均呈正相关。对11个RHD免疫兔场1130份血清样品的抗体检测表明，各免疫兔群血清RHDV抗体水平不完全一致，D值在1．09～1．76之间，显著高于非免疫兔(0．05)及SPF兔(0．02)，低于高免兔(2．34)。在此基础上，研制了RHDV抗体酶联免疫检测试剂盒，测定了其主要指标，制定了各成分的质量控制标准，为兔群进行免疫学监测及评价疫苗的免疫效果提供了便利。     

Effect of pooling bovine fecal samples on the sensitivity of detection of E. coli O157:H7

To assess the effect of pooling fecal samples on the sensitivity of detection of E. coli O157:H7, 12 calves, inoculated orally with 10(8)cfu per calf of nalidixic acid resistant E. coli O157:H7, were used to provide positive fecal samples. After inoculation, calves were sampled twice weekly. Negative fecal samples were from calves at a local dairy. Samples from inoculated calves were incubated without pooling or were mixed with known negative fecal samples in a 1:4 ratio or a 2:3 ratio (positive:negative) for detection of E. coli O157:H7. Samples were enriched 6h in Gram negative broth with vancomycin, cefixime, and cefsoludin, underwent immunomagnetic separation with Dynabeads, and were plated onto sorbitol MacConkey agar with cefixime, and tellurite (SMACct). Morphologically typical colonies were plated onto blood agar, incubated overnight at 37 degrees C and an indole test was performed on each colony. Indole positives colonies were plated on SMAC agar with 20 microg/ml nalidixic acid (SMACnal). Colonies that grew on SMACnal were confirmed by O157 agglutination. Sensitivity of detection in non-pooled samples was 77%. Samples pooled 1:4 and 2:3 with negative samples were 55 and 52% sensitive, respectively. Pooling decreased sensitivity of detection for E. coli O157:H7 in bovine fecal samples (P<0.01). A deterministic binomial probability model was developed to assess the probability of detecting pens of cattle shedding E. coli O157 using a pooling protocol or individual samples. Pooling decreased sensitivity of detection at low pen prevalence compared to individual samples but was similar at high prevalence.     

关中奶山羊乳房炎灭活菌苗的制备及其免疫效果测定

对自制乳房炎疫苗免疫后的抗体效价进行评估.用甲醛37℃过夜灭活大肠埃希菌、葡萄球菌,分别制备蜂胶灭活疫苗、转移因子灭活苗及无佐剂疫苗,接种泌乳期奶山羊后,分别在不同时间采集免疫羊的血清和乳汁,ELISA测定血清大肠埃希菌和葡萄球菌的抗体效价.研究结果显示,大肠埃希菌和葡萄球菌经甲醛灭活彻底;与免疫前相比,血清和乳汁中的...     

Pre-harvest factors influencing the acid resistance of Escherichia coli and E. coli O157:H7

The effects of pH, acetate, propionate, or butyrate concentration, and diet on acid resistance of fecal Escherichia coli and E. coli O157:H7 were determined by in vitro and in vivo experiments. The pH tested was from 4.0 to 8.0, and the VFA concentrations tested were 0 to 100 mM. The E. coli O157:H7 used was strain 505B. In an in vivo study, cattle were fed a grain-based diet, then either not switched or switched to a grain-based diet with 3% added calcium carbonate or two fiber-based diets (soybean hulls or hay). Acid resistance was expressed as viability after acid-shock at pH 2.0 for 1 h and 4 h for fecal E. coli and E. coli O157:H7, respectively. Enumeration methods used were multitube fermentation, agar plate, and petri-film methods. The E. coli O157:H7 was not found in continuous culture inocula or in vivo samples. The viability of fecal E. coli decreased linearly (P < 0.01) as the culture pH increased, and viability of E. coli O157:H7 was highest (P < 0.01) when cultivated at pH 6.0. The viability of fecal E. coli and E. coli O157:H7 showed quadratic responses (P < 0.05) as acetate and butyrate concentrations increased at pH 7.2, with maximal acid resistance at 20 and 12 mM, respectively. As propionate concentration increased, the acid resistance was not different (P > 0.05) for fecal E. coli. Acid resistance of E. coli was induced by acetate and butyrate, even though the environmental pH was near neutral. Similar results were measured in the in vivo study, where viability after acid shock was more dependent on VFA concentration than on pH. Increasing the dietary calcium carbonate concentration also increased (P < 0.05) acid resistance of fecal E. coli. Results from these studies demonstrated that culture pH and VFA affect acid resistance of E. coli.     

猪乙型脑炎病毒囊膜E蛋白间接ELISA诊断方法的建立与初步应用

本研究利用纯化的原核表达乙型脑炎囊膜E蛋白作为包被抗原,建立了乙型脑炎间接ELISA诊断方法。对检测的各种条件进行了优化,优化反应条件后确定的抗原最适包被浓度为2μg/mL,抗原最佳包被条件为37℃包被2 h,血清的最适稀释度为1∶160,酶标抗体最适稀释度为1∶5000,最佳封闭条件为1%BSA,阴阳性临界值判定标准为D492 nm=0.254。该方法不与猪瘟、猪繁殖与呼吸综合征、猪圆环病毒2型、猪伪狂犬病毒阳性血清反应,其D492 nm0.254,说明该方法具有良好的特异性。采用该方法对150份疑似乙型脑炎血清样品进行检测,结果显示,与某猪乙型脑炎试剂盒相比符合率为90.77%,表明建立的间接ELISA方法具有较高的敏感性和特异性,因此,本研究成功建立了能特异性检测抗乙型脑炎血清抗体的ELISA检测方法。     

Testing of a Chemiluminescence Enzyme Immunoassay for selective detection of E. Coli O157 from ground beef samples

The aim of this study was to evaluate a Chemiluminescence Enzyme Immunoassay (CLIA) developed for the detection of E. coli O157:H7, using different E. coli O157 serotypes. The sensitivity and specificity of the kit were determined from the tenfold dilutions of the 24-hour broth cultures of the test strains. According to the results obtained in this trial, the sensitivity of the kit is 10(3)-10(4) cells ml-1, and it is specific for E. coli O157. Twenty-five g ground raw beef samples were prepared and inoculated with E. coli O157:H7 at different CFU g-1. The samples were incubated in 225 ml of modified E. coli broth with novobiocin (mEC + n) at 42 degrees C for 4 h and the immunoassays were performed following the instructions of the manufacturer. According to the results obtained by the CLIA test 10(1)-10(2) E. coli O157 g-1 can be detected from the sample. So this kit seems to be suitable for screening the samples before selective cultivation of E. coli O157:H7.     

Effects of storage conditions and hemolysis on vitamin E concentrations in porcine serum and liver.

Vitamin E (alpha-tocopherol) is an antioxidant vitamin important in protecting unsaturated fatty acids in lipid membranes from peroxidation. Variation in collection, storage, and shipping conditions of samples can potentially lead to breakdown of vitamin E prior to analysis. Therefore, the purposes of this project were 1) to determine the stability of vitamin E in refrigerated and frozen porcine liver and serum and 2) to evaluate the effects of red blood cell (RBC) hemolysis on porcine serum vitamin E concentrations. Porcine liver and nonhemolyzed serum were collected and stored refrigerated or frozen. Samples were analyzed for vitamin E immediately or on days 2, 3, 7, or 14. In addition, porcine RBCs were added to normal serum at concentrations from 1 x 10(6) to 1 X 10(9) RBC/ml and hemolyzed by freeze-thaw prior to analysis for vitamin E or products of lipid peroxidation.     

Evaluation of the opsonic capacity of core lipopolysaccharide antiserum of equine origin against smooth Escherichia coli 0111:B4, using macrophage chemiluminescence

A study was performed to determine whether equine antiserum to core lipopolysaccharide (LPS) would enhance phagocytosis of smooth gram-negative (GN) organisms by equine macrophages. Five healthy adult horses (group A) were immunized with a bacterin prepared from the J-5 mutant of Escherichia coli 0111:B4 and Salmonella minnesota R595 to produce antibodies to core LPS. Five horses (group B) served as nonimmunized controls and were given physiologic saline solution instead of the rough mutant bacterin. Serum antibody titers to core LPS and to smooth E coli 0111:B4 were determined by indirect ELISA. Four serum pools were prepared: pool 1 = sera from horses in group B prior to immunization; pool 2 = sera from horses in group A prior to immunization (preimmune serum); pool 3 = sera from horses in group B, 7 days after the last saline injection; pool 4 = sera from horses in group A, 7 days after the last immunization (core LPS antiserum). The serum pools, either unheated or heated 30 minutes at 56 C, in 3 dilutions (1/50, 1/100, 1/500) were used to opsonize smooth E coli 0111:B4 in an assay of equine peritoneal macrophage chemiluminescence (CL). Peritoneal fluid was collected from clinically normal horses and the macrophages were purified by adherence to borosilicate glass scintillation vials. Each serum type and dilution was added to triplicate vials containing 10(7) colony-forming units of E coli 0111:B4. Luminol-dependent CL was measured with a liquid scintillation counter in the out-of-coincidence mode. Each serum dilution was tested in duplicate vials without bacteria to asses serum-induced nonspecific CL.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of selenium and vitamin E on antibody production by dairy cows vaccinated against Escherichia coli.

Sixty clinically healthy Holstein cows were randomly assigned to one of four groups according to their age and parity and vaccinated in late pregnancy (day 190) with a multivalent vaccine against Escherichia coli. The 15 cows in the first group (SeE) were injected intramuscularly with a solution of sodium selenite (0.1 mg Se/kg bodyweight) and vitamin E (alpha-tocopherol acetate, 8 U/kg bodyweight), the cows in the second group (Se) received only selenium and the cows in the third group (E) received only vitamin E at the same doses and by the same route of administration; the cows in the fourth group were used as controls. The vaccination and the injections of selenium and vitamin E were repeated 42 days later. The concentration of selenium in whole blood and of vitamin E in serum was determined by fluorometric methods. Specific antibody titres against E coli were determined in serum samples by ELISA. The results showed that the injection of selenium either alone or in combination with vitamin E significantly improved the production of specific antibodies against E coli, and that the production of specific antibodies was greater after the administration of selenium alone.