重组N蛋白抗原检测PRRSV抗体ELISA的研究Ⅱ.试剂盒阴阳性临界值的测定及其与IDEXX公司试剂盒的比较

对临床上采集的899份猪血清样本。用以纯化的重组N蛋白为包被抗原建立的检测猪繁殖与呼吸综合征病毒（PRRSV）抗体的间接ELISA进行检测．运用统计学方法摸清了检测结果的分布规律。并扣国外IDEXX公司PRRSV抗体检测试剂盒同时对460份血清样本进行检测。结果表明。2种方法的符合率为91．73％。利用TG—ROC软件确定了自制的ELISA酶标板（NP—ELISA）的临界值。并标定试剂盒的特异性扣敏感性均为92．6％。ELISA的结果判定标准是：当以血清样本L为标准参考阳性血清时，样品与阳性血清的比值（S／P）小于或等于0．4为阴性；S／P在0．4与0．5之间为可疑；S／P大于或等于0．5为阳性。与IDEXX公司PRRSV抗体检测试剂盒对临床样品的检测结果进行比较后，初步判定所建立的ELISA之所以出现较多的假阴性。可能是目前临床上出现了PRRSV欧洲型所致。     

An ELISA for porcine reproductive and respiratory syndrome: production of antigen of high quality.

A reliable method was developed to produce a viral antigen preparation from porcine reproductive and respiratory syndrome virus (PRRSV) infected MARC-145 cells by solubilizing the virus with Triton X-100. This method eliminated problems previously encountered with high background reactions associated with PRRSV antigen or cell control antigen. With this new antigen, an indirect enzyme-linked immunosorbent assay (ELISA) was adapted to detect swine serum anti-body against PRRSV. In the ELISA, non-specific reactions associated with test serum samples have been eliminated by utilizing an effective blocking serum diluent. The ELISA is more sensitive than an indirect immunofluorescent assay (IFA), particularly with late-infection sera, while maintaining a high diagnostic specificity. In a comparison of IFA and ELISA using sera collected from 250 pigs of various ages from 5 herds that had PRRS histories, IFA revealed 178 positive samples and 72 negative samples. All of the IFA-positive sera were proven to be ELISA reactors. However, nearly one-half (34/72) of the IFA-negative samples were also ELISA reactors. The diagnostic specificity and sensitivity of the ELISA were 100% and 96.6% with 257 serum samples collected from known healthy PRRS-negative swine herds and 57 sera collected from infected swine at 6 to 56 days after infection, respectively. The ELISA is technically superior to IFA, time-efficient and cost-effective, and suitable for testing of a large number of samples over a short period of time.     

Enzyme-linked immunosorbent assay for the detection of porcine epidemic diarrhea coronavirus antibodies in swine sera

An enzyme-linked immunosorbent assay (ELISA) for detecting serum antibodies to the porcine epidemic diarrhea coronavirus (PEDV) was established by using cell culture-grown PEDV as antigen for coating. Ultracentrifugation through 20 and 45% (w/w) sucrose cushions proved to be the best antigen purification method. Examination of 1024 swine sera showed a high specificity and a greater sensitivity of the ELISA, when compared with indirect immunofluorescence. Reference sera with high antibody titers to PEDV originated from two pigs experimentally infected with PEDV. Three different antigen purification methods and the advantages of the ELISA compared with an immunofluorescence test are discussed.     

重组M蛋白-乳胶凝集试验检测PRRS病毒血清抗体的研究

利用纯化的 PRRS病毒重组 M蛋白致敏乳胶制成乳胶抗原 ,成功地建立了一种检测 PRRS病毒血清抗体的乳胶凝集试验 (L AT)诊断方法。用制备的乳胶 M抗原分别检测猪瘟、猪伪狂犬病、猪细小病毒病、猪弓形体病、猪衣原体病、猪乙型脑炎阳性血清 ,结果均为阴性 ,无交叉反应 ,说明建立的 L AT方法具有良好的特异性。用建立的乳胶凝集试验方法与国外IDEXX公司 PRRS病毒抗体检测试剂盒同时对 76份猪血清样本进行检测 ,结果表明建立的 L AT方法的特异性和敏感性均为 95 % ,两种方法的总符合率为 87% ,检出率基本一致。研究结果表明 L AT方法具有操作简便、快速、敏感性高、特异性强、价格低廉且可用于现场检测等优点 ,是一种适合基层兽医单位用于 PRRS病毒血清抗体检测的新方法     

Evaluation of enzyme-linked immunosorbent assay (ELISA) and immunofluorescent antibody (IFA) test for the detection of porcine reproductive and respiratory syndrome virus (PRRSV) antibody in pigs from conventional farms

To evaluate the immunofluorescent antibody (IFA) test and enzyme-linked immunosorbent assay (ELISA) for detecting the porcine reproductive and respiratory syndrome virus (PRRSV) antibody, conventional pigs in PRRSV-positive and -negative commercial farms were examined. Antibody development patterns in ELISA and IFA tests were compared in 3 week old piglets experimentally infected with the PRRSV. The virus was detected from 2 days post infection (PI) and then the antibody titers and S/P ratios rose by both methods. A total of 208 serum samples were collected from 4 PRRSV-negative farms and 210 samples from PRRSV-positive farms, and were tested for the PRRSV antibody by IFA and ELISA. The titer of 64 should be set as the cut-off point in IFA for field sera. Similarly, the cut-off S/P ratio should be set at 0.4 in ELISA. A high degree of correlation was observed between antibody titers by the two methods in these 418 samples, with a correlation coefficient of 0.84. The coincidence rate between the two tests was 84.7% (354/418). In non-coincident cases, ELISA was able to detect the antibody with a low titer in the serum samples which were negative in IFA but from PRRSV positive farms. ELISA was more sensitive than IFA to detect PRRSV infected animals or farms.     

猪流行性腹泻病毒N蛋白阻断ELISA抗体检测方法的建立及初步应用

旨在建立一种猪流行性腹泻病毒(PEDV)N蛋白阻断ELISA抗体检测方法.本研究将纯化的N蛋白作为包被抗原,通过棋盘滴定法优化ELISA反应条件,建立了检测PEDV抗体的阻断ELISA方法,并对其进行特异性、敏感性和重复性试验.对140份临床血清样品进行检测,并将检测结果与市售IDvet PEDV间接ELISA抗体检测...     

猪瘟野毒感染抗体阻断ELISA检测方法的建立与初步评价

以猪瘟野毒E2蛋白为包被抗原、辣根过氧化物酶标记的猪瘟野毒单抗作为酶标抗体,建立检测猪瘟野毒抗体的阻断ELISA方法。猪瘟野毒E2最适包被浓度为0.03μg/mL,待检血清最适稀释度为1∶4,酶标猪瘟野毒单抗稀释度为1∶1 000。用建立的阻断ELISA方法检测369份临床阴性血清,计算阻断率,确定临界值,阻断率>40%为猪瘟野毒抗体阳性,阻断率≤40%为猪瘟野毒抗体阴性。用建立的ELISA方法检测84份血清,其中78份为免疫猪瘟疫苗的血清,6份为猪瘟病毒感染血清。结果显示,78份免疫血清均检测为猪瘟野毒抗体阴性,6份猪瘟感染血清均检测为猪瘟野毒抗体阳性。因此可初步判定该方法可用于鉴别诊断猪瘟病毒自然感染动物和C株疫苗免疫动物的血清抗体,并为临床检测猪瘟野毒抗体提供便捷、快速,精准的检测工具,对猪瘟的临床诊断、预防以及猪瘟净化工作具有非常重要的参考意义。     

Characterization of antibody response to porcine reproductive and respiratory syndrome virus ORF5 product following infection and evaluation of its diagnostic use in pigs.

The sensitivity and specificity of recombinant open reading frame 5 products used in the Western blotting assay for confirmation of porcine reproductive and respiratory syndrome virus (PRRSV) serologic status were evaluated. The recombinant antigen-based assays were specifically compared with a commercial enzyme-linked immunosorbent assay (ELISA) for PRRSV antibodies using 1) PRRSV antibody-negative reference sera (n = 30), 2) naturally infected pig sera (n = 40), 3) sequential sera obtained from 24 experimentally infected pigs, and 4) sera submitted to 3 state diagnostic laboratories (n = 200). The recombinant antigen assay yielded an average increased sensitivity of 10% over the commercial PRRSV ELISA. The negative controls (group 1 sera) showed no difference between the 2 assays. This comparison confirmed that the recombinant antigen-specific assay was more sensitive than the commercial ELISA and is well suited for routine confirmation of the presence of PRRSV antibodies.     

基于重组NS1蛋白猪细小病毒野毒抗体间接ELISA诊断方法的建立与应用

本研究以原核表达的重组NS1蛋白作为诊断抗原,建立了检测猪细小病毒(PPV)野毒抗体的NS1-ELISA诊断方法。该方法检测猪瘟病毒、猪繁殖与呼吸综合征病毒、猪伪狂犬病病毒、猪圆环病毒2型、猪流行性腹泻病毒5种常见猪病病毒的阳性血清均为阴性;检测灵敏度为1:12800;批内、批间重复性试验的变异系数分别小于5%和10%;与血凝抑制试验(HI)符合率为100%。本研究建立的PPV NS1-ELISA检测方法具有良好的特异性、敏感性和重复性,为PPV的野毒抗体检测及PPV流行病学调查等快速诊断提供了一种技术手段。     

Comparison of sensitivity and specificity in three commercial foot-and-mouth disease virus non-structural protein ELISA kits with swine sera in Taiwan

Three commercialized ELISA kits for the detection of antibodies to the non-structural proteins (NSPs) of FMD virus were compared, using sera from uninfected, vaccinated, challenged and naturally infected pigs. The kinetics of the antibody response to NSPs was compared on sequential serum samples in swine from challenge studies and outbreaks. The results showed that ELISA A (UBI) and ELISA B (CEDI) had better sensitivity than that of the 3ABC recombinant protein-based ELISA C (Chekit). The peak for detection of antibodies to NSPs in ELISA C was significantly delayed in sera from natural infection and challenged swine as compared to the ELISA A and B. The sensitivity of the three ELISAs gradually declined during the 6-month post-infection as antibodies to NSP decline. ELISA kits A and B detected NSP antibody in 50% of challenged pigs by the 9-10th-day and 7-8th-day post-challenge, respectively. ELISA B and C had better specificity than ELISA A on sequential serum samples obtained from swine immunized with a type O FMD vaccine commercially available in Taiwan. Antibody to NSPs before vaccination was not detected in swine not exposed to FMD virus, however, antibody to NSPs was found in sera of some pigs after vaccination. All assays had significantly lower specificity when testing sera from repeatedly vaccinated sows and finishers in 1997 that were tested after the 1997 FMD outbreak. However, when testing sera from repeatedly vaccinated sows or finishers in 2003-2004, the specificity for ELISAs A, B and C were significantly better than those in 1997. This effect was less marked for ELISA A. The ELISA B was the best test in terms of the highest sensitivity and specificity and the lowest reactivity with residual NSP in vaccinates.     

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%。     

Detection of antibody to turkey coronavirus by antibody-capture enzyme-linked immunosorbent assay utilizing infectious bronchitis virus antigen

An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of antibody to turkey coronavirus (TCV) utilizing infectious bronchitis virus (IBV) antigen was developed. Anti-TCV hyperimmune turkey serum and normal turkey serum were used as positive or negative control serum for optimization of the ELISA system. Goat anti-turkey immunoglobulin G (light plus heavy chains) conjugated with horseradish peroxidase was used as detector antibody. The performance of the ELISA system was evaluated with 45 normal turkey sera and 325 turkey sera from the field and the cutoff point was determined. Serum samples of turkeys experimentally infected with TCV collected sequentially from 1 to 63 days postinfection were applied to the established antibody-capture ELISA using IBV antigens. The optimum conditions for differentiation between anti-TCV hyperimmune serum and normal turkey serum were serum dilution at 1:40 and conjugate dilution at 1:1600. Of the 325 sera from the field, 175 were positive for TCV by immunofluorescent antibody (IFA) assay. The sensitivity and specificity of the ELISA relative to IFA test were 93.1% and 96.7%, respectively, based on the results of serum samples from the field turkey flocks using the optimum cutoff point of 0.18 as determined by the logistic regression method. The ELISA values of all 45 normal turkey sera were completely separated from that of IFA-positive sera. The ELISA results of serum samples collected from turkeys experimentally infected with TCV were comparable to that of the IFA assay. Reactivity of anti-rotavirus, anti-reovirus, anti-adenovirus, or anti-enterovirus antibodies with the IBV antigens coated in the commercially available ELISA plates coated with IBV antigens could be utilized for detection of antibodies to TCV in antibody-capture ELISA.     

Establishment and Application of an Indirect ELISA with Recombinant N Protein of Porcine Reproductive and Respiratory Syndrome Virus

To establish a sensitive,specific and efficient method of antibody detection for porcine reproductive and respiratory syndrome virus（PRRSV),PRRSV N protein was expressed through prokaryotic expression system and purified by affinity chromatography to act as a coating antigen.Then an indirect ELISA detection method for serum PRRSV antibody was finally set up after the optimization of reaction conditions.Besides,the research also involved cross reaction,repeated experiments,and comparison with other ELISA kits.It was determined that the optimum concentration of coating antigen was 2 μg/mL and that the dilution ratio for serum was 1:100,with 30 min of incubation and 10 min of chromogenic reaction.With this method,positive serum samples of five common swine pathogens,including classical swine fever virus（CSFV),porcine circovirus（PCV）and porcine pseudorabies virus（PRV）and so on,were tested,and the results were negative.Both intra-assay and inter-assay coefficients of variation were below 10%,and the comparison with commercial ELISA kits indicated that its accuracy was 94.7%.So this indirect ELISA,which had been established in this research,could provide a rapid diagnosis for swine infected by wild PRRSV and applied in epidemiological investigation,as a convenient and efficient serological antibody detection method.     

猪圆环病毒2型间接ELISA抗体检测试剂盒的研制及初步应用

以大肠杆菌原核表达系统表达的猪圆环病毒2型Cap蛋白为抗原,建立猪圆环病毒2型间接ELISA检测方法,优化ELISA反应条件,研制猪圆环病毒2型ELISA抗体检测试剂盒。与商品化试剂盒相比,该检测试剂盒敏感性、特异性和符合率分别为95.12%、92.86%和94.55%;同时与猪圆环病毒1型（PCV1）、猪瘟病毒（CSFV）、猪繁殖与呼吸综合征病毒（PRRSV）等多种病毒阳性血清无交叉反应。试剂盒具有较好的重复性,在-20 ℃至少可保存1年以上,将其应用于临床血清样品的检测,结果安徽、广东、广西采样猪场的PCV2阳性率分别为100%、48.39%、100%。     

牛传染性鼻气管炎病毒单克隆抗体的制备及阻断ELISA方法的建立

为建立检测牛传染性鼻气管炎病毒(IBRV)血清抗体的阻断ELISA方法,本研究以经蔗糖密度梯度离心法纯化的IBRV作为免疫原制备1株单克隆抗体(MAb),命名为cp-1-1。经间接ELISA、IFA和western blot鉴定,该MAb与IBRV呈阳性反应,与牛病毒性腹泻病毒(BVDV)及牛副流感病毒3型(BPIV3)呈阴性反应,具有较强的特异性。质谱分析结果显示MAb cp-1-1识别的表位位于IBRV VP8蛋白。以纯化的IBRV作为包被抗原、MAb cp-1-1作为检测抗体,建立检测IBRV血清抗体的阻断ELISA方法。该检测方法的抗原包被量为0.89μg/孔,样品稀释度为12,检测抗体MAb量为1.3μg/孔,二抗稀释度为15000。利用50份IBRV抗体呈弱阳性的牛血清(中和抗体效价为14~116)作为标准参考血清,确定该检测方法的阻断率Cut Off值为52.06%,即阻断率高于52.06%时判为阳性,低于52.06%时判为阴性。阻断ELISA方法特异性试验显示仅IBRV阳性血清检测为阳性,而BVDV、BPIV3、牛腺病毒3型(BADV-3)和O型口蹄疫病毒(O-FMDV)阳性牛血清均检测为阴性,表明该方法具有较强的特异性;该方法可检测的最低中和抗体效价为14,与病毒中和试验的敏感性一致,表明该方法具有较高的敏感性;重复性试验显示该方法批内、批间变异系数均小于10%,显示较好的重复性。对130份现地牛血清检测结果显示,该方法与病毒中和试验的符合率为98.46%。用该方法对某牛场接种IBRV灭活疫苗的牛血清进行检测,抗体阳性率为99.51%(205/206)。另外,采用该方法对我国8个省(市、自治区)的801份牛血清进行检测,IBRV的抗体阳性率为41.6%(333/801)。本研究建立的阻断ELISA方法可以用于IBRV疫苗免疫监测和血清流行病学调查,为我国IBR的防控提供技术支持。     

非洲猪瘟病毒p72蛋白阻断ELISA检测方法的建立

本研究旨在建立一种非洲猪瘟病毒(ASFV)p72蛋白阻断ELISA抗体检测方法。以纯化的重组p72蛋白作为包被抗原,HRP标记的6E5抗体作为阻断抗体,通过对反应条件进行优化,建立了基于ASFV p72蛋白的阻断ELISA方法。用建立的阻断ELISA方法检测119份临床阴性血清,计算血清阻断率确定临界值,确定了该方法的判定标准：当阻断率PI≥50%时判定为ASFV抗体阳性;PI≤40%时判定为ASFV抗体阴性;当阻断率介于两者之间时,判定为可疑。该方法与猪伪狂犬病病毒、猪繁殖与呼吸综合征病毒、猪瘟病毒、猪圆环病毒2型、A型塞内卡病毒、猪口蹄疫病毒、猪大肠杆菌、猪多杀性巴氏杆菌、副猪格拉瑟菌和猪胸膜肺炎放线杆菌的抗体阳性血清无交叉反应,批间、批内试验的变异系数均小于15%。用该方法与商品化ASFV抗体检测试剂盒同时检测447份猪临床血清样品,两种方法的相对敏感性和相对特异性分别为95.3%和94.5%,符合率为94.9%。本研究建立的阻断ELISA方法具有较高的敏感性和良好的特异性,可用于ASFV感染诊断和流行病学调查。     

猪繁殖与呼吸综合征病毒重组N蛋白间接ELISA检测方法的建立及应用

为建立一种敏感、特异、快速的猪繁殖与呼吸综合征病毒（PRRSV）抗体检测方法,本研究利用原核表达技术表达了PRRSV N蛋白,亲和层析纯化后作为包被抗原,通过对各反应条件优化选择,建立了PRRSV血清抗体的间接ELISA检测方法,并进行了交叉反应和重复性试验,以及同类成品试剂盒间的应用效果对比试验。最终确定了抗原包被最佳浓度为2 μg/mL,血清最佳稀释度为1∶100,血清及酶标二抗孵育时间均为30 min,显色时间为10 min,检测猪瘟病毒、猪圆环病毒、猪伪狂犬病病毒等5种常见猪病病原的阳性血清均为阴性;该ELISA检测方法批内和批间重复性的变异系数均小于10%;与商品化ELISA试剂盒效果比较显示符合率为94.7%。本研究建立的间接ELISA方法将为猪群感染野毒PRRSV后的快速诊断及流行病学调查提供一种简便易行、快速高效的血清学抗体检测方法。     

Comparison of antibody detection assays for the diagnosis of equine herpesvirus 1 and 4 infections in horses

OBJECTIVE: To compare methods of detecting equine herpesvirus type 1 (EHV1)- and EHV4-specific antibodies in horse sera. SAMPLE POPULATION: 33 acute and convalescent serum samples from experimentally or naturally infected horses after confirmed EHV1 or EHV4 infection. PROCEDURE: For each sample, serum antibody titers against EHV1 and EHV4 were determined by use of virus neutralization (VN) and complement fixation (CF) assays. The ELISA absorbance values for each serum sample were determined against the EHV1 and EHV4 recombinant ELISA antigens. Values obtained for acute and convalescent sera in each assay were compared. RESULTS: Following experimental infection of foals, EHV1 or EHV4 antibodies that were specific for the inoculating virus were detected only by use of the ELISA. Results of VN and CF assays indicated that the foals seroconverted to EHV1 and EHV4 following infection with EHV4 only. After EHV1-induced abortion, myeloencephalitis, or respiratory tract disease, the VN and CF assay results revealed seroconversion to EHV1 and EHV4, whereas results of the ELISA revealed seroconversion to EHV1 only. Similarly, after confirmed EHV4-induced respiratory tract disease, increases in EHV4-specific antibodies were detected only by use of the ELISA with no indication of an increase in EHV1 antibodies. The CF and, to a lesser degree, VN assays revealed that seroconversion to EHV1 and EHV4 occurred between the time of obtaining acute and convalescent serum samples. CONCLUSIONS AND CLINICAL RELEVANCE: The EHV1/EHV4 type-specific antibody ELISA clearly identifies horses that have been infected with EHV1 or EHV4 by use of acute and convalescent sera. Results of VN and CF assays indicate that cross-reactive antibodies greatly limit their use.     

非洲猪瘟病毒p30蛋白单克隆抗体的制备及阻断ELISA抗体检测方法的建立

为建立检测非洲猪瘟病毒(ASFV)抗体的阻断ELISA方法,本研究利用原核表达的ASFV p30重组蛋白免疫BALB/c小鼠制备单克隆抗体。以重组p30蛋白作为包被抗原,以辣根过氧化物酶(HRP)标记的p30单克隆抗体作为检测抗体,经条件优化,建立了一种检测ASFV抗体的阻断ELISA方法。ROC曲线分析显示,该方法最佳阻断率临界值为16.63%。该方法与CSFV、FMDV-O/A、PRRSV、PEDV、SVA的阳性血清均无交叉反应;最低能检出1∶128稀释的阳性血清;批内和批间变异系数(CV)均＜10%。用本方法与商品化试剂盒平行检测208份血清样品,Kappa值为0.96,表明具有高度一致性。上述结果表明,本研究建立的阻断ELISA方法具有较高的特异性和敏感性,可用于血清ASFV抗体的检测,为ASFV流行病学调查及猪群疫情监控提供技术支持。