重组马传染性贫血病病毒核心蛋白抗原在AGID和ELISA中应？…

用昆虫杆状病毒青海比试 马传染性贫血病病毒核心蛋白和Ｐ２６蛋白，作为免疫琼脂双扩散和酶联免疫吸附试验抗原。对７６份已知马传贫非特异性血清进行检查，同时与市售ＡＧＩＤ和ＥＬＩＳＡ试剂盒作比较。     

禽白血病／肉瘤病毒群特异性抗原P_（27）~（gag）的分离和纯化

本试验用差束离心和非线性蔗糖密度梯度离心法从感染雏鸡血浆中分离和提纯了禽成髓细胞性白血病病毒（ＡＭＶ）。并以ＳＤＳ法裂解病毒，用ＳＤＳ－ＰＡＧＥ分析ＡＭＶ结构蛋白成分，最后选用（ＬＫＢ）水平板式电泳系统，经ＳＤＳ－ＰＡＧＥ比较大量地分离提纯了Ｐｇａｇ２７。用Ｄｏｔ－ＥＬＩＳＡ和琼脂扩散试验检验其抗原活性，并且用ＳＤＳ－ＰＡＧＥ测定其分子量和纯度。结果表明，提纯的病毒蛋白具有抗原活性，且达到电泳纯。     

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。     

马立克氏病病毒囊膜糖蛋白B抗原I型特异性和群共同性决定簇的…

用能表达马立克氏病病毒（ＭＤＶ）糖蛋白Ｂ（ｇＢ）的重组杆状病毒感染的Ｓｆ９细胞免疫小鼠，制备针对ＭＤＶｇＢ的单克隆抗体，以Ｉ型马立克氏病病毒ＧＡ株感染的鸡胚成纤维细胞作为检测抗原，同时以免疫荧光试验（ＩＦＡ）和酶联免疫吸附试验（ＥＬＩＳＡ）来筛选杂交瘤细胞，结果获得了ＩＦＡ和ＥＬＩＳＡ均为阳性的１株单克隆抗体细胞株，定义名ＢＡ４和ＢＤ８。在ＩＦＡ和免疫沉淀试验中，单抗ＢＤ８与Ｉ，ⅡⅢ型ＭＤＶ均呈阳     

马立克氏病病毒囊膜糖蛋白B抗原Ⅰ型特异性和群共同性决定簇的单克隆抗体

用能表达马立克氏病病毒（ＭＤＶ）糖蛋白Ｂ（ｇＢ）的重组杆状病毒感染的Ｓｆ９细胞免疫小鼠，制备针对ＭＤＶｇＢ的单克隆抗体。以Ⅰ型马立克氏病病毒ＧＡ株感染的鸡胚成纤维细胞作为检测抗原，同时以免疫荧光试验（ＩＦＡ）和酶联免疫吸附试验（ＥＬＩＳＡ）来筛选杂交瘤细胞，结果获得了ＩＦＡ和ＥＬＩＳＡ均为阳性的２株单克隆抗体细胞株，定名为ＢＡ４和ＢＤ８。在ＩＦＡ和免疫沉淀试验中，单抗ＢＤ８与Ⅰ、Ⅱ、Ⅲ型ＭＤＶ均呈阳性反应；单抗ＢＡ４只对Ⅰ型ＭＤＶ（包括ＣＶＩ９８８疫苗株）呈阳性反应。免疫沉淀反应进一步确证２株单抗识别的是ＭＤＶ糖蛋白Ｂ抗原。     

斑点免疫金银染色法检测鸡传染性支气管炎病毒抗原的研究

用建立的斑点免疫金银染色（Ｄｏｔ－ＩＧＳＳ）法检测鸡传染性支气管炎病毒（ＩＢＶ）抗原,确定兔抗ＩＢＶ血清工作浓度为１：４００,ＳＰＡ－胶体金探针的工作浓度为１：８０,该法对纯化ＩＢＶ抗原的最低检出量为０．４３１４ｎｇ／点,用Ｄｏｔ－ＩＧＳＳ与斑点酶联免疫吸附试验（Ｄｏｔ－ＥＬＩＳＡ）同时检测１５只人工感染ＩＢＶ鸡的气管,肺,肾病科,ＩＢＶ阳性检出率均为１００％,对３２份疑似ＩＢＶ感染鸡病料检测,Ｉ     

表达大肠杆菌肠毒素ST1-LTB融合蛋白双价基因工程菌株的构建

重组菌株ＢＬ２１（ＤＥ３）（ｐＸＥＴＳＬＴ１）经ＩＰＴＧ诱导后,其表达产物经ＳＤＳ－ＰＡＧＥ和ＥＬＩＳＡ检测,结果表明重组菌株可以高效表达大肠杆菌肠毒素ＳＴ１－ＬＴＢ 融合蛋白,该融合蛋白占菌体总蛋白的３３．２１％ ,而且已失去天然ＳＴ１肠毒素生物毒性。用从ＩＰＴＧ 诱导的工程菌中提取的包涵体或经甲醛灭活的工程菌制成抗原免疫小鼠,结果免疫小鼠至少能抵抗１．５ＭＬＤ 的大肠杆菌强毒株Ｃ８３９０２（Ｋ８８ａｃ,ＳＴ＋ ,ＬＴ＋ ）的攻击。用提取的包涵体免疫家兔后,采集的血清能够中和天然ＳＴ１肠毒素的毒性。这表明构建的工程菌株ＢＬ２１（ＤＥ３）（ｐＸＥＴＳＬＴ１）可以作为预防幼畜大肠杆菌性腹泻基因工程菌苗的候选株     

异源抗原在建立ELISA检测传染性法氏囊病毒抗体中的应用

本文报告采用ｖｅｒｏ细胞增殖的ＩＢＤＶ抗原建立了间接酶联免疫吸附试验（ＥＬＩＳＡ），用于定量检测鸡传染性法氏囊病毒（ＩＢＤＶ）抗体。该法快速、敏感性高、特异性强、重复性好。同时，通过３０份血清样品ＥＬＩＳＡ效价（ＥＴ）的对数值（ｌｏｇＥＴ）与血清Ｐ／Ｎ值（待检血清ＯＤ值与阴性血清ＯＤ值之比）的线性回归分析，得直线方程ｙ＝３．０５８９＋０．０７３９ｘ（ｒ＝０．９１７４），从而血清样品的ＥＴ可通过血清单一稀释度的Ｐ／Ｎ值来计算。用不同来源抗原作ＥＬＩＳＡ表明，从ｖｅｒｏ细胞增殖的抗原比从鸡胚成纤维（ＣＥＦ）细胞增殖的抗原可提高检测血清ＯＤ值近２０％，表现出异源抗原具有更高的特异性     

应用重组猪生殖与呼吸综合征病毒核衣壳蛋白为抗原建立I—ELISA检？…

用重组杆状病毒表达的钎生殖和呼吸综合征病毒（ＰＲＲＳＶ）Ｎ蛋白作为抗原，建立了诊断猪生殖和呼吸综合征（ＰＲＲＳ）的Ｉ－ＥＬＩＳＡ，与ＩＤＥＸＸ公司试剂盒检测结果的符合率为９７．３％，与间接 光抗体试验９ＩＦＡ）的符合率为１００％。用该方法的检测国内猪血清８５份，阳性率为１８．８％；能检出ＰＲＲＳ疫苗免疫猪６ｄ的血清抗体，；与猪瘟、伪狂犬病、猪巴氏杆菌病、猪霉形体病阳性血清无交叉反应。     

Dot—ELISA检测猪生殖和呼吸综合征抗体的研究

用差速离心法提纯ＰＲＲＳ病毒，利用ＮＣ膜作为载体，在国内外首次成功建立了检测ＰＲＲＳ血清抗体的斑点酶联免疫吸附试验（Ｄｏｔ－ＥＬＩＳＡ）。抗原包被浓度为１００μｇ／ｍｌ，被检血清工作浓度为１：１０，酶标兔抗猪ＩｇＧ工作浓度为１：６００。对７２份北京地区猪血清分别用Ｄｏｔ－ＥＬＩＳＡ和ＩＦ检测，Ｄｏｔ－ＥＬＩＳＡ检测阳性率为３３．３％，ＩＦ检测阳履率为３０．６％，与ＩＦ符合率较高，对部分待检血清检测     

An enzyme-linked immunosorbent assay (ELISA) test for the diagnosis of equine infectious anemia in Brazil

An enzyme-linked immunosorbent assay (ELISA) test was developed for the detection of specific antibodies against the unique infectious anemia (EIA) virus in equine sera. The ELISA test was faster and more sensitive when compared with the classic test of agar gel immunodiffusion (AGID). A total of 200 sera were tested: 100 from negative horses and 100 from positive horses by AGID. The ELISA test showed 92 horse sera negative and 100 horse sera positive by AGID with values of optical density (OD) less than 0.139 and higher than 0.139, respectively. Eight horse sera were negative by AGID and higher than 0.139 by ELISA. Six of these became AGID positive also when re-tested 30 days later, and two were of the horses that showed clinical signs of EIA and died before re-testing.     

Laboratory diagnosis of African horse sickness: comparison of serological techniques and evaluation of storage methods of samples for virus isolation

Five serological methods of diagnosing African horse sickness were evaluated, using a battery of serum samples from experimental horses vaccinated and challenged with each serotype of African horse sickness virus (AHSV1 through AHSV9): agar gel immunodiffusion (AGID), indirect fluorescent antibody (IFA), complement fixation (CF), virus neutralization (VN), and enzyme-linked immunosorbent assay (ELISA). The 5 tests were also compared using a panel of field samples, convalescent equine sera with antibodies to domestic equine viral diseases, and sera from horses awaiting export. The ELISA described in this paper was group specific. It did not require calibration with a standard positive serum but did yield elevated values with negative sera that were repeatedly frozen and thawed or heat inactivated. The IFA test was sensitive but could not be used on some field sera as the control cells exhibited fluorescence, possibly due to the animal being recently vaccinated with cell culture material. Sixty-two experimental sera were compared by VN, CF, AGID, and ELISA. Forty sera, 10 positive and 30 negative, were correctly classified by the 5 serologic assays. The 22 remaining sera gave mixed reactions. The AGID had no false positive results but had false negative results for up to 20% of the samples, depending upon the comparison. The VN, CF, and ELISA were similar in their variability. The length of time that virus could be recovered from a viremic blood sample was compared in an evaluation of storage methods for virus isolation samples. Washed erythrocytes were held at 4 C, washed erythrocytes plus stabilizer were held at -70 C, and blood that was drawn into a preservative (oxalate/phenol/glycerol) was held at 4 C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Preparation and evaluation of antigens used in serological tests for caprine syncytial retrovirus antibody in sheep and goat sera

Methods used to prepare antigens from caprine syncytial retrovirus (CSR) for use in the agarose gel immunodiffusion test (AGID) or an indirect enzyme-linked immunosorbent assay (ELISA) are described. Caprine and ovine sera were tested for antibody to CSR using the AGID test and ELISA incorporating a caprine system (CSR antigen and rabbit anti-goat IgG) or an ovine system (maedi-visna virus antigen and rabbit anti-sheep IgG). Good correlation was achieved in the results of the 3 tests when sera were devoid of antibody or were strongly positive. Variations in the results on weakly positive sera were considered to be more a matter of interpretation than due to basic differences in the reagents employed.     

Comparison of competitive ELISA, indirect ELISA and standard AGID tests for detecting blue-tongue virus antibodies in cattle and sheep

The performances of a competitive enzyme-linked immunosorbent assay (ELISA) using a group specific monoclonal antibody against bluetongue virus, an indirect ELISA and the standard agar gel immunodiffusion (AGID) test were compared in the detection of serum antibody against bluetongue virus. Test sera consisted of 1300 bovine, 530 ovine and 160 carpine samples from bluetongue-free areas of Canada, 605 bovine and ovine field samples from the USA and Barbados and 464 samples from 79 cattle and sheep experimentally infected with 19 South African and five USA serotypes of bluetongue virus. The diagnostic specificity of the competitive ELISA, as determined for the bluetongue virus-free cattle sera was superior (99.92 per cent) to that of the indirect ELISA (99.85 per cent) and the AGID (99.0 per cent). The specificities of the competitive ELISA for sheep (99.63 per cent) and goats (100.0 per cent) sera were also higher than those of the AGID test. The performance of the ELISA tests was similar whether a gamma-ray-irradiated (2.0 Mrad) or a non-irradiated bluetongue virus antigen preparation was used. The competitive ELISA results for bovine field sera from endemic areas demonstrated a relatively low level of agreement (92.04 per cent) with AGID test results, with 9.7 per cent false negatives. The possible presence in these sera of antibody to cross-reacting antigens or to other orbiviruses, eg, epizootic haemorrhagic disease virus, which react in the AGID but not in the competitive ELISA may account for this lack of agreement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bovine leukemia virus infection in Taiwan: evaluation of the enzyme-linked immunosorbent assay and agar gel immunodiffusion test.

I evaluated an enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) test simultaneously for the detection of bovine leukemia virus (BLV) antibodies. Total 1,293 serum samples were tested for ELISA and AGID test and the results were compared. The results of ELISA and AGID agreed by 1,156 out of 1,293 (89.4%). All of AGID-positive 356 sera were positive by ELISA. However, of 451 ELISA-positive sera, 95 sera were either negative or equivocal by AGID test. Eleven animals which showed ELISA-positive but AGID-negative or equivocal became AGID-positive in a year. It may be inferred that ELISA detects infected cattle earlier and with greater sensitivity than AGID.     

Development and evaluation of an enzyme-linked immunosorbent assay for detection of bovine antibodies to epizootic hemorrhagic disease of deer viruses.

An indirect enzyme-linked immunosorbent assay (I.ELISA) is described for detection of bovine serum antibody to epizootic hemorrhagic diseases of deer virus (EHDV). Serum samples, at a dilution of 1:200, were incubated with group-specific EHDV antigens, pre-adsorbed to microtiter plates. Bound antibodies were detected by a murine monoclonal antibody to bovine immunoglobulin (Ig)G1 (heavy-chain specific) conjugated with horseradish peroxidase. The performance of the I.ELISA in detecting antibodies to EHDV in sequential serum samples from calves experimentally infected with serotypes 1,2,3 and 4 was evaluated. The I.ELISA detected EHDV antibodies from 14 days postinfection when seroconversion by the standard agar gel immunodiffusion (AGID) test was also evident. The group-specific antibodies to EHDV increased exponentially during the first two to four weeks postinfection and remained relatively stable for about 12 months in some calves. Unlike observations with the AGID test, no reaction was seen in the I.ELISA between blue-tongue virus (BTV) antigen and sera from calves given a single dose of EHDV. The performance of the I.ELISA and AGID were compared using 3,135 AGID negative bovine field sera from herds in Ontario, Alberta and British Columbia and 130 AGID positive samples collected from cattle in 1987 and 1988 during and after outbreaks of EHD in the Okanagan Valley, British Columbia. The specificity and sensitivity of the assay relative to the AGID test were 99.3% and 91.5% respectively, with an overall agreement of 99.0% between the tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Specificity of absorbed ELISA and agar gel immuno-diffusion tests for paratuberculosis in goats with observations about use of these tests in infected goats

OBJECTIVE: To determine the specificity of serological tests that are currently used in veterinary diagnostic laboratories in Australia for detection of Mycobacterium avium subsp paratuberculosis infection in goats. DESIGN: A laboratory study. PROCEDURE: Four tests were studied, comprising AGID with M. a. paratuberculosis antigen derived from cattle isolates of caprine or bovine origin, the EMAI caprine Johne's disease absorbed ELISA and the CSL PARACHEK Johne's absorbed EIA. The specificities of AGID and ELISA for paratuberculosis (Johne's disease) were estimated after examining a panel of 1000 serum samples collected from goats in Western Australia, a region free of paratuberculosis. In addition a comparison was made of test performance in a small number of paratuberculous goats from New South Wales using sera from two archival collections. RESULTS: The specificity of the AGID tests was 100% while the specificities of the two absorbed ELISA were 99.7 to 99.8% at appropriate positive-negative cut-offs. Based on testing the small sample of sera from infected goats, the absorbed ELISA tests detected about twice as many goats with Johne's disease as the AGID. Each test detected paratuberculous animals regardless of whether infection was caused by cattle or sheep strains of M. a. paratuberculosis. CONCLUSIONS: Both ELISA and AGID tests for paratuberculosis have high specificity and can be used in a market assurance program without risk of generating large proportions of false positive test results. However, the results suggested the ELISA is more sensitive for detection of infected goats and should be used in preference to the AGID. The two formats of ELISA evaluated in this study have similar characteristics and could be used in paratuberculosis control programs for the goat industries, but further data on sensitivity would increase confidence in their application.     

Comparison of four serologic tests for the detection of antibodies to bovine leukemia virus

Four tests for detection of antibodies to bovine leukemia virus (BLV) were compared. The sera that were tested came from cattle in naturally infected commercial dairy herds, cattle that were infected under experimental conditions, and cattle in an isolated BLV-free herd. The tests that were compared included a radioimmunoprecipitation assay (RIA) with p24 antigen, a RIA with glycoprotein (gp) antigen, an agar-gel immunodiffusion (AGID) test with gp antigen, and a virus-neutralization (VN) test that was based on inhibition of BLV-induced syncytia in cell culture. Results of the 4 serologic tests agreed for 96.8% of the sera from cattle in commercial herds. The gp RIA detected the greatest number of positive sera (188); it was followed in turn by the p24 RIA (187), the VN test (183), and the AGID test (176). The gpd RIA titers of the 12 sera that gave negative AGID results were 175 or less. In RIA, the percentage of precipitation of labeled antigen by positive sera was almost always higher with gp antigen than with p24 antigen. Satisfactory sensitivity in the p24 RIA required the acceptance of a low level of antigen precipitation, 15%, as a positive test. In the gp RIA, however, almost all positive sera precipitated at least 50% of the labeled antigen. Nonspecific precipitation of antigen in the RIA by sera from BLV-free cattle ranged from 4% to 10%. Examination of sequential serum samples from 17 experimentally infected cattle showed that BLV antibody was first detected 2 to 8 weeks after inoculation. In 9 cattle, seroconversion was detected simultaneously by all of the tests. Results from the other 8 cattle indicated that seroconversion could be detected first by p24 RIA, followed by the gp RIA and the VN test. The longest interval between RIA seroconversion and AGID seroconversion was 10 days. Monthly tests of sera from 10 laboratory cattle that were infected by contact exposure showed that 7 animals seroconverted in all tests at the same time. Two cattle were positive first in RIA, but the next month they were also positive in the VN and AGID tests. One animal was positive in the RIA and the VN test for 2 months before antibody was detected by AGID.     

Use of Brucella canis antigen for detection of ovine serum antibodies against Brucella ovis

Brucella ovis causes a genital disease of sheep manifested by epididymitis in rams and placentitis in ewes producing reduced fertility in the flock. Clinical diagnosis is not sensitive enough and bacteriological testing is not feasible for detection of the disease in large numbers of animals. Indirect methods of serological testing are preferred for routine diagnosis, of which agar gel immunodiffusion (AGID), complement fixation (CF) and ELISA tests are recommended as the most efficient. Since B. ovis shares antigenic components with Brucella canis, it would seem that either strain could be used as antigen with the same results; however, the advantage of the B. canis (M-) strain variant is that it can be used to develop a satisfactory antigen for agglutination tests. We present data on AGID and IELISA tests using B. ovis antigen and rapid screening agglutination test (RSAT), 2-mercapto-ethanol RSAT (2ME-RSAT) and IELISA using B. canis antigen. We tested 225 animals. The cut-off values were adjusted by ROC analysis using 51 negative and 32 positive sera; the IELISA-B. canis cut-off value was 39 (%P) and IELISA-B. ovis, 51 (%P), with 100% sensitivity and specificity. Of the 32 positive sera from the infected flock RSAT detected 32 (100%), 2ME-RSAT 29 (91%) and AGID 31 (97%). Of the 142 sera from suspicious flocks, 46 were negative and 56 positive in all the tests; 16 were positive by RSAT, IELISA-B. canis and IELISA-B. ovis, 20 positive only with RSAT and 2 positive only by both IELISAs. RSAT is a very sensitive screening test that, because of its simplicity and easy interpretation, following a study in larger sample, could replace AGID as a screening test for diagnosis of ovine brucellosis caused by B. ovis. The IELISA-B. canis or IELISA-B. ovis could be used as confirmatory tests, since they show equal specificity and sensitivity.     

Comparison of the commercial agar-gel immunodiffusion test and radioimmunoprecipitation assay for detection of antibodies to bovine leukemia virus

In a double-blind study, the commercial agar-gel immunodiffusion test (AGID) was compared with a radioimmunoprecipitation assay (RIA) performed with glycoprotein (gp) antigen for detection of antibodies to bovine leukemia virus. Of 240 sera tested, 115 were from adult cows and 125 were from precolostral calves. Most adult animals were tested within 1 week of parturition. Sera from 74 cattle were positive and sera from 166 cattle were negative by gp RIA. Sensitivity of the AGID, compared with the gp RIA, was 85.1% when the test was read at 48 hours and was 94.6% when read at 72 hours. Specificity increased from 92.2% at 48 hours to 96.4% at 72 hours. Reading the AGID again at 72 hours also clarified most reactions that were questionable at 48 hours due to a haze around the test serum well. Of 3 RIA-positive precolostral calf sera, 2 were AGID-negative and 1 had a questionable reaction by the AGID at 48 hours. Of 5 RIA-positive sera that were AGID-negative at 48 hours, 2 were precolostral calves and 3 were cows tested at parturition. Of 166 RIA-negative reactions, none was falsely positive by the AGID at 48 or at 72 hours.