Enzyme-linked immunosorbent assay for detection of equine infectious anemia antibody to purified P26 viral protein

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of equine infectious anemia (EIA) antibody in horse sera. Purified P26 viral protein was the antigen; alkaline phosphatase linked to rabbit anti-horse immunoglobulin G was the conjugate. The ELISA detected EIA antibodies in horse sera as early as 11 to 14 days after experimental inoculations. There was full agreement between the results of ELISA and the agar-gel immunodiffusion tests on EIA proficiency test sera. The ELISA readily detected EIA antibody in horse sera that had weak positive reactions on agar-gel immunodiffusion.     

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.     

Enzyme-linked immunosorbent assay for the detection of antibodies to infectious bronchitis virus

An enzyme-linked immunosorbent assay (ELISA) for antibodies to avian infectious bronchitis (IB) virus is described. The immune response of chickens following vaccination with IB virus was monitored using this test, and the titers were compared with those obtained by serum neutralization. The ELISA appears to be suitable for IB serology.     

Enzyme-linked immunosorbent assay for bovine apolipoprotein A-IV

The present report describes an enzyme-linked immunosorbent assay for bovine apolipoprotein (apo) A-IV. This assay was applied to the determination of its concentration and distribution in sera from cattle. The distribution of apoA-IV in lipoprotein fractions separated by ultracentrifugation was mostly recovered in the non-lipoprotein fractions (d>1.21 g/ml, 90%), but, in the case of gel filtration chromatography, apoA-IV was mainly eluted in HDL and non-lipoprotein fractions. The apoA-IV concentrations during early, mid- and late lactating stages in cows were significantly higher than during the nonlactating stage (p<0.05). From early to late lactating stages, the concentration of apoA-IV was unaltered. After 4 days of fasting, the concentration of plasma apoA-IV had decreased significantly (p<0.05) at days 3 and 4, and was returned to the basal level by 3 days of refeeding. These results suggested that the concentration of apoA-IV is modified by nutritional conditions.     

Enzyme-linked immunosorbent assay for diagnosis of Corynebacterium (Rhodococcus) equi infection in foals

An enzyme-linked immunosorbent assay (ELISA) was used to diagnose Corynebacterium (Rhodococcus) equi infection in foals. In tests done with different antigen-extraction procedures (sodium dodecyl sulfate, sodium deoxycholate, polyoxy-ethylene [9] p-tert-octylphenol, polyoxy-ethylene [9-10] p-tert-octylphenol, sonification, homogenization, and heat treatment at 121 C), Tween 20 was a satisfactory reactive antigen. Using hyperimmune rabbit sera or infected foal sera, we investigated the specificity and the sensitivity of the ELISA with the Tween 20 antigen of the different serotypes or of the isolates. Corynebacterium equi strain ATCC 6939 antigen had the best activity for detecting antibodies to C equi in foals. Sera from 218 healthy horses, 11 healthy foals, 17 healthy newborn foals, a foal with suspected C equi infection, and 5 infected foals were evaluated for antibodies to C equi, using ELISA. The optical density values of 206 healthy horses, 17 healthy newborn foals, and 9 healthy foals were less than 0.1. Infected foal sera, except from foal 3, and serum from a foal with suspected C equi infection had higher optical density values. Using ELISA, specific antibodies against C equi were detected in a naturally infected 6-week-old foal after the foal had a rapid increase in the number of bacteria in the feces and after the initial development of clinical signs of illness at 5 weeks of age. Therefore, ELISA was useful for the early diagnosis of C equi infection in foals.     

Enzyme-linked immunosorbent assay for the detection of bovine papillomavirus

An enzyme-linked immunosorbent assay has been developed to detect and quantitate bovine papillomavirus in partially purified and in purified viral preparations, using rabbit antiserum against group-specific papillomavirus structural antigens and alkaline phosphatase-labeled affinity purified goat antibody to rabbit immunoglobulin G. Viral detection correlated well with negative-stain electron microscopy of the various preparations and peroxidase-antiperoxidase staining of paraffin sections of the original fibropapillomas. The technique is rapidly done and will detect minute amounts of viral protein (1 ng/ml).     

Enzyme-linked immunosorbent assay for detection of bluetongue virus antibodies

The immune response to bluetongue virus in sheep and cattle was studied by applying a newly developed indirect enzyme-linked immunosorbent assay (ELISA). Purified virus obtained by sucrose gradient centrifugation was used at a concentration of 0.01 optical density units (formula: see text) to coat individual wells (200 microliter) of a microtitration plate. Dilution of antigen was performed in 0.05 M carbonate buffer, pH 9.6, and adsorption lasted for at least 16 hours at 4 C. Coated plates retained their activity for 10 weeks when stored at 4 C. Sera recovered from experimentally infected sheep and cattle were tested together with known negative sera. A good correlation between results was obtained with the modified complement-fixation test and the ELISA; however, the ELISA proved to be more sensitive. The group specificity of the ELISA was proven by testing various type-specific sheep and cattle immune sera. The ELISA has potential for the detection of group-specific antibodies to bluetongue virus infection.     

A western blot test for the serological diagnosis of equine infectious anemia

After electrophoretic separation in SDS-PAGE structural proteins of the virus of Equine Infectious Anemia (EIA) were easily blotted by the semi-dry-blotting method onto nitrocellulose filters. Strips of these filters were used for antibody demonstration, and positive reactions thereof were intensified by a biotin-avidin-peroxidase system. Sensitivity of this system was so high as to allow readable interpretation of bands up to the dilution of 1:6,400 of a strongly positive serum. Frequently this procedure allowed to make a firm diagnostic Western-Blot diagnosis on far weaker equine sera. Interpretation of results proved, however, difficult with sera, which formed one single band only. This observation, although of weak grade, had to be made in some 5% of sera stemming from horses with a certainly negative history of EIA. Consequently, we conclude, that a policy followed in the serodiagnostic Western-Blot of human AIDS should also be adopted for the interpretation of the EIA Western-Blot, namely to declare as positive merely horse sera which evidence more than one single band, whereof at least one band should represent a viral glycoprotein.     

酶联免疫法测定鸡肉中尼卡巴嗪残留

为了建立鸡肉中尼卡巴嗪残留标志物4,4’-二硝基均二苯脲（DNC）残留酶联免疫（ELISA）检测方法。将N-琥珀酰-L-丙氨酰-L-丙氨酰-L-丙氨酸4-硝基苯胺（SAN）与载体蛋白偶联作为抗原免疫动物,获得抗DNC抗体,在此基础上建立了鸡肉中尼卡巴嗪残留的检测方法。人工抗原中SAN与载体蛋白的结合比约为12：1,血清效价1：2000倍,鸡肉中检测限为9．2μg／kg,添加回收率在49．4％～118％之间,批内、批间变异系数均小于20％。该方法在灵敏度、精密度和准确度方面均能满足兽药残留筛选检测要求。