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1.
An ammonium sulfate fraction of Taenia hydatigena cyst fluid (ThFAS) was further fractionated by hydrophobic interaction chromatography, using alkylagarose and omega-amino alkylagarose columns, in an effort to isolate and purify a specific diagnostic antigen in the ThFAS preparation. The less than 12 kDa antigen was found to have an affinity for immobilized alkanes with chain length of six carbons or greater. The antigen was recovered in an ethylene glycol eluate from a hexylagarose column then analyzed by Western blot; it reacted with bovine and human cysticercosis infection sera and with specific monoclonal antibodies but not with control sera or fascioliasis infection sera. When the eluate was used as coating antigen in a plate ELISA assay no false positive reactions were seen in sera from cattle infected with Fasciola hepatica; false positive reactions were observed for the unfractionated ThFAS antigen preparation.  相似文献   

2.
Serodiagnosis of bovine besnoitiosis by ELISA and immunofluorescence tests   总被引：1，自引：0，他引：1  
Sera from non-infected cattle and cattle infected with Anaplasma, Babesia, Theileria and Sarcocystis were tested for antibodies to Besnoitia in ELISA and immunofluorescence tests (IFT) with Besnoitia besnoiti of blue wildebeest origin as antigen. Only 2 out of 86 sera gave false positive reactions in ELISA and none in the IFT, indicating a high specificity for the tests. Three-hundred-and-three bovine sera from 3 farms in an area endemic for besnoitiosis were similarly tested and the results were correlated with clinical findings based on visual inspection for typical symptoms and the presence of cysts in the scleral conjunctiva. Most of the positive tests were observed in cattle older than 1 year. Of the cases with scleral cysts, 68,7% were positive in the ELISA and 81,74% in the IFT. However, 45,74% (ELISA) and 49,47% (IFT) of the clinically negative cattle were clinically positive, indicating a high incidence of clinically inapparent infection. These results indicate a relatively low sensitivity for these serological tests. An unexpected finding was that the ELISA remained negative for at least 60 days after experimental infection of the cattle, the maximum period for which tests were done, whereas the IFT became positive. No antibodies against B. besnoiti could be found in human sera. Besnoitia jellisoni antigen gave positive results with B. besnoiti antibodies in ELISA, but not in the IFT.  相似文献   

3.
It was observed that mild acidification (pH less than 4.0) together with solvent extraction of the soluble sonicate of a crude preparation of Babesia bigemina infected cattle erythrocytes caused a quantitative loss of B. bigemina-specific antigen. Cross-reacting antigen activities with Babesia bovis remained intact. These properties were utilized in an assay system wherein antibody response to the specifically depleted antigen preparation was subtracted from the response to the initial crude preparation leaving the net B. bigemina response. The radioimmunoassay based on this antigen system was verified using sera from known negative cattle and from cattle previously infected with B. bigemina, B. bovis or Anaplasma marginale. The following discrimination values were obtained: B. bigemina-positive sera less than 2% false negatives; negative sera, 2% false positives; B. bovis-positive sera, 4% false positives; A. marginale-positive sera, 0% false positives. Levels of cross-reactivity in the false positive results were in the "suspect" rather than positive class and in the case of B. bovis-positive sera, may have been due to non-specific antibodies induced by blood inoculation. In animals naturally infected with B. bovis only, there were no false positive reactions. B. bigemina antibodies were readily detectable in field sera for at least 10 months post-infection following infection by the cattle tick Boophilus microplus. This assay overcomes the problems of currently used tests for B. bigemina infection as it is both sensitive and specific and is able to discriminate between both field and laboratory infections of B. bigemina and B. bovis.  相似文献   

4.
An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies to Mycobacterium paratuberculosis in the sera of cattle. This assay was designed to minimize the nonspecific ELISA reactions caused by immunoglobulin (Ig)M by measuring only IgG1 antibodies against a protoplasmic antigen from the organism. The ELISA detected IgG1 antibodies in the sera of 58% of cattle with positive fecal cultures for M paratuberculosis compared with detection of 45% of culture-positive animals with an immunodiffusion test. In addition to its sensitivity, the ELISA apparently is highly specific because only 4% of the sera from fecal culture-negative animals gave a false-positive result.  相似文献   

5.
An antigen was isolated from the protoplasm of Mycobacterium paratuberculosis by a combination of gel filtration, ion exchange, and affinity chromatography. The purified antigen constituted 7.8% of the total protein in the protoplasm. The specificity and sensitivity of the enzyme-linked immunosorbent assay (ELISA) for paratuberculosis, using the purified antigen, were evaluated with sera from 104 cattle which were examined (surveyed) for M paratuberculosis infection by fecal cultural technique. The ELISA was positive in 50 of 60 infected animals. Five of 44 noninfected animals were also test-positive. When a crude protoplasmic extract was used as antigen in the ELISA, sera from 37 infected and from 18 noninfected animals were test-positive. Cross-reactions were encountered in both complement-fixation test and the ELISA between crude or partially purified M paratuberculosis antigens and antisera to Nocardia asteroides, M avium, M phlei, and M fortuitum. The purified antigen gave no complement-fixation reaction with any of these antisera. In the ELISA, cross-reaction was not found when purified antigen was used and the sera were screened at 1:40 dilution.  相似文献   

6.
A reliable bovine viral diarrhea (BVD) viral antigen was prepared from BVD virus grown on Madin Darby bovine kidney (MDBK) cells by solubilizing the virus with detergent MEGA-10 (decanoyl-N-methylglucamide) followed by removal of hydrophobic proteins with Triton X-100 treatment. By these treatments, problems of high background associated with BVD viral antigen in the enzyme-linked immunosorbent assay (ELISA) were eliminated. With this new antigen, an ELISA was adapted to detect bovine serum antibody against BVD virus. The diagnostic specificity of the assay in 403 bovine sera collected from a BVD virus-free herd was 100%; in 296 bovine sera with serum neutralizing antibody titers of greater than or equal to 1:2, 289 sera were ELISA positive (relative sensitivity of 97.6%), two sera gave false negative reactions (0.7%) and five sera gave suspicious reactions (1.7%). These interpretations were based on positive/negative (P/N) ratio readings, i.e. a P/N ratio of less than 1.50, 1.50-1.99 and greater than or equal to 2.00 were interpreted as negative, suspicious and positive reactions, respectively. The ELISA results gave excellent agreement with serum neutralization in detecting both seropositive and seronegative animals (Kappa = 0.994). The ELISA assay was considered to be technically superior to the serum neutralization test for the routine detection of BVD viral antibody in bovine sera.  相似文献   

7.
Tick-borne encephalitis (TBE) in animals is not well understood yet. TBE virus (TBEV) serology in several host species could be valuable for epidemiological analyses in the field as well as for the detection of clinical cases. However, performance and suitability of the available test systems are not well assessed. Therefore, we evaluated two commercial TBEV-ELISA kits in a pilot study and compared them for their suitability in veterinary applications. For this purpose, we tested 163 field collected goat sera and evaluated the results by serum neutralization test (SNT) as "gold standard". Twenty-eight SNT positive sera (17.2%) were detected. The best suited ELISA kit was used for determination of a species-specific cutoff for horses, cattle, sheep, goats, pigs, mice, dogs, rabbits and monkeys with defined sera from animals without known or with improbable contact to TBEV. The level of non-specific ELISA results does not only differ between animal species but may also be influenced by the age of the tested animals. The number of sera which tested false positive by ELISA was higher in older than in young sheep. In order to obtain defined polyclonal sera as references, two dogs, cattle, goats, sheep, rabbits and pigs each, as well as one horse and 90 mice were immunized four times with a commercially available TBEV vaccine. In conclusion, our results demonstrated that commercial TBEV-ELISA kits are suitable for application in veterinary medicine for both, verification of clinical TBE cases and epidemiological screening. However, positive ELISA results should be verified by SNT. Only a very low number of false negative ELISA-results were found.  相似文献   

8.
Six 6-month-old bulls were experimentally infected with five different isolates of Trypanosoma evansi; two received the same isolate and the other four received different isolates. The parasitaemias and serum antigen levels were monitored regularly by the haematocrit centrifuge technique (HCT) and antigen-detection ELISA (Ag-ELISA), respectively. Trypanosomal antigen was demonstrated by the Ag-ELISA by 10–14 days post inoculation in four cattle, while parasitaemias were first found to be positive in individual cattle over a longer period of time post inoculation (6–28 days). In two cattle, the Ag-ELISA values were also positive when the animals were found to harbour trypanosomes by the HCT and only turned negative 3 days after treatment, while the ELISA values fluctuated during the experiment in another two bulls. The remaining two cattle never produced positive ELISA results despite positive parasitological results. The antibody titres in all six cattle started to rise around 10 days post inoculation and then stayed high throughout the experiment. It was concluded that the Ag-ELISA would produce some false negative results in the early stages of T. evansi infection owing to variations in the balance of parasitaemia and antibody levels in the circulation, and in the pathogenicity of parasite strains.  相似文献   

9.
The level of non-specific reactions found in the brucellosis serology of ruminants in New Zealand was very low until July 1992. This changed when, in an export consignment of 1071 deer, 35% reacted in the Brucella abortus tube agglutination test with titres varying from 50 to 200 IU. The reactors were also positive in the Rose-Bengal agglutination test and most of them reacted in the complement fixation test with titres varying from 10 to 80 IU. Yersinia enterocolitica 0:9 was later isolated from one deer of this consignment. It was the first isolate of this serotype recovered in New Zealand from an animal. Shortly after, false reactors occurred more frequently than before in sera from Brucella abortus accredited free cattle herds. As the involvement of Yersinia enterocolitica 0:9 was suspected in these cases, faecal samples from reactors and in-contact animals were cultured for this organism. Yersinia enterocolitica 0:9 was isolated from nine of 19 herds showing one or more false Brucella abortus seroreactions. Prior to 1990, Yersinia enterocolitica serotype 0:9 had not been isolated in New Zealand, despite the recovery of a number of other bio- or serotypes of the organism from humans and animals. From 1990 onward, serotype 0:9 began to be isolated from human faecal samples with increasing frequency. Since the first isolations from deer and cattle in 1992, it has now also been recovered from a cat and an alpaca and from cattle without any association with false positive Brucella abortus reactions. All serotype 0:9 isolates were of biotype 2.  相似文献   

10.
用昆虫杆状病毒表达系统获得的马传染性贫血病病毒（ Ｅ Ｉ Ａ Ｖ） 核心蛋白（ Ｇａｇ） 和 Ｐ２６ 蛋白, 作为免疫琼脂双扩散（ Ａ Ｇ Ｉ Ｄ） 和酶联免疫吸附试验（ Ｅ Ｌ Ｉ Ｓ Ａ） 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 Ａ Ｇ Ｉ Ｄ 和 Ｅ Ｌ Ｉ Ｓ Ａ 试剂盒作比较。证明, 用表达蛋白作抗原的 Ａ Ｇ Ｉ Ｄ 和 Ｅ Ｌ Ｉ Ｓ Ａ 检测结果均为阴性反应, 而用市售 Ａ Ｇ Ｉ Ｄ 试剂盒检查有５４ 份马血清出现非特异性反应, 市售 Ｅ Ｌ Ｉ Ｓ Ａ 试剂盒检查也出现了非特异性反应, Ｏ Ｄ 值比表达抗原 Ｅ Ｌ Ｉ Ｓ Ａ 高３５ 倍。初步证明在 Ａ Ｇ Ｉ Ｄ 和 Ｅ Ｌ Ｉ Ｓ Ａ 法中, 表达抗原优于常规马传贫病毒抗原。  相似文献   

11.
The aim of this study was to evaluate the value of commercially available kits for the detection of foot-and-mouth disease (FMD) virus infection in vaccinated cattle. The cattle were vaccinated with a commercial aqueous FMD vaccine type A24 and subsequently challenged 28 days post vaccination with homologous FMD virus. Seven of eight animals were protected from clinical disease and all became carriers. They were bled sequentially for up to 130 days post infection and samples of sera were tested with three ELISA kits: CHEKIT FMD-3ABC, Ceditest FMDV-NS and SVANOIR FMDV 3ABC-Ab ELISA. The Ceditest kit appears to be relatively higher sensitive than the others. When examined with this ELISA, all cattle developed of FMDV nonstructural proteins (NSPs) antibodies and remained positive throughout the period of the experiment. The response of antibodies against 3ABC antigen delayed in two cattle challenged with FMDV A24 virus. One of the cattle reacted negatively in Svanoir ELISA kit and sera from two animals were found negative in CHEKIT ELISA. It can be concluded that all tested kits can be a promising tool for FMD control and eradication campaigns in situation where emergency vaccination was applied.  相似文献   

12.
A rapid, inexpensive and rugged serological test that distinguishes cattle and swine infected with Brucella sp. or Yersinia enterocolitica O:9 is described. The test protocol, which is an indirect enzyme immunoassay uses a high concentration of divalent cation chelating agents to minimize binding of Y. enterocolitica O:9 antibody to rough lipopolysaccharide antigen derived from B. abortus RB51. No false positive reactions were observed when testing 100 Canadian cattle and swine without any evidence of brucellosis. The assay detected 91.6% of cattle (n=155) and 93.5% (n=31) of swine infected with Brucella sp. Sera from 58 cattle and 38 swine exposed to Y. enterocolitica O:9 were negative while only 20 sera from 121 'false positive' reactors of unspecified origin gave low level positive reactions, eliminating 84% of the false positive reactions.  相似文献   

13.
Five commercially available ELISA tests for the detection of antibodies against Mycobacterium avium subsp. paratuberculosis in bovine serum were evaluated at the individual animal level using sera from 286 paratuberculosis-free and 110 paratuberculosis-infected dairy cattle. Sensitivity (Se) and specificity (Sp) of the tests were estimated after determination of the cut-off dtheta by TG-ROC analysis or using the cut-off values recommended by the manufacturers, respectively. When the dtheta cut-off values were applied, the five ELISA tests showed sub-optimal Se and Sp. Adopting the cut-offs recommended by the manufacturers, the Sp of four of the five ELISA increased, two tests reaching Sp > or = 99.0%. Test sensitivity clearly depended on the disease state of the animals examined. Se was significantly higher in clinically diseased than in latently infected dairy cattle. Calculation of the positive and negative predictive values indicated that, depending on the test, a considerable proportion of false positive and false negative results have to be expected. Therefore, the suitability of antibody detection for the diagnosis of paratuberculosis in individual animals is questioned.  相似文献   

14.
The Dutch national Brucella abortus eradication programme for cattle started in 1959. Sporadic cases occurred yearly until 1995; the last infected herd was culled in 1996. In August 1999 the Netherlands was declared officially free of bovine brucellosis by the European Union. Before 1999, the programme to monitor the official Brucella-free status of bovine herds was primarily based on periodical testing of dairy herds with the milk ring test (MRT) and serological testing of all animals older than 1 year of age from non-dairy herds, using the micro-agglutination test (MAT) as screening test. In addition, serum samples of cattle that aborted were tested with the MAT. The high number of false positive reactions in both tests and the serum agglutination test (SAT) and complement fixation test (CFT) used for confirmation seemed to result in unnecessary blockade of herds, subsequent testing and slaughter of animals. For this reason, a validation study was performed in which three indirect enzyme-linked immunosorbent assays (ELISAs), the CFT and the SAT were compared using a panel of sera from brucellosis-free cattle, sera from experimentally infected cattle, and sera from cattle experimentally infected with bacteria which are known to induce cross-reactive antibodies (Pasteurella, Salmonella, Yersinia, and Escherichia). Moreover, four ELISAs and the MRT were compared using a panel of 1000 bulk milk samples from Brucella-free herds and 12 milk samples from Brucella abortus- infected cattle. It is concluded that the ELISA obtained from ID-Lelystad is the most suitable test to monitor the brucelosis free status of herds because it gives rise to fewer false-positive reactions than the SAT.  相似文献   

15.
OBJECTIVE: To determine the proportion of cattle, whose sera gave positive reactions in a commercial enzyme linked immunosorbent assay (ELISA) for bovine Johne's disease, that were confirmed infected with Mycobacterium avium subsp paratuberculosis by histology and culture of tissues. PROCEDURE: Dairy cattle (n = 493) from the Echuca district of Victoria, whose sera were positive in the ELISA, were slaughtered at an abattoir where standard specimens were collected for histology and culture. Only if samples were histologically negative were further samples submitted for culture. RESULTS: The proportion of cattle in which infection was confirmed increased from 70.4% in 1996 to 89.4% in 2001 giving an overall confirmation rate of 79.9%. This was mainly because more reactors were confirmed by culture each year, the proportion increasing from 0% in 1997 to 27.5% in 2000 but decreasing to 16.7% in 2001. If all unconfirmed reactors were presumed to be uninfected, the minimum specificity of the ELISA was 99.62%. There were no significant differences between the age groups in the proportion confirmed infected. CONCLUSION: Confirmation rates and specificity of the ELISA were high when used in a typical JD-infected Victorian dairy cattle population. Imperfect sensitivity of histology and culture and the selection of reactors which favoured more false positives, means the estimates were probably conservative. Confirmation rates were not affected by age of ELISA reactor.  相似文献   

16.
A potentially infectious aetiology for digital dermatitis in dairy cattle was investigated and centred on the possible involvement of spirochaetes. An enzyme-linked immunosorbent assay (ELISA) was developed to detect bovine anti-Borrelia burgdorferi (B31) and anti-Treponeme (USA bovine isolates) antibodies in the sera of cows; sera were further tested for antigen specificity by Western blotting. Compared to normal cows, those with digital dermatitis had a much higher seropositivity rate to B. burgdorferi and the treponemes. Significant correlations were shown between antibodies to B. burgdorferi and to Treponemes (P < 0.001), suggesting strong cross-reacting epitopes shared by these spirochaetes. In Western blotting of B. burgdorferi antigens, the main band detected by ELISA positive sera was the 41 kDa flagellar protein; lesser frequency of staining was seen with 34 (OspB), 39 and 55 kDa bands. For the USA treponeme antigens, ELISA positive sera gave reactions to the 34-kDa band and also bands at 41 and 55 kDa. Polyclonal antibodies to Treponema denticola and T. vincentii showed reactions with the bovine treponemes which were predominantly to the 34-kDa antigen. Monoclonal antibodies to B. burgdorferi flagella (41 kDa) antigen and OspA (31 kDa) did not detect any treponeme bands in Western blotting. The study has provided serological evidence that spirochaetes (which are related to human treponemes) may be involved in the pathogenesis of digital dermatitis.  相似文献   

17.
Antibodies directed against two bovine lentiviruses, Jembrana disease virus (JDV) and bovine immunodeficiency virus (BIV), were detected in Balinese cattle sera using two new enzyme-linked immunosorbent assays (ELISAs) based on the combination of capsid (CA) protein and transmembrane (TM) peptides derived from JDV or BIV sequences.

Twenty eight of the 77 sera tested on the JDV ELISA showed anti-JDV antibodies with an unequal distribution of seropositive animals throughout the different districts of Bali. Furthermore, when 17 of the JDV positive sera were tested on Western blot, using the same JDV CA antigen, only 13 were judged positive confirming that the ELISA was a more sensitive technique for the detection of seropositive animals. Finally, 9 of the 49 JDV seronegative animals showed anti-BIV antibodies when tested on BIV-specific ELISA.

These two ELISAs appeared to be highly sensitive for the detection of anti-JDV and anti-BIV antibodies. Moreover, for the first time, animals showing antibodies against BIV were identified on the main island of Bali and on the JDV-free Nusa Penida island.  相似文献   


18.
Seroepidemiology of Breda virus in cattle using ELISA   总被引：3，自引：0，他引：3  
Two direct blocking enzyme linked immunosorbent assays (ELISA) for the detection of antibodies to Breda virus in sera of cattle were compared. An ELISA with consecutive addition of antigen and test serum to an antibody-coated plate gave higher positive: negative absorbence ratios than an ELISA in which antigen and test serum were added simultaneously. Sera collected from breeding and fattening herds in The Netherlands (n = 1313) and the F.R.G. (n = 716) were tested, and antibodies to Breda virus were demonstrated in 94% of adult cattle. Ninety percent of newborn calves had high levels of maternal antibodies, which waned until the age of 3 months. Active seroconversion occurred between 7 and 24 months in most animals.  相似文献   

19.
Isolated Anaplasma marginale initial bodies were successfully used in a dot ELISA for rapid detection of antibodies to Anaplasma organisms. The enzyme immunoassay used only 25 ng of antigen dotted onto nitrocellulose disks. Antigen-antibody complexes were detected by use of alkaline phosphatase-conjugated protein A, and reactions were read visually after addition of a precipitable, chromogenic substrate. The test allowed the processing of multiple sera, either for screening or for titer determination, in less than 3 hours and was found to be as sensitive as the indirect fluorescent antibody test. The overall performance of the dot ELISA, using isolated A marginale initial bodies, for 580 bovine serum samples was as follows: sensitivity, 93%; specificity, 96%; and predictive value, 95%. Cross-reactivity was not observed with sera positive to Babesia bovis and B bigemina, Trypanosoma vivax, or common bacteria or viruses infecting cattle. The antigen dotted onto nitrocellulose disks was stable when stored at -20, 4, or 25 C. Compared with the indirect fluorescent antibody test, the dot ELISA allowed easier, faster, and more objective interpretation of results. Its simplicity and low cost combined with high sensitivity and specificity indicate that this assay could effectively replace serologic assays currently used for diagnosis of anaplasmosis in cattle.  相似文献   

20.
A commercially available ELISA for detecting antibodies to liver fluke was evaluated for use in Australia. Milk and serum samples from cattle and sheep in which infection with Fasciola hepatica was confirmed by detection of eggs in faeces were used to estimate sensitivity. Similar samples collected from cattle and sheep outside the F. hepatica-endemic area were used to estimate specificity. The ELISA was also evaluated for detecting antibodies to F. hepatica in milk from sheep and antibodies to Fasciola gigantica in sera from cattle and buffaloes, but with small numbers of samples. In cattle, the sensitivity and specificity of the ELISA were 98.2% and 98.3% using serum and 97.7% and 99.3% using milk. In infected herds, 41.4% and 41.5% of animals were positive in the serum and milk ELISAs, respectively, whereas F. hepatica eggs were found in faecal samples from 26.5% of animals. In sheep, the sensitivity of the ELISA was 96.9% and the specificity was 99.4%. In infected flocks, 60.2% of animals were positive in the serum ELISA and F. hepatica eggs were found in faecal samples 52.2% of animals. There was perfect agreement in the ELISA between paired serum and milk samples collected from ewes. The assay detected antibodies in sera from cattle and buffaloes with natural and experimental F. gigantica infections. In the experimentally infected animals, antibodies were detected 2 weeks post-infection. We conclude that the ELISA will be a valuable tool for diagnosing F. hepatica infections in cattle and sheep. The assay may also be useful for diagnosing F. gigantica infections but further studies are required to establish sensitivity and specificity.  相似文献   

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