Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Intra- and inter-laboratory validation of a dipstick immunoassay for the detection of tropane alkaloids hyoscyamine and scopolamine in animal feed
Mulder, P.P.J. ; Holst, C. von; Nivarlet, N. ; Egmond, H.P. van - \ 2014
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 31 (2014)7. - ISSN 1944-0049 - p. 1165 - 1176.
quantitative-determination - monoclonal-antibody - enzyme-immunoassay - plant-material - radioimmunoassay - datura - cultures
Tropane alkaloids (TAs) are toxic secondary metabolites produced by plants of, inter alia, the genera Datura (thorn apple) and Atropa (deadly nightshade). The most relevant TAs are (-)-L-hyoscyamine and (-)-L-scopolamine, which act as antagonists of acetylcholine muscarinic receptors and can induce a variety of distinct toxic syndromes in mammals (anti-cholinergic poisoning). The European Union has regulated the presence of seeds of Datura sp. in animal feeds, specifying that the content should not exceed 1000 mg kg(-1) (Directive 2002/32/EC). For materials that have not been ground, visual screening methods are often used to comply with these regulations, but these cannot be used for ground materials and compound feeds. Immunological assays, preferably in dipstick format, can be a simple and cost-effective approach to monitor feedstuffs in an HACCP setting in control laboratories. So far no reports have been published on immunoassays that are capable of detecting both hyoscyamine and scopolamine with equal sensitivity and that can be used, preferably in dipstick format, for application as a fast screening tool in feed analysis. This study presents the results obtained for the in-house and inter-laboratory validation of a dipstick immunoassay for the detection of hyoscyamine and scopolamine in animal feed. The target level was set at 800 µg kg(-1) for the sum of both alkaloids. By using a representative set of compound feeds during validation and a robust study design, a reliable impression of the relevant characteristics of the assay could be obtained. The dipstick test displayed similar sensitivity towards the two alkaloids and it could be concluded that the test has a very low probability of producing a false-positive result at blank level or a false-negative result at target level. The assay can be used for monitoring of TAs in feedstuffs, but has also potential as a quick screening tool in food- or feed-related poisonings.
Development and validation of a rapid multiplex ELISA for pyrrolizidine alkaloids and their N-oxides in honey and feed
Oplatowska, M. ; Elliott, C.T. ; Huet, A.C. ; McCarthy, M. ; Mulder, P.P.J. ; Holst, C. von; Delahaut, P. ; Egmond, H.P. van; Campbell, K. - \ 2014
Analytical and Bioanalytical Chemistry 406 (2014)3. - ISSN 1618-2642 - p. 757 - 770.
linked-immunosorbent-assay - dietary-supplements - enzyme-immunoassay - mass-spectrometry - plants - food - toxicity - invitro - pollen - system
Pyrrolizidine alkaloids (PAs) are a group of plant secondary metabolites with carcinogenic and hepatotoxic properties. When PA-producing plants contaminate crops, toxins can be transferred through the food chain and cause illness in humans and animals, most notably hepatic veno-occlusive disease. Honey has been identified as a direct risk of human exposure. The European Food Safety Authority has recently identified four groups of PAs that are of particular importance for food and feed: senecionine-type, lycopsamine-type, heliotrine-type and monocrotaline-type. Liquid or gas chromatography methods are currently used to detect PAs but there are no rapid screening assays available commercially. Therefore, the aim of this study was to develop a rapid multiplex ELISA test for the representatives of three groups of alkaloids (senecionine, lycopsamine and heliotrine types) that would be used as a risk-management tool for the screening of these toxic compounds in food and feed. The method was validated for honey and feed matrices and was demonstrated to have a detection capability less than 25 µg/kg for jacobine, lycopsamine, heliotrine and senecionine. The zinc reduction step introduced to the extraction procedure allows for the additional detection of the presence of N-oxides of PAs. This first multiplex immunoassay for PA detection with N-oxide reduction can be used for the simultaneous screening of 21 samples for >12 PA analytes. Honey samples (n¿=¿146) from various origins were analysed for PA determination. Six samples were determined to contain measurable PAs >25 µg/kg by ELISA which correlated to >10 µg/kg by LC-MS/MS.
Multiplex flow cytometric immunoassay for serum biomarker profiling of recombinant bovine somatotropin
Smits, N.G.E. ; Ludwig, S.K.J. ; Veer, G. van der; Bremer, M.G.E.G. ; Nielen, M.W.F. - \ 2013
The Analyst 138 (2013)1. - ISSN 0003-2654 - p. 111 - 117.
growth-factor-i - enzyme-immunoassay - antibody-formation - biological-fluids - binding-proteins - lactating cows - hormone - cattle - identification - osteocalcin
Recombinant bovine somatotropin (rbST) is licensed for enhancing milk production in dairy cows in some countries, for instance the United States, but is banned in Europe. Serum biomarker profiling can be an adequate approach to discriminate between treated and untreated groups. In this study a multiplex screening tool of a small set of biomarkers for pinpointing recombinant bovine somatotropin (rbST) (ab)use was developed and evaluated: insulin-like growth factor 1 (IGF-1), IGF binding protein 2 (IGFBP2) and rbST-induced antibodies were selected as rbST dependent markers and combined in one parallel assay format. For this, the color-encoded microspheres were used in a suspension array, with a dedicated flow cytometer. Serum samples obtained from an animal experiment with rbST-treated and untreated dairy cows were measured with the developed triplex immunoassay and biomarker responses on rbST treatment were evaluated. This resulted in characteristic treatment-dependent responses for all three individual biomarkers. Combining these results with the statistical prediction model k-nearest neighbours (kNN), resulted in good discrimination of treated and untreated animals: an overall sensitivity (true positive rate) of 89.1% and an overall specificity (true negative rate) of 97.7% were reached. Therefore, this is the first multiplex method which can be applied with high confidence for screening of unknown herds of cattle pinpointing at rbST (ab)use.
Single Laboratory Validation of a Surface Plasmon Resonance Biosensor Screening method for Paralytic Shellfish Poisoning Toxins
Campbell, K. ; Haughey, S.A. ; Top, H.J. van den; Egmond, H.J. van; Vilarino, N. ; Botana, L.M. ; Elliott, C.T. - \ 2010
Analytical Chemistry 82 (2010)7. - ISSN 0003-2700 - p. 2977 - 2988.
linked-immunosorbent-assay - prechromatographic oxidation - quantitative-determination - fluorescence detection - liquid-chromatography - enzyme-immunoassay - saxitoxin - neosaxitoxin - antibodies
A research element of the European Union (EU) sixth Framework project BioCop focused on the development of a surface plasmon resonance (SPR) biosensor assay for the detection of paralytic shellfish poisoning (PSP) toxins in shellfish as an alternative to the increasingly ethically unacceptable mouse bioassay. A biosensor assay was developed using both a saxitoxin binding protein and chip surface in tandem with a highly efficient simple extraction procedure. The present report describes the single laboratory validation of this immunological screening method, for this complex group of toxins with differing toxicities, according to the European Decision 2002/657/EC in conjunction with IUPAC and AOAC single laboratory validation guidelines. The different performance characteristics (detection capability CC beta, specificity/selectivity, repeatability, reproducibility, stability, and applicability) were determined in relation to the EU regulatory limit of 800 mu g of saxitoxin equivalents (STX eq) per kg of shellfish meat. The detection capability CC beta was calculated to be 120 mu g/kg. Intra-assay repeatability was found to be between 2.5 and 12.3% and interassay reproducibility was between 6.1 and 15.2% for different shellfish matrices. Natural samples were also evaluated and the resultant data displayed overall agreements of 96 and 92% with that of the existing AOAC approved methods of mouse bioassay (MBA) and high performance liquid chromatography (HPLC), respectively.
Serodiagnosis of Mycobacterium avium infections in pigs
Wisselink, H.J. ; Smits, C.B. ; Oorburg, D. ; Soolingen, D. ; Overduin, P. ; Maneschijn-Bonsing, J.G. ; Stockhofe, N. ; Buys-Bergen, H. ; Engel, B. ; Urlings, B.A.P. ; Jelle, E.R. ; Thole, J.E.R. - \ 2010
Veterinary Microbiology 142 (2010)3-4. - ISSN 0378-1135 - p. 401 - 407.
complex pulmonary-disease - slaughter pigs - lymph-nodes - glycopeptidolipid antigens - enzyme-immunoassay - rhodococcus-equi - subsp avium - prevalence - proposal - lesions
The aim of this study is the development and evaluation of a serodiagnostic assay for Mycobacterium avium (MA). After screening MA lipid fractions in an ELISA format, a polar lipid fraction was selected as antigen because of its superior recognition by serum antibodies in experimentally infected pigs. The resulting MA-ELISA was evaluated as an alternative for detection of MA infection by traditional pathological examination of pig lymph nodes for granulomatous lesions by meat inspectors. By comparing with bacteriological examination, the MA-ELISA showed significantly better sensitivity (69%) as compared to pathological examination (31%) in experimentally infected pigs. The MA-ELISA also appeared significantly more specific in a set of serum samples from MA negative pigs: only 1 out of these 153 serum samples reacted positive, whereas 99 (65%) of these had displayed false positive results by detection of lymph nodes lesions that appeared not to be associated with MA (Komijn et al., 2007). The MA-ELISA was subsequently evaluated using serum samples from two farms with pigs known to be infected with MA. Bacteriological examination of the sub-maxillary and mesenteric lymph nodes showed that 56% (103/184) and 35% (41/117) of the pigs, respectively were positive for MA in these farms. In the first farm, 16% (29/184) of the pigs tested positive in MA-ELISA and 31% (57/184) by pathological examination. On the contrary, in the second farm, more pigs tested positive 17% (15/117) in MA-ELISA with 8% (9/117) positivity by pathological examination. Taking the results on both farms together, the sensitivity of the MA-ELISA was 14% and the specificity 83%, whereas the sensitivity of the pathological examination was 31% and the specificity 86%. For practical reasons use of a serological test as the MA-ELISA may be preferred over pathological or bacteriological examinations. Our studies in experimentally infected and negative “field” sera indicate that the MA-ELISA is significantly more specific and more sensitive than detection by classical pathological examination. However, the studies in two MA infected farms show a variable picture with pathological examination overall performing better. Study in a wider range of “positive” farms will be needed to provide a more comprehensive view of the quality of both tests for detection of MA in infected farms. At the same time further optimization of MA-ELISA with use of lipid antigens from a broader range of serotypes may improve its performance in the face of infections with different MA serotypes
Perspectives for on-site monitoring of progesterone
Posthuma-Trumpie, G.A. ; Amerongen, A. van; Korf, J. ; Berkel, W.J.H. van - \ 2009
Trends in Biotechnology 27 (2009)11. - ISSN 0167-7799 - p. 652 - 660.
performance liquid-chromatography - lateral flow immunoassay - milk progesterone - bovine-milk - enzyme-immunoassay - dairy-cattle - mass-spectrometry - human-serum - cows milk - pregnancy diagnosis
The steroid hormone progesterone is the primary biomarker of the reproductive status of female mammals. Current techniques of monitoring progesterone are based predominantly on (enzyme) immunoassays, but these are too expensive to be affordable in daily screening programmes because of their associated labour costs and the need for laboratory facilities and/or equipment. Here, we discuss existing methods as well as new perspectives for (automated) application at point of care/need, e.g. the milking parlour. These make it apparent that a low-cost, fully automated progesterone assay system to monitor the reproductive status is far from being realised at present. Timely ovulation prediction techniques for artificial insemination and reproductive cycling are thus urgently needed, and promising perspectives will be highlighted
Development of a novel and automated fluorescent immunoassay for the analysis of beta-lactam antibiotics
Benito-Pena, E. ; Moreno-Bondi, M.C. ; Orellana, G. ; Maquieira, K. ; Amerongen, A. van - \ 2005
Journal of Agricultural and Food Chemistry 53 (2005)17. - ISSN 0021-8561 - p. 6635 - 6642.
linked-immunosorbent-assay - solid-phase extraction - enzyme-immunoassay - penicillin antibiotics - monoclonal-antibodies - immunoanalysis system - liquid-chromatography - milk - water - biosensor
An automated immunosensor for the rapid and sensitive analysis of penicillin type -lactam antibiotics has been developed and optimized. An immunogen was prepared by coupling the common structure of the penicillanic -lactam antibiotics, i.e., 6-aminopenicillanic acid to keyhole limpet hemocyanin. Polyclonal antibodies raised in rabbits after immunization with this conjugate have been applied for the development of a competitive fluoroimmunoassay (FIA), using a novel fluorescent penicillin {[2S,5R,6R]-3,3-dimethyl-7-oxo-6-[(pyren-1ylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxilic acid, PAAP} as the tracer and penicillin G as the reference antibiotic. Protein A/G covalently bound to an azlactone-activated polymeric support was used for the orientated capture of the antibody-antigen immunocomplexes. Upon desorption from the immunosupport, the emission signal generated by the PAAP-Ab complexes is related to the antibiotic concentration in the sample. The 50% binding inhibition concentration of penicillin G standard curves was at 30 ng mL-1 with a detection limit (10% binding inhibition) of 2.4 ng mL-1 and a dynamic range from 6.0 to 191 ng mL-1 (20-80% binding inhibition) penicillin G. The generic nature of the antiserum was shown by good relative cross-reactivities with penicillin type -lactam antibiotics such as amoxicillin (50%), ampicillin (47%), and penicillin V (145%) and a lower response to the isoxazolyl penicillins such as oxacillin, cloxacillin, and dicloxacillin. No cross-reactivity was obtained for cephalosporin type -lactam antibiotics (cephapirin), cloramphenicol, or fluoroquinolones (enrofloxacin and ciprofloxacin). The total analysis time was 23 min per determination, and the immunoreactor could be reused for more than 200 cycles without significant loss of activity. The immunosensor has been successfully applied to the direct analysis of penicillin G and amoxicillin in spiked influent and effluent sewage treatment plant water samples with excellent recoveries (mean values for penicillin G and amoxicillin, 99 and 105%, respectively). Results displayed by comparative analysis of the immunosensor with a chromatographic procedure for penicillins showed excellent agreement between both methods
Application of a multi-sulfonamide biosensor immunoassay for the detection of sulfadiazine and sulfamethoxazole residues in broiler serum and its use as a predictor of the levels in edible tissue
Haasnoot, W. ; Ploum, M.E. ; Lamminmaeki, U. ; Swanenburg, M. ; Rhijn, J.A. van - \ 2005
Analytica Chimica Acta 552 (2005)1/2. - ISSN 0003-2670 - p. 87 - 95.
enzyme-immunoassay - sulfamethazine residues - antibody - milk - pharmacokinetics - immunobiosensor - trimethoprim - urine - pigs
A multi-sulfonamide biosensor immunoassay (BIA), based on a previously developed mutant antibody (A.3.5) in an optical biosensor (Biacore 3000), was applied to analyse the serum and plasma samples obtained from the broilers treated with sulfamethoxazole and sulfadiazine. The assay was fast (5 min per sample), the sample preparation easy (dilution in antibody containing buffer only) and an equal sensitivity for the two sulfonamides was obtained with limits of detection (LOD) in serum and plasma below 10 ng ml¿1. The concentrations found with the BIA in serum and plasma of the treated broilers were comparable and higher than the concentrations found in the tissue by LC¿MS/MS. The average serum/tissue ratios for sulfamethoxazole were 6.2 (leg meat), 2.5 (liver) and 1.3 (skin + fat) and for sulfadiazine 8.7 (leg meat), 3.1 (liver) and 2.2 (skin + fat). To predict the concentrations of the two sulfonamides below the maximum residue limit (MRL) of 100 ng g¿1 in the tissue with the highest level (skin + fat), the proposed action level of the multi-sulfonamide BIA in serum is 130 ng ml¿1. A later developed mutant antibody (M.3.4), with a better sensitivity towards more sulfonamides, was applied during a survey. Serum samples (n = 300) of broilers from 30 different flocks were found negative. Concentrations between
Comparison of multi-sulfonamide biosensor immunoassays
Ploum, M.E. ; Korpimaeki, T. ; Haasnoot, W. ; Kohen, F. - \ 2005
Analytica Chimica Acta 529 (2005)1-2. - ISSN 0003-2670 - p. 115 - 122.
enzyme-immunoassay - sulfamethazine residues - antibodies - assay - immunobiosensor - sulfadimidine - sulfadiazine - generation - extraction - tissues
Three different group-specific anti-sulfonamide antibodies were compared in inhibition assay formats in an optical biosensor (BIACORE 3000) using CM5 sensor chips coated with three different sulfonamide derivatives. The antibodies used were an anti-sulfamethazine monoclonal antibody (Mab) 21C7, the sulfonamide binding protein (SBP) in the Qflex Kit Sulfonamides and a recently developed mutant antibody (M.3.4). Each of these antibodies showed interactions with all 17 sulfonamides tested and one (Mab 21C7) was sensitive for the N4-acetyl metabolites also. The limits of detection of the different sulfonamides in chicken serum varied between 7 and >1000 ng ml¿1 (Mab 21C7), 15 and 340 ng ml¿1 (Qflex) and 4 and 82 ng ml¿1 (Mutant M.3.4). The mutant M.3.4 based assay was found to be the most sensitive towards most of the sulfonamides whereas the Qflex Kit Sulfonamides detected the five sulfonamides registered for application in poultry in The Netherlands within the narrowest measurement range
Application of an immunosensor for the detection of the beta-lactam antibiotic, cephalexin
Dillon, P.P. ; Daly, S.J. ; Browne, S.J. ; Manning, B.M. ; Loomans, E.E.M.G. ; Amerongen, A. van; O'Kennedy, R. - \ 2003
Food and Agricultural Immunology 15 (2003)3-4. - ISSN 0954-0105 - p. 225 - 234.
surface-plasmon resonance - monoclonal-antibody - enzyme-immunoassay - biosensor assay - raw-milk - residues - serum - validation
Public concern surrounding antibiotic contamination in food and food products has made it imperative to develop analytical methods for their detection. Polyclonal antibodies were used in the development of a surface plasmon resonance (SPR)-based inhibition immunoassay for cephalexin. A conjugate consisting of cephalexin-bovine serum albumin (BSA) was immobilized on the dextran gel surface of the sensor chip. Binding/regeneration studies of antibody to immobilized cephalexin were studied and dissociation of the antibody from the immobilized cephalexin was easily achieved with 10 mmol l¿1 NaOH. Forty surface regeneration cycles were carried out and found to be reproducible with only a 7.4% decrease in binding over this number of regenerations. Model inhibition immunoassays for cephalexin were developed in PBS and spiked milk samples with detection ranges of 4.88 to 2,500 ng ml¿1 and 244 to 3,906 pg ml¿1, respectively.
Generation of group-specific antibodies against sulfonamides
Cliquet, P. ; Cox, E. ; Haasnoot, W. ; Schacht, E. ; Goddeeris, B.M. - \ 2003
Journal of Agricultural and Food Chemistry 51 (2003)20. - ISSN 0021-8561 - p. 5835 - 5842.
enzyme-immunoassay - monoclonal-antibodies - sulfamethazine residues - sulfathiazole - elisa - tissue - recognition - antibiotics - milk - meat
To develop a sulfonamide-specific ELISA, different attempts were made to obtain monoclonal antibodies specific for the common structure of sulfonamides. In a first approach, sulfanilamide was linked to albumins using glutaraldehyde or a succinimide ester as cross-linker. A weak immune response or none at all was induced after immunization of mice with those conjugates. High antibody titers were obtained with conjugates where sulfanilamide was linked to albumins or casein (azocasein) with a diazotation reaction. However, the antibodies were only highly specific for the bound sulfanilamide molecule. In a second approach, sulfonamide-protein conjugates were used in which the sulfonamide molecule is linked at its side chain, leaving the common structure of sulfonamides unchanged. Three sulfonamide derivatives (S, TS, and PS, previously described in the literature) containing a carboxyl group in their side chain were linked to proteins using a carbodiimide mediated reaction. Immunization with the S-conjugates led to high antibody titers, but the antibodies were only highly specific for the bound S-molecule. Group-specific antibodies were obtained after immunization with the PS- and TS-conjugates. It was described that immunization with PS-conjugates lead to the recognition of other sulfonamides (sulfamethazine, -merazine, -diazine, and -dimethoxine) that are not well recognized by antibodies induced after immunization with TS-conjugates. Therefore, we tried to guide the immune response in the direction of recognition of the common structure of sulfonamides by immunizing the animals alternately with PS- and TS-conjugates. The polyclonal antibodies of the mice indeed had a broader specificity, but the specificity of the monoclonals obtained after fusion experiments was not influenced. Immunization with TS-conjugates seemed sufficient to obtain sulfonamide-specific monoclonal antibodies. With the best monoclonal (mAb 3B5B10E3) two competitive inhibition (ci) ELISA's were developed: one coated with antigen and the other coated with the monoclonal antibody. Sulfadiazine, -dimethoxine, -thiazole, -pyridine, and -methoxazole were detected in both ELISA's at their MRL-value (100 ppb) in buffer solution. Sulfadiazine, sulfathiazole, and sulfamethoxazole could even be detected at 10 ppb.
Preliminary evaluation of a lateral flow immunoassay device for screening urine samples for the presence of sulphamethazine
O'Keeffe, M. ; Crabbe, P. ; Salden, M. ; Wichers, J. ; Peteghem, C. van; Kohen, F. ; Pieraccini, G. - \ 2003
Journal of Immunological Methods 278 (2003)1-2. - ISSN 0022-1759 - p. 117 - 126.
enzyme-immunoassay - swine urine - predictors - tissues
A lateral flow immunoassay (LFIA) device was developed and applied to testing urine samples for residues of the antimicrobial sulphamethazine (SMZ). This report describes the preparation of a rat monoclonal antibody to SMZ and its characterisation in an ELISA format. Apart from SMZ, the antibody showed high (50¿cross-reactivity to N4-acetyl-sulphamethazine (55¿ sulphamerazine (59¿and sulphisoxazole (50¿and lower cross-reactivity of 18 o sulphachlorpyridazine and sulphadiazine. The LFIA device consisted of a nitrocellulose membrane spotted with SMZ-ovalbumin and goat anti-mouse antibody as capture line and control line, respectively. Mouse anti-rat IgG F(ab')2 fragment specific antibody, adsorbed to colloidal carbon, was used as the detection ligand in the LFIA. The LFIA device had a cut-off value of 6.3 ng/ml in diluted (1/10) urine. Urine samples from SMZ-treated pigs, and bovine and porcine urine samples fortified with SMZ were used for a blind, four-laboratory evaluation of the performance of the LFIA device. Concentrations of SMZ in the test samples (n=29), as determined by LC-MS/MS, ranged from 0 (
Biosensor immunoassay for the detection of eight sulfonamides in chicken serum
Haasnoot, W. ; Bienenmann-Ploum, M. ; Kohen, F. - \ 2003
Analytica Chimica Acta 483 (2003)1-2. - ISSN 0003-2670 - p. 171 - 180.
enzyme-immunoassay - sulfamethazine residues - 2 sulfonamides - antibodies - assay - immunobiosensor - sulfadiazine - extraction - tissues - kidney
A monoclonal antibody (MAb) raised against sulfamethazine (21C7) was applied in an optical biosensor (Biacore Q) to develop a rapid biosensor immunoassay (BIA) for the detection of several sulfonamides in chicken serum. The performance of this MAb was compared with two polyclonal antibodies (PAbs) raised against sulfamethazine (Qflex sulfamethazine binding protein (SBP) and RIKILT 464b). Using these PAbs, the limits of detection (LODs) in 10 times diluted chicken serum were approximately 30 ng ml-1 and the two BIAs were found to be specific for sulfamethazine. Using MAb 21C7, the LOD for sulfamethazine in 10 times diluted chicken serum was lower (10 ng ml-1), high cross-reactivities were measured for sulfisoxazole (149¿ sulfachlorpyridazine (112¿ sulfachlorpyrazine (94¿ sulfamerazine (87¿ sulfadiazine (56¿ sulfatroxazole (56¿and sulfathiazole (50¿and low cross-reactivities (11¿25¿were measured with six other sulfonamides. Compared with the polyclonal antibodies, the MAb-based BIA resulted in a better sensitivity and was found suitable for the detection of 8 sulfonamides in 10 times diluted chicken serum with LODs between 7 and 20 ng ml-1. The total run time for each cycle was 7 min.
The Dutch Brucella abortus monitoring programme for cattle: the impact of false-positive serological reactions and comparison of serological tests
Emmerzaal, A. ; Wit, J.J. de; Dijkstra, T. ; Bakker, D. ; Ziiderveld, F.G. van - \ 2002
Veterinary Quarterly 24 (2002)1. - ISSN 0165-2176 - p. 40 - 46.
bovine brucellosis - enzyme-immunoassay - diagnosis
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 I 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.
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