Immunobiosensor Detection of Domoic Acid as a Screening Test in Bivalve Molluscs: Comparison with Liquid Chromatography-Based Analysis

Abstract A rapid and sensitive immuno-based screening method was developed to detect domoic acid (DA) present in extracts of shellfish species using a surface plasmon resonance-based optical biosensor. A rabbit polyclonal antibody raised against DA was mixed with standard or sample extracts and allowed to interact with DA immobilized onto a sensor chip surface. The characterization of the antibody strongly suggested high cross-reactivity with DA and important isomers of the toxin. The binding of this antibody to the sensor chip surface was inhibited in the presence of DA in either standard solutions or sample extracts. The DA chip surface proved to be highly stable, achieving approximately 800 analyses per chip without any loss of surface activity. A single analytical cycle (sample injection, chip regeneration, and system wash) took 10 min to complete. Sample analysis (scallops, mussels, cockles, oysters) was achieved by simple extraction with methanol. These extracts were then filtered and diluted before analysis. Detection limits in the ng/g range were achieved by the assay; however, the assay parameters chosen allowed the test to be performed most accurately at the Euopean Union's official action limit for DA of 20 g/g. At this concentration, intra- and interassay variations were measured for a range of shellfish species and ranged from 4.5 to 7.4% and 2.3 to 9.7%, respectively.</jats:p

Development of Antibodies and Immunoassays for Monitoring of Nitrofuran Antibiotics in the Food Chain

Nitrofurans are a broad group of drugs once widely used for the treatment of microbial and proto-zoal infections in many livestock species. However, as concerns grew globally with regard to the potentially carcinogenic and mutagenic effects of their residues in foods, they have been banned from use in many parts of the world. In order to monitor compliance to these bans, it is essential to have fit-for-purpose testing meth-ods. Immunoassays are the screening tool of choice for many testing laboratories due to their relative low cost, ease of use and high sensitivity. As is the case with all immunoassays, the most important reagents required are high quality, high affinity antibodies that exhibit the required sensitivity and specificity. Generating such antibodies for the nitrofuran family of compounds has required a great deal of effort in the design of immuno-gens, as the compounds, due to size, are not capable of eliciting an immune response in hosts and are not eas-ily conjugated to carrier proteins. This article reviews the range of strategies used to successfully generate suitable antibodies to a wide range of these drugs and their metabolites. In addition, the platform technologies for nitrofuran detection have moved from simple enzyme-linked immunosorbent assay (ELISA)-based proce-dures to more sophisticated multiplexing systems which can undertake faster and broader spectrum testing for the parent drugs and their metabolites. Reviews of the technologies used for immunochemical detection of the nitrofurans and of commercially available test kits are also presented

Use of antigen mimics to produce specific antibodies to anti-coccidial drugs

A range of polyclonal antibodies was successfully produced to the coccidiostatic drugs diclazuril and robenidine. Initial attempts to make immunogenic complexes of both drugs were ineffective due to difficulties encountered while trying to couple the compounds to large carrier proteins. Structural mimics, which could act as haptens for each drug, were sought and identified. The compounds identified were more open to chemical manipulation and were conjugated to carrier proteins to produce effective immunogens. The most sensitive antisera produced displayed IC(50)s of 1.5 ng/ml and 13 ng/ml for diclazuril and robenidine respectively. The antibody for diclazuril was shown to be specific, cross-reacting only with clazuril by 15%. The robenidine antibody displayed a low cross-reactivity of 1.2% to the compound used to produce the antibody. (C) 2007 Elsevier B.V. All rights reserved

Approaches for the simultaneous detection of thiamphenicol, florfenicol and florfenicol amine using immunochemical techniques

Thiamphenicol and florfenicol are antibacterial agents permitted for use as veterinary drugs in animals used for food production. However, as the EU has established maximum residue limits for both and the metabolite florfenicol amine, there is a requirement to monitor animal food products for their residues. In this study antisera were generated which can simultaneously detect thiamphenicol, florfenicol and florfenicol amine in an immunoassay. Details of the various coupling techniques employed to prepare immunogens and enzyme labels are provided and the antibodies produced have been assessed, in homologous and heterologous ELISA formats, with respect to sensitivity and specificity. It was found that while the antisera raised to thiamphenicol and florfenicol generally performed better in a heterologous set up, those raised to florfenicol amine were not only less affected by the assay format but also produced the most sensitive antibodies to all three target analytes. Antisera matched previous sensitivity (IC50&lt;1ngmL-1) but had improved cross-reactivity (&gt;100%) to thiamphenicol and florfenicol.</p