title: Enzyme-linked immunosorbent assay development for the beta-adrenergic agonist zilpaterol.
abstract: Zilpaterol is an beta-adrenergic agonist approved for use in cattle in South Africa and Mexico as a growth promoter. It is not currently approved for use in the EU, USA, or Asia. Here, we report the development of an ELISA for zilpaterol. Zilpaterol was reacted with ethyl 4-bromobutyrate followed by refluxing in 0.1 M potassium hydroxide. The resulting hapten was reacted with two carrier proteins, bovine serum albumin (BSA) or keyhole limpet hemocyanin (KLH), using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as an activating agent. Immunization of goats with the zilpaterol-butyrate-KLH resulted in an antibody useful for an ELISA. We utilized zilpaterol-butyrate-BSA as a coating antigen for ELISA development. The average IC(50) derived from the developed zilpaterol immunoassay was 3.94 +/- 0.48 ng/mL (n = 25). The antibody did not cross react with N-alkyl [bamethane, clenbuterol, (-)-isoproterenol, (+)-isoproterenol, metaproterenol, or salbutamol] or N-arylalkyl (dobutamine, fenoterol, isoxsuprine, ractopamine, or salmeterol) beta-agonists. The assay was tolerant of up to 10% (v/v) of acetone, ethanol, or methanol, and 15% (v/v) of acetonitrile or DMSO. Salt concentrations ranging from 0.05 to 1.0 M minimally affected B(0) or IC(50) values. When buffer pH was <7 or >8.8, the IC(50) values increased in comparison to those measured at pH 7.4. In conclusion, a sensitive, specific zilpaterol ELISA has been developed that can serve as a rapid screening assay.
authors.affiliation: USDA Agricultural Research Service, Biosciences Research Laboratory, 1605 Albrecht Boulevard, Fargo, North Dakota 58105, USA. shelverw@fargo.ars.usda.gov
authors.forename: Weilin L
authors.initials: WL
authors.lastname: Shelver
authors.forename: David J
authors.initials: DJ
authors.lastname: Smith
mesh_terms: D000318:Adrenergic beta-Agonists / Q000032:analysis*; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D012680:Sensitivity and Specificity; D014297:Trimethylsilyl Compounds / Q000032:analysis* / Q000276:immunology
chemical_list: D000318:Adrenergic beta-Agonists; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol