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Expression of Codon Optimized β2-Adrenergic Receptor in Sf9 Insect Cells for Multianalyte Detection of β-agonists Residues in Pork.

β2-adrenergic receptor (β2-AR) was expressed efficiently using Bac-to-Bac Baculovirus Expression System in Sf9 cells as a bio-recognition element for multianalyte screening of β-agonist residues in pork. Sf9 cells was selected as the expression system, codon optimization of wild-type nucleic acid sequence and time-dependent screening of expression conditions were then carried out for enhancing expression level and biological activity . Under the optimum conditions of multiplicity of infection (MOI) =5 and 48h post transfection, the protein yield was up to 1.23 mg/mL. After purification by chromatographic techniques, the purified recombinant protein was applied to develop a direct competitive enzyme-linked receptor assays (ELRA) and the efficiency and reliability of the assay was determined. The IC50 values of clenbuterol, salbutamol, and ractopamine were 28.36, 50.70 and 59.57 μg/L, and clenbuterol showed 47.61% and 55.94% cross-reactivities with ractopamine and salbutamol, respectively. The limits of detection (LOD) was 3.2 μg/L and the relevant recoveries in pork samples were in the range of 73.0-91.2%, 69.4-84.6% and 63.7-80.2%, respectively. The results showed that it had better performance comparing with other present nonradioactive receptor-based assays, indicating that the genetically modified β2-AR would have a great applied potential in detection of β-agonist residues.