Hapten synthesis, monoclonal antibody production and development of a competitive indirect enzyme-linked immunosorbent assay for erythromycin in milk

Erythromycin is an antibiotic used extensively in veterinary practice worldwide for treatment, prevention and growth promotion. In this work, monoclonal antibodies (Mabs) against erythromycin were produced and used to develop a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for the determination of erythromycin in milk. A novel carboxyphenyl derivative of erythromycin (ERO-CMO) was synthesized and conjugated with bovine serum (BSA) for use as the immunogen or ovalbumin (OVA) as the coating antigen. Four hybridoma cell lines were isolated, which produced Mabs that competed with erythromycin. The 6C1 and 5B2 Mabs had IC50 values for erythromycin of 14.40 and 0.94 μg L−1, respectively. These Mabs demonstrated high cross-reactivity to the macrolides containing 14-membered rings, but not to oleandomycin. No cross-reactivity was observed for 12 macrolides that contained 15 or 16-membered lactone rings or for 2 pleuromutilins. The ciELISA developed using the 5B2 Mab afforded recovery values that ranged from 76.9% to 85.7% with only a 10-fold sample dilution prior to analysis.