CEFTIOFUR SODIUM - MONOCLONAL-ANTIBODY DEVELOPMENT AND CROSS-REACTIVITY STUDIES WITH STRUCTURALLY RELATED CEPHALOSPORINS

Monoclonal antibodies were prepared against ceftiofur using its hydrol yzed form, desfuroylceftiofur, as the hapten. Desfuroylceftiofur was p repared in situ and conjugated directly to maleimide-activated carrier proteins bovine serum albumin and keyhole limpet hemocyanin (KLH). Ba lb/c mice were immunized with the desfuroylceftiofur-KLH conjugate (KL H-SMCC-desCef), Splenic lymphocytes from these mice were fused with SP 2/0 myeloma cells to produce hybridomas. Two stable monoclonal antibod ies, Cef-68 and Cef-116, of subclasses IgG(2a) and IgG(1), respectivel y, were isolated. An indirect competitive inhibition enzyme-linked imm unosorbent assay (ciELISA) was developed for the quantitative detectio n of ceftiofur in liquid samples using a heterologous assay system to provide a more sensitive ELISA. Detection limits for ceftiofur were 32 and 0.3 ppb for the two clones Cef-68 and Cef-116, respectively. The ciELISA described here provides a sensitive assay for the detection of ceftiofur. Cross-reactivity studies with a variety of related cephalo sporins and penicillins indicated that only a limited number of the ce phalosporins and none of the penicillins that were tested competed in the ciELISA.