A competitive enzyme-linked immunosorbent assay (ELISA) to detect retronecine and monocrotaline in vitro

Antibodies to the nonesterified pyrrolizidine nucleus, retronecine (155 mol.wt), were produced in rabbits and detected using an avidin-biotin antibody ELISA. A competitive ELISA for the detection of retronecine and the cyclic diester monocrotaline was also developed using the antiserum produced against the hapten conjugate, retronecine-bovine serum albumin. Retronecine was obtained by hydrolysis of monocrotaline, succinylated and directly coupled to bovine serum albumin or ovalbumin. Antibodies to the pyrrolizidine nucleus, retronecine, can be detected within 5 min after the addition of substrate using the avidin-biotin ELISA. Competitive inhibition of antibodies to retronecine is obtained by the addition of known amounts (0–11.42 μg/μl) of either the homologous antigen, retronecine, or the heterologous antigen, monocrotaline, however, retronecine acts as the better competitor.