USE OF A HETEROLOGOUS BRIDGE COATING ANTIGEN FOR THE IMMUNOASSAY OF 3-ACETYLDEOXYNIVALENOL IN BARLEY

The study describes procedures that were used to develop a highly sens itive enzyme-linked immunosorbent assay (ELISA) for the quantitation o f a trichothecene mycotoxin, 3-acetyldeoxynivalenol (3-AcDON), in barl ey. Polyclonal antibodies were produced in rabbits immunized with a co njugate of 3-AcDON and human serum albumin linked by an ester linkage (hemisuccinate bridge). High anti-3-AcDON titers were obtained after m ultiple immunizations. However, only a negligible degree of inhibition was obtained with 3-AcDON in a competitive ELISA when the coating con jugate contained the same ester linkage group (hemiglutarate bridge) a s the immunogen. The use of a conjugate containing a heterologous ethe r linkage (O-methylcarboxyl bridge) compared to that of the immunogen yielded an inhibition curve for 3-AcDON that was highly sensitive (IC5 0 = 0.21 ng/ml) with essentially no interference from the bridging gro up. This conjugate was synthesized using iodoacetate and 1,1'-carbonyl diimidazole chemistries. The assay showed low cross-reactivity with ot her trichothecenes including several analogs of deoxynivalenol (DON) w ith the exception of acetylated DON. The ELISA developed on the basis of this new conjugate was able to detect low concentrations of 3-AcDON (16 ppb) in spiked barley without any cleanup treatments.