Rapid methods for the detection of anti-parasitic drugs

Abstract

The benzimidazoles (BZD), thiabendazole (TBZ), triclabendazole (TCB) and albendazole (ABZ), are veterinary agents employed for the eradication of parasitic infections in ruminant animals. Treatment with these drugs commonly results in trace residues remaining in the food product, thus requiring the development of tests capable of detecting below maximum acceptable residue levels (MRLs) as determined by European legislation. This research describes the development of novel, rapid, antibody-based methods for benzimidazole residue detection below the required MRL. A recombinant antibody fragment (Fab) generated from a hybridoma secreting an anti-TBZ monoclonal antibody was utilised for the development of an ELISA for TBZ with a limit of detection (LOD) of 2.5 ng/mL. Thee sensitivity of this Fab was improved two fold by generation of a modified plasmid vector which converts the Fab from a mono-valent to a bivalent antibody. An avian polyclonal antibody (pAb) was raised against TCB and ABZ. This antibody was incorporated into competitive ELISA and Biacore-based assay with LODs for TCB in spiked pasteurised organic milk samples of 609 and 203 pg/mL, respectively. A short chain fragment (scFv) antibody library of 5.9 x 1011 was also constructed, bio-panned and screened for clones specific for TCB and ABZ. Finally, the anti-TCB IgY was incorporated into a lateral flow immunoassay (LFIA) and a novel TCB-green fluorescent protein (GFP) LFIA assay with a detection threshold of 75-100 ng/ml of TCB in milk, which is at or below the required MR