Cloning, expression and characterization of a single-chain antibody specific for the herbicide atrazine

The antigen-binding domain of an antibody specific for the herbicide atrazine was cloned from hybridoma 4063-21-1 and expressed as a single-chain antibody (scAb) in the vector pPM1-His. The observed heavy and light chain gene sequences were consistent with those in subgroup VH I (B) and VK IV, as defined by the Kabat database of sequences. Subsequent expression in Escherichia coli strain XL-1 Blue produced up to 0.3 μg of functional single-chain antibody, from periplasmic protein preparations, per millilitre of culture. The scAb was purified as a monomer by immobilized metal chelate affinity chromatography via a hexa-histidine tail or as a dimer by antibody affinity chromatography. The functionality and specificity of the recombinant antibody was confirmed by binding to an atrazine-bovine serum albumin conjugate and free atrazine and simazine in a competition ELISA. This is the first example of the production and purification of a recombinant antibody that retains antigen binding for a triazine herbicide.