Molecular and immunochemical characteristics of monoclonal and recombinant antibodies specific to bisphenol A

Four anti-bisphenol A monoclonal antibodies (mabs) were obtained and each characterized by an enzyme-linked immunosorbent assay (ELISA). Among these mabs, BBA-2187 was the most reactive towards bisphenol A. The quantitation limit of the ELISA assay for bisphenol A was 0.13 ng/ml, which is more sensitive than the other immunoassays reported. Then, the cDNA clones encoding variable heavy and variable light chains of these four mabs were isolated, and used for construction of four single-chain Fv (scFv) antibody genes, which were expressed in Escherichia coli cells. The reactivity of four scFv antibodies towards bisphenol A in ELISA was comparable to those of the parent mabs. The most sensitive assay was achieved with BBA-2187scFv. Its cross-reactivity to the related compounds was similar to that of the parent mab. Based on the reactivity of heterologous combinations of VH and VL fragments, it was found that the unique structure of the framework region 2 in the VL of BBA-2187 appeared to be important for specific assembly together with the VH.