A sandwich type ELISA for the detection of Listeria monocytogenes using the well oriented single chain Fv antibody fragment
Abstract Listeria monocytogenes (LM) poses a serious threat to public health. The present study details the development of a sandwich type enzyme linked immunosorbent assay (S ELISA) for the detection of LM using well oriented single chain Fv antibody fragment (scFv) and a polyclonal antibody. The anti LM scFv, used as capture antibody, was gene optimized and expressed with a C terminal PS tag in Escherichia coli BL21(DE3) for oriented immobilization on hydrophilic polystyrene microtiter plates. The anti LM rabbit polyclonal antibody, used as the detection antibody, was prepared using heat killed LM cells as an immunogen. The developed S ELISA showed great specificity to LM and had a detection limit of lg 6.5 CFU/mL, which was better than the control S ELISA using non oriented scFv as the capture antibody. When the S ELISA was applied to pork and pasteurized milk samples spiked with LM, strong responses were observed. In conclusion, the developed S ELISA shows great potential for the rapid detection of LM.