Label-free real-time monitoring of reactions between internalin a and its antibody by an oblique-incidence reflectivity-difference method

Surface protein internalin (InlA) is a major virulence factor of the food-borne pathogen L. monocytogenes. It plays an important role in bacteria crossing the host's barrier by specific interaction with the cell adhesion molecule E-cadherin. Study of this protein will help to find better ways to prevent listeriosis. In this study, a monoclonal antibody against InlA was used to detect InlA. The reaction was label-free and monitored in real time with an oblique-incidence reflectivity-difference (OI-RD) technique. The kinetic constants k on and k off and the equilibrium dissociation constant K d for this reaction were also obtained. These parameters indicate that the antibody is capable of detecting InlA. Additionally, the results also demonstrate the feasibility of using OI-RD for proteomics research and bacteria detection.