Invited Talk: Isolation of Selective Nanobodies Against Illegal Antibiotics Used in Food Supply Chains

Economically motivated adulteration of food supply chains presents a major threat to public health and, more generally, on the public trust in the integrity of the food system. The predominant adulterants in food products are illegal antibiotics that are used to prevent bacterial infection of poultry livestock and aquaculture. Overuse of these antibiotics in food supply chains risk the unintentional creation of “superbugs” that are totally drug resistant. Tools that allow rapid detection of antibiotics in food products could have a major and longstanding positive impact on local food systems. Current capabilities, however, include either expensive lab-based tests which are quantitative and slow or rapid kits with low accuracy, low throughput, and an inability to test for multiple adulterants. This situation leads to very sparse testing of food supply chains that cannot meet the monitoring need in areas with a large volume of transactions. In order to improve monitoring of food supply chains, we have developed single-domain antibodies, or “nanobodies”, that are highly selective for an individual antibiotic. The small size of nanobodies allows for improved solubility, shelf-life, and functionalization to existing sensor technologies. As an example, we have developed a nanobody that binds to chloramphenicol with a dissociation constant of 50nM by using crystallography and molecular dynamic simulations to improve its binding affinity. This paradigm can be used to develop additional nanobodies that target small molecule adulterants of interest in food supply chains with the goal of creating an array of recognition elements for sensor-based applications.