Affinity maturation of single-chain variable fragment specific for aflatoxin B1 using yeast surface display

As aflatoxin B-1 is one of the most toxic mycotoxins, it is important to detect and to quantify aflatoxin B-1 accurately by immunological methods. To enhance aflatoxin B-1-binding affinity of the single-chain variable fragment, yeast surface display technique combined with fluorescence-activated cell sorting was applied. A randomly mutated scFv library was subjected to 4 rounds of fluorescence-activated cell sorting, resulting in isolation of 5 scFv variants showing an affinity improvement compared to the parental wild type scFv. The best scFv with a 9-fold improvement in affinity for aflatoxin B-1 exhibited similar specificity to the monoclonal antibody. Most of the mutations in scFv-M37 were located outside of the canonical antigen-contact loops, suggesting that its affinity improvement might be driven by an allosteric effect inducing scFv-M37 to form a more favorable binding pocket for aflatoxin B-1 than the wild type scFv. (C) 2015 Elsevier Ltd. All rights reserved.