Rapid Fine Conformational Epitope Mapping Using Comprehensive Mutagenesis and Deep Sequencing

Knowledge of the fine location of neutralizing and non-neutralizing epitopes on human pathogens affords a better understanding of the structural basis of antibody efficacy, which will expedite rational design of vaccines, prophylactics, and therapeutics. However, full utilization of the wealth of information from single cell techniques and antibody repertoire sequencing awaits the development of a high throughput, inexpensive method to map the conformational epitopes for antibody-antigen interactions. Here we show such an approach that combines comprehensive mutagenesis, cell surface display, and DNA deep sequencing. We develop analytical equations to identify epitope positions and show the method effectiveness by mapping the fine epitope for different antibodies targeting TNF, pertussis toxin, and the cancer target TROP2. In all three cases, the experimentally determined conformational epitope was consistent with previous experimental datasets, confirming the reliability of the experimental pipeline. Once the comprehensive library is generated, fine conformational epitope maps can be prepared at a rate of four per day. Background: A new method using comprehensive mutagenesis libraries, yeast display, and deep sequencing is proposed to determine fine conformational epitopes for three antibody-antigen interactions. Results: For three separate antigens, the experimentally determined conformational epitope is consistent with orthogonal experimental datasets. Conclusion: We conclude that this new methodology is reliable and sound. Significance: With this new method, four antibody-antigen interactions can be mapped per day.