Figure 3.

SPAN-TCR Distance Measurements. A. Using fine bins, SPAN-TCR compares CDR3 chains of variable lengths. B. Comparison of distance metrics. While a binary metric does not discriminate between a Tyrosine substituted with either Phenylalanine or Cysteine, the BLOSUM metric quantifies the chemical difference (ΔTyr-Phe < ΔTyr-Cys). C. The distance between a putative antigen-specific repertoire and the existing set of reported antigen-specific CDR3s is represented by Levenshtein distance (x-axis) and Binary and BLOSUM SPAN-TCR metrics (y-axis of separate plots) to resolve finer differences. CDR3s found in the lower left quadrant are most similar to the known CDR3s and thus more likely to share antigen specificity. SPAN-TCR reveals that among the nearest Levenshtein neighbors, the Y->F replacement produces the nearest neighbor.