Fig. 2.

Peptide sharing among human pathogens. (A) Shared nine-mer peptides constitute a very small part of the human pathogen peptidome. The pie chart represents the proportions of shared (N = 615,904) and unique (N = 51,861,826) nine-mer peptides, whereas the bar chart shows the extent of sharing across pathogen species for all shared peptides. (B) Distribution of the pairwise peptide sharing among all pathogens (N = 36). The fraction of shared peptides out of all peptides bound by either pathogen is shown for all pathogen pairs (N = 630). (C) Pairwise peptide sharing among a subset of pathogens (N = 16) decreases with increased evolutionary distance. Evolutionary distance between pairs of pathogens was calculated as tip-to-tip distances within the tree of life. See supplementary table S1, Supplementary Material online, for organisms used in the analysis.