Fig. 1.

Conceptual representation of selection of different MHC variants depending on the peptidome compositions of pathogens. Empty circles represent peptidomes of three different pathogens, whereas orange icons represent representative antigens. If peptide sharing among pathogens is extensive (A), a single MHC variant would be enough to mount an immune response against all pathogens. If the peptide sharing among pathogens is very low (B), different MHC variants would be required for effective overall pathogen control.