Figure 4.

Comparison of point mutant energy costs with documented B*57 associated escape mutations in the TW10 (Gag_240-249) epitope in p24. The 10 residues constituting the epitope are indexed along the abscissa, and the energy cost associated with making a point mutation at each position, ΔE, along the ordinate. The greater the energy cost, the higher the fitness penalty. Mutations at position 246 were not observed within our sequence alignments, leading to the specification within our model of an infinite energy cost of a point mutation at this position, which we denote by *. The observed escape mutations at 242 and 248 (Brumme et al., 2009) occur precisely at the two positions carrying the lowest energy cost (smallest fitness penalty).