Figure 5.

Mixed haplotypes offer the highest protection. A host population having iNKRs and aNKRs was inoculated with a wild-type virus after a period of t = 5000 years; we allowed for the evolution of decoy viruses 10,000 years after the initial epidemic (i.e., t₁). (A) The population size during the initial spread of decoy viruses (t₁) is lower than that at the end of the simulations (i.e., t₂ = 3 million years), indicating that over time, the population recovers from the viral infection. (B) The initial haplotype is composed of five iNKRs and five aNKRs. The number of aNKRs and iNKRs per haplotype varies over time, resulting in a selection for haplotypes with a larger activating potential. (C) The probability of NKRs recognizing any random MHC molecule in the population, decreases over time, indicating that more specific receptors are being selected for. (D) The degree of NKR polymorphism (expressed as the SRI score) increases in time, as a result of the heterozygote advantage due to the evolved higher specificity. Averages are taken out of ten different simulations. In (A), the boxes represent the interquartile range, and the thick horizontal lines the median (**represent p values <0.005, and were calculated using the Mann–Whitney U test). In (B–D), the solid lines represent the average out of ten simulations, and the dashed lines are the standard deviation.