CD4⁺CD25⁺ T_Regs of HCV-recovered chimpanzees and CD4⁺CD25⁺ T_Regs of persistently HCV-infected chimpanzees differ from CD4⁺CD25⁺ T_Regs of HCV-naive chimpanzees in their TREC content. The TREC copy number of CD4⁺CD25⁺ cells was divided by that of CD4⁺CD25^– cells for normalization. The dotted line indicates an equal TREC copy number in CD4⁺CD25⁺ and CD4⁺CD25^– populations. The TREC copy number was assessed in the same cell populations as in the suppression assays (Figure 3).