CD4 and HIV infectious disease: Herein, neither FoxP3 expression by CD3highCD4+ T-cells (Figure 4A) nor the tTreg frequency (Figure 4B) changed upon in vitro HIV infection alone or in combination with TGF-β1 treatment, suggesting that thymocyte infection with HIV does not affect FoxP3 expression by CD4 T-cells or tTreg differentiation.