FOXP3 and infection: Analysis of transcription factors in intrahepatic CD4 T cells indicated a simultaneous increase in proportions of T-bet+ and FOXP3+ CD4 T cells immediately after infection, followed by significant contraction of FOXP3+ CD4 T cells between day 10 and 14 p.i., while the expansion of T-bet+ CD4 T cells continued until day 14 (Fig 1E).