Treg proliferation and activation during MCMV infection.

(A) Brain tissue from MCMV-infected, DTx-treated and untreated Foxp3-DTR transgenic mice were collected at 30 dpi. Brain-infiltrating leukocytes were isolated and stained for flow cytometry. CD4+ T-cells were gated on from the CD45+CD11blow leukocyte population for analysis of Foxp3 expression. Isotype control Abs for Foxp3 was used as a gating control. Plots show Ki67-positive and ICOS-expressing Tregs, and are representative of two separate experiments using four animals/time point. (B) Data show the MFI of Ki67-expressing Tregs from the DTx-treated and untreated groups at the indicated time points from 2 independent experiments. **p = 0.0047 DTx- versus DTx+ MCMV-infected at 30 dpi. (C) Pooled data present the MFI of ICOS expression on Tregs between groups at the indicated time points. *p = 0.0165 DTx- versus DTx+ MCMV-infected at 30 dpi. (D) The number of ICOS+ Treg cells in infected brains with and without DTx treatment at the indicated time points is shown. E. The number of Ki67+Treg cells in infected brains with and without DTx treatment at 7, 14, & 30 dpi is shown. **p < 0.001 DTx- versus DTx+