As a positive control, in one group of MFYcre mice, we intraperitoneally injected 1 x 106 CD4+CD25+GFP+ Tregs from wild-type (WT) Foxp3-GFP reporter mice or CD4+CD25+ Tregs from congenic CD45.1 mice 2 weeks prior to the infection. Here, CD4 is linked to infection.