Collectively, these data indicate that the function of Egr2 and 3 in regulation of clonal expansion differs from their roles in NFAT-mediated anergy and Lag3-Treg cells (Harris et al., 2004; Okamura et al., 2009), demonstrating that distinct mechanisms regulate T cells under homeostatic conditions and during viral infection. This evidence concerns the gene LAG3 and viral infectious disease.