Treatment of male mice with either E2 or the ERα agonist protects against myocarditis and stimulates T regulatory cell response. Male C57Bl/6 GFP-FoxP3 Tg mice, 4-7 weeks of age, were injected s.c. with 0.05 mM/kg ERα agonist (PPT), ERβ agonist (DPN) or 200 ng/mouse E2 on days −4, 0, or +4 relative to infection with 102 PFU CVB3 on day 0. Control animals were injected s.c. with DMSO/corn oil only (vehicle). Groups contained 10 mice each. (A) Animal survival by day 7 after infection, (B) Percentage (%) of myocardium inflamed as determined by image analysis of hematoxylin and eosin stained sections, and (C) Percentage (%) of spleen cells which are positive for CD4 and the GFP-FoxP3. Results are given as mean ± SEM. * and **Significantly different than mice given vehicle at p<0.05 and p<0.01, respectively. Results are from 5-6 mice/group.