Myocarditis and cardiac virus titers in intact and gonadectomized (Gdx) male and female C57BL/6 mice infected with coxsackievirus B3 (CVB3). Male and female C57BL/6 mice were injected intraperitoneally with 100 PFU CVB3 and surviving mice were killed 7 days later. Half of the animals were gonadectomized 4-6 weeks prior to infection. Hearts were removed, divided and either homogenized for determining virus by the plaque-forming assay or fixed in formalin, paraffin embedded, sectioned and stained by hematoxylin and eosin. (a) Mean ± SEM myocarditis score based on a 0-4 scale with 0 = no inflammation; 1 = 1-10 lesions/section; 2 = 11-20 lesions/section; 3 = 21-40 lesions/section and 4 = ≥ 41 lesions/section ; and (b) virus titers given as mean ± SEM plaque-forming units (PFU) log10/g heart tissue of 4-7 mice/group. *Significantly different at P < 0.05.