Figure 4.
Severity of myocarditis in infected mice. Wild-type mice (MF1, 129, and MF1/129 hybrid F2) and NOS2 null mice (MF1/129 KO) were infected with (A) 105 or (B) 107 pfu of CVB3. Hearts were harvested from noninfected animals or from infected mice at times 1, 3, 5, 7, 10, and 15 days after infection. Tissue sections were stained with hematoxylin and eosin, and the severity of the myocarditis was graded. For A the differences between the NOS2 null mice and all other wild-type controls for day 5 are P < 0.05 and for days 7–15 are P < 0.001. For B the differences between the NOS2 null mice and all other wild-type controls are P < 0.005. (n = 3 sections from each of 3 mice ± SD.)