FIG. 4.

SMN expression is increased in reovirus 8B-infected myocardial tissues, coincident with myocardial apoptotic injury. Neonatal Swiss-Webster mice were intramuscularly infected with 1,000 PFU of 8B virus. Myocardial tissues were analyzed on days 1 to 7 postinfection for histologic evidence of myocarditis as well as for expression of SMN by immunohistochemistry, since we have previously shown that apoptotic myocardial injury is detected at 7 days postinfection in this model. SMN protein was detected (brown stain) in infected myocardial tissue beginning on day 7 postinfection (at the time that histologic evidence of myocarditis was detected, within discrete myocardial lesions). Neither SMN nor evidence of myocardial injury was detected at earlier time points postinfection, as demonstrated on days 3 and 5 postinfection. Original magnification, ×40.