Exercise-induced cardiac hypertrophy in adult mice infected with CVB3 at an early age leads to dilated cardiomyopathy.

Three day-old mice were infected with eGFP-CVB3 (10⁵ pfu IP) or mock-infected. After 13 weeks, swimming exercise was used to induce physiologic hypertrophy in surviving mice. (A) Virus-infected mice (n = 5) showed a significant increase (*p<0.05; Student's T-test) in heart weight to tibia length ratio following a 21 day swimming procedure compared to mock-infected control mice (n = 4). (B) Hearts of infected mice displayed cardiac hypertrophy by H&E staining. (C) Higher magnification of heart sections stained by H&E and Masson trichrome revealed signs of inflammation and fibrosis (respectively) in infected mice following the swimming procedure. (D) Little to no T cell infiltration was observed in the heart following the swimming procedure in both infected and mock-infected mice. Representative slide scanner images or microscopic images for three infected or mock-infected mice are shown.