Beta-adrenergic stimulation-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, a 10 day treatment with isoproterenol (ISO) was used to induce physiologic hypertrophy in infected (No treatment, n = 6; Vehicle only, n = 4; ISO, n = 4) or mock-infected mice (No treatment, n = 4; Vehicle only, n = 8; ISO, n = 5). Alternatively, swimming exercise was used to induce physiologic hypertrophy in surviving mice. (A) Virus-infected mice showed a significant increase in heart weight to tibia length ratio following ISO treatment compared to mock-infected control mice (*p<0.001; two-way ANOVA). (B), Hearts of infected mice displayed cardiac hypertrophy by H&E staining following ISO treatment. (C) Higher magnification of heart sections stained by Masson trichrome revealed fibrosis (blue) in both infected and mock-infected mice only after ISO-treatment. (D) Little to no T cell infiltration was observed in the heart following ISO treatment in both infected and mock-infected mice. A spleen positive control for CD3 staining and a No Primary antibody control are shown.