Figure 2. No discernible cardiac hypertrophy or immunopathology in the adult heart following juvenile CVB3 infection.

Three day-old mice were infected with eGFP-CVB3 (10⁵ pfu IP) or mock-infected, and inspected for viral titers over time. (A) Viral copies in the heart were determined by quantitative real time RT-PCR. The R² value (0.997) was determined by plotting C_T values versus viral copy number (upper right corner). An R² value of 1.00 indicates that all data points lie perfectly on the graphed data set line. (B) The ratio of positive-sense to negative-sense viral genome was calculated over time in the heart. (C) Viral titers in the heart were determined using standard plaque assay on HeLa cells. (D) Using two-way ANOVA statistical analysis, no differences in heart weight to body weight ratios were observed between infected (day 2, n = 10; day 6, n = 8; day 9, n = 5; day 28, n = 12; day 77, n = 8) and mock-infected mice (day 2, n = 19; day 6, n = 8; day 9, n = 5; day 28, n = 6; day 77, n = 6) up to 77 days PI. (E) Heart sections from mice immunostained for T cells (CD3) and macrophages (Iba1) at 2 and 77 days PI showed the relatively low levels of inflammatory cells in the myocardium. Also, heart sections were inspected for histopathology by hematoxylin & eosin (H&E), or Masson's trichrome staining. H&E staining confirmed normal myofibrillar arrangements and Masson's trichrome staining showed an absence of fibrosis following infection. Representative images of three infected or mock-infected mice are shown. Also, spleen positive controls for both CD3 and Iba1 staining are shown.