Figure 4.

IFN-γ deficiency increases DCM and mortality during chronic myocarditis. A: Hypertrophy of the myocardium is observed in CB3-infected BALB/c mice during acute myocarditis at day 12 after infection. B: Age-matched, uninfected, mock-treated BALB/c, IL-12Rβ1-deficient, or IFN-γ-deficient mice do not develop DCM at day 35. CB3-infected mice deficient in IL-12Rβ1 (D) or IFN-γ (E) were compared to control BALB/c (C) mice for the level of DCM in the heart 35 days after infection. F: Survival was assessed in CB3-infected and uninfected mouse strains by observing mice from day 0 to day 45 after infection. No deaths were observed in uninfected, mock-treated IFN-γ-deficient, or CB3-infected BALB/c, or IL-12Rβ1-deficient mice. Mice received 10³ PFU of CB3 or PBS intraperitoneally on day 0 and hearts were collected on day 12 or 35 after infection. Hearts were cut longitudinally and assessed for dilation by gross inspection of H&E-stained sections at low power. Individual experiments were conducted five times with 7 to 10 mice per group, with one representative heart shown for each group. Original magnifications, ×2.5.