Modification of exercise-aggravated coxsackievirus B3 murine myocarditis by T lymphocyte suppression in an inbred model.

The effects of T lymphocyte suppression on coxsackievirus B3 (CB3) myocarditis and its augmentation by exercise were determined in this study. Three-week-old male C3H/HeN mice were divided into four groups. Group 1 mice were infected intraperitoneally (IP) on day 0 with CB3 10(2.5) TCID50, were made to swim daily from days 1 to 9, and were immunosuppressed with daily doses of cyclosporine A (25 mg/kg IP) from days -2 to 8, plus 0.1 ml antithymocyte 1.2 IgG 2a monoclonal antibody IP on day 0. Mice in group 2 were infected and made to swim daily from days 1 to 9. Mice in group 3 were infected and immunosuppressed as outlined. Mice in group 4 were infected IP with CB3. Mortality rates during the acute phase of infection (days 1 to 9) were as follows: group 1, 4% (1/25); group 2, 52% (13/25); groups 3 and 4, 0. Overall mortality rates through day 21 were as follows: group 1, 67% (17/25); group 2, 72% (18/25); group 3, 40% (10/25); and group 4, 4% (1/25). Mean viral titers in serum were highest in the immunosuppressed groups throughout the study. Myocardial viral titers (mean log10 TCID50) were higher in group 2 mice than in group 1 on days 6 (10(6.9) vs 10(4.6)) and 9 (10(8.4) vs 10(7)); however, these titers peaked in group 1 mice on day 13 (10(9.7)). Myocardial inflammation, necrosis, and mean heart weight/body weight ratios were lower in group 1 compared with group 2 on days 6 and 9 but were maximal on day 13 in group 1. Neutralizing antibody titers were lower in immunosuppressed mice on days 6 and 9; however, a rebound increase occurred on day 13.(ABSTRACT TRUNCATED AT 250 WORDS)

Coxsackievirus B3 myocarditis in C3H/HeJ mice: description of an inbred model and the effect of exercise on virulence.

The effect of forced exercise on the development of coxsackievirus B3 myocarditis in inbred C3H/HeJ mice was studied. Four groups of mice (30 per group) were formed: infected-exercised (Group I); infected-unexercised (Group II); uninfected-exercised (Group III); and uninfected-unexercised (Group IV). Infected mice were inoculated intraperitoneally with 1.0 x 10(2.1) TCID50 coxsackievirus B3. Exercised animals were swum daily for 60 minutes on days 1-9. Myocardial viral titers were acutely elevated on day 3 of infection and were augmented significantly by exercise on days 6 and 9. Exercise increased the overall mortality from 0-10% to 20-40%; significantly increased heart: body weight ratios on days 6, 9 and 13; and increased the extent of myocardial fiber necrosis. We have reproduced the acceleration of CB3 myocarditis by exercise in the inbred C3H model.