Objective: To establish a BALB/c mice model system of cytomegalovirus-induced myocarditis.
Methods: Twenty five specific pathogen-free inbred female BALB/c mice (5 weeks old, 16 - 18 g, seronegative for MCMV) were infected with 1 x 10(4) PFU MCMV by the intraperitoneal (i.p.) route. All experimental mice were sacrificed at 3, 5, 7, 10, 14 days i.p. (n = 5 per time point). Hearts were removed under aseptic conditions, and were transected along the midline. One part of each heart was processed with Bouin's fixative for histological examination. The other part of each heart was immediately frozen in liquid nitrogen and stored at -80 degrees C until MCMV titre was determined by plaque assay. Serum cTnI level was assayed by ELISA.
Results: MCMV was detected in the hearts at extremely low levels on 3 days i.p. and could not be detected on 10 days i.p. A mixed cellular infiltrate composed of polymorphonuclear neutrophils and mononuclear lymphocytes was observed on 3 days, which reached a peak at 7 to 10 days after MCMV infection and was maintained for at least 3 - 4 months postinfection. Serum cTnI levels were elevated on 3 days i.p., reaching a peak at 7 to 10 days i.p..
Conclusions: These data highlight the possible therapeutic uses of antiviral drugs in viral myocarditis as well as further elucidating the pathogenic nature of the disease.