Detection of viral RNA in experimental coxsackievirus B3 myocarditis of mice using the polymerase chain reaction.

The presence of the viral RNA in the myocardium in experimental coxsackievirus B3 myocarditis of mice was investigated using the polymerase chain reaction (PCR). Four-week-old C3H/He mice (n = 35) were inoculated with coxsackievirus B3 (Nancy strain, 10(5) plaque-forming units/mouse). We used a pair of primers, which encompass a part of the 5' end sequence of the coxsackievirus B3 genome and can also detect many enteroviral RNAs. We found that hearts were positive for the viral RNA from 2 to 21 days after virus inoculation by PCR, but negative after day 28 and in non-infected control mice (n = 5). The viral RNA were detected by PCR later than by culture. Thus, the detection of the viral RNA using enzymatic amplification is more rapid and easier and may be more useful for clinical diagnosis of viral myocarditis than conventional culture methods. However, virus persistence in the myocardium long after virus inoculation is unusual in this model.