PSMB8 and myocarditis: To address the question of whether ablation of LMP7 in A/J mice affects the virus concentration during acute myocarditis, we quantified the virus titer in heart tissue by plaque assay and found an equivalent virus load of 5.4 × 105 ± 0.4 × 105 pfu/g in LMP7+/+ mice and 5.1 × 105 ± 0.2 × 105 pfu/g in LMP7−/− mice (Fig. 1g).