Regulation of PA28αβ during CVB3 infection.

(A) 6–8 weeks old, male C57BL/6 mice (n = 4) were infected with CVB3 and sacrificed at day 8 after infection. Age- and gender-matched naive mice (n = 4) served as a control. Tissue homogenates of heart and spleen were analyzed by Western blotting to determine PA28α and PA28β protein levels. Actin served as a loading control. Densitometric analysis was performed and PA28α/PA28β levels are shown as relative intensities with a normalization based on the respective levels of actin (means + SEM, n = 4). (B) Primary embryonic cardiomyocytes (eCMs) obtained from wild-type mice and HeLa cells were infected with CVB3 at MOI 0.1 for 0 or 24 h. PA28α/PA28β mRNA levels were determined by real-time qPCR (means + SEM, n = 3). (C) HeLa cells were infected with CVB3 at MOI 0.1 for indicated lengths of time. PA28α and PA28β protein levels in total protein extracts were determined by Western blotting. The densitometric analysis of PA28α/PA28β protein levels is depicted as relative intensities (means + SEM, n = 3).