Figure 3

p53 mediates PCV2-induced S phase accumulation and promotes viral multiplication. A Flow cytometry analysis of cell cycle subversion in serum-starved WT PK15, 148PK15^P53−/−, and 813PK15^P53m/m cells upon PCV2 infection (MOI = 1). Cells were fixed in ethanol at 24 h pi, DNA was stained with propidium iodide and applied to flow cytometry. The percentages of each cell cycle phase (G0/G1, G2, S) were output and analyzed by ModFit LT software in the right panel. B Quantitative analysis of S-phase entry (percentage of BrdU-positive cells) exposed to the 1 MOI PCV2 for 12 h and successively cultured in the BrdU for 1 h. C Absolute quantification of PCV2 replication in WT, 148PK15^P53−/−, and 813PK15^P53m/m cells. 1 MOI of PCV2-infected asynchronously growing WT, 148PK15^P53−/−, or 813PK15^P53m/m, and viral ORF1 DNA were determined by the combination of the supernatant fluids and cytoplasmic extraction at 12, 24, 48 h pi. The data are mean ± SEM of three independent experiments. *p < 0.05 versus mock infection in the same kinds of cells. ^# p < 0.05 versus PCV2-infected WT cells at same time point.