FIG 3.

Overexpression of HMGB1 inhibited PCV2 replication. PK-15 cells were transfected with recombinant plasmid expressing HMGB1 (pHMGB1) or control plasmid (pFlag) for 24 h and then infected with PCV2 (MOI = 1) for 36 h. (A) Effect of HMGB1 overexpression on PCV2 Cap expression as shown by immunoblotting using protein samples from the whole-cell lysates. β-Actin was used as a loading control. The gel shown is representative of three independent experiments. (B) The ratios of band intensity of HMGB1 or PCV2 Cap to β-actin (as shown in panel A). (C) Effect of HMGB1 overexpression on PCV2 orf2 (encoding Cap) transcription measured by qPCR using total RNA extracted from the whole-cell lysates. (D) PCV2 replication in cells overexpressing HMGB1 as assessed by indirect immunofluorescence. Percentages of PCV2-infected cells were calculated as described in the legend for Fig. 2. Relative percentages of PCV2-infected cells in the HMGB1 overexpressing cells are shown with nontransfected but PCV2-infected cells set at 100%. (E) PCV2 genomic DNA copies in cells overexpressing HMGB1 quantified by qPCR using total DNA extracts from whole-cell lysates. Bar charts in panels B, C, D, and E show means ± SDs from three independent experiments. ns, not significant; **, P < 0.01; ***, P < 0.001.