ISG15 controls apoptosis in macrophages after VACV infections.

<p><b>A–B.</b> Time course of apoptosis markers during VACV infection in ISG15+/+ or ISG15<b>−/−</b> MEFs (<b>A</b>) or peritoneal macrophages (<b>B</b>). ISG15+/+ or ISG15−/− cells were mock-infected (M) or infected with VACV (WR strain, 10 PFU/cell). At the indicated times post-infection, cells were harvested and total proteins were separated by SDS-PAGE, transferred to nitrocellulose and immunoblotted with anti-PARP-1, anti-caspase-9, anti-activated-capsase-3 and anti bcl-2 specific antibodies. Actin was measured as protein loading control. Protein standards are indicated. <b>C–D.</b> Apoptosis activation in ISG15+/+ or ISG15−/− MEFs (<b>C</b>) or peritoneal macrophages (<b>D</b>). Apoptosis was measured using the Caspase-Glo 3/7 assay kit at 24 hpi Results represent the mean ± the standard deviation of three independent experiments. P-values from a two-tailed t test assuming non-equal variance were determined. In all the cases, P<0.05.