The increased VACV replication in cultured cells is DUSP1 specific.

<p><b>A</b>) HeLa cells were treated with 50 nM of either DUSP1 siRNAs or scramble siRNA as a control and after 24 hours of incubation cells were infected with WR or MVA at 0.1 PFU/cell. Samples were collected at 0, 24 and 48 hours and viral titers were determined by immunostaining plaque assay in DF-1 cell line. Lower panel shows fold decrease of DUSP1 mRNA levels in siRNA-treated cells compared to mRNA levels in scramble siRNA-treated cells. <b>B</b>) DUSP1 KO MEFs were nucleofected with 6 µg of either pSG5-empty or pSG5-DUSP1 and DUSP1 protein expression analyzed by WB at 24 and 48 hours post-transfection (lower panel). After 24 hours of incubation with siRNAs, cells were infected with WR or MVA at 0.1 PFU/cell. Samples were collected at 0, 24 and 48 hours and viral titers were determined as in A. One representative example of two independent experiments assayed in duplicate is represented. p<0.05 (*), p<0.005 (**) and p<0.001 (***).