FIG 9.

PRRSV nsp5 inhibits STAT3 signaling. (A) HEK293 cells transfected with nsp5 have a much lower OSM-mediated STAT3 phosphorylation level than that of the control cells with empty vector (EV). The cells were treated with OSM for 30 min before harvested for WB. The relative levels of phosphorylated STAT3 (pSTAT3) and total STAT3 are shown below the images. (B) nsp5 inhibits OSM-stimulated STAT3 reporter expression. HEK293 cells were cotransfected with 0.5 μg of nsp5 plasmid, 0.5 μg of STAT3 reporter, and 0.05 μg of Renilla plasmid. At 24 hpt, the cells were treated with OSM and harvested for luciferase activity assay 24 h later. The relative levels of firefly luciferase activity are shown as fold values compared to the EV control after normalization with the Renilla activity. A significant difference in firefly luciferase activity from the EV+OSM control is denoted by asterisks (***, P < 0.001).