FIG 2.

DMXAA activation of stably expressed human STING^AII impedes HCoV-OC43 infection. (A) A549 cells stably expressing STING^WT or STING^AII were treated with PBS, IFNs, DMSO, or DMXAA for 3 h. The cells were washed with PBS prior to HCoV-OC43 infection. In one of the groups, the infected cells were treated with IFNs for an additional 23 h. At 24 h postinfection, cells were fixed and immunostained with antibodies against the HCoV-OC43 N protein (OC43 N) and STING and counterstained with DAPI. Bar: 50 μm. (B) Whole-cell lysates harvested from the cells treated as in (A) were immunoblotted using the indicated antibodies. GAPDH was used as a loading control. (C) DMXAA does not show significant cytotoxicity in A549 cells. A549 cells stably expressing STING^WT or STING^AII were treated with the indicated doses of DMSO or DMXAA (stock concentration: 10 mg/ml) for 3 h. The cells were washed with PBS and fed with fresh culture medium. At 27 h posttreatment, cell viability was measured using the CellTiter-GLO 3D cell viability assay.