FIG 4.

The MEK-ERK1/2 pathway is required for PRRSV-induced COX-1 production. PAMs were pretreated for 1 h with candidate inhibitors of signaling molecules, including GF-109203X (GF; a PCK inhibitor; 2 μM), LY294002 (LY; a PI3K inhibitor; 5 μM), PD98059 (PD; an MEK inhibitor; 10 μM), BAY11-7082 (BAY; an NF-κB inhibitor; 1 μM), or SB202190 (SB; a p38 MAPK inhibitor; 10 μM), and then infected with HP-PRRSV strain JXnw06 (MOI, 2) in the absence or presence of inhibitors. COX-1 expression was then examined by real-time PCR (A) and Western blotting (B) at 24 hpi, and the PGE₂ level in the supernatant was detected using ELISA (C). (D) PAMs were inoculated with PRRSV (MOI, 2); cells were harvested at 0, 4, 8, 12, 24, and 36 h postincubation; and p-ERK1/2 and ERK1/2 were determined by immunoblotting with β-actin as a reference control. (E) PAMs were pretreated with PD98059 at a concentration of 0 μM, 5 μM, 10 μM, or 25 μM for 1 h and then infected with HP-PRRSV strain JXnw06 (MOI, 2) in the absence or presence of the inhibitor. At 24 h postinfection, COX-1, p-ERK1/2, and ERK1/2 were examined by Western blotting with α-tubulin as a reference control. Data are means ± SEMs from three independent experiments. Differences were evaluated by Student's t test. (*, P < 0.05; **, P < 0.01).