FIG 8.

CO inhibits PRRSV replication mediated via the cGMP/PKG signaling pathway. (A to C) MARC-145 cells were infected with PRRSV at an MOI of 0.1 for 1 h, and cells were then treated with either ODQ (10 μM) or KT5823 (1 μM) in the presence or absence of 100 μM CORM-2 for 36 h. The abundance of intracellular ORF7 mRNA and supernatant viral RNA copy numbers were analyzed by qPCR (A and C). Expression of N protein was determined by Western blotting (B). (D to F) MARC-145 cells were treated with various doses of 8-Br-cGMP (1, 2, 5 mM) from 1 hpi onward. Cells and culture supernatants were harvested at 36 hpi for further analysis. PRRSV replication was determined using qPCR for intracellular ORF7 mRNA (D) and supernatant virus copy numbers (F) and Western blotting for PRRSV N protein (E). SK-N-SH cells infected with EV71 (MOI of 0.1) were treated with 2 mM 8-Br-cGMP from 1 hpi onward. Cells were harvested at 24 hpi, and then EV71 VP1 mRNA (D) and supernatant progeny virus production (F) and VP1 protein expression (E) were determined by qPCR and Western blotting, respectively. Data are expressed as the means ± SD of the results of three independent experiments. P values were calculated using Student's t test. **, P < 0.01; ***, P < 0.001.