FIG 4.

PRRSV mediates STAT3 reduction via the ubiquitin-proteasomal degradation pathway. (A) MG132 treatment restores STAT3 level in PRRSV-infected cells. MARC-145 cells were infected with VR-2385 at an MOI of 1. At 30 hpi, the cells were treated with MG132 for 6 h and then harvested for Western blotting with antibodies against STAT3 and GAPDH. Nontreated and mock-infected cells were included as controls. The relative levels of STAT3 protein are shown as fold values below the images after normalization with GAPDH. (B) PRRSV replication is not affected by the MG132 treatment. The relative PRRSV RNA levels determined by real-time PCR are shown compared to mock-treated cells.