ANXA2 knockdown by siRNA and its effect on PRRSV multiplication. A Reduced ANXA2 expression by siRNA. Marc-145 cells transfected with 100 nM siANXA2 or a non-targeting control (siNC), transfection reagent (mock treatment), or left untreated (no treatment; NT) for 36 h were infected with PRRSV HuN4 at a MOI of 0.01 for 24 and 48 h, and then collected the samples for Western blotting using mouse anti-β actin monoclonal antibody (GenScript), rabbit anti-ANXA2 monoclonal antibody (Cell Signaling Technology) and mouse anti-PRRSV N protein monoclonal antibody. B The relative intensity ratios of N protein and C ANXA2 in a Western blot showing successful knockdown. D PRRSV replication in ANXA2 knockdown cells obtained from cell culture supernatants treated with PRRSV HuN4 was assessed by RNA copy number by quantitative real-time RT-PCR assay and E PRRSV protein titers. *P < 0.05; **P < 0.01.