Knockdown of lnc641 by siRNAs inhibits PRV replication. A 3D4/21 cells were transfected with two siRNAs (si641-1, si641-2) or negative control (siNC). At 36 h post-transfection, the knockdown efficiency of lnc641 was determined by qRT-PCR. B–E 3D/21 cells placed in 24-well plates were transfected with the two siRNAs for 36 h and then infected with ZJ01 (0.01 MOI). After 24 h, the cell samples were collected to measure the replication of PRV by qRT-PCR (B) and Western blot assays (C). The supernatant was used to measure the viral titers by TCID50 analysis (D). The cells were treated as described previously, and IFA was performed with a primary anti-gB protein monoclonal antibody to analyze the antiviral effect of PRV. Viral gB-protein is green, and nuclei are blue (E). Results are presented as means ± SEM of data from three independent experiments. * P value < 0.05, ** P < 0.01, *** P < 0.0001.