FIG 2.

PRRSV infection reduces NDRG1 mRNA and protein levels. (A) MARC-145 cells were infected with PRRSV BJ-4 at an MOI of 10 for the indicated times. RNA was extracted from uninfected and infected cells. NDRG1 mRNA levels were detected by RT-qPCR. Values were normalized to β-actin (ACTB) mRNA levels. Data are the means ± standard errors of the means from three independent experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.0001 (by one-way ANOVA). hpi, hours postinfection. (B) Lysates of uninfected or infected cells were analyzed by immunoblotting using anti-NDRG1 and anti-PRRSV-N antibodies. β-Actin was used as the loading control. (C) PAM cells were infected with PRRSV BJ-4 at an MOI of 5 for the indicated times. RNA was extracted from uninfected and infected cells. NDRG1 mRNA levels were detected by RT-qPCR. (D) 3D4/21-CD163 cells were infected with PRRSV BJ-4 at an MOI of 10 for the indicated times. RNA was extracted from uninfected and infected cells. NDRG1 mRNA levels were detected by RT-qPCR. (E) Staining for NDRG1 was reduced in PRRSV-infected cells. MARC-145 cells were infected with PRRSV BJ-4 at an MOI of 10 for 48 h and then fixed and stained with antibodies directed against PRRSV-N (green) and NDRG1 (red). White dotted lines highlight infected cells, and asterisks indicate uninfected cells. Fluorescence intensities were quantified in both uninfected and PRRSV-positive cells (n = 40) with ImageJ. ***, P < 0.0001 (by an unpaired two-tailed t test).