FIG 5.

FMDV replication in cells overexpressing ISG15. (A) Viral titers were examined in LFPKαVβ6 previously transfected with ISG15 and infected at an MOI of 0.1 with WT, LLV, or LproW105A. FMDV yield was determined by plaque assay in BHK-21 cells. Plaques were counted 24 hpi, and titers were expressed as plaque forming units (PFUs) per ml. Values are presented as the mean ± standard deviation from three independent experiments. (B) Schematic representation of the replication-defective Ad5-pISG15 plasmid. HA-tagged pISG15 was cloned in the Ad5-Blue plasmid using ClaI and XbaI restriction enzyme sites. (C) Western blot analysis of protein ISGylation in mock or Ad5-GFP/Ad5-HA-pISG15-transduced LFPKαVβ6 cells in the presence or absence of increasing amounts of porcine IFN-β (5 to 40 U). Eighteen hours after IFN-β treatment, protein ISGylation was detected by using anti-HA antibodies. (D) Viral titers were examined in LFPKαVβ6 previously transduced with Ad5-HA-pISG15 and infected at an MOI of 0.1 with WT virus. Virus yield were determined by plaque assay in BHK-21 cells. The values are presented as the mean ± standard deviation of three independent experiments. Statistical analysis was performed using Student’s t test. *, P < 0.05.