Fig. 5

Absence of the N-terminal region of PL1pro promotes phosphorylation of STAT1 and nuclear expression of p-STAT1. (a) The absence of the N-terminal region of PL1pro upregulates the expression of p-STAT1. H1299 cells were infected with rIBV and rIBV-ΔPL1pro-N at MOI of 0.5 and 1, respectively, then stimulated with IFN-α (100ng/ml) at 6 h post-infection. Western blot was used to detect the expression of STAT1 and p-STAT1 at the indicated times post-infection, respectively. The full-length blots are in Additional file 1: Supplemental Fig. 5. (b) Immunostaining against p-STAT1 in nuclei of H1299 cells. H1299 cells were infected with rIBV and rIBV-ΔPL1pro-N at a MOI of 0.5. At the indicated times post-infection, cells were fixed and stained for p-STAT1 (green). The histogram shows the nuclear expression ratio of p-STAT1. Data were presented as mean ± SD (N = 3). *P < 0.05. Scale bars: 50 μm