FIG 4.

IBV Nsp15 endoribonuclease activity partially inhibited Newcastle disease virus (NDV)-induced SG production. (A) Cloning strategy to incorporate the Nsp15, Nsp15-H238A, Nsp15-Y334A, and IAV-NS1 genes into the full-length NDV. (B) CEK cells were infected with recombinant NDV virus and stained for immunofluorescence at 18 hpi. Proteins were stained with anti-Flag antibody (green); SGs were detected with anti-G3BP1 (red). Cell nuclei were stained with DAPI (blue). Representative images of three independent experiments are shown. The selected outlined fields represent cells that are infected by NDV and have no SGs formation. (C) SG formation was quantified by counting infected cells with and without SGs in 3–5 randomly selected fields of view at 18 hpi (>100 cells). Error bars = SD for three independent experiments. ***, P < 0.001.