FIG 3.

The interaction between TRIM25 and RIG-I is inhibited by the SARS-CoV N protein. (A) 293T cells were transfected with Flag–RIG-I and Myc-TRIM25 with or without Myc-N. Anti-Flag immunoprecipitates were analyzed by immunoblotting with anti-Flag or anti-Myc. (B) 293T cells were transfected with Flag-TRIM25, Myc-RIG-I, and the indicated amount of GFP-N. Anti-Flag immunoprecipitates were analyzed by immunoblotting with anti-Flag, anti-Myc, or anti-GFP. (C) HeLa cells expressing the GFP-N or GFP plasmid were fixed with 4% paraformaldehyde and incubated with anti-TRIM25 and anti-RIG-I antibodies. The in situ PLA assay was conducted as described in the text, and the results were imaged with a confocal microscope at magnification of ×100. Red dots indicate the interaction. (D) Red dots indicating positive PLA signals were counted in 30 randomly selected cells. The data are expressed as the means ± SD (*, P < 0.05).