2.3. Immunofluorescence Staining
1× 105 A549 cells were seeded in 48-well plates with partitions, and the experiment was set as NC group, IAV group, and IAV+ AS-IV group. 2 h after virus infection, the cells were cleaned with PBS solution twice, and then AS-IV solution was added to IAV+ AS-IV group, and maintenance medium was added to the other groups. After a certain time, the cells were fixed with 4% paraformaldehyde for 30 min and then blocked with 1% bovine serum albumin + 0.2% TritonX-100 for 1 h. Influenza A Nucleoprotein/ NP antibody (Sino Biological, Cat: 11675-MM03T, Beijing, China; 1:200) was then added to the cells and incubated overnight at 4°C. The primary antibody was then absorbed and abandoned, fluorescein Dye488-conjugated goat anti-mouse antibody was supplied by (Biqdoo-Bio, B100812, Wuhan, China; 1:200) was added and incubated in the dark for 1h, and finally Hoechst (Beyotime, C1022, Shanghai, China) was added to stain the nucleus for 15min. The expression of NP was observed under the fluorescence microscope. Use Photoshop (2021) to merge images.