The NCAM siRNAs inhibit PHE-CoV infection by indirect immunofluorescence. After a 48 h viral infection, the N2a cells were fixed with 80% acetone for 10 min at -20°C, rehydrated in PBS, labeled with rabbit PHE-CoV antiserum, and washed three times with PBS. FITC-conjugated goat anti-rabbit IgG (H+L) (1:50 dilution) was added to the N2a cell mixtures for 30 min at room temperature, and the cells were washed and observed with an Olympus FV1000 laser scanning confocal microscope. Microscopic magnification, 400×. (A) Mock transfection (stained with PHE-CoV-positive serum); (B) Mock transfection (stained with PHE-CoV-negative serum); (C) siCtrl transfection; (D) siNCAM79 transfection; (E) siNCAM81 transfection; (F) siNCAM90 transfection.