Cells were fixed with 4% paraformaldehyde for 30 min, then permeabilized with 0.5% Triton X-100 for 10 min. After 2 washes with PBS, cells were blocked with 10% skim milk in PBS. NF-kB p65 subcellular location was determined by immunostaining with rabbit anti-NF-kB p65, then Alexa Fluor-568-conjugated goat antirabbit IgG antibody (Invitrogen). DENV-2 NS3 was detected by a specific monoclonal antibody against NS3 (#YH3304, 1:500 dilution, Yao-Hong Biotechnology) plus Alexa Fluor-488-conjugated goat anti-mouse IgG antibody (Invitrogen). Fluorescence signals were observed under a fluorescence microscope (Olympus BX51).