Figure 4.

The antiviral activity of IFITM3‐containing exosome. After 24 h incubation with IFITM3‐containing exosomes, HeLa cells (parental) or HeLa cells with IFITM3 silenced were incubated with DENV‐2 virus for 24 h. Intracellular (A and C) and extracellular (in supernatant) (B and D) viral RNA was measured by real‐time RT‐PCR assay, and the results are presented as relative ratios of total cellular RNA. (E) IFITM3‐containing exosome suppressed CPE triggered by DENV‐2 infection. Intracellular viral RNA was measured in a real‐time RT‐PCR assay, and the results are expressed as relative fold of total cellular RNA. Conditioned media obtained from exosomes derived from each group of cells treated as indicated were quantitatively measured for contained IFN‐α (E) and IFN‐β (F) proteins by ELISA, using Sendai virus (SeV; 100 HAU ml⁻¹) as a positive stimulus control. Data points are presented as means ± SD of triplicated experiments. Student's two‐tailed t test was performed, and statistical significance is shown with asterisks (*P < 0.05, **P < 0.01).