IFITM3 and influenza: HeLa cells transfected with siRNA for IFITM3 (or with its scrambled control; Scr) were infected with A(H1N1)pdm09, exposed to HIV-1 or culture medium, and, 24 h after influenza infection, cell supernatants and monolayers were harvested to quantify influenza and IFITM3 levels, respectively.