IFITM3 Clusters on Virus Containing Endosomes and Lysosomes Early in the Influenza A Infection of Human Airway Epithelial Cells

Kummer, Susann; Avinoam, Ori; Kräusslich, Hans-Georg

The IFITM3-mediated inhibition of IAV infection has been suggested to be caused by changes in the membrane tension resulting in a block of fusion pore formation [71] , and may be due to constitutively expressed protein or interferon induction [38, 41, 57, 72] . Applying confocal and super-resolution imaging of endogenous IFITM3, we show that pre-existing IFITM3 clusters at early and late endosomal structures carry IAV at early time points of infection, prior to interferon induction. As shown previously [32] and in our study ( Figure S2 ), interferon alpha led to increased protein levels of IFITM3 at later time points. On the other hand, no increase in the IFITM3 protein levels was observed up to 6 h p.i. in IAV infected A549 cells.