Overall it is an interesting study, using sophisticated microscopy techniques to examine the intracellular distribution of IFITM3 during viral infection.
Since this paper is primarily studying IFITM localization and clustering at endosomes/lysosomes it should reference studies in which endocytic localization motifs of the IFITMs were identified and characterized (Jia, Cell Microbiol, 2014; Chesarino, JBC, 2014; Li, JBC, 2015) Line 65 states that subsequent studies have failed to confirm an association between SNP rs12252 and severe influenza.