Therefore we tested IFITM3's impact on the most proximal phase of infection, viral binding, by incubating influenza A virus A/WSN/33 H1N1 (WSN/33, multiplicity of infection (moi) 50) with A549 lung carcinoma cells either stably overexpressing IFITM3 (A549-IFITM3) or an empty vector control cell line (A549-Vector, Fig. 1A). The gene discussed is IFITM3; the disease is infection.