(A, B) Depletion of Hrs, Tsg101, Vps22, Vps24, and Alix. A549 cells were subjected to siRNA knock down of Hrs, Tsg101, Vps22, Vps24, and Alix as in Figs. 4A and 8A. Depletion of Hrs, Tsg101, and Alix was verified by Western blot as in 4A and 8A. The know-down of Vps22 and Vps24 was validated by detection of mRNA using RT-qPCR as in 4B. (C) LCMV WE22 retains the low fusion pH of WE54. LCMV WE54, WE22, cl-13 and rLCMV-LASVGP (107 PFU/ml) were exposed to buffer solution with the indicated pH for 15 minutes. Samples were immediately neutralized and infectious virus titers determined by immunofocus assay on fresh monolayers of A549 cells. Means of 2 independent experiments are shown. (D) Infection with LCMV WE22 depends on Hrs, Tsg101, Vps22, Vps24, and Alix. A549 cells were subjected to RNAi silencing of Hrs, Tsg101, Vps22, Vps24, and Alix as in (A) and (B) respectively. After 72 hours cells were infected with the indicated viruses (500 PFU/well) and infection assessed after 16 hours by IFA (mean ± SD; n = 3).