Endosomal and lysosomal acidification and lysosomal enzyme activities are required for type I IFN production by BMDCs in response to MVA infection.

<p>(A) GM-CSF-BMDCs (1×10⁶) were infected with MVA at a MOI of 10 for 1 h. Cells were washed and incubated in fresh medium in the presence or absence of chloroquine (50 µM), bafilomycin A1 (100 nM), or CA-074-Me (10 µM). Supernatants were collected 22 h later. The concentrations of IFN-α/β were determined by ELISA. Data are means ± SEM (n = 6). The combined results of three independently performed experiments are shown. **, <i>p</i><0.01; ***, <i>p</i><0.001; compared with no drug treatment. (B) GM-CSF-BMDCs were generated from Cathepsin B KO (CathB^−/−) and age-matched WT controls (CathB^+/+). Cells (1×10⁶) were infected with MVA at a MOI of 10. Supernatants were collected 22 h later. The concentrations of IFN-α/β were determined by ELISA. Data are means ± SEM (n = 3). A representative experiment is shown, repeated twice. **, <i>p</i><0.01; comparisons were made between CathB^+/+ and CathB^−/− cells as indicated.