pDC activation by FMDV varies between different FMDV isolates. IFN-α responses of enriched pDCs (CD14-depletion/CD172a-enrichment) stimulated by different FMDV isolates at various MOIs (A) or with various FMDV isolates at an MOI of 5 TCID50/cell (B). After 24 h, IFN-α was measured in the supernatants by ELISA. The bars represent the mean value of triplicates and the errors bars show the standard deviation. The data are representative of three independent experiments.