A line of murine BALB/c-derived DCs (D1 cells) was prepared and propagated according to the method described by Chua et al [26] . After a minimum of 21 days in culture, cells were stained for Class II MHC using FITC conjugated anti-IA/IE antibody (Clone M5/114.15.2; Becton Dickinson, USA) and PE-conjugated CD11c (Clone 2G9; Becton Dickinson, USA) prior to use. Cells were verified to be CD11c + MHC Class II + by flow cytometry using a FACSCaliber (Becton Dickinson, USA). D1 cells (2610 5 ) were seeded onto a petri dish in 1 ml of fresh D1 media [26] and incubated at 37uC and 5% CO 2 in the presence or absence of 5 mg FITC-labelled VLPs alone or with VLPs mixed with E 8 Pam 2 Cys (0.2 pmole/ml).