Antibody staining 16 hours after infection of mature DCs with rVV. (A) Infection of DCs and LCL was compared using FACS staining (y-axis) and MoAbs against early and late vaccinia virus proteins (Table 2). VV1-4G9 was a surface stain, whereas all other antibodies required cell permeabilization. IgG2a was used as an isotype control. Infected DCs (arrows) only stained for the early vaccinia virus protein recognized by VV1-6B6, whereas infected LCL (arrows) stained for early and late vaccinia virus proteins. (B) The VV1-6B6 antibody was compared with the LMP-1 antibody, after infection of mature DCs with rVV-LMP-1. The VV1-6B6 and LMP-1 are early proteins, with the latter being an EBV protein. Both antibodies stained the same percentage of DCs, thereby confirming the accuracy of the VV1-6B6 antibody.