Detection of lytic Zta and BMRF1 protein expression in in vitro-infected MDA-MB468 cells. (A and B) Immunoperoxidase staining of MDA-MB468 cells fixed 48 h after infection with cell-free BX1 virus. (A) Anti-Zta primary antibody. (B) Anti-BMRF1 (EA-D) primary antibody. Positive-staining cells are indicated with arrows. (C and D) Immunofluorescence assay showing Zta expression in a converted MDA-MB468-BX1 cell line established by BX1 infection followed by selection for neomycin resistance. (C) Cells were stained with anti-Zta primary antibody and rhodamine-conjugated secondary antibody. (D) 4′,6′-Diamidino-2-phenylindole (DAPI) staining of cell nuclei. (E and F) MDA-MB468-BX1 cells triple stained for LMP1 expression (indocarbocyanine, orange), nuclear Zta expression (rhodamine, red), and DAPI (nuclear, blue) (E) or stained with DAPI alone (F).