SIV virus expressing LMP1 or LMP1-CD40 induces morphological changes in DCs and macrophages. (A) Western blot of 293T cell lysates transfected with SIV expressing LMP1 or LMP1-CD40. Virus expressing GFP served as a negative control. Gag p27 was present in all lysates. LMP1 and CD40 intracellular domains were present only in cells transfected with LMP1 or LMP1-CD40 viral constructs respectively. Blots were stained with anti-Gag (upper panels), anti-LMP1 intracellular domain (middle panels), or anti-CD40 intracellular domain (lower panels). (B) Representative images of human monocyte derived dendritic cells (DCs) or macrophages infected with the various SIV viruses. DCs or macrophages were infected with the parent single cycle virus SIVmac239 FS-ΔPR-ΔIN (expressing Nef) (10) or a Nef-deleted scSIV expressing GFP, LMP1, or LMP1-CD40. Only LMP1 or LMP1-CD40 expressing viruses induced elongation of human DCs or macrophages, suggesting the activation and maturation of cells in the culture.