Motifs of Nef involved in phagocytosis inhibition. (A-B) Primary human macrophages transiently expressing GFP or Nef-GFP or the indicated Nef mutants: Nef D174-175A GFP, Nef G2A GFP, Nef E62-65A GFP, and Nef L164-165A GFP were allowed to phagocytose IgG-RBCs or C3bi-RBCs for 60 minutes at 37°C. The samples were processed as in Figure 1. The efficiencies of association (A) and phagocytosis (B) were calculated for 50 GFP-positive and 50 GFP-negative cells (control). Results are expressed as a percentage of control GFP-negative cells. One experiment is shown. (C-D) RAW264.7 macrophages transiently expressing GFP or Nef-GFP or the indicated mutants were allowed to phagocytose IgG-RBCs, C3bi-RBCs, or Cy3-zymosans for 60 minutes at 37°C. The samples were processed as in Figure 1. The efficiencies of association (C) and phagocytosis (D) were calculated for 50 GFP-positive and 50 GFP-negative cells (control). Results are expressed as a percentage of control cells. The means ± SEM of at least 3 independent experiments are plotted.