Co-expression of Vif and APOBEC3G in HeLa cells. HeLa cells were transfected with pNL-A1 and pcDNA-APO3G at a 1:1 molar ratio. Transfected cells were grown on cover slips, fixed in methanol and processed for confocal microscopic analysis as described in Methods. Cells were stained with a rabbit polyclonal antibody to APOBEC3G (A & D) and a monoclonal Vif antibody (B & E). APOBEC3G was visualized using a Texas red-conjugated secondary antibody; Vif was visualized with a Cy2-conjugated secondary antibody. Panels C and F are merged images of panels A & B and D & E, respectively. Arrow heads are defined as follows: white = APOBEC3G:Vif-double-positive cells; yellow = Vif-negative cells; red = cells exhibiting nuclear and cytoplasmic staining for Vif.