coated with poly-L-Lysine. Cells were transfected using the calcium phosphate protocol described above; 48 h post-transfec- tion, cells were washed twice with PBS, fixed in 4% paraformal- dehyde (PFA) at room temperature for 20 min, and washed four times with PBS. Cells were incubated for 30 min with blocking/ permeabilization buffer (1% bovine serum albumin (BSA), 0.1% Triton X-100, and 10% human heat inactivated serum (HHIS)). After four additional washes with PBS, cells were stained with the anti-p24 183-H12-5C antibody. Following washes with PBS, cells were incubated with an Alexa 488-conjugated goat anti-mouse secondary antibody (Invitrogen, Burlington, Canada) and, finally, the nuclei were stained with 49,6-diamidino-2-phenylindole (DAPI) provided by Invitrogen (Burlington, Canada). After several washes, slides were mounted in Fluoromount G (Invitrogen, Burlington, Canada). The samples were visualized using a Nikon eclipse TE 300 inverted microscope at a 1000X magnification. 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