FIG. 2.

HIV-1 internalization by oral epithelial cells. (A) Attachment and uptake of HIV-1 Gag-GFP virus-like particles (VLP) by oral epithelial cells is temperature and time dependent. TERT-2 cells were incubated with HIV-1 Gag-GFP VLPs (200 VLPs per cell) for the indicated times at 4°C or 37°C before washing and fixation. Cells with green fluorescent particles localized within the plasma membrane (cell-associated) were counted under a fluorescent microscope. Data shown represent the means from two duplicate experiments (error bars indicate range). At 4°C, the range was less than the radius of the symbol for each point. (B) Oral epithelial cells internalize infectious HIV-1 in the presence of saliva. TERT-2 cells were incubated with BaL (0.4–0.1 TCID₅₀/cell) and HIV-1 IIIb (0.4 and 0.1 TCID₅₀/cell) for 6 h with and without clarified whole saliva at a final concentration of 50% as described in the text. At 6 h, cells were washed, trypsinized, and washed again to remove noninternalized virus. Detached TERT-2 cells were cocultured with the TZM-bl reporter cells for 18 h. Transferred infectious virus is expressed as the number of positive TZM-bl foci compared to control (infectious virus without saliva at an MOI of 0.1). Data shown are the mean±SE for three independent replicate experiments.