FIG. 6.

Fusion of R5- and X4-tropic HIV to naïve cells is less efficient than that to memory resting CD4⁺ T cells. CD4⁺ T-cell and DC mixtures were spinoculated with either pNL-AD8 (R5 HIV) (B) or pNL4-3 (X4 HIV) (D) particles that carry BlaM-Vpr. After inoculation the cells were loaded with the dye CCF2-AM. Uninfected cells (A and C) loaded with CCF2-AM were used as a negative control for each inoculation. After infection of the cells with R5 HIV (B) or X4 HIV (D), naïve and memory resting CD4⁺ T cells were gated for cells that had taken up the green dye and fusion was measured based on the percentage of cells that fluoresced blue. Fusion was measured independently among the naïve (CD45RA⁺ CD62L⁺) and memory (CD45RA⁻ and/or CD62L⁻) subsets of resting CD4⁺ T cells (CD69, CD25, and HLA-DR negative). This experiment is representative of four.