FIG. 4.

Analysis of HIV-1 infection in the presence of SDF-1 in various cell lines. HeLa CD4 cells (clone P4), U937 and HL60 monocytic cells, and CEMX174 and Jurkat lymphoid cell lines were infected with the HIV-GFP defective virus pseudotyped with the VSV-G envelope, which contains, in place of nef, the gene coding for GFP. Following integration and proviral expression, the cells synthetize GFP, which can be detected by flow cytometry. The cell lines were exposed to HIV-GFP(VSV) (100 ng of p24) with (+ SDF-1) or without (− SDF-1) SDF-1 (200 nM). After an overnight incubation, the cells were washed to remove unbound virus and further incubated with or without SDF-1 for 8 h. Infection was then revealed by flow cytometry analysis on gated living cells. The values are presented as two-color dot blots, with the green fluorescence (GFP) on the abscissa and the red fluorescence on the ordinate. The percentage of GFP⁺ cells is indicated in each panel. In the absence of viral infection, these percentages were <1% (not shown). The data are representative of three independent experiments.