CEM A3.01 cells are highly susceptible to HIV-1 infection unless protected by the therapeutic gene Chim3. (A) Kinetics of HIV-1 infection. Empty-LV– and Chim3-LV–transduced cells were infected with the NL4-3 HIV-1 at an MOI of 0.1. Virus production was measured on the culture supernatants by RT activity assay at the indicated time points. Values represent means ± SEM of n = 3. (B) Cell viability. The empty-LV– and Chim3-LV–transduced infected cells of panel A and uninfected cells were analyzed using forward scatter (FSC) and side scatter (SSC) profiles by FACS at the indicated time points. Values represent the percentage of alive cells on the total events acquired expressed as means ± SEM of n = 3. (C) CD4 expression. The level of CD4 receptor expression was measured by FACS in empty-LV– and Chim3-LV–transduced cells, either uninfected or infected at 2 time points of the cell culture. (D) Chim3-LV cells do not show clonal phenotype after HIV-1 infection. Southern blot analysis of gDNA isolated from 3 independent wells of empty-LV– and Chim3-LV–transduced cells of panel A after 28 days of infection. The filter was hybridized with a 1-kb fragment ΔLNGFR probe.