CD4+ T cell depletion and viral replication in HIV-1 wt- and Δ nef -infected cultures of human tonsil tissue ex vivo. HLACs were infected in quadruplicates with equal amounts (3 ng p24) of HIV-1 wt and Δnef. Results for one such quadruplicate are shown in A and C, B and D depict mean values and SD of quadruplicate infections analyzed in parallel. (A) HLACs were stained on day 12 p.i. for CD3 and CD8 and analyzed in flow cytometry to assess numbers of CD4+ and CD8+ T cells. (B) CD4/CD8 ratios of infected cultures were calculated, and the percentage of CD4 T lymphocyte depletion was plotted relative to mock-infected cultures that were arbitrarily set to 0%. (C) Concentration of p24 in the culture medium over time as determined by p24 ELISA at the indicated time points. (D) p24 production over the culture period (area under the curve, AUC) of the graphs shown in C. Shown is the mean and standard deviation of all quadruplicates.