FIG. 3.

Localization of HIV IC in B-cell cultures. Tonsil B cells were incubated for 2 h at 4°C with HIV IC, which were prepared by preincubation of PI 1 with matched autologous serum and complement (see details in Fig. 1 legend). Cells were washed and cultured for 72 h in complete medium in 24-well plates (2 × 10⁶ cells/ml). At 0, 15, 24, 48, and 72 h, cells were washed and lysed with 0.5% Triton X-100 and the amount of cell-associated virus was determined by p24 ELISA. The total amount of virus released was also measured in the supernatant after treatment with 0.5% Triton X-100. The amount of intact released virus in a supernatant was calculated by subtracting the free p24 measured in the absence of detergent from the total amount of released p24. Some aliquots of B cells were treated with proteinase K (1.0 μg/ml; Sigma) in serum-free medium for 10 min before the cells were washed and lysed with 0.5% Triton X-100 to assess the amount of protease-resistant p24 associated with B cells. The means of results from three experiments ± the standard errors of the means are shown.