FIG 5.

Suppression of HIV-1 NL4-3 or NL4-3/VSV G by ectopically expressed MxB. (A, B) SupT1 cells that were stably transduced with a tetracycline-inducible MxB expression retroviral vector were treated with increasing doses of doxycycline (Dox), followed by challenge with NL4-3 (equivalent to 100 ng p24) or NL4-3/VSV G (equivalent to 10 ng p24) viruses. The levels of MxB and viral Gag/p24 proteins were measured by Western blotting, and representative blots from one of the three independent infection experiments are shown for NL4-3-infected cells (A) and for NL4-3/VSV G-infected cells (B). The p24 signals were quantified using ImageJ software and are presented with the value of p24 for NL4-3 in control cells (0 ng/ml doxycycline treatment) arbitrarily set as 100. (C) SupT1 cells were treated with 500 U/ml IFN-α2b for 16 h to induce the expression of endogenous MxB. The MxB-expressing SupT1 cell line was treated with different doses of doxycycline (in ng/ml) for 16 h. Cell lysates were examined by Western blotting using anti-MxB antibody. The levels of tubulin were also probed as the internal control. (D) The levels of viruses in the supernatants were determined by infecting TZM-bl indicator cells. The virus amount from the infection without doxycycline treatment was arbitrarily set as 1. The data shown are averages from three independent transfections. Error bars indicate standard deviations.