FIG. 2.

IFITM proteins inhibit HIV-1 replication in SupT1 cells. (A) Illustration of the domain structures of IFITM proteins. The transmembrane domains are highlighted in boxes. A Flag tag was attached to the N termini of IFITM proteins. The conserved amino acid residues are highlighted in red letters. (B) Doxycycline-induced expression of IFITM proteins in SupT1 cells. Stably transduced SupT1 cells were exposed to different amounts of doxycycline (0, 50, and 500 ng/ml) for 16 h before the cell lysates were harvested and subjected to Western blotting using anti-Flag antibodies to detect the expression of IFITM proteins. Control represents a cell line that was stably transduced with the empty retroviral vector. (C) HIV-1 replication in IFITM-expressing SupT1 cells. The cells were treated with doxycycline (Dox) (500 ng/ml) for 16 h before they were exposed to wild-type HIV-1. Virus production over different time intervals was monitored by measuring viral reverse transcriptase activity in the culture supernatants. The results shown represent four independent infection experiments.