FIG. 1.

Kinetic analysis of HIV-1 restriction by TRIM-CypA. (A) Experimental strategy. HXB-enveloped HIV-1 particles were bound to OMK-CD4/CXCR4 cells, and infection was initiated by a temperature shift. Infection events were quantitated 48 h after the temperature shift by enumerating GFP-positive cells using fluorescence-activated cell sorter analysis. The time taken to acquire resistance to subsequently applied inhibitors of entry and reverse transcription and the opposing effects of CsA application and removal were measured. (B) Quantitation of infection events (percent GFP-positive cells at 48 h after the temperature shift) following timed addition of an entry inhibitor, dextran sulfate (Dex S) or UC781, a nonnucleoside reverse transcriptase (RT) inhibitor (dashed lines). Addition of either inhibitor at the time of the temperature shift (0 h) reduced infection to undetectable levels (>1,000-fold). Alternatively, TRIM-CypA restriction was activated or inhibited by the withdrawal or addition of CsA (solid lines). (C) A portion of the data in panel B is shown, except that only early time points are plotted on an expanded time axis and infection events are plotted on a linear scale as a percentage of their maximum uninhibited level.