FIG. 3.

Fv1^b is functionally independent of TRIM5α in human cells. (A) TE671 and TE671 cells expressing Fv1^b (TEB) were infected with a lentiviral vector carrying an shRNA against TRIM5 (T5) or a control shRNA against RFP. Unmodified cells were also infected as a control (Ct). Seventy-two hours later, cells were challenged with serial dilutions of MLV-N (black bars), MLV-B (white bars), or EIAV (dotted bars), and infectious titers per milliter are plotted. Errors are standard errors of the means. (B) TE671 (circles) and TEB cells (triangles) were infected with serial dilutions of MLV-N GFP in the absence (hollow symbols) or presence (filled symbols) of 2 μM arsenic trioxide (As₂O₃). Permissivity was measured 48 h after by FACS. (C) Saturation experiment. TE671 (circles) and TEB cells (triangles) were coinfected with a fixed dose of MLV-N encoding GFP and serial dilutions of EIAV VLPs. VLP dose (in nanograms of reverse transcriptase [RT]) (x axis) is plotted against the fold increase in MLV-N GFP infectivity (y axis). (D and E) The TRIM5δ splice variant was expressed in TE671 (D) and TEB cells (E) using a retroviral vector delivery system. Seventy-two hours later, cells were challenged with MLV-N or MLV-B encoding GFP. MLV-N and MLV-B infectivity on unmodified cells is also shown as a control. Infected cells were enumerated 48 h later by FACS. Results are representative of at least two independent experiments performed with two independent preparations of virus. i.u., infectious units. SSC, side scatter.