Fig. 3.

Sensitivity of XMRV to human and monkey tetherins. (A) 293T cells were transiently transfected with XMRV proviral DNA in combination with a retroviral vector that encodes an eGFP reporter, increasing plasmid doses of a human, Rhesus, and AGM tetherin-expression vector, and either empty vector or HIV-1 Vpu. Viral supernatants were harvested 48 h posttransfection and used to infect 293T cells. After 24 h, the number of GFP-positive cells was analyzed by flow cytometry. (B and C) HeLa cells that constitutively express human tetherin were transfected with XMRV/CNCG, HIV-1 NL4.3 (HIV-1wt), or a Vpu-defective HIV-1 NL4.3 (HIV-1Vpu-) with or without Vpu or XMRV env expression in trans, as indicated. Forty-eight hours posttransfection, the viral supernatants were harvested and processed as in A.