FIG. 3.

Inhibition of HIV-1 replication by membrane-anchored T20. (A) PM-1 cells were transduced with different retroviral vectors encoding T20 and then selected with G418. These bulk cultures were infected with NL4–3 at a multiplicity of infection of 0.1. On day 5, medium was replaced and the concentration of p24 antigen was determined in supernatants collected on day 6. ∗, detection limit. (B) In parallel, the selected PM-1 cultures were infected with NL4–3AGFP and the spread of virus was monitored by flow cytometry. × M85; □ M86; ▴ M87; ○ MPIN. (C) Selected cultures were infected with NL4–3AGFP, and the spread of virus was monitored by flow cytometry. ▴ M87; ○ MPIN; □ M87m1; ▪ M87m2; □ M87m3. (D) Inhibition of a single round of infection by membrane-anchored T20. PM-1 transduced with the control vector MPIN or the vector M87 expressing the membrane-anchored T20 was infected with fivefold dilutions of a replication-deficient virus NL4–3env⁻GFP pseudotyped either with VSV G protein or an HIV-1 envelope glycoprotein from one of the HIV strains depicted (solid bars). Cells were also transduced with an MLV vector with EGFP as a marker gene pseudotyed with the envelope glycoprotein of HIV-1 strain BH10 (shaded bar). Titers of different pseudotypes were determined on day 3 by flow cytometry for each of the PM-1 cultures. Titers on PM-1/M87 relative to the titer on PM-1/MPN are given.