CCR5 and infection: NL4-3-derived virus clones pseudotyped with some of the different full-length (gp160) Envs used above, or gp160 from the JR-FL or JR-CSF strains, were investigated for their sensitivity to inhibition by the mAbs 2D7, 45531 or CTC5 in single-round infection assays of U87-CD4-CCR5 cells (S3E Fig).