To determine whether the HIV-1 infection phenotype in CPSF6 knock-out cells is strain specific, we repeated our virus challenge experiments with the lab-adapted, CCR5-tropic HIV-1 JR-FL iGFP strain (Fig 3c) and the CCR5-tropic transmitted founder HIV-1 CH040 strain (Fig 3d). This evidence concerns the gene CPSF6 and HIV-1 infection.