We show that Ghost X4 cells modified with #6 or #7 gRNA/Cas9 lentivirus were negative for GFP expression compared to control cells (Fig. 3a), indicating that CRISPR/Cas9-mediated genome editing of CXCR4 protects Ghost X4 cells from HIV-1 infection. This evidence concerns the gene CXCR4 and HIV-1 infection.