Since CCL3L1 encodes the natural ligand of CCR5 and increasing copy number of CCL3L1 down-regulates the expression of CCR5 on the cell surface [10], the HIV-1 entry-dependent effect of CCL3L1 on CCR5 used to be accepted as the major mechanism that inhibiting HIV-1 infection. This evidence concerns the gene CCR5 and HIV-1 infection.