As illustrated in Figure 2, the 2P23 gel exhibited no in vitro cytotoxicity to PBMCs, CEMss-CCR5, MT-4, or TZM-bl cells at concentrations as high as 6270 nM, which is approximately 1,126-fold higher than the IC50 of 2P23 for inhibiting HIV-1 infection, suggesting that the 2P23 gel has a good safety profile. Here, CCR5 is linked to HIV-1 infection.