CD4 and infection: As shown in Figure5B, D1D2 at the concentrations from 5 to 200 nM significantly enhanced the infection of the virus in the CD4-/CCR5+ cells, while 2DLT and T1144 at the same concentrations showed no enhancement of HIV-1 infection, suggesting that 2DLT exhibits no enhancing effect on HIV-1 infectivity in CD4-/CCR5+ cells.