To further characterize at which step of infection CE inhibited HIV-1, multi-dosing time assay experiments were performed with U373-CD4-CXCR4/CCR5 cells against infection of pseudotyped virus pNL4.3ΔEnvLuc-HXB2 and pNL4.3ΔEnvLuc-BAL.Pseudotyped viruses pNL4.3ΔEnvLuc-HXB2/BAL are only able for one cycle of viral infection and allow us to assess the infection level by measuring the luciferase value in the cell supernatant. Here, CXCR4 is linked to infection.