FIG. 4.
HIV-VM env-mediated fusion and functional activity for binding and entry into cells expressing the chemokine receptors. env regions from HIV-VH, after extraction of DNA from PBMCs, were cloned into HIV-IIIB (1c/IIIB, 3c/IIIB, and 5a/IIIB) and HIV-JRFL (3i/JR), and they were tested for functional activity by measuring their ability to utilize a panel of chemokine receptors (CCR5, CCR3, CCR2b, CXCR4, ChemR1, GPR15, US28, and the parental CD4 expressing cells) in a luciferase reporter virus infection assay, as previously described (16). Further details can be found in Materials and Methods. Infection of target cells by pseudotyped virus leads to expression of luciferase, which was quantified in cell lysates 2 to 3 days after the addition of virus.