FIG. 6.

Evaluation of chimeric Env proteins in fusion assays. Chimeric Env proteins between HXBc2 and 8x shown in Fig. 5 were evaluated in fusion assays on QT6 target cells expressing CXCR4 alone, CXCR4 and CD4, or CD4 alone. Results are expressed as luciferase activity (RLU) relative to that of HXBc2 on CXCR4⁺ CD4⁺ cells. Bars indicate the mean RLU for at least five experiments + SEM.