FIG. 3.

Human and nonhuman primate CCR5 homologue proteins support membrane fusion. QT6 cells expressing the SIVmac Env 239.2 and SIVmac Env 316 proteins and T7 polymerase were mixed with QT6 cells expressing CD4, luciferase under the control of the T7 promoter, and the different primate CCR5 homologues. Cell-cell fusion was measured 8 to 10 h later by quantification of luciferase activity in relative light units. All results are the averages of at least three experiments with the different CCR5 homologues. Values are normalized to the luciferase activity for the M. fascicularis CCR5 homologue. Apes are highlighted in blue, Old World monkeys are highlighted in magenta, and New World monkeys are highlighted in green.