Fig. 5.

Phenotypic coreceptor usage experiments for participant B using GHOST cells expressing a variety of alternative HIV-1 coreceptors. Cells were infected with pseudoviruses incorporating 2008 plasma RNA full-length population envelope sequences. Low but reproducible levels of entry as determined by luciferase activity were observed in cell lines expressing CXCR6, and to a lesser extent GPR15 and CCR1. No entry was observed in cells expressing CXCR4 as demonstrated in the prior coreceptor usage experiments, but a strong signal was observed in cells expressing CCR5. Pseudoviruses incorporating envelope from a known X4 viral clone (pNL4-3) was used as a control in parallel experiments, and was able to use CXCR4 for entry as shown in the right panel. Error bars represent standard error measurement from duplicate experiments. Luciferase activity from X4 control pseudoviruses in the CD4 parental cell line was intermittently detectable at low levels, suggesting the possibility of endogenous coreceptor expression in the parental cell line.