All infant variants used CCR5 for entry, as determined from infection assays using pseudotyped HIV virions bearing the infant envelope sequences and TZM-bl cells in the presence of high TAK-779 concentrations, and/or from infection of GHOST cells co-expressing CD4 and either CCR5 or CXCR4 (data not shown). The gene discussed is CXCR4; the disease is infection.