CCR5 and infection: The selected cells expressed similar levels of CD4, CXCR4 and CCR5 on the cell surface and maintained a functional tat-inducible firefly luciferase and β-galactosidase reporter cassette like the parental TZM-bl cell line (data not shown), thus are suitable indicator cells to study the influence of human TRIM5α over expression on HIV envelope mediated infection.