Fig. 3C shows that although all these cells exhibit similar relative luciferase activity (RLA) when infected with 10A1 and HIV-1 X4-tropic pDOL pseudotype viruses, significantly lower RLA was observed in the CCR5-/CR1, CCR5-/CR2 and CCR5-/CR3 mutant cells than in mock-transduced TZM.bl cells after infection with the four different R5-tropic Env pseudotyped viruses. The gene discussed is CCR5; the disease is infection.