Recombinant HIV-1 viruses that express the luciferase reporter gene were generated by transfection of 293T cells using the calcium phosphate transfection method (Promega). Cells were seeded in 100-mm tissue culture dishes (approximately 46106 cells per dish) and transfected the next day with 10 mg of the HIV-1 packaging construct pCMVDP1DenvpA [50], 10 mg of the firefly luciferase-expressing const