CD4 and infection: Therefore, to directly and quantitatively test the impact of the distinct reporter genes in the context of the wild-type NL4-3 Env allele, dual-infection competitions between NL4-3-MSS-eGFP and NL4-3-MSS-DsRed2, along with parallel control mono-infections were set up on U87.CD4.CXCR4 cells at multiplicity of infection (MOI) of 0.01, 0.1, and 1.0.