Similar to that observed in TZM-bl cells and PHA/IL2 stimulated PBMC, titration of NL.LucR-Env.ecto viruses expressing Env proteins from subtype B HIV-1 (NL.LucR-SF162.ecto and NL.LucR-BaL.ecto) and CRF01_AE HIV-1 (NL.LucR-CM235.ecto), respectively, showed virus replication 1log10 over background at dilutions exceeding 1:1000 in the A3R5.6 line as measured by levels of virus-encoded LucR reporter gene expression 48 hours post infection (Figure 1B). Here, ERVW-1 is linked to infection.