However, as these multi-cycle infections could mask potential anti-HIV-1 genes acting early in the life cycle, we also conducted a single-cycle ISG screen using lab-adapted HIV-1 NHG (Fig 2F), which is an NL4.3-derived virus, that contains portions of the HxB envelope, and that encodes GFP in place of nef [51]. This evidence concerns the gene S100B and infection.