A second estimate, based on immunofluorescent detection of HIV-1 Gag expressed in 293T/ACE2(B) cells following infection with the HIV-1NLΔEnv-NanoLuc/SARS-CoV-2 pseudotype (Fig. S2 D), suggested that single infected cells generate ∼5 × 103 RLUs. Here, ACE2 is linked to infection.