Figure 1

SAMHD1 restricts a variety of retroviruses through its RNase activity. a U937 cells stably expressing SAMHD1 mutants were differentiated with PMA. The cells were then pre-incubated with nevirapine for 24 h and then infected with HIV-1-GFP (60 ng of p24 per 6 × 10⁵ cells) for 2 h. The GFP-positive cells were examined by flow cytometry at 48 h post-infection. U937 cells pre-incubated with 10 μM nevirapine (NVP) for 24 h prior to HIV-1 transduction were used as a negative control. b PMA-treated U937 cells-expressing SAMHD1 mutants were infected with FIV-GFP at an MOI of 1. c SAMHD1 variants-expressing U937 cells were incubated in the presence of PMA and challenged with F-MLV-GFP at an MOI of 5. Reporter gene expression was analyzed by flow cytometry at 2 days post-infection. d PMA-treated U937 cells-expressing SAMHD1 mutants were differentiated with PMA and subsequently infected with EIAV-GFP at an MOI of 1. After 48 h, the infected cells were evaluated by flow cytometry. Values were normalized against the percentage of infected, mock-transfected cells. The data presented in a, b, c, and d are expressed as the mean ± SD of three independent experiments. *p < 0.05 and **p < 0.01 compared with the mock-transfected control (two-tailed Student’s t test).