Vpx-mediated SAMHD1 degradation in DCs efficiently increases HIV-1 infection and accumulation of late reverse-transcription products. Monocyte-derived DCs were transduced with SIV VLPs containing HIV-2 Vpx (Vpx +) or not (Vpx -). Mock transduction (no VLPs) was used as a negative control. (A) Whole cell lysates were subjected to immunoblotting for SAMHD1 at 24 hr post-transduction. β-actin was used as a loading control. Relative levels of SAMHD1 compared to β-actin are shown. (B) VLP-transduced DCs were infected with HIV-Luc/VSV-G at a multiplicity of infection (MOI) of 1 and the infection was detected by measuring luciferase activity in the cell lysates at the indicated times post-infection. Fold enhancement of HIV-1 infection (VLP without Vpx control set to 1) is shown. (C) HIV-1 early reverse-transcription products (early RT) in DCs transduced with VLPs. The early reverse-transcription copies were measured by qPCR at the indicated times post-HIV-1 infection (MOI of 1). (D) Increased HIV-1 late reverse-transcription products (late RT) in DCs transduced with VLPs. The late reverse-transcription copies were measured by qPCR at the indicated times post-HIV-1 infection (MOI of 1). (E and F) VLP-transduced DCs were infected with replication-competent, R5-tropic, HIV-1NLAD8 (MOI of 0.5). At 3 days post-infection, HIV-1 p24 in the supernatant was measured by ELISA. (F) Expression of SAMHD1, HIV-1 Gag (p55 and p24), and β-actin in NLAD8 HIV-1 infected DCs was detected by immunoblotting. The data shown represent one of three independent experiments. Error bars represent standard deviation of the mean of duplicate samples. (B, D, and E) The asterisks indicate a significant difference (p <0.05) compared with the controls of no VLP and/or (Vpx -).