Effect of naturally occurring mutations in the NLS of HIV-2 Vpx proteins on SAMHD1 degradation and macrophage infection. (A) HeLa cells stably expressing FLAG tagged SAMHD1 were mock transfected or transfected with constructs expressing the indicated AU-1 tagged Vpx proteins for 48 h before whole-cell extraction and analysis by western blot using the indicated antibodies. (B) Quantitation of Vpx-mediated degradation of SAMHD1. Shown are the average levels and SEM of SAMHD1 expression in Hela cells in the presence of the indicated Vpx alleles. Results were derived from four independent experiments. (C) MDM isolated from four donors were transduced by VSV-G-pseudotyped SIVmac239 eGFP reporter viruses produced in the presence of the indicated Vpx proteins and GFP+ MDM were quantified four days later.