Most HIV-2 Vpx proteins from controllers and non-controllers of virus replication degrade SAMHD1. (A) SAMHD1, ß-actin, eGFP control and Vpx-AU-1 levels in HeLa cells stable expressing Flag-SAMHD1 with pCGCG constructs expressing the indicated HIV-2 Vpx proteins, the control HIV-2 ROD or SIVmac239 Vpx alleles or only eGFP. Protein expression levels were determined by western blot two days post-transfection. (B) Average levels of SAMHD1 in the presence of the indicated HIV-2 Vpx proteins. The SAMHD1 signals were obtained by western blot analysis as described in panel A, quantified by Licor Odyssey software and normalized to the ß-actin signals. The graph shows mean values and standard deviation (SD) of normalized SAMHD1 expression levels from four independent experiments. HIV-2 vpx genes were grouped based on the viral loads of the patients and are color coded green (ECs) or red (NCs). (C) The levels of SAMHD1 expression were determined in stable transfected HeLa cells in the presence of vpx alleles from HIV-2-infected ECs and NCs and are shown relative to those measured in the absence of Vpx (100%).