Fig. 2.

ERT activity comparison of HIV-1 89.6 produced from macrophages treated with Vpx (−) and Vpx (+) virus like particles. a Comparison of cellular dATP concentrations among Vpx (−) virus like particles (VLPs) treated macrophages, Vpx (+) VLP treated macrophages, and activated CD4 + T cells. Human primary monocyte derived macrophages from 5 healthy donors were treated with Vpx (−) and Vpx (+) VLPs as well as without VLP treatment (NT) for 24 h, and cellular dNTPs were extracted from the cells for the RT-based dNTP assay. The dNTP concentrations were calculated based on their cell volumes. The dNTP concentration from activated CD4 + T cells were also determined, and the fold differences of the dNTP concentrations were calculated. Other three dNTP concentrations are shown in Additional file 1: Figure S1A. The VLP treatment and dNTP assay were conducted in triplicates. b Protocol for virus collection produced from macrophages for ERT assay. Human primary monocyte-derived macrophages were pre-treated with Vpx (−) and Vpx (+) VLPs for 24 h, and then infected with HIV-1 89.6 in triplicates. The remaining uninfected viruses were washed at 9 h post infection, and the viruses produced from these cells were collected for the ERT activity measurement at every 24 h for 4 days. The SAMHD1 degradation in these VLP treated macrophages were confirmed by western blots (Additional file 1: Figure S1B). c ERT activity of HIV-1 89.6 produced from macrophages treated with Vpx (−) (red line) and Vpx (+) (blue line) VLPs. ERT activity of the produced viruses were determined as described in Fig. 1. The ERT activity of HIV-1 89.6 from activated CD4 + T cells (black line) was used for the comparison. The data are the mean of three independent experiments with qPCR or dNTP assay performed in duplicate, and error bars represent the standard error of the mean. *P < 0.05; **P < 0.01; ***P < 0.001