SAMHD1 and HIV-1 infection: SAMHD1 is the only deoxynucleoside triphosphohydrolase (dNTPase) of mammalian cells to be a restriction factor against human immunodeficient virus type 1 (HIV-1) infection in resting CD4+ T cells and terminally differentiated immune cells, such as macrophages and dendritic cells [1–3].