Restriction of HIV-1 by common human TRIM5α variants. HeLa cells were stably transduced by oncoretroviral vectors expressing the Rhesus (Rh) TRIM5α, the common huTRIM5α and its variants, separately or in a hypothetical four-mutation protein. Panel A: Single-cycle infectivity assays used VSV-pseudotyped recombinant viruses (HIV.1-GFP) at various m.o.i. After 48 h, cells were analysed by fluorescence-activated cell sorter, and scored for number of GFP-positive cells. Panel B: Expression of HA-tagged TRIM5α proteins was determined by western blotting using an anti-HA antibody. Tubulin was detected with the anti-α tubulin antibody. Control: HeLa cells transduced with an empty oncoretroviral vector.