Restriction of HIV-1 expressing vif fromSIVmac in CEM.NKR cells. A) SIVmac vif effectively neutralized human APOBEC3 proteins in single cycle HIV-1 replication assay. Proviral constructs pNL-ΔVif, pNL-hVif, or pNL-macVif were co-transfected with pcDNA3.1 (Ctrl), pcDNA-A3G, pcDNA-A3B or VR-A3H into 293T cells at 1:1 ratio. After normalized by p24Gag, equal amounts of viruses were used to infect TZM-BI cells, and viral infectivity was determined by measuring cellular luciferase activity 24 hours postinfection. Results were shown as relative values, where the infectivity of viruses produced in the presence of pcDNA3.1 was set as 100. B) Replication of HIV-1 expressing vif from SIVmac in different human T cell lines. A total of 2 × 105 cells from indicated cell lines were infected with 150 ng p24Gag of HIV-1 from pNL-macVif, and viral replications were determined for 16 days.