Antiviral effect of gag or vif shRNAs against viruses from diverse clades. GFP-positive CD4⁺ T cells expressing luc, gag, or vif shRNAs were infected with primary viruses representative of multiple HIV clades and analyzed for intracellular p24 expression by flow cytometry 6 days later. (A) Representative histogram of CD4 cells transduced with indicated shRNA and infected with clade C, Indian virus IN17. (B) The reduction in p24 expression in HIV shRNA-transduced cells relative to luc shRNA-transduced cultures is graphed. Data represent means and SD of 3 independent experiments. The target sequences of the various viruses used are depicted in Table 3.