Lentiviral delivery of shRNAs targeting viral genes inhibits HIV_IIIB replication. HeLa-CD4 cells stably expressing shRNAs targeting luc, gag, rev, or vif generated by sorting GFP-positive cells 3 to 5 days after lentiviral transduction were infected with HIV_IIIB and analyzed 5 days later. (A) The level of infection was determined by flow cytometry after staining for intracellular p24 expression. Numbers indicate percentage of cells in the respective quadrants. (B) The 9.3-kb HIV RNA was detected on Northern blots using a gag RNA probe.